All right, let's dive right into something that's
becoming, well, a major challenge in orthopedics,
especially with more and more people living longer,
having active lives. We're talking about fractures
around existing hip replacements. Now, these
aren't your typical broken bones. They present
a unique sort of puzzle for us in the medical
field. They really do. And the global rise in
these periprosthetic hip fractures, it's directly
linked to the incredible success and just the
sheer volume of total hip arthroplasties, THAs
being performed worldwide. What's also quite
fascinating is that we're seeing THAs not just
in the elderly, but increasingly in younger,
more active individuals. And that naturally broadens
the spectrum of potential complications, and
it challenges us to adapt, doesn't it? Absolutely.
It changes the game somewhat. And beyond the
immediate clinical complexity for the patient,
there's also a significant economic impact these
injuries have on health care systems. It's not
insignificant. Not at all. Today, we have Professor
Mo Imam with us, an expert guide who will help
us navigate this, well, intricate and evolving
area. Our mission for this deep dive is to give
you, our listener, a comprehensive, up -to -date
understanding of how these fractures are managed
right from the moment they're diagnosed through
to rehabilitation. It's truly a compelling area
because, you know, these fractures represent
a critical crossroads. It's trauma surgery meeting
arthroplasty. They demand a very specific combined
skill set from orthopedic surgeons, often pushing
the boundaries of our expertise. And their effective
management isn't just about technical surgical
skill, it truly requires seamless multidisciplinary
input to achieve the best, most lasting outcomes
for the patient. This isn't a problem one specialist
can solve alone. That immediately highlights
just how multifaceted this challenge is. So let's
begin by trying to understand the sheer scale
of the issue. Just how common are these periprosthetic
fractures? And what are the main factors putting
patients at such a heightened risk? Could you
give us a sense of the incidence and maybe the
typical mechanisms of injury we're seeing? Certainly.
Periprosthetic fractures around the hip, they
can occur during two distinct periods, either
intraoperatively so, right there on the operating
table during the surgery itself. Okay. Or post
-operatively, which is, you know, after the procedure
has been completed. Now, looking at intraoperative
fractures, they are notably more common in unsubstmented
total hip arthroplasties. We're talking about
roughly 5 .4 % of cases. 5 .4%, okay. Which stands
in stark contrast to cemented THAs, where the
incidence is much lower, maybe around 0 .3%.
Big difference. Huge difference. And what's particularly
striking is that this risk escalates significantly
during revision surgery. It jumps to an alarming
20. 0 .9%. Wow, 20%. Compared to a primary arthroplasty
where it's about 3 .6%. Now this tells us something
profound about the perhaps compromised bone quality
or the altered anatomy we often encounter in
those revision cases. Right, the underlying bone
isn't pristine anymore. Exactly. Then, postoperatively,
the incidence of paraprosthetic femoral fractures
is less than 1 % after a primary THA, which sounds
low, but it can rise to as much as 4 % following
revision surgery. So that indicates a kind of
cumulative risk over time. The overall lifetime
risk after any THA is estimated somewhere between
0 .4 % and 3 .5%. And it's crucial to understand
their significance in the bigger picture. These
fractures are the third most common reason overall
for THA revision. Third most common. Yes. And
interestingly, they climb to become the second
most common reason beyond the fourth year post
-primary THA. That's a trend consistently observed
in large national data sets, like the Swedish
national hip arthroplasty register, which gives
us invaluable long -term data. That long -term
perspective is key. It is. And while periprosthetic
femoral fractures are overwhelmingly the most
common type we discuss, it's worth remembering
that acetabular fractures affecting the hip socket
can also occur. Ah, yes. These are much rarer,
making up only about one -tenth of all THA -related
fractures. And they predominantly happen intraoperatively,
often to the force involved in planting a new
cup. Right, getting that cup seeded. Precisely.
As for the mechanism of injury for the post -operative
fractures, the vast majority, around 86%, result
from surprisingly low energy trauma. 86 % low
energy. Yes. We're talking about simple falls
from standing height. This isn't about high impact
car accidents in healthy individuals. It speaks
volumes about the fragility and often the comorbidities
present in this patient demographic. I find that
fascinating that these low energy falls account
for such a high percentage. It almost feels counterintuitive.
You'd expect high impact trauma, but it's often
the simple trip that causes the catastrophic
failure, isn't it? That's precisely the point.
It's often not a major external force, but an
underlying systemic vulnerability. Right. So
given that, what are the key patient related
risk factors that truly contribute to this underlying
vulnerability? Well, several patient characteristics
consistently contribute to an increased risk.
Female gender and advanced age are frequently
cited, largely due to age -related bone density
loss and higher rates of osteoporosis. However,
it's worth noting that while these are common
associations, the evidence across the literature
can sometimes be a bit inconsistent on their
independent impact. Ah, okay. Nuance there. Exactly.
But what is consistently identified are certain
underlying medical conditions. Ochaeoprosis,
of course, is a significant one, but also rheumatoid
arthritis, Paget's disease, and developmental
hip dysplasia, all of which compromise bone quality
and integrity. Crucially, an increased time from
the initial archerplasty procedure is also a
significant factor, as implants' age, bone remodels,
and bone quality can naturally deteriorate over
decades. So the longer you have the hip replacement,
the higher the risk, potentially? Potentially,
yes. The cumulative risk increases. Beyond these
specific diagnoses, age -linked comorbidities,
particularly osteoporosis and cognitive decline,
pose substantial and compounding challenges.
