Welcome to the deep dive. Today, we're setting
course for a really fascinating area in surgery.
The shoulder. Not just any shoulder surgery,
though. We're going to, well, dig into a procedure
that fundamentally flips the script on how we
think about shoulder replacements, reverse shoulder
arthroclasty. Hello? Yes, this procedure is quite
the game changer for patients with specific,
very challenging shoulder problems where, frankly,
traditional approaches just wouldn't work. It's
really about rebuilding function when the body's
natural design has failed in a critical way.
Exactly. And to navigate this complex terrain,
we've pulled together insights from some really
solid sources, the bone school, orthobullets,
and stat pearls. They give us a fantastic blend
of, well, technical precision and clinical application?
Yes. These sources really lay out the biomechanical
rationale, the specific conditions where this
procedure is indicated, the intricate surgical
steps involved, and crucially, what the outcomes
and potential challenges are. It's a pretty complete
picture of a powerful tool in orthopedics. Our
mission today, then, is to take all of that detailed
material and distill it down for you. We want
you to walk away understanding what makes this
procedure reverse, why that reversal unlocks
movement, who benefits most from it, what actually
happens during the surgery, and what recovery
and life afterward look like, including the successes
we see and the hurdles that can arise. It's a
procedure really born out of necessity. leveraging
engineering principles to overcome quite severe
biological limitations, particularly the loss
of a functional rotator cuff. Okay, let's unpack
this then. Let's start with that core concept.
What does it actually mean to reverse the shoulder
joint? At its most fundamental level, reverse
shoulder arthroplasty, or RTSA as it's often
called, maybe RSA sometimes, it's a total shoulder
replacement where the normal ball and socket
anatomy is completely swapped. Right, because
in a healthy shoulder, or even a standard anatomical
total shoulder arthroplasty, an ATSA, the setup
is pretty intuitive, isn't it? Precisely. In
an anatomical shoulder, you have the glenoid,
that's the socket on the shoulder blade, which
is concave, and the humeral head, the top of
the arm bone, which is convex, you know, ball
-shaped. An ATSA mimics this, putting a plastic
socket on the glenoid and a metal ball on the
humerus. It replaces worn surfaces, but keeps
the original design, essentially. So the reverse
procedure literally puts the ball where the socket
should be and the socket where the ball should
be. Is it that straightforward? That's spot on,
yes. In RTSA, a convex component, a metal sphere
called a glenosphere, is fixed to the glenoid
side, so onto the shoulder blade. And a concave
plastic component, the humeral cup or liner,
is attached to a stem placed down inside the
humerus, the arm bone. So yes, the ball is on
the scapula and the socket is on the arm bone.
Okay, that's a clear structural difference. But
this isn't just cosmetic, it's all about function,
isn't it? Why does flipping the anatomy actually
work? This is where it gets really interesting,
I think. This is the genius behind the design,
really. And it's all about fundamental biomechanics.
The absolute key change in RTSA is the shift
in the center of rotation of the shoulder joint.
Shifting the center of rotation like relocating
the joints pivot point. Exactly that. In the
natural shoulder, the center of rotation is effectively
within the humeral head itself. In RTSA, that
center of rotation is deliberately moved. It's
moved merrily, so downwards, and medialized,
meaning closer towards the midline of the body.
Okay. And how does moving that pivot point enable
movement, especially when you've got a damaged
rotator cuff? Well, this is the crucial insight.
By shifting the center of rotation down and in,
something profound happens to the deltoid muscle,
the deltoid, that large muscle covering the outside
of your shoulder. It now acts on a significantly
longer lever arm relative to this new center
of rotation. Ah, right, like getting a longer
handle on a wrench. More power with the same
effort. Precisely. That's a great analogy. This
increased mechanical advantage means the deltoid
muscle can now perform the functions that the
damaged or irreparable rotator cuff simply can
no longer do. The rotator cuff is essential for
initiating and controlling abduction, lifting
the arm away from the body. When it's gone, you
often can't do that. The RTSA allows the deltoid,
with its newfound mechanical advantage, to become
the primary muscle capable of lifting the arm.
So the deltoid essentially takes over the job
the rotator cuff couldn't do anymore? It does,
yes. And furthermore, the geometry of the implant,
with the humeral component sitting below the
glenosphere, results in a slight downward displacement
of the humerus relative to the shoulder blade.
This actually increases the resting tension in
the deltoid muscle fibers, which further enhances
its ability to function effectively. Okay, so
increased leverage and increased muscle tension.
Yes, and there's more. The design also changes
how forces are transmitted across the joint.
The natural shoulder, and even an anatomical
replacement, relies on muscle forces for compression
and stability, but it also experiences significant
shear forces during certain movements. The RTSA
design converts those shear forces, which can
be destabilizing in a cuff -deficient shoulder,
into more compressive forces, and compression
inherently helps stabilize the joint. So you
gain leverage, increased muscle tension, and
improve stability through forced conversion.
That's quite a combination. It is. It's a multi
-pronged biomechanical solution. Additionally,
the larger, more constrained articulation between
the glenosphere and the humeral cup increases
the overall contact surface area, which further
contributes to joint stability. And the design
also helps to, well, neutralize the deltoid's
tendency to pull the humeral head upwards. Ah,
that superior escape issue. Exactly. In a cuff
-deficient shoulder, without the rotator cuff
holding the head down, the deltoid can cause
the humeral head to migrate superiorly and impinge
against the acromion, sometimes called superior
escape, or the rocking horse phenomenon. The
RTSA prevents this upward translation, keeping
the joint centered and stable during movement.
It's really remarkable how altering the structure
completely changes which muscles can function
and how forces are managed. This design was truly
engineered to solve a specific biomechanical
failure. What's the story behind this development?
When did this come about? Well, the initial concept
was actually described quite a while ago back
in the 1970s by Beto and Alloy, though their
outcomes weren't widely reported at the time.
The real pioneer who brought this concept to
clinical fruition was Paul Gramet in France.
He reported his first cases in 1987 with what
was called the Trompet prototype. Trompet, a
very distinctive name. It was, yes. Gramet's
key contribution was the concept of medialization,
shifting that center of rotation closer to the
body, which we just discussed. This idea emerged
from his work in the early 1980s. A second generation
of the Gramet prosthesis was developed in 1991,
featuring a larger glenoid hemisphere, and quite
specifically, a 155 -degree neck shaft angle
on the humeral component. And when did it become
available more widely? I assume it took time
to cross the pond? It did. It gained popularity
in Europe first, before being introduced in the
USA in 1998. Since then, designs have continued
to evolve, naturally. Newer systems often feature
smaller neck shaft angles, perhaps 135 or 145
degrees. Was changing that angle a response to
issues with the earlier 155 degree design? Precisely.
While the 155 degree angle was very effective
for achieving the medialization and the lever
arm effect, it became strongly associated with
a specific complication, scapular notching. That's
where on the bone of the shoulder blade, just
below the implant. Newer designs aim to reduce
this notching and potential impingement while
retaining the essential biomechanical benefits
by adjusting the angles and incorporating other
design features like lateralization or eccentricity
of the components. Okay, so what does this whole
evolution and these mechanics tell us, fundamentally?
It tells us that RTSA is a sophisticated, tailored
solution. It's not a standard replacement. It's
a procedure specifically designed to restore
the ability to lift the arm by dramatically altering
the joint's mechanics. It enables the deltoid
muscle to substitute for a non -functional rotator
cuff. This addresses a problem that traditional
anatomical replacements simply cannot fix effectively.
Fascinating. It's really about working with the
remaining muscle power by changing the leverage.
Given its unique mechanics, then, this procedure
can't be used for every shoulder problem, right?
What are the specific conditions or indications
where reverse shoulder arthroplasty is actually
the appropriate choice? That's a critical point,
absolutely. RTSA is indicated for specific clinical
scenarios where the conventional ball and socket
mechanics have failed or are predicted to fail.