Osteoporosis, as you might expect, doesn't just
make fractures more likely. It also makes them
significantly harder to stabilize once they occur.
The bone itself just lacks the structural integrity
for screws or plates to hold securely. Right.
Fixation becomes a real issue. A major issue.
And cognitive decline, on the other hand, creates
this cascade of risks. It impairs a patient's
judgment and balance, making falls more frequent.
But it also profoundly impacts their ability
to understand and comply with the complex post
-surgical regimens, things like weight -bearing
restrictions or specific movements, which are
absolutely vital for successful recovery and
preventing further complications. It's a truly
holistic risk picture, you see. It sounds like
a deeply intertwined web of patient health and
as you touched upon, the implant itself. On that
note, what about the implant design and the surgical
technique itself? How do those contribute to
the risk profile? Are there certain choices or
technical considerations that increase or decrease
the likelihood of these fractures? Indeed. Implant
design and the meticulousness of surgical technique
play a profound role. Several key factors here
are well established. Stem malposition during
the initial surgery, for instance. Ah, placement.
Exactly. Where the femoral stem isn't aligned
perfectly, that can create stress risers in the
bone, making it more prone to fracture. Pre -existing
osteolysis, that's bone loss due to where particles
from the implant or asymptotic loosening of the
implant, means the bone around the prosthesis
is already compromised before any trauma occurs.
Right, it's weakened. It's weakened already.
And the patient's surgical history specifically,
the number of previous surgeries to the same
region also increases risk, often due to altered
anatomy, scarring, and reduced blood supply.
Now, when we delve into implant types, cementless
femoral implants have been consistently associated
with a higher incidence of periprosthetic fractures,
both during the surgery itself and in the postoperative
period. Okay, cementless specifically. Yes. For
example, studies have indicated that intraoperative
fractures occur up to 14 times more often with
uncemented components. 14 times? Wow. It's significant.
And this risk is particularly pronounced in female
patients over 65 years old who receive unsubmitted
components, highlighting a specific vulnerable
subgroup. While postoperative fractures are also
more common with unsubmitted implants, interestingly,
this seems to be independent of age and gender.
Interesting. Specific implant designs also matter
significantly. There's been a notable three -fold
increase in periprosthetic fracture rates observed
with single -wedge and double -wedge implants
when compared to anatomical, fully -coated, or
taper -drowning components. For shape matters.
The shape and how it engages the bone absolutely
matters. The difference lies in how these stems
engage with the bone and distribute stress. For
cemented implants, exitotype, or force -closed
stems, which are designed to subside slightly
into the cement mantle, creating stability through
a wedge effect. They tend to show a higher risk
of periprosthetic fracture than charnel type
or composite beam stems. Charnel type aim for
more rigid fixation and distribute stress differently
along the bone cement interface. It's a fundamental
difference in biomechanical philosophy that directly
impacts how the implant interacts with the bone
and consequently its susceptibility to fracture.
That makes sense. And lastly, Paraprosthetic
acetabular fractures are typically linked to
unsubmitted press -fit elliptical cups, again
due to the mechanics of their initial fixation.
So yes, the choice of implant, its precise placement,
and its inherent biomechanical properties are
absolutely paramount. That level of detail on
implant mechanics is crucial. Now, once a fracture
is suspected, the initial assessment is, as you
said, absolutely critical. What's involved in
thoroughly evaluating these cases? And how do
classification systems guide your decision making,
especially considering the challenges you mentioned
in preoperative stability confirmation? Right,
the initial clinical and radiological assessment
is the absolute cornerstone of managing these
complex cases. It always begins with a detailed
clinical history and a thorough examination.
Most patients present following a low -energy
trauma, so establishing that clear context is
vital. However, it's equally crucial to dig deeper
and ascertain if there were any pre -existing
worsening symptoms before the acute injury. Ah,
like warning signs. Exactly. Things like persistent
thigh pain, the notorious start -up pain, or
groin pain. These could be subtle indicators
of an already loose or failing prosthesis, which
would fundamentally alter your management strategy.
A critical, often overlooked step is actively
ruling out infection. periprosthetic joint infection,
or PGI. It's been reported in about 11 .6 % of
periprosthetic fractures. 11%, that's quite high.
It is, and it can be devastating. However, a
significant challenge is that standard inflammatory
markers like white cell count, ESR, and CRP,
while healthful, have been shown to have, well,
poor predictive value for deep PGI. So they aren't
reliable enough on their own? Not always, no.
If clinical suspicion for PGI is low, we typically
proceed with surgery. taking multiple intraoperative
tissue samples for culture and histology to confirm.
But if there's a high clinical suspicion based
on the patient's history or exam, preoperative
aspiration and biopsies are strongly recommended
to guide subsequent antibiotic and surgical planning.
You need that information up front. Makes sense.
Radiological imaging is, of course, vital. Full
-length X -rays of the entire femur extending
from the hip to the knee and a comprehensive
pelvis view are essential. These allow us to
determine the fracture's precise location, its
characteristics as it's spiral, transverse, commonoted,
and crucially, to assess the prosthesis' stability
and, for cemented components, the integrity of
the cement mantle. It's also incredibly helpful
to retrieve all previous imaging, if available.
A patient's radiological history can often reveal
subtle signs of component migration or pre -existing
osteolysis, guiding us to potential weak spots.