The primary most common indication is something
called rotator cuff tear arthropathy. And you
mentioned before that this isn't just a simple
tear, is it? It's the combination of problems.
Exactly. Rotator cuff tear arthropathy is a severe
type of glenohumeral arthritis, so wear and tear
in the joint, that develops specifically because
of the massive, irreparable tear of the rotator
cuff. Without the cuff to dynamically center
the humeral head on the glenoid during movement,
the head drifts upwards, superiorly. This superior
migration leads to abnormal contact and wear
between the humeral head and the acromime bone
above it, causing significant joint destruction
and pain, alongside a loss of function from the
torn cuff itself. And this often leads to something
called pseudoparalysis. What exactly is that?
It does, yes. Pseudoparalysis is a key clinical
sign of severe rotator cuff deficiency, often
seen in cuff care arthropathy. It's the inability
to actively lift or elevate the arm, despite
having normal or perhaps near normal passive
range of motion when someone else moves your
arm for you. It's not due to a nerve problem,
that's the key thing. It's because the mechanical
link needed for the deltoid to elevate the arm
is essentially broken by the lack of a functional
rotator cuff and that superior migration of the
humeral head. Sometimes this is termed an incompetent
coracromial arch. You might even see the humeral
head sitting visibly higher under the skin in
severe cases. So RTSA is specifically designed
for this scenario where the rotator cuff is beyond
repair and the joint is arthritic and unstable,
often with that inability to lift the arm. What
other situations call for this reverse approach?
Well, another significant indication, particularly
in older adults, is complex fractures of the
proximal humerus that's the top part of the arm
bone near the shoulder joint. We're talking about
acute three - or four -part fractures, especially
in patients typically over 70 years old, or perhaps
those with complex head -splitting fracture patterns.
In these cases, the bone quality is often poor,
and the fragments where the rotator cuff attaches
to tuberosities are severely damaged, making
it very difficult or sometimes impossible to
successfully repair the bone and restore rotator
cuff function. An RTSA can provide a more reliable
way to restore some functional elevation compared
to trying to fix shattered bone or performing
a hemiarthroplasty where the cuff will likely
fail anyway. That makes sense if the foundation
you'd normally attach the cuff tendons to is
destroyed, you need a different kind of anchor
point and mechanism. Exactly. RTSA is also often
a go -to procedure for revision shoulder arthroplasty.
That's when a previous shoulder replacement,
either an anatomical TSA or a hemiarthroplasty
has failed. Failure can happen for various reasons,
but often it's due to subsequent rotator cuff
failure after an ATSA, or maybe ongoing pain
and poor function after a hemiarthroplasty, especially
if the cuff wasn't functional to begin with or
subsequently failed. So it's the salvage option
when the first replacement didn't work out, particularly
if the cuff is now involved. Correct. Other indications
mentioned include post -traumatic glenohumeral
arthritis, so arthritis developing years after
a significant shoulder injury, and also chronic
irreducible shoulder dislocations where the shoulder
has been dislocated for a long time and simply
cannot be put back into place non -surgically.
And what about inflammatory conditions like rheumatoid
arthritis? Can RTSA help there? It can be an
option in inflammatory arthritis like RA, yes,
but there's a very important caveat mentioned
in the sources. The patient must have sufficient
glenoid bone stock. Rheumatoid arthritis can
cause significant bone erosion, and you absolutely
need a solid base of bone on the shoulder blade
to securely fix the RTSA glenoid component. Without
good bone, it's likely to fail. That brings us
back to the importance of bone quality, which
was also key in the fracture scenario, wasn't
it? Indeed. We also sometimes see RTSA used for
conditions considered sort of rotator cuff insufficiency
equivalence. This could be something like a nonunion
or malunion of the greater tuberosity after a
fracture, where the bones the rotator cuff attaches
to haven't healed properly. This effectively
renders the cuff nonfunctional, despite the muscle
itself potentially being intact. You mentioned
a slight question mark indication earlier in
the outline, something debated. Yes. Some sources
discuss RTSA as an option, although it remains,
well, debated and requires careful comparison
to ATSA for patients over 70 who have glenohumeral
osteoarthritis but actually have an intact rotator
cuff. While ATSA is the traditional choice here,
some surgeons consider RTSA, particularly if
there are concerns about significant glenoid
wear or perhaps other factors. Research, like
the systematic reviews we'll discuss later, is
helping to clarify the trade -offs and outcomes
and complication profiles between the two procedures
in this specific older intact cuff population.
Okay, so it sounds like the ideal RTSA candidate
generally is an older patient with significant
pain and loss of function, often due to a non
-functional rotator cuff, but importantly with
enough bone quality and a working deltoid muscle.
That's a very good summary of the typical patient
profile. Key characteristics often include lower
functional demand. They're usually not looking
to return to high -level sports, for example,
a physiological age, often over 70, adequate
bone density on the glenoid side, and crucially,
as you say, an intact functional deltoid muscle
and a working axillary nerve to power it. Without
a functioning deltoid, the core mechanism of
RTSA simply doesn't work. That makes perfect
sense. The deltoid is the engine, really, which
brings us neatly to the flip side. When should
reverse shoulder arthroplasty absolutely not
be done? What are the contraindications? Right,
the contraindications are situations where the
procedure either won't work biomechanically or
carries an unacceptably high risk of failure
or harm. The most absolute contraindication is
significant axillary nerve dysfunction resulting
in a non -functional deltoid muscle. If that
nerve is permanently damaged, the deltoid won't
fire and the RPSA relies on it completely. It's
very important during assessment to distinguish
between temporary nerve stunning, maybe from
an injury, and permanent damage. Right. You need
to be sure the nerve isn't just temporarily bruised
or stretched. Exactly. And relatedly, global
deltoid deficiency is a contraindication. If
the entire deltoid muscle is absent or severely
atrophied, perhaps from previous surgery or injury,
there's no muscle to drive the reverse mechanics.
Partial delta deficiency might be considered
a relative contraindication, meaning it's not
an absolute no, but the functional outcome might
be compromised, and the patient needs to understand
that. Are there structural issues, bone problems,
that make it impossible? Yes. Significant acromion
deficiency is a contraindication. The acromion
provides important bony coverage and stability,
and if it's severely deficient, the biomechanics
and stability of the reverse construct are compromised.
Severe deficiency in glenoid bone stock, or very
poor bone quality due to conditions like severe
osteoporosis, can also contraindicate the surgery
as you need that stable base for the glenoid
component that won't loosen over time. Okay.
And infection. Active infection anywhere in or
near the shoulder joint is an absolute contraindication.
You can never put a large form body, like an
implant, into an infected field. The infection
must be completely eradicated first, often requiring
a staged surgical approach with antibiotics.
And what about age on the younger side? Skeletal
immaturity is a contraindication because the
bones are still growing and developing. Finally,
any severe neuromuscular disorder that would
significantly increase the risk of the prosthesis
dislocating or severely impair the patient's
ability to participate in rehabilitation would
also generally contra -indicate the procedure,
as maintaining stability and achieving function
post -operatively is paramount. This clearly
shows that patient selection is incredibly important.
It's not a procedure for everyone. Given these
specific requirements, the need for a functioning
deltoid, good bone. How do surgeons actually
make this decision and what rigorous preparation
is needed before a patient heads into the operating
theater? Patient selection and meticulous preoperative
planning are absolutely crucial for a successful
RTSA. It's definitely not a surgery to be taken
lightly and the work begins long before the patient
arrives in the operating room. So it starts with
that detailed history and clinical exam we touched
on really understanding the patient. Precisely.
A comprehensive patient history is vital understanding
their overall health, any medical conditions,
comorbidities like diabetes, heart disease, obesity,
smoking status, medications they're taking, and
importantly, their functional goals and expectations
for the surgery. Optimizing these medical conditions
before surgery is necessary to minimize risks.
The physical examination is equally thorough.
assessing both active and passive range of motion,
specifically testing the strength and function
of the deltoid and any remaining rotator cuff
muscles, and confirming axillary nerve integrity.