Looking for changes over time. Exactly. A CT
scan is also standard practice now. It provides
more detailed information on bone stock, the
exact fracture pattern in three dimensions, and
the integrity and stability of the components,
especially around the stem. Now, regarding the
challenge of preoperative THA stability confirmation,
you hit on a key point. There's a reported 20
% discrepancy between what we think we see on
preoperative imaging and what we actually find
intraoperatively. 20%. That's a big gap. It's
a significant gap. Indirect methods such as assessing
distal implant translation or using fluoroscopy
in the clinic are often inconclusive if they
are negative. Ultimately, the most reliable method
remains the hands -on intraoperative assessment
during surgical exploration. So you really only
know for sure once you're in there? Pretty much.
This 20 % discrepancy isn't just a number. It
fundamentally shifts how surgeons must approach
these cases. It forces an extraordinary level
of intraoperative adaptability. A true test of
surgical intuition, beyond what any scan can
tell you beforehand. It highlights the art as
much as the science of orthopedics. This is why
thorough planning with clear contingency strategies
is absolutely crucial. You have to be ready for
Plan B or even Plan C. That 20 % unknown is enough
to keep any surgeon up at night, isn't it? So
once you have that comprehensive assessment,
understanding these nuances, How do classification
systems like the Vancouver system help guide
precise management decisions, especially given
those diagnostic challenges you highlighted?
Indeed, it emphasizes the need for surgical readiness.
Classification systems are absolutely fundamental
to guiding management. They provide a common
language and a framework. The Vancouver classification
system remains by far the most widely used and
accepted system for femoral pair prosthetic fractures.
It's rather elegant in its simplicity, categorizing
fractures based on three key parameters. The
precise location of the fracture relative to
the implant, the stability of the implant itself,
and the quality of the surrounding bone. Okay,
location, stability, bone quality. Precisely.
To quickly summarize its main types, AG describes
fractures of the greater trochanter, AL for the
lesser trochanter. Then we move into the more
complex B types, which are around the stem. B1
indicates a fracture where the implant is stable.
B2 means the implant is unstable. And B3 signifies
an unstable implant combined with poor, deficient
bone stock. Okay, B1 stable, B2 unstable, B3
unstable, plus bad bone. You've got it. Finally,
type C fractures occur well below the stem tip.
However, despite its widespread utility, the
Vancouver classification has its limitations.
A significant finding from a Swedish study, for
instance, revealed only a 34 % agreement between
surgeon and radiologist classifications for B1
fractures. Only 34 % agreement? That's low. It
is surprisingly low. Yeah. And it dramatically
highlights the real challenge in accurately differentiating
a B1 from a B2 based solely on radiographs before
surgery. This again underscores why intraoperative
assessment of stem stability through direct palpation
and manipulation is absolutely paramount to confirm
the classification and therefore guide the definitive
treatment. So the x -ray gives you a clue, but
the final decision is made in theater. Essentially
yes. Beyond Vancouver, the Unified Classification
System, or UCS, is a newer, more comprehensive
system. It's designed to classify all paraprosthetic
fractures, regardless of their anatomical site,
so not just the hip. It's shown strong intra
-observer agreement for experienced orthopedic
surgeons around .920, which is good, but notably
lower for residents at .772, indicating there's
a learning curve. Right. It's a broader role
in everyday clinical decision -making versus
research is still being thoroughly evaluated.
We also have other... more specific systems,
such as the Poprosky system and Pasquerella et
al.'s method, tailored specifically for periprosthetic
acetabular fractures. These systems provide a
vital framework, but as you rightly pointed out,
profound clinical judgment, continuously informed
by intraoperative findings, is always the ultimate
guide. So we've nailed down how to classify these
fractures, but the real challenge, the art of
orthopedics, begins now. Yeah. Choosing the right
weapon for the right battle. Because, as you've
highlighted, a Vancouver B3 is a world away from
an AG fracture. How do you even begin to tailor
a strategy when there's no true one -size -fits
-all for such varied injuries? What are those
fundamental principles guiding your approach
to optimal management? You've perfectly articulated
the core dilemma. There's simply no cookbook
for these cases. A highly individualized approach
is utterly essential. Treatment decisions must
carefully consider a whole constellation of factors.
The patient's existing comorbidities, are they
diabetic? Do they have cardiac issues? What were
their functional levels before the fracture?
What's the confirmed stability of the implant?
And critically, what are the available resources
and surgical expertise? That last point is important,
isn't it? Not every hospital has the same kit
or experience. Precisely. Not every center has
the same level of specialized equipment or surgeon
experience with complex revisions. And not infrequently,
multidisciplinary input is critical, often involving
geriatricians, infectious disease specialists,
or intensivists. There's a growing recognition
of the need for focused clinical pathways for
paraprosthetic fractures, mirroring what we've
successfully implemented for other fragility
fractures like native hip fractures. Ah, like
the neck of femur pathways. Yes, exactly. This
signifies a systemic evolution in how we approach
comprehensive care, moving beyond just the immediate
surgical fix to a more holistic standardized
patient journey. Historically, non -operative
treatment of paraprosthetic fractures has generally
been associated with pretty dismal outcomes.
We're talking non -unions, malunions, and significantly
increased medical complications. This is why
operative intervention is now overwhelmingly
the contemporary choice for almost all cases.