You also carefully check the skin condition around
the shoulder and the neurovascular status of
the entire limb. Sometimes an examination under
anesthesia is performed just before the surgery
starts to get a truly relaxed assessment of passive
motion and soft tissue tension. Imaging must
be absolutely key, then, to understand the underlying
bone and soft tissue issues in detail. It is
fundamental, yes. Standard shoulder x -rays are
the foundation. True AP or grassy views, axillary
laterals, and scapular Y views. These are used
for a nickel assessment, seeing the degree of
arthritis, confirming that telltale superior
migration of the humerus and cuff tear arthropathy,
assessing for posterior glenoid wear, identifying
any bony lesions, and getting a general sense
of bone quality. They're also used for initial
templating, which is estimating the likely implant
size needed. And what additional detail does
a CT scan provide that x -rays don't? A CT scan
is very often necessary, particularly if standard
x -rays don't provide enough clarity or if there
are complex bone defects or fractures suspected.
CT gives a much more detailed three -dimensional
picture of the bony stock on both the humerus
and, critically, the glenoid. It's essential
for accurately measuring glenoid version that's
the tilt or angle of the socket relative to the
scapula blade and assessing the degree of osteopenia
or bone loss. Preoperative 3D CT reconstructions
are becoming increasingly valuable, almost standard
of care in complex cases, because they allow
for precise 3D planning. This helps determine
the optimal proximal humeral retroversion for
implant placement and, critically, allows for
a detailed 3D assessment of any glenoid bone
defects. This guides accurate baseplate positioning
and sometimes even facilitates the design of
patient -specific instruments or bone graphs.
So 3D imaging allows for almost a virtual rehearsal,
letting the surgeon plan how to tackle tricky
bone situations beforehand. Exactly. It allows
the surgeon to anticipate challenges, plan the
correction of deformities, and tailor the implant
placement specifically to the patient's unique
bone structure. This is crucial for achieving
long -term stability and reducing complications
like component loosening or scapular notching.
An MRI scan might also be part of the planning
process. It's primarily used to assess the status
of the remaining rotator cuff tendons and look
for fatty infiltration within the muscles before
surgery. This helps confirm the diagnosis of
an irreparable cuff tear or assess the quality
of any residual muscle tissue that might contribute
to function or need to be protected during the
surgery. So you combine the clinical picture,
the detailed imaging, ensure the patient is medically
fit, check relevant blood tests perhaps to rule
out underlying infection, and manage any medications
like blood thinners. It sounds like a lot of
pieces have to align perfectly before the surgery
itself can proceed. It is a significant amount
of preparation, yes. This meticulous preoperative
phase is fundamental to choosing the right patient,
selecting the appropriate implant components
and sizes, anticipating potential intraoperative
challenges like managing bone defects, and ultimately
maximizing the likelihood of a successful outcome
with restored function and minimal complications.
With that comprehensive planning complete, the
next stage is, of course, the procedure itself.
Right, let's walk through the surgery then. What
position is the patient in and how is the anesthesia
typically managed for this? Okay, so patients
undergoing RTSA are typically placed in what's
called the beach chair position. This is where
the patient is essentially semi -sitting with
their chest tilted up often to about 60 degrees.
The operative shoulder needs to be positioned
right at the edge of the operating table. This
allows the surgeon maximum flexibility and access,
particularly enabling the arm to be extended
backwards during specific parts of the procedure
for optimal exposure of the joint. And anesthesia.
Anesthesia usually involves general anesthesia,
often supplemented with a regional nerve block,
such as an interscaling brachial plexus block.
This provides excellent pain control both during
and immediately after the surgery. Prophylactic
intravenous antibiotics are given just before
the skin incision to reduce the risk of surgical
site infection, and sometimes tranexamic acid
is administered intravenously to help minimize
blood loss during the operation. And before the
actual incision, is there a final check or assessment?
Yes, frequently an examination under anesthesia
is performed, as I mentioned briefly before.
This allows the surgeon to accurately assess
the true passive range of motion and the tension
in the surrounding soft tissues without the patient
experiencing any pain or involuntary muscle guarding.
This information can be valuable in confirming
the preoperative plan and informing decisions
about the extent of capsule release needed during
the procedure to achieve good motion. Okay. Now,
for actually accessing the joint, the sources
mention two main surgical approaches. What are
they, and how does the surgeon typically choose
between them? That's right. The two primary approaches
described are the delta -pectoral approach and
the anterosuperior approach. The choice often
depends on several factors, including the specific
pathology being treated, like fracture versus
arthritis, whether the patient has had previous
surgery, the surgeon's own experience and preference,
and sometimes specific patient factors. Let's
start with the delta pictorial approach, which
the sources described as the most common one
used. Yes. The delta pictorial approach utilizes
an incision that follows the natural groove between
the delcoid muscle laterally and the pectoralis
major muscle medially on the front of the shoulder.
It's developed through what's called an inner
nervous plane, which means you're essentially
working between the territory supplied by the
axillary nerve to the deltoid and the pectoral
nerves to the pec major, aiming to minimize muscle
damage. You carefully identify and protect the
cephalic vein, usually moving it laterally out
of the way. You then identify and gently retract
the conjoined tendon that's the common tendon
of the short head of the biceps and the corcobrachialis
muscle medially, being very careful to protect
the muscular cutaneous nerve which runs nearer
through it. The clavpectoral fascia overlying
this is incised and then the subscapularis muscle,
the most anterior rotator cuff muscle, is accessed.
To expose the joint fully, the subscapularis
muscle is typically released or taken down, usually
laterally near its insertion on the humerus.
The joint capsule underneath is then incised
and released circumferentially to gain full access
to the glenohumeral joint. That sounds like quite
a careful dissection through several layers.
What are the main advantages of using this approach
for RTSA? The delta -pectoral approach has several
key advantages. Crucially for RTSA, it preserves
the origin of the deltoid muscle from the clavicle
and acromeon, which is vital for ensuring good
deltoid function post -surgery, and the deltoid
is doing all the work, remember. It provides
excellent exposure of the inferior part of the
glenoid, which is absolutely essential for accurate,
inferior placement of the glenoid baseplate,
a key factor in reducing complications like scapular
notching. The incision can also be easily extended
downwards if more exposure of the humerus is
needed, for example in revision cases or complex
fractures. It also allows for potential simultaneous
procedures, like a latissimus dorsi transfer,
if that's indicated. And generally, the risk
of direct injury to the main trunk of the axillary
nerve is considered lower with this approach
compared to the anterior superior one. And the
trade -offs. What are the disadvantages? The
main disadvantage is that you have to release
the subscapularis muscle. While this muscle is
often torn or non -functional in rotator cuff
tear arthropathy anyway, taking it down and potentially
repairing it at the end requires protection during
the early healing phase, typically involving
a period of immobilization and restricted movement.
This carries a risk of the repair re -tearing
and potentially leading to anterior instability
if it fails. It can also offer slightly less
direct exposure to the very posterior aspect
of the glenoid compared to other approaches.
And the required immobilization period might
contribute to some postoperative stiffness in
certain patients. Okay, so there's that balance
between preserving the deltoid origin versus
needing to manage the subscapularis tendon. What
about the alternative, the anterosuperior approach?
How does that differ? The anterosuperior approach
uses a different incision pattern. typically
starting near the AC joint and extending laterally
over the top in front of the shoulder. In this
approach, some of the anterior fibers of the
deltoid muscle are actually detached from their
origin on the acromion. or the muscle is split
in line with its fibers. You then access the
joint by incising through this deltoid split
or detachment, and the underlying rotator interval
tissues, exploring the subacromial space and
any remaining cuff tendons. Detaching deltoid
fibers sounds potentially significant. What are
the advantages that make surgeons choose this
route sometimes? The anterospupillary approach
can offer potentially better exposure of the
glenoid, particularly the superior portion. A
key perceived advantage is that it allows for
pressure preservation of the subscapularis muscle
as you don't typically need to release it. This
can lead to a decreased risk of anterior instability
post -operatively. It can also simplify the preparation
of the humeral canal in some situations and may
make it easier to manage and fix tuberosity fragments
directly, which can be beneficial in certain
fracture cases. And the disadvantages associated
with detaching or splitting the deltoid. The
main concern here is an increased potential risk
of injury to the distal branches of the axillary
nerve that supply the anterior deltoid as you
are working directly through or near the muscle
belly itself. It inherently involves violating
the anterior deltoid muscle origin or substance,
which some surgeons prefer to avoid if possible,
given the reliance on the deltoid post -RTSA.
There's also potential risk, though generally
manageable with careful technique, of positioning
the glenoid component slightly too high or with
a superior tilt, which is something you definitely
want to avoid as it increases notching risk.
So the surgeon carefully weighs these factors
prior surgery, the specific bone defects, the
need for exposure in certain areas, the relative
risks to nerves and tendons to choose the most
appropriate approach for that individual patient.
Once the joint is successfully opened, what's
the next major step in preparing the bones? Regardless
of the approach used to get there, the next major
step is preparing the humerus, the arm bone.
This begins by dislocating the humeral head from
the glenoid socket. This is achieved by carefully
manipulating the arm, often adducting it across
the chest, externally rotating it, and applying
gentle upward and forward force to lever the
head out of the socket. Once dislocated, you
then remove any significant bone spurs or osteophytes
from around the proximal humerus. This helps
to clearly identify the anatomical landmarks
and the correct level for the humeral head resection.
Where is the humerus typically cut for an RTSA?
Is it the same as for an anatomical replacement?
It's often slightly different. The humeral head
is resected using a surgical saw and specific
cutting guides. The cut is typically positioned
slightly below the tip of the greater tuberosity.
The angle of the cut relative to the long axis
of the humerus, specifically its rotation or
retroversion, is crucial. The source has mentioned
cutting the humerus in anywhere from 0 to 30
degrees of retroversion relative to the axis
of the forearm when the elbow is bent. A retroversion
of at least 20 degrees seems to be increasingly
favored. As studies suggest, it may help improve
post -operative external rotation, which can
be limited after RTSA. OK. So the head is resected.
Then what happens to the humerus? The intramedullary
canal. The hollow center of the humerus is then
prepared using a series of instruments called
reamers and brooches. These gradually shape and
size the canal to accept the humeral stem component
of the prosthesis. A version rod is often attached
to the final brooch instrument to help the surgeon
ensure the correct amount of retroversion is
maintained during this preparation stage. And
how do they determine the correct height for
the humeral component? That must be important
for getting the tension right later on. Yes,
determining the correct humeral height is very
important for achieving proper soft tissue tension
and stability. In non -fracture cases, the surgeon
can often reference remaining anatomical landmarks,
like the calcarbone medially or the tuberosity
fragments laterally. However, in complex fracture
cases, these landmarks are often missing or unreliable.
In those situations, a reliable reference point
is the insertion site of the pectoralis major
tendon on the humerus. Studies have shown this
insertion is consistently located around 5 .6
centimeters below the normal top of the humeral
head, providing a useful guide for positioning
the humeral component at the correct height.
That's a very specific anatomical measurement
guiding the surgery. What about the different
types of humeral stems used? Cemented or unsemented?
There are generally two types. Press -fit cementless
stems, which are designed to have a tight fit
within the bone and rely on the patient's bone
growing into the implant surface for long -term
stability, and cemented stems, which are fixed
into place using bone cement. For press -fit
stems, the final size of the stem used is typically
determined by the size of the last broach instrument
used during preparation. For cemented stems,
a slightly smaller stem is usually chosen to
allow for an even mantle of bone cement all around
it. If cement is used, antibiotic -loaded cement
is often favored to help reduce the risk of infection,
and a cement restrictor, like a small plastic
plug, is placed further down the canal first
to prevent the cement from going too far down
the bone. Right. Once the humerus is prepared,
the focus shifts across to the glenoid side,
the socket. Yes, exactly. The glenoid is now
fully exposed. If the subscapularis was released
during the approach, it's retracted immediately
out of the way. Any remaining labrum tissue around
the glenoid rim is removed, and the joint capsule
is released circumferentially to ensure maximum
visualization and access, particularly to the
inferior aspect of the glenoid. It's vital to
clearly identify the bony anterior margin of
the glenoid, typically around the 5 o 'clock
position on a right shoulder or the 7 o 'clock
position on the left shoulder, looking at it
face on. The surgeon then carefully inspects
the glenoid surface and its bony margins for
any wear patterns or bone defects, which are
actually quite common, especially posterior wear
or superior wear in cases of cuff tear arthropathy.
And how are those bone defects managed? You can't
just put the implant on uneven bone, presumably.
No. Managing glenoid bone defects is absolutely
crucial for achieving secure baseplate fixation
and preventing long -term complications like
loosening. Smaller defects, perhaps representing
less than 25 degrees aversion deformity or wear,
can often be managed by techniques like eccentric
reaming, which means reaming more bone from the
high side than the low side to create a flat
surface, or sometimes by adding bone graft to
the deficient area. For example, with typical
superior wear, you might read more inferiorly
or add a small bone graft superiorly to build
it up. However, for larger defects, often exceeding
25 degrees of version abnormality or significant
bone loss, patient -specific structural bone
grafts, often planned meticulously using those
preoperative 3DCT scans, are frequently required
to reconstruct the glenoid shape before the baseplate
can be placed securely. And getting the baseplate
positioned correctly sounds critical. It is absolutely
critical for the long -term survival of the implant
and minimizing complications like loosening or
notching. A crucial step here is performing a
superior steel elevation just below the inferior
glenoid rim. This elevates the soft tissues to
ensure the glenoid base plate can be seated flush
against the bone surface as far inferiorly as
possible. So aiming low on the glenoid face?
Yes. The goal is to position the base plate as
inferiorly on the glenoid face as possible. often
with a slight intentional inferior tilt. Studies
have suggested that around 10 degrees of inferior
tilt might help reduce the risk of the base plate
loosening over time by converting shear forces
into compression, although its effect on preventing
notching is more debated. A central pilot hole
is drilled, usually guided by a wire, to center
the glenoid reamer. The glenoid surface is then
reamed to create a flat, bleeding surface of
subchondral bone, preparing it perfectly for
the base plate. The base plate itself is then
applied, ensuring it's flush with the bone and
initially compressed onto the surface using a
central screw. Then, multiple peripheral screws
are inserted, typically aiming superiorly towards
the strong bone at the base of the coracoid process
and inferiorly towards the dense bone of the
lateral scapular body to achieve strong, stable,
multi -directional fixation. Advancements like
variable angle locking screws and central compressive
locking screws have been introduced in newer
systems to further improve this initial stability
and resist micro -motion at the interface, which
is thought to be a precursor to loosening. So
the base plate is locked solidly onto the shoulder
blade. What comes next on the glenoid side, the
ball part? That's right, the glenosphere. Once
the base plate is securely fixed, the glenosphere
trial component is placed onto it. Glenospheres
come in various sizes, typically ranging from
about 32 up to 42 millimeters in diameter, with
common sizes being perhaps 36 millimeters for
many female patients and 40 millimeters for males,
although it depends on the individual patient's
anatomy. Modern designs also offer variations
in lateralization, how far the sphere sits out
from the base plate or eccentricity, where the
center of the sphere is offset from the center
of the base plate. These newer geometries are
specifically designed to try and reduce that
scapular notching problem and potentially improve
the range of motion by moving the area of potential
impingement further away from the bone. And you're
trialing different sizes and offsets at this
stage to get the best fit. Exactly. The surgeon
will trial different glenosphere diameters, offsets
lateralization, and potentially eccentricities
to find the combination that achieves optimal
soft tissue tension around the joint and allows
for the best possible range of motion without
the components impinging on each other or on
the surrounding bone. They visually check for
clearance between the glenosphere and the scapular
pillar anteriorly. posteriorly and especially
inferiorly, and ensure the planned humeral component
won't hit the acromion bone above during arm
elevation. Once the glenosphere trial is satisfactory,
you then go back to the humerus side to trial
those components. Yes, precisely. You then trial
the humeral components. The humeral tray, which
attaches to the top of the stem already prepared
in the humerus, and the polyethylene insert,
the plastic socket part which will articulate
with the metal glenosphere, are placed onto the
humeral stem trial. The entire trial prosthesis
is then carefully reduced, meaning the humeral
component is seated onto the glenosphere, bringing
the arm and shoulder blade components together
into the final joint configuration. The surgeon
then meticulously tests the range of motion in
all directions, checks for stability throughout
the arc of movement, and assesses the soft tissue
tension. They'll manually feel the tension of
the deltoid, the conjoined tendon, and sometimes
the triceps to ensure it's not too loose, which
would risk dislocation, or excessively tight,
which could risk stiffness, pain, or even nerve
traction. So you're really fine -tuning the implant
fit and the resulting muscle tension at this
stage. It sounds like a delicate balancing act.