The only real exceptions are critically ill patients
who simply cannot physiologically withstand major
surgery. However, it's worth noting some newer
emerging evidence on anabolic drug therapies
like teraparotide combined with specific non
-operative protocols. Even for very minimally
displaced B2 fractures, this could potentially
offer an alternative for extremely frail patients
who are otherwise inoperable. Still early days,
perhaps. Interesting potential development there.
It is. Once surgical treatment is decided, several
fundamental principles come into play. Meticulous
preoperative planning is paramount. And this
isn't just a cursory glance at x -rays. It involves
detailed revision templating, virtually placing
implants on images to plan size and position,
and verifying that all appropriate surgical kits,
including revision instruments and possible backup
implants, are physically available in the hospital.
Checking the kit beforehand is vital. Absolutely.
The surgical approach must be chosen carefully
to minimize soft tissue damage, preserving the
critical blood supply to the bone. And, given
the potential for unexpected findings, particularly
with that 20 % discrepancy we discussed, having
robust backup plans for different scenarios is
always essential. This truly highlights the necessity
of having combined advanced trauma and arthroplasty
skills within the operating team. You need both
skill sets. You really do. The overarching aim
of the procedure is always consistent. Restore
anatomical alignment with a stable implant. preserve
existing bone stock wherever possible, promote
predictable fracture union, and, crucially, enable
early patient mobilization and preservation of
joint motion. The specific choice of implant
and technique is then ultimately guided by the
fracture's precise location and complexity, the
prosthesis's confirmed stability, and the quantity
and quality of remaining bone stock. all balanced
against individual patient factors like their
physiology, bone healing potential, and any existing
comorbidities. That's a remarkably comprehensive
framework. Let's talk specifics now, starting
with Vancouver type A fractures, which involve
the proximal trochanteric region. How are these
typically managed and what are the nuances for
each subtype? Right, Vancouver type A fractures
are typically the least complex. They involve
either the greater trochanter, classified as
AG, or the lesser trochanter, AL. For AG fractures
involving the greater trochanter, these are generally
considered stable fractures. They're very often
managed not operatively. So no surgery usually?
Often not. Just a period of protected weight
bearing and restricted active hip abduction for
approximately 6 to 12 weeks. This allows the
trochanter to heal in place. However, surgical
fixation, using simple techniques like wires,
cables, or small, speculized plates, becomes
indicated if there's a symptomatic nonunion,
meaning persistent pain, or functional issues
like limping or weakness. OK. Or if there's significant
migration of the trochanter fragment, typically
defined as more than 2 centimeters displacement.
And if the fracture is also associated with particle
-induced osteolysis, which is that bone loss
to -to -wear particles, the underlying osteolysis
must also be addressed. Right, tackle the root
cause. Exactly. Depending on the extent of bone
loss and the stability of the main implant, this
might range from a simple bearing surface exchange
with bone grafting to a full acetabular and femoral
stem revision. As for AL fractures affecting
the lesser trochanter, these are usually treated
non -operatively, similar to undisplaced AG fractures.
Also non -op usually. Yes. The rationale here
is that the lesser trochanter is often not critical
for hip stability. Surgical intervention is typically
only considered if the fracture is unusually
large and extends into the calcar region of the
femur, potentially compromising the stability
of the main stem. In such rarer cases, circlage
wiring, where wires are wrapped around the bone
to provide compression with or without grafting,
or even stem revision with diaphysial fixation,
may be necessary. If an ale fracture occurs and
is identified intraoperatively, which is common
due to instrument placement, circlage wiring
is usually advised immediately to prevent displacement,
followed by a period of protected weight bearing
post surgery. So, relatively less invasive approaches
for type A fractures unless there are those specific,
complicating factors. Now let's move to Vancouver
type B fractures, which you noted are arguably
the most challenging category and certainly the
most prevalent. How do you approach these, starting
with B1, where the prosthesis is stable but the
bone around it is fractured? Yes. Type E fractures
truly represent the bulk of the challenge. They
account for the vast majority, with B1 at maybe
29 % and B2 at 53 % in some large registries
like the Swedish hip arthroplasty register. So
B2 is the most common overall? It often appears
to be yes. The difficulty often lies in accurately
determining the prosthesis' stability and the
bone stock quality, even interoperatively. For
subtype B1 fractures, which occur around a stable
prosthesis, the conventional approach is indeed
open reduction and internal fixation, or RIF,
primarily using extra medullary devices such
as plates and circlage cables. Fixing it with
plates and wires. That's the traditional idea.
However, this approach comes with significant
inherent challenges. These extramedulary implants
were off -axis load -bearing devices. This means
they are exposed to incredibly high -bending
stresses, particularly when the patient begins
weight -bearing. Ah, the physics work against
you. They do. Combined with the typically slow
bone healing process in elderly patients who
often have osteoporotic bone, this can frequently
lead to early fatigue failure of the plating
system before bony union is achieved. The very
nature of osteopenic or osteoporotic bone, coupled
with the existing stiff implant or cement mantle,
severely complicates screw anchoring and fixation.
It substantially increases the risk of mechanical
failure. The screws just don't hold well enough.
Exactly. There's also the potential for the existing
cement mantle to fracture during screw insertion
and a negative impact on the already compromised
intramedullary blood supply due to prior reaming
or the exothermic reactions of cement. So, to
address these issues, modern techniques often
favor bridging locking plates. These plates act
as strong extra medullary bridging splints, creating
a fixed angle construct that is ideal for osteopenic
bone. Locking plates. How do they help? Well,
they are considered more biologically friendly
because they don't rely on plate -to -cortex
friction or precise screw thread purchase for
stability. They lock into the plate, providing
angular stability. This preserves the crucial
periosteal blood supply. Contemporary plates
feature anatomical designs, variable interlocking
options that allow surgeons to navigate around
the existing stem, extensions for trochanteric
fragments, and multi -directional screw placement
to target available healthier bone. These can
often be applied using minimally invasive plate
osteosynthesis or MIPO techniques. MIPO, so smaller
incisions. Yes, further reducing soft tissue
damage and preserving that vital blood supply.
Studies consistently show excellent union rates
and reduce complications with MIPO compared to
traditional open approaches for B1s. Crucially
though, surgical parameters must be meticulously
observed. Plate working length. That's essentially
how much of the plate bridges the fracture, should
ideally be two to three times the width of the
femur at the fracture level. Too short, and you
concentrate stress. Too long, and you might unnecessarily
stiffen the bone, risking a fracture at the plate
ends. Similarly, plate span width for Combinated
fractures dictates the length of the plate relative
to the shattered bone segment, typically two
to three times the fracture length. And critically,
plate screw density, aiming for less than 0 .5,
means strategically spacing your screws to distribute
load evenly and prevent stress risers that could
lead to early fatigue failure, especially in
compromised bone, spreading the load precisely.
While bicortical fixation is biomechanically
superior, if not possible, a combination of circle
-ish wires or cables for bending resistance,
combined with unicortical locking screws for
torsion and axial compression, can be used. And
a key rationale today is to use long plates that
span the whole femur. Sometimes even the entire
diaphysis. Protecting the whole bone. Yes, to
protect against future injuries, as these patients
are unfortunately prone to subsequent falls and
new stress risers. So, MIPO and advanced locking
plates are truly changing the game for B1 fractures,
allowing for more biologically friendly and robust
fixation. But you mentioned a fascinating paradigm
shift, even within B1, where revision might be
preferred over fixation despite a stable prosthesis.
That's truly counterintuitive. What's the biggest
hurdle for surgery? margins in making that shift
away from simply fixing a B1, and in what specific
scenarios does this alternative approach become
the superior choice? That's a really insightful
question, and it gets to the heart of evolving
surgical philosophy. The biggest hurdle is often
the initial inclination to preserve an apparently
stable, well -integrated femoral stem. You think,
well, why dismantle something that appears to
be working? Exactly. Seems like more surgery.
It is more surgery initially. However, for some
particularly challenging B1 fractures, revision
arthroplasty with a long stem, essentially acting
as an intramedullary splint, can genuinely be
a more effective and durable strategy. This is
especially true for short, oblique, or transverse
B1 fractures located precisely at the stem tip,
or very combinated fractures right there. Ah,
the really awkward ones at the tip. Precisely.
With an extramedullary plate alone, the construct
remains an off -axis load -bearing system. Achieving
optimal biomechanical strain at the fracture
site, especially where stress transitions acutely
from the very stiff proximal segment, which includes
the well -fixed existing stem and the proximal
part of the plate to the distal femoral fragment,
can be exceedingly difficult. This often leads
to delayed healing, non -union, or plate fatigue
failure, requiring further surgery down the line.
So the plate fix might fail eventually. It has
a higher risk of failing in those specific scenarios.
In these challenging B1 cases, the decision shifts
towards a more pragmatic approach. While it means
a greater initial surgical intervention by revising
an otherwise stable femoral stem, this is often
counterbalanced by the biomechanically advantageous
in -axis load sharing provided by the new, longer
femoral stem. This revised stem should extend
well beyond the fracture by passing the fracture
level by at least two cortical diameters, ideally
more, to act as a strong internal splint. Using
the new stem as the fixation. Exactly. Essentially
for these challenging B1s, the decision shifts
from a technically simpler fix to a patient -specific
strategy that prioritizes overall long -term
survival, earlier and safer mobilization, and
a more uneventful post -operative course. It
reduces the likelihood of repeat surgery. It's
about looking beyond the immediate fracture and
considering the entire biomechanical system and
the patient's overall journey. That's a profound
strategic shift. Now, if B1s can be this complex,
what happens when you're dealing with an unstable
prosthesis, as in subtype B2? But you still have
decent bone stock. How does that shift the treatment
paradigm? Right. For subtype B2 fractures, where
the prosthesis is confirmed to be unstable, but
the surrounding bone stock is still adequate,
the consensus approach is generally a long -stem
revision archroplasty. Revision is the main plan
here. Yes, generally. This is often supplemented
by additional plate fixation and or allograft
strut fixation to help consolidate the fracture.
Evidence strongly supports this. Systematic reviews
and data from national registries, such as the
SAR again, consistently show significantly higher
re -operation rates for B2 fractures treated
with RIF alone, around 32 % compared to a much
lower 10 % for those treated with revision surgery.
Big difference in re -operation rates. Huge.
This is because fixing the fracture without addressing
the underlying unstable implant is often doomed
to failure. The loose stem will just continue
to move and prevent healing. In these revision
surgeries, the choice of stem is crucial. Long
porous coated cementless stems or tapered fluted
modular titanium known as TFMT stems are very
commonly used due to their excellent discal fixation
capabilities in the healthier bone further down.