It is, exactly. You might try different heights
of the polyethylene insert if necessary to adjust
the tension. If the soft tissue tension feels
too high even with the thinnest insert, or if
the prosthesis is very difficult to reduce, the
surgeon may make the decision to resect the proximal
humerus at a slightly lower level to effectively
shorten the humerus slightly, reducing tension
and creating a bit more space. Once everything
feels optimal with the trial components, then
the definitive final components are implanted.
That's right. The trial components are all removed.
The definitive glenosphere is implanted onto
the base plate first. This is generally easier
to do while there's still more space before the
humeral component is fully in place. Then the
definitive humeral stem is implanted, either
cemented or press -fit depending on the plant.
The definitive metal humeral tray is attached
securely to the top of the stem, followed by
the final polyethylene insert which snaps into
the tray. The definitive prosthesis is then reduced
one last time, and a final check for stability,
range of motion, and appropriate soft tissue
tension is performed. Before closing, the surgical
site is thoroughly washed out with saline solution.
In that final step we touched on earlier, what
about repairing the subscapularis muscle if it
was released? That's often the final decision
made just before starting the closure. As the
sources mention, whether or not to repair the
subscapularis after taking it down during the
delta -pectoral approach is still somewhat debated
among surgeons. There is some evidence suggesting
that repairing it might lead to improved internal
rotation strength or function postoperatively,
but studies haven't consistently shown a significant
difference in postoperative instability rates
compared to not repairing it, especially if the
tissue quality is poor. The decision often rests
on the surgeon's preference and their intraoperative
assessment of the quality of the remaining subscapularis
tissue. If it's very thin, degenerated, or retracted,
a repair might not be feasible or likely to hold
anyway. Wow. That level of detail in the procedure
really highlights how much goes into tailoring
this surgery to each patient's specific anatomy,
bone quality, and pathology. It's clearly not
a one -size -fits -all operation. No, it is a
highly technical and complex procedure requiring
significant surgical expertise and judgment at
multiple steps along the way to ensure correct
implant positioning, appropriate component sizing,
stable fixation, and optimal soft tissue balance
for the best possible outcome. Okay. Once the
surgery is successfully completed, the patient
moves into that crucial phase of recovery and
rehabilitation. What does life after a reverse
shoulder arthroplasty typically look like in
terms of post -operative care and the rehab process?
Postoperative care and rehabilitation are absolutely
essential for maximizing the functional outcome
after RTSA. It really is just as important as
the surgery itself. It's a phased process, carefully
guided to protect the healing tissues while gradually
restoring movement and strength over several
months. Let's talk about the immediate post -surgical
phase first, say the first few weeks. What happens
then? In the immediate phase, typically the first
four to six weeks, the operated arm is immobilized
in a sling to protect the shoulder. A specific
type of sling, sometimes called a board arm sling
or abduction pillow sling, might be used for
about the first two weeks for added protection
and comfort. A critical restriction during this
early time is avoiding active external rotation
and usually passive external rotation beyond
neutral zero degrees for at least the first four
weeks. This is particularly important if the
subscapularis muscle was repaired during surgery
to allow that repair time to start healing without
tension. What kind of movement is loud early
on then? You can't just keep it completely still,
can you? Yeah. No. Early controlled movement
is important to prevent stiffness elsewhere.
Pendulum exercises, gentle swinging motions of
the arm initiated by body movement, are usually
started very soon after surgery. Along with that,
gentle active and passive movements of the elbow,
wrist, and hand on the operated side are encouraged
to maintain their function. The sling itself
is generally discontinued around three weeks
if the subscapularis was not repaired, but often
worn for a longer period, sometimes up to six
weeks, if it was repaired, based on surgeon preference
and the repair quality. Patients are also given
specific instructions on activities to avoid,
such as avoiding using the operated arm to push
themselves up out of a chair, which puts significant
stress on the implant and any repairs. So the
initial focus is very much on protection and
very gentle controlled motion. Exactly. The main
goals in this early phase are joint protection,
managing pain and swelling effectively, often
using ice packs or cryotherapy devices, achieving
passive or active assisted range of motion within
prescribed safe limits, and helping the patient
regain basic independence with personal care
tasks while wearing the sling. The first formal
physical therapy visit usually takes place around
8 to 10 days post -op once the initial womb healing
is underway to begin the structured rehabilitation
program under guidance. What about the risk of
that subscapularis repair tearing if one was
done? Is that a concern in this early phase?
Yes, if the subscapularis was repaired, a re
-tear is a potential complication in this early
phase, particularly if the restrictions aren't
followed. A significant retear could potentially
lead to anterior instability of the prosthesis.
This would typically manifest as pain, a feeling
of instability, or difficulty with certain movements,
and would require early recognition and potentially
further intervention, possibly surgical exploration,
and re -repair if feasible. Okay. Moving into
the mid -recovery phase then, say from around
six weeks to three months post -op, what changes?
By the mid -recovery phase, patients are typically
attending outpatient physical therapy sessions,
perhaps two or three times a week. The focus
starts to shift gradually from mainly passive
protection towards more active movement and the
initiation of gentle strengthening exercises.
Patients are usually cleared to begin using their
arm for light, below shoulder height everyday
activities. But still, with significant restrictions
on lifting weight, usually nothing heavier than
a cup of tea initially. The goals during this
phase include managing any residual pain and
swelling, progressing stretching exercises to
improve range of motion further within limits,
and beginning very light strengthening exercises
such as controlled isometric contractions and
gentle active exercises like shoulder flexion
and scapular retraction exercises. Sounds like
a gradual but definite increase in activity and
strengthening, and then into the late recovery
phase, perhaps from three to six months. Yes,
this period, from three to six months, is typically
when most patients experience really significant
functional gains. Physical therapy becomes more
intensive, focusing on building greater muscle
strength, endurance, and coordination required
for more complex movements and functional activities.
However, even during this phase, patients are
generally advised to continue avoiding heavy
lifting, repetitive overhead activities, and
certainly any high impact sports or activities
that could put excessive stress on the implant.
Adhering closely to the physical therapy program
and the surgeon's specific guidelines remains
essential to consolidate the recovery and protect
the long -term outcome. And what's the typical
timeline for feeling like you've reached, well,
full recovery or as good as it's going to get?
Full recovery can vary quite a bit between individuals,
but most patients see substantial improvement
and are able to perform most of their desired
daily tasks with much less pain and significantly
improved function by around the six -month mark.
However, continued improvements in strength,
endurance, and even range of motion can often
occur for up to a year, or sometimes even longer,
after the surgery as the muscles adapt and conditioning
improves. Regular follow -up appointments with
the surgical team throughout this period, perhaps
at six weeks, three months, six months, and a
year, are important to monitor progress, check
on the implant's stability radiographically,
and address any issues or concerns that may arise.