Getting fixation distally. Exactly. For very
frail or unreliable patients, or those with more
distal fracture extension and poorer bone stock
distally, cemented stems can also be considered.
They offer immediate stability for early weight
bearing, which can be critical in that group.
And as with B1 fractures requiring revision,
the new stem should bypass the most distal fracture
line by at least two cortical femoral diameters
to provide sufficient stability and protection
against refracture. Now there's an interesting
and unique nuance for periprosthetic fractures
that occur around cemented, polished tapered
stems, which are common implants like the Exeter
stem. Ah, the tapered ones. Yes. Due to their
design principle, they are forth closed and rely
on controlled subsidence into the cement mantle.
These stems are, by their very nature, inherently
unstable when a fracture occurs around them.
So while revision with a new long stem is still
considered the gold standard, or IFF alone can
sometimes be a viable option if the fracture
is reducible and the existing cement mantle is
well fixed to the bone. So fixing the bone might
be enough if the cement is solid? Potentially,
in selected cases. This approach can be less
demanding surgically, quicker, and potentially
involve less blood loss, which can be advantageous
for very sick or elderly patients. Some studies
have shown good results with this ORIF alone
approach in specific patient groups. However,
it's critically important to acknowledge that
other studies have reported higher non -union
rates when ORIF is used for B2 fractures, especially
if the underlying instability isn't fully accounted
for. It's a calculated risk. And, as I mentioned
earlier, for very frail, inoperable patients
with minimally displaced B2 fractures, anabolic
agents might even be considered for conservative
management, particularly around these specific
cemented stems. The key is truly individualized
decision making based on the whole picture. So
while revision arthroplasty is the undeniable
gold standard for B2s, there are indeed specific,
highly selected scenarios where ORF can be a
viable, less invasive alternative. What happens
then with subtype B3 fractures, where you're
dealing with both an unstable prosthesis, and
a severe, inadequate bone stock? This sounds
incredibly challenging, almost like trying to
build on sand. You've hit the nail on the head.
Subtype B3 fractures are exceptionally challenging,
precisely because of that combination. A loose
prosthesis and massive bone deficiency. It is
indeed often like building on crumbling ruins.
A real reconstructive nightmare. It can be. The
primary treatment options typically involve major
femoral component revision, often requiring techniques
like using a proximal femoral allograft that's
cadaver bone. Right. Or even a proximal femoral
replacement, where you replace the whole top
end of the femur with metal. Impaction grafting,
where a morselized bone graft is tightly packed
into defects, can also be used effectively for
large, contained bone defects, essentially rebuilding
the foundation. Surgeons have an array of specialized
implants available for these complex reconstructions.
Fully portis -coated stems, tapered fluted stems,
modular or monoblock designs, distally locking
stems, and as I said, dedicated proximal femoral
replacement prostheses. Lots of options, but
complex ones. Very complex. The key here isn't
just having these implants, but surgeon familiarity
with the chosen system and the ability to apply
a reproducible meticulous surgical technique,
often refined over many years. Achieving adequate
distal stem stability in the dysphysial bone
is paramount. Sometimes it's the only healthy
bone available for fixation. Meticulous preoperative
templating along with careful intraoperative
assessment of leg length and overall stability
is crucial to prevent postoperative issues. It's
also vital to preserve as much proximal metaphysical
bone as possible, even if it's fractured, and
to wrap the remaining femur with its soft tissue
attachments around the new prosthesis. This provides
biological stability and optimizes muscle function.
Trying to solid everything you can. Absolutely.
Allograft prosthetic composites, which combine
a cadaveric bone segment and allograft with a
new prosthesis, can be invaluable for massive
bone loss. particularly in younger patients where
long -term durability and bone stock restoration
are priorities. These can be used with uncemented,
cemented, or partially cemented techniques depending
on the specific case. And finally, for older
patients with severe bone efficiency or very
poor prognosis, a proximal femoral replacement
despite a relatively high complication rate and
the sheer magnitude of the surgery can sometimes
be the only viable option to get them mobilized.
A last resort in some ways. In some ways, yes.
These B3 cases They are often the ones that truly
test a surgeon's mettle, not just technically,
but in terms of resourcefulness and judgment.
You have to be prepared for almost anything,
knowing you might be trying to build a stable
foundation on what often feels like crumbling
ruins. It's clear that B3s demand an extraordinary
level of reconstructive surgery and planning.
Now, moving away from the area immediately around
the stem, what about Vancouver type C fractures,
which occur well below the implant tip? How do
these differ in their management strategy? Right.
Vancouver type C fractures are distinct because
they are located in the distal third of the femur,
well below the femoral stem. Typically more than
two to three times the femoral diameter discol
to the implant tip. Critically, these fractures
do not compromise the stability of the hip prosthesis
itself, which remains well fixed proximally.
So the hip joint part is okay? Exactly. Therefore,
the primary treatment involves open reduction
and internal fixation using standard osteosynthesis
techniques. Mostly bridge plating or, less commonly,
retrograde nailing from the knee end. The key
principle here is that while the hip prosthesis
itself is stable, its presence in the proximal
femur must be accounted for to minimize the risk
of secondary fractures or stress risers forming
between the hip stem and the new fixation distalate.
Ah, avoiding a weak spot in the middle. Precisely.
Even if a short plate might appear biomechanically
adequate for the immediate fracture, the contemporary
consensus born out of experience is to protect
the entire diaphysis by overlapping the femoral
component proximally. Anchoring proximally with
crooklish cables or screws around or past the
tip of the stem, this approach ensures a better
balance of the construct's working length, plate
span width, and crew ratio, distributing stresses
more evenly across the bone. More importantly,
it provides crucial protection against future
injuries. You're thinking ahead again. Yes, as
these patients are highly susceptible to subsequent
falls that could easily lead to new fractures
if parts of the diaphysis are left unprotected,
creating a new stress riser at the end of a short
plate. Therefore, most surgeons now prefer to
span the whole femur with a long retrograde locking
plate, ensuring maximum fixation at the distal
metaphysis and a combination of screws and cables
proximally. This is about preventing the next
fracture, not just fixing the current one. So
we've taken a deep dive into femoral periprosthetic
fractures, which are undoubtedly the most common
and challenging. But what about those equally
demanding, albeit less frequent, fractures involving
multiple implants, known as interprosthetic femoral
fractures, or those affecting the acetabulum?
Let's start with interprosthetic femoral fractures.
Right. Interprosthetic femoral fractures or IFFs.
These are defined as fractures occurring between
an ipsilateral hip and knee implant. So a hip
replacement and a knee replacement on the same
leg. Exactly. And the fracture happens in the
femur shaft between those two prostheses. While
still relatively uncommon, they represent a growing
challenge in our practice. They account for about
5 % to 7 % of all paraprosthetic femoral fractures,
and their incidence will certainly rise as more
patients receive both implants. That makes sense.
Classification is absolutely key here to guide
treatment. Pyres et al.'s 2014 classification
is considered the most comprehensive. It strategically
divides IFFs into three major categories based
on the fracture location, the stability of both
the hip and knee implants, and importantly, whether
there's a stemmed knee femoral component, as
this significantly impacts reconstructive options.
This system then provides a guiding treatment
algorithm based on these variables. So it considers
both ends? Precisely. For management, if both
the hip and knee implants are stable, then fracture
fixation is the primary approach, with locking
plates being the implant of choice due to their
versatility and fixed angle stability. However,
if either the hip or knee implant or both are
unstable, then revision arthroplasty of the unstable
component is necessary, often supplemented by
internal fixation to stabilize the fracture itself.
Right, address the loose bit first. You have
to. For complex or severe cases, especially those
with significant comminution or bone loss, various
composite constructs, including intramedullary
options where a rod is placed inside the bone
and strike grafting, can provide both intra -
and extramedullary stability. A critical surgical
principle, regardless of the chosen strategy,
is to bypass the fracture adequately, avoid creating
new stress risers at the ends of implants, and
ideally span the entire femur between the two
prostheses, or at least overlap the prosthesis
by at least two cortical diameters beyond the
fracture. In the most severe cases, particularly
certain pyres types, especially with poor bone
stock, options can include advanced arthroplasty
with adjuvant fixation or even total femur replacement.
That's a truly massive reconstructive procedure.
Releasing the whole thigh bone. Essentially,
yes. The outcomes for IFFs can be quite challenging,
reflecting the complexity of these injuries and
the often frail patient population. Reported
non -union rates are around 8%, with mortality
rates around 6 .5 % and revision rates for failure
at about 10 .7%. However, it's worth noting that
some studies, such as Bonviale et al.'s series,
have reported significantly higher mortality
rates, up to 31%, and revision rates of 24%.
31 % mortality? That's very high. It is sobering.
These statistics truly underscore the fragile
nature of this patient cohort and the absolute
necessity for meticulous planning and execution
to avoid catastrophic failures. Those mortality
rates are indeed sobering, highlighting the severe
challenge these fractures pose. Now, turning
our attention to the acetabulum at the socket
side, periprosthetic acetabular fractures are
less common, but I imagine equally, if not more,
severe and challenging to treat. What are the
unique aspects of these injuries? Absolutely.
Periprostatic acetabular fractures, while less
common than the femoral ones, present profound
challenges to the surgeon. Their incidence is
also expected to rise with the increasing numbers
of elderly and more active individuals undergoing
THA. These fractures can occur either intraoperatively,
during the primary or revision surgery, or postoperatively.
Intraoperatively, they are most frequently associated
with uncemented press fit elliptical cups. The
uncemented cups again? Yes, where the force of
insertion can cause micro -fractures or larger
breaks. They're also more common during revision
THRs than primary ones, often due to a combination
of patient factors like severe osteoporosis and
surgeon -related technical challenges in working
with altered anatomy or removing old components.
Post -operatively, they can result from high
-energy trauma or more commonly from severe bone
loss due to underlying conditions like osteoporosis,
aseptic loosening of the implant, osteolysis,
pelvic discontinuity we will discuss in a moment,
malignancy or infection. So similar underlying
causes to femoral fracture sometimes. Similar
risk factors, yes, but manifesting in the pelvis.
For classification, the Proprosky system is commonly
used, describing various types based on the extent
and location of bone loss and fracture patterns.
Pascarella et al. have also presented a comprehensive
system that guides surgical planning based on
the timing of diagnosis, the stability of the
acetabular prosthesis, and the pre -injury arthroplasty
state. Diagnosis requires a highly comprehensive
approach to identify and precisely classify the
fracture and, crucially, determine the stability
of the implant. Interoperative fluoroscopy can
be immensely useful to confirm reduction and
fixation during surgery. Postoperatively, patients
typically present with significant pain, loss
of function, reduced range of motion, inability
to weight -bear, or a leg -length discrepancy.