It's certainly clear from that description that
the rehabilitation after the surgery is just
as important, if not more so in some ways, than
the surgery itself for achieving a good result.
Absolutely. The surgery provides the necessary
mechanical alteration, the foundation for potential
improvement. But dedicated? Appropriate and often
prolonged rehabilitation guided by experienced
therapists is crucial to translate that surgical
potential into meaningful, lasting functional
recovery for the patient. It requires significant
patient commitment. Now the crucial part for
many patients considering this. Let's talk about
the results. What can patients realistically
expect in terms of outcomes, both good and bad?
And what are the potential problems or complications
they really should be aware of? Yes, this is
a critical conversation for informed consent
and setting realistic expectations. Let's start
with the positive outcomes, what we generally
hope to achieve. What do the studies and perhaps
the big joint registries tell us about pain relief
and overall patient satisfaction after RTSA?
The data is generally very positive regarding
pain relief, which is often the primary goal
for many patients. Studies like the 2023 systematic
review by Doyle and colleagues, which looked
at over 1 ,600 RTSAs with at least five years
of follow -up, reported that around 88 % of patients
had good or excellent patient -reported outcomes
overall. This aligns well with other findings
suggesting that roughly 85 -90 % of patients
experience excellent relief from the often severe,
debilitating pain associated with conditions
like end -stage rotator cuff tear or arthropathy.
For patients whose lives are dominated by shoulder
pain, this level of relief can be truly life
-changing. That's a very high success rate for
pain relief. And what about restoring the ability
to lift the arm? What kind of range of motion
gains are typically seen? We know it relies on
the deltoid. Yes, there are usually significant
gains in active motion. particularly in elevation.
The 2022 systematic review by Galvin and colleagues
found mean improvements of about 56 degrees in
active forward flexion, lifting the arm forwards,
and 50 degrees in active abduction, lifting the
arm out to the side. The Doyle review reported
specific mean ranges of motion achieved at a
minimum five -year follow -up. Active forward
flexion averaged 126 degrees, active adduction
averaged 106 degrees, active internal rotation,
like reaching behind the back, was more limited,
averaging about six degrees of improvement, often
reaching the lumbar spine. So while it doesn't
typically restore completely normal full range
of motion, these improvements allow most patients
to use their arm much more effectively for activities
of daily living, particularly lifting the arm
above shoulder height, which they often couldn't
do at all before surgery. Do these outcomes very
much based on the original problem the patient
had, why they needed the RTSA in the first place?
Yes, they do seem to. The 2022 systematic review
by Paris and colleagues specifically compared
outcomes when RTSA was done for rotator cuff
arthropathy versus complex proximal humerus fractures.
They found that patients treated for fractures
generally had somewhat worse functional outcome
scores and achieved less range of motion compared
to those treated for rotator cuff arthropathy.
This suggests that the underlying pathology,
the amount of initial trauma, and perhaps the
complexity of the surgical reconstruction required
can influence the functional sealing that's ultimately
achievable. Emily, revisit that question mark
indication we discussed earlier. Older patients
say over 70 with osteoarthritis, but an intact
rotator cuff. How does RTSA stack up against
the traditional anatomical TSA in that specific
group? The evidence seemed a bit mixed. It is
an area of active research and ongoing debate,
and the studies show some interesting, perhaps
complex trade -offs. A large 2023 systematic
review by Dragunus and colleagues comparing over
1 ,400 anatomical TSAs and over 1 ,200 RTSAs
in patients over 70 with intact cuffs found that
ATSA resulted in better overall functional outcome
scores. However, quite notably, they also found
an increased revision rate associated with ATSA
in this specific older population compared to
RTSA. So potentially better functional scores,
maybe better rotation with the anatomical approach,
but a higher chance of needing another surgery
later down the line compared to the reverse in
this older group. That's a really complex decision
point for both surgeon and patient. It certainly
is. Another meta analysis by Kim and colleagues
in 2022 look at six studies comparing ATSA and
RTSA in patients with intact cuffs. They found
no significant difference in overall functional
scores between the two procedures. They did note,
however, that ATSA generally led to better external
rotation, while ATSA was associated with increased
rates of glenoid component loosening over time.
Conversely, RTSA was associated with increased
rates of scapular notching. So neither procedure
appears clearly superior across all metrics for
this specific group, and the potential long -term
risks seem to differ. It really requires careful
patient counseling. What about differences between
the implant designs themselves? The sources mention
inlay versus onlay humeral components. Does that
make a difference to outcomes? Studies comparing
inlay and onlay humeral component designs show
somewhat varied results when it comes to functional
scores. Some systematic reviews, like those by
LaRose et al. and Meshram et al. suggested slightly
higher functional scores, like the AC score with
inlay designs. However, other studies, like one
by Giordano, found no significant difference
in ACs or constant Murley scores. Jackson's systematic
review reported slightly better average forward
flexion with on -lay designs around 142 degrees
compared to in -lay designs around 136 degrees,
although this difference wasn't statistically
significant. So, perhaps not huge functional
differences reported consistently, but maybe
differences in the types of complications seen
with each design. That appears to be the emerging
picture, yes. In -lay designs have been more
strongly associated with an increased risk or
severity of scapular notching. On -lay designs,
on the other hand, seem to be linked to a potentially
increased risk of scapular spine fractures. These
are important considerations for the surgeon
when choosing a specific implant system, balancing
the potential benefits and risks of each design
philosophy. Okay, let's shift focus now and talk
more directly about those potential complications.
The sources provide some quite robust data, particularly
referencing large joint registries like the Australian
one. What does that registry data tell us about
how often revisions needing a second operation
are actually required after RTSA? The Australian
Joint Registry provides invaluable real -world
long -term data on large numbers of patients,
which is incredibly useful. Their 2024 report
shows the overall 14 -year revision rates for
RTSA broken down by the original indication for
the surgery. For rotator cuff arthropathy, which
is the most common indication over 20 ,000 cases,
the 14 -year revision rate was 6 .1%. For osteoarthritis,
which includes some of those intact cuff cases
over 24 ,000 cases, the rate was slightly higher
at 6 .7%. And for fracture cases, around 8 ,000,
the 14 -year rate was 5 .9%. So these long -term
revision rates are actually relatively similar
across the main indications, hovering around
6 -7%. That's lower than I might have guessed
for 14 years. Are there demographic factors that
influence these revision rates significantly?
Age or gender? Yes. And some of the findings
in the registry are quite interesting, perhaps
even counterintuitive. Looking at age groups,
the 14 -year revision rate is highest for patients
aged 55 -64 at 9 .3%, followed by those aged
65 -74 at 7 .2%. Surprisingly, patients aged
over 75 years old actually have the lowest 14
-year revision rate recorded, at just 4 .3%.
The rate for the youngest group, under 55, was
reported as 5 .5 % at five years, suggesting
it might also be higher long -term. That is surprising.
You might intuitively expect older patients,
maybe with poorer bone, to have more issues leading
to revision. But the registry shows the opposite
trend for overall revision risk. Perhaps lower
activity levels or demands play a role. That's
a very common hypothesis that lower functional
demands or activity levels in the oldest age
group place less stress on the implant over time,
leading to better longevity. There's also a very
significant difference noted based on gender.
The 14 -year revision rate for males is reported
as 9 .5%, which is almost double the rate for
females, which stands at 5 .0%. Wow, that's a
substantial difference between genders needing
revision surgery. What about differences related
to how the implant itself is fixed or designed?
Does cement matter? The registry data shows some
differences based on humeral fixation method.
Uncemented humeral SPEMs have a 14 -year revision
rate of 6 .9 % based on a very large cohort of
over 21 ,000 cases. Hybrid fixation, where the
humeral stem is cemented but the glenoid base
plate is usually uncemented, shows a lower 14
-year revision rate of 4 .9%, although this is
based on a smaller cohort of around 2 ,600 cases.
So, cementing the humeral stem seems potentially
beneficial for long -term survivorship according
to this large registry data. What about the length
of the stem, short versus long? That's another
interesting comparison. Short humeral stems,
defined as less than 100 millimeters in length,
have a 14 -year revision rate of 5 .7%. based
on about 10 ,000 cases. This compares favorably
to conventional length stems over 100 millimeters,
which had a 14 -year revision rate of 7 .3 percent
based on over 13 ,500 cases. So shorter stems
potentially having a lower long -term revision
risk according to the registry. This kind of
granular real -world data is invaluable for surgeons
and patients trying to understand long -term
performance. Beyond needing a full revision,
what are the most frequent or perhaps most problematic
complications associated with with RTSA? Well,
overall complication rates reported in various
studies do vary, ranging from about 6 .5 % up
to perhaps 15 .2 % in some series. It's worth
noting, as mentioned in the sources, that complication
rates tend to decrease as surgeons gain more
experience with the procedure, indicating a definite
learning curve. This is often cited as plateauing
after performing somewhere between 18 to 45 cases.
But yes, several specific complications are well
recognized and important to discuss. Scapular
notching is one we've mentioned a few times now.
Can you explain exactly what it is and how common
is it really? Scapular notching refers to bone
erosion or wear that occurs on the inferior aspect
of the scapular neck, just below the implanted
glenoid base plate. It's a common radiographic
finding, meaning it's seen on x -rays. Historically,
it was reported with very high incidence, sometimes
quoted as 44 % up to 96%, particularly with the
original Gramon -style prosthesis design. This
was strongly linked to that 155 degree neck shaft
angle, which placed the humeral component very
medially. The notching occurs because the medial
rim of the humeral cup component impinges, essentially
rubs against the bone of the inferior scapular
neck during certain movements, particularly adduction,
bringing the arm toward the body, and internal
rotation. So the implant is literally rubbing
against the bone and wearing it away. What makes
someone more likely to get notching? Can it be
prevented? Risk factors identified include placing
the glenoid component too high on the glenoid
face or tilting it superiorly, using an implant
design with a highly medialized center of rotation,
like the original grammet, and possibly high
-patient BMI. Modern implant designs with features
like lateralization of the baseplate or glenosphere,
or using eccentric glenospheres, along with surgical
techniques focusing on achieving secure inferior
placement of the baseplate with perhaps slight
inferior tilt, have all been aimed at reducing
the incidence and severity of significant notching.
Notching is typically graded on x -rays using
classification systems like the Servo classification,
which describes the extent of the bone defect
ranging from grade 1 Minimal, confined to the
scapular pillar, up to grade four. Severe erosion
extending under the base plate, potentially compromising
fixation. What about the joint actually dislocating
after surgery? How often does that happen? Dislocation
or instability. is another potential complication,
reported in about 2 % to 3 .4 % of cases in various
series. It's considered a relatively common cause
of early failure requiring intervention, usually
occurring in the initial postoperative period
before tissues have fully healed. The most common
position or movement pattern that leads to dislocation
is described as a combination of arm extension,
internal rotation, and adduction, sort of reaching
behind the back and across the body. Are there
specific factors that put a patient at higher
risk for dislocation? Yes. Several risk factors
have been identified. Perhaps the strongest is
having an irreparable or failed subscapularis
muscle. While RTSA is designed for a deficient
rotator cuff overall, the complete absence or
failure to heal of any repair of the subscapularis
significantly increases the risk of anterior
instability. Other risk factors include significant
proximal humeral bone loss, making the humerus
unstable, having the RTSA performed as a revision
of a failed prior arthroplasty, dealing with
a non -union of the proximal humerus, or having
had a fixed irreducible shoulder dislocation
preoperatively. Some sources also suggest a potentially
higher rate of dislocation associated with the
delta pictorial approach compared to the anterosuperior
approach, although the reasons for this are debated
and likely multifactorial. Given how critical
the glenoid fixation is, what about the base
plate itself loosening over time? You mentioned
that was a risk. Yes. Glenoid prosthetic loosening
is unfortunately considered the most common long
-term failure mechanism that necessitates revision
surgery for RTSA. While the initial fixation
achieved with modern techniques can be very strong,
factors like micromotion at the bone implant
interface, inadequate initial bone quality, or
progressive bone loss around the implant over
time can eventually lead to loosening. It's noted
that the incidence of glenoid loosening significantly
increases after a revision. RTSA, one study cited
reported rates around 25 % at five -year follow
-up in that challenging revision setting. Treatment
for established glenoid loosening is complex
and often involves a staged surgical approach.
First, removing the loosened components, thoroughly
debriding the area, addressing any significant
bone defects, often requiring bone grafting to
fill the cavity, allowing time for healing, and
then returning later to re -implant a new glenoid
component, often using specialized techniques
like bone grafting and locking screws for enhanced
stability in the compromised bone. That sounds
like a very challenging problem to fix successfully.
What about the risk of infection? Deep infection
is a serious, although fortunately less common,
complication after RTSA. The reported incidence
rates vary somewhat in the literature, with stat
pearls mentioning a range of 110%, while the
bone school suggests 12 % is more typical for
primary RTSA. The risk is known to be higher
in revision surgery scenarios, in patients with
inflammatory conditions like rheumatoid arthritis,
or when the surgery is performed for traumatic
reasons like complex fractures. The large dead
space created around the implant components can
potentially be susceptible to bacterial colonization.
Common organisms implicated include cutobacterium
acnes, formerly P. acnes, which is a skin commensal,
as well as Staphylococci species. Risk factors
identified in registry data and studies include
younger age, perhaps under 65, male gender, having
the RTSA for a traumatic indication, and a history
of previous failed shoulder arthroplasty. The
gold standard for treating an established deep
prosthetic joint infection is typically a two
-stage revision procedure. This involves removing
all implants, performing extensive surgical debridement,
administering prolonged, targeted antibiotics,
and then, only once the infection is confirmed
to be eradicated, proceeding with re -implantation
of new components. Specific antibiotics like
vancomycin and cleandomycin are often used as
part of the treatment regimen, particularly for
C. acnes infections. Are there other bone -related
complications besides the glenoid loosening?
Can the bones fracture around the implant? Yes,
fractures around the prosthesis can occur, particularly
fractures of the acromeon or the scapular spine.
The reported incidence is around 4 % after RTSA.
Identified risk factors include female gender
underlying osteoporosis, poor bone quality, having
a preoperative anatomy with a very medialized
center of rotation, and having rheumatoid arthritis.
These fractures can sometimes heal with conservative
treatment, like sling immobilization, but the
union rates are often relatively low, perhaps
only 40 -50%. Therefore, operative fixation using
plates, screws, or tension band wiring techniques
is often recommended to improve the chances of
union and restore the structural integrity needed
for deltoid function. These fractures are sometimes
classified using the levy classification system
based on their location and pattern. And what
about potential nerve injury during the surgery
itself? Is the axillary nerve at risk? Neuropraxia,
which is a temporary nerve injury, typically
due to stretching or bruising, of the axillary
nerve is a potential complication. The reported
incidence is relatively low, around 0 .5 % to
1%. This is usually transient, meaning the nerve
function typically recovers over time, although
it can take weeks or months. It can result from
traction on the nerve during positioning of the
arm for exposure, particularly with hyperextension
or abduction, or if there is significant lengthening
of the humerus achieved during the procedure,
which can stretch the nerve. Identified risk
factors include the entero -superior surgical
approach due to proximity to nerve branches and
any surgical technique that results in substantial
lengthening of the humerus compared to the preoperative
state. Permanent nerve injury is much rarer,
but a devastating complication. Finally, you
mentioned base plate failure, specifically as
distinct from loosening. Yes, base plate failure
can occur, typically resulting from excessive
micro -motion at the bone implant interface,
leading to fatigue, fracture of the metal, or
failure of the fixation screws, or perhaps due
to inadequate initial bone -in growth in un -semitic
designs leading to instability. As we discussed
earlier regarding fixation techniques, advancements
in baseplate design, like porous coatings for
bone -in growth, and screw technology, variable
angle locking screws, central compression screws,
along with meticulous surgical technique ensuring
flush seating and appropriate tilt, often inferior,
are all aimed at reducing shearing forces and
micromotion at that critical interface to prevent
this failure mode. Studies, like one by Holcomb
and colleagues back in 2009, have specifically
investigated the causes and management strategies
for revision surgery required due to base plate
failure. It's certainly clear that while this
procedure offers very significant benefits for
complex shoulder problems, it also comes with
a distinct and important set of potential complications
that both patients and surgeons must carefully
consider and navigate. Absolutely. A thorough
discussion covering these potential issues is
a crucial part of the informed consent process.
The sources also list other less common complications
that can occur, including things like an iatrogenic
paraprosthetic fracture happening during the
surgery itself, rare but serious vascular injury,
the development of heterotopic ossification,
which is abnormal bone growth in the soft tissues
around the joint, and issues related to the surgical
scar healing. And as mentioned, the learning
curve for surgeons with this procedure is also
recognized as a factor that can influence complication
rates, particularly early in their experience.
With all this accumulated experience and data
now on outcomes and complications, the field
of reverse shoulder arthroplasty clearly isn't
static. What research and advancements are happening
now and what's on the horizon looking ahead?
No, the field is continuously evolving, definitely,
driven by that constant desire to improve patient
outcomes further and reduce the rates of those
complications we've just discussed. A key area
of focus currently is generating robust, high
-quality evidence, particularly for health technology
assessments, HKA, of newer implant designs and
surgical techniques. This is really important
to ensure that new technologies are thoroughly
evaluated for both safety and effectiveness before
they become widely adopted in clinical practice.
So rigorous testing and evaluation of new developments
is paramount. Precisely. Research is ongoing
in clinical effectiveness, often utilizing large
patient cohorts and long -term follow -up data
derived from sources like those national joint
registries we talked about. These large -scale
observational studies are vital for comparing
our TSA to other treatments, such as anatomical
TSA in specific populations like the older intact
cuff group, and for detecting rarer but serious
long -term outcomes like revisions or specific
adverse events that might not be captured adequately
in smaller clinical trials. They provide invaluable
real -world evidence that complements the insights
we get from randomized controlled trials, which
often focus more on short to medium term function
and cost effectiveness. And technology is playing
a big role too, isn't it? Both perhaps before
and during the surgery. Absolutely. Technological
advancements are making a significant impact
on both preoperative planning and the implants
themselves. We're seeing increasing development
and use of personalized, patient -specific implants,
often created using 3D printing technology based
on detailed analysis of the patient's preoperative
CT scans. These are designed to be perfectly
tailored to an individual's unique bone anatomy.
The potential benefit here is to improve the
fit and stability of the implant components,
particularly the glenoid base plate in cases
with significant bone loss, potentially reducing
complications like loosening, instability, or
impingement. Patient -specific implants sound
like they could really change the game in complex
cases. They are a very promising direction, yes.
Alongside that, augmented reality, AR tools,
are also being developed and explored as a way
to enhance the precision of implant placement
during the surgery itself. By providing real
-time intraoperative visual guidance, potentially
overlaying the surgical plan onto the surgeon's
view, AR could potentially improve the accuracy
of bony cuts and component positioning, which
might lead to better functional outcomes and
improved long -term implant survival. Still early
days for widespread use, but developing fast.
And are there completely new types of implants
being developed as well? Yes, there's ongoing
innovation in implant design. The stemless humeral
component is one significant development that's
gained traction. sometimes called a canal sparing
design, this fixes the humeral component directly
into the metaphysis, the upper part of the humerus,
without needing a long stem going down the bone
canal. The main theoretical advantage is preserving
more of the patient's native bone stock in the
humerus, which could be very beneficial if a
revision surgery is ever needed in the future.
It might also potentially reduce operative time
and blood loss slightly compared to stem designs.
Midterm results for stemless RTSA seem encouraging.
Systematic reviews like the one by Kastretzis
have reported relatively low rates of humoral
-related complications and revisions specifically
for stemless designs. Studies by researchers
like Taissier and Moroder are contributing to
the growing body of evidence supporting their
use in appropriate patients. So pulling all that
together, what are the overall future directions
for the field of reverse shoulder arthroplasty?
Where is it heading? I think the main focus is
on continuous refinement. refinement of surgical
techniques based on a better understanding of
biomechanics and complication avoidance, and
refinement of implant designs based on clinical
evidence gathered from studies and registries.
There's also a push towards establishing more
international standards for assessing safety
and efficacy of new technologies. Research is
also delving deeper into understanding the wear
properties of the different materials used in
the implants, like polyethylene liners against
metal or ceramic linospheres, and the biological
effects of any wear particles generated, as this
ultimately impacts how long the implant will
last. Additionally, there is ongoing work to
better understand how specific patient demographic
factors, like age, gender, BMI, bone density,
really influence outcomes, so that treatments
can be further optimized and tailored to individual
patient risks and needs. The sources rightly
emphasize that as the volume of RTSA procedures
continues to increase globally, it's paramount
for surgeons in the healthcare system to stay
informed about the latest advancements, the supporting
clinical evidence, and relevant regulatory processes.
This growth must always align with principles
of patient -centered care and sound ethical considerations.
What's really fascinating here is seeing that
clear feedback loop, how the data gathered on
complications and long -term outcomes directly
drives the research and the technological development
that's aimed at making the procedure even better
and safer for patients in the future. It's a
truly dynamic field, yes, with a clear commitment
from surgeons and industry to improving the lives
of patients who often suffer from very debilitating
shoulder problems. Well, we've certainly taken
a very deep dive into reverse shoulder arthroplasty
today. We have indeed. We've explored that core
concept, reversing the normal anatomy to empower
the deltoid muscle when the rotator cuff is irreparably
damaged, a truly ingenious biomechanical solution
when you think about it. And we've mapped out
the specific indications, things like cuff tear,
arthropathy, and certain complex fractures, understanding
why those conditions often require this unique
approach, alongside discussing the crucial contraindications
where it shouldn't be used. We've walked through
the meticulous preoperative planning process,
emphasizing the increasingly important role of
advanced imaging, like 3DCT scans, in understanding
complex bone defects and guiding accurate implant
placement. And we delved into the intricate steps
of the surgery itself, highlighting the key decisions
regarding approach, component positioning, and
soft tissue balancing. And we've outlined the
phased rehabilitation protocol, stressing just
how crucial that is for translating the surgical
changes into real functional improvement and
guiding patients safely through their recovery
journey. And finally, we've examined the real
-world outcomes, noting the generally excellent
pain relief and functional gains achieved for
activities of daily living, while also squarely
facing the potential complications like scapular
notching, instability, infection, and component
loosening. We saw some surprising insights from
registry data too, particularly around how factors
like age and gender can influence long -term
revision rates. It's clear that reverse shoulder
arthroplasty, while undoubtedly complex and carrying
specific risks, offers significant hope for substantial
pain relief and improved function in many challenging
shoulder cases where traditional options might
fall short. It truly represents a powerful solution
for a specific, carefully selected group of patients
who, in the past, might have had very limited
options for meaningful improvement. If you found
this deep dive valuable, please do consider rating
and sharing it so others who might benefit can
discover it too. Indeed. This whole discussion
does raise an important question for the future,
doesn't it? As technology continues to advance,
allowing for increasing personalization with
things like 3D printed patient -specific implants
and augmented reality guidance systems, how will
the orthopedic field effectively balance these
highly tailored, potentially complex solutions
with the ongoing need for standardized evidence
-based practices to ensure the best, most reliable,
and safest possible outcomes for every patient
undergoing this life -changing procedure? That's
a fascinating challenge and a key consideration
as the field continues to push boundaries. Thank
you for joining us for this exploration.