In acute traumatic injuries, there's even a potential
for life -threatening hemorrhage due to the rich
vascularity of the pelvis. Bleeding is a major
risk there. A very significant risk. Imaging
includes plane radiographs, standard AP pelvis,
Judith views, which highlight specific pelvic
columns, and inlet -outlet views and CT scans
with 3D reconstruction. These are essential to
provide detailed information on the fracture
pattern, the extent of bone loss, and the relationship
of the implant to the bone. In cases of severe
displacement, CT and geography may even be recommended
to rule out potential vascular injuries. So once
diagnosed, what are the core treatment principles
for these acetabular fractures? Especially given
the complexities of bone stock and component
stability, it sounds like a delicate balance
between fixation and revision. That's precisely
the challenge. The fundamental treatment principles
for perprostetic acetabular fractures revolve
around achieving a stable acetabulum that can
adequately support the component, preventing
any micromotion at the implant bone interface.
This almost always necessitates adequate bone
stock with or without additional augmentation
to ensure secure implantation and long -term
stability. For intraoperatively identified fractures,
If they are undisplaced and the cup is stable,
they can sometimes be left in situ with standard
rehabilitation. But supplemented screw fixation
of the cup is generally recommended to provide
additional stability and reduce the risk of secondary
displacement. Add a few screws for safety. Usually
a good idea. If the cup is unstable and there's
fracture displacement, the meticulous open reduction
and posterior column plating followed by the
insertion of a revision cup is advised. For missed
intraoperative fractures, which can happen, close
follow -up with serial radiographs is critical
to monitor for any delayed displacement or cup
migration, which would then necessitate revision
surgery. Keep a close eye on them. Definitely.
For postoperative fractures, acute traumatic
undisplaced fractures with a stable cup may initially
be treated conservatively with protected weight
bearing and gentle mobilization. However, close
follow -up with serial radiographs is mandatory
due to the insidious risk of secondary loosening
even if the fracture appears to heal. So even
if it looks okay initially? It can loosen later.
If that occurs, revision surgery over consolidated
bone may be needed. However, if the fracture
fails to heal, or if there's an unstable fracture
pattern with an unstable component, then prompt
ORF, most often posterior column fixation combined
with revision surgery, is unequivocally required.
And what about pelvic discontinuity, which sounds
particularly severe. Can you elaborate on what
that is and how it's approached? Pelvic discontinuity,
or PD, is indeed a particularly challenging condition.
Imagine the acetabulum, the socket of the hip
joint, actually detaching or splitting from the
rest of the pelvis, essentially losing its structural
integrity in both the anterior and posterior
columns. The whole socket breaks away. Effectively,
yes. It's a catastrophic failure of the bone
that normally supports the hip cup, making reconstruction
incredibly complex because you're trying to reestablish
a stable ring from what is now two separate fragments.
Treatment for PD is highly individualized, factoring
in bone quality and quantity, the soft tissue
environment, and the patient's overall health
and functional demands. Rogers et al. proposed
a useful algorithm distinguishing between acute
and chronic discontinuity. Acute, mobile discontinuities
are typically treated with RAF and revision surgery,
aiming to anatomically reduce and fix the fracture
while simultaneously revising the unstable cup.
Chronic, more rigid discontinuities where the
fragments have healed in a malunited or non -united
position often require a more extensive approach,
commonly a cupcage reconstruction. What's that?
It's essentially a mel construct, often made
of titanium, that bridges the gap between the
separated pelvic fragments and provides a stable
platform to cement or fix a new cup into. It
bypasses the deficient bone. Other options for
managing pelvic discontinuity include the use
of robust column plates to bridge the defect,
structural grafting to fill bone voids, anti
-pertrusio cages to prevent the cup from migrating
inwards into the pelvis, or jumbo cups, often
combined with porous trabecular metal augments,
particularly for cases with good healing potential
and minor bone loss. For chronic cases with little
inherent support and poor of vascular bone, distraction
techniques like a cupcage are often invaluable.
They literally bridge the gap, allowing bone
to potentially heal around them and create a
new stable bridge. In situations of truly massive
bone loss, a triflange component, which is a
custom -made implant based on the patient's CT
scan, is typically required. It essentially rebuilds
the complex pelvic anatomy with metal flanges
that fix the remaining healthy bone. Extremely
complex. Other techniques might include impaction
grafting, non -cemented hemispherical reconstruction,
structural allografts though largely superseded
by porous metal augments, now oblong cups, or
other cages like Gans and Virtschneider or the
Kerbal Tanaka Plate. The key is selecting the
technique that best reestablishes the structural
integrity of the acetabulum and allows for secure
long -term cup fixation. We've covered a remarkable
amount of ground on the clinical management and
the sheer technical complexity. So what does
this all mean for the patient in the long run?
Given these complexities, what are the typical
outcomes? And crucially, what are we doing as
a field to prevent these fractures in the first
place? And what does the future hold for orthopedic
practice in this area? Right, the overall outcomes
and complications for periprosthetic hip fractures
really highlight their significant impact on
patients' lives. In the acute phase, these fractures
carry a mortality risk comparable to that of
native neck of femur fractures in the elderly.
Same mortality as a standard hip fracture. Initially,
yes, which is a stark comparison. We see a one
-year mortality rate reported at around 9 .7%.
This risk does seem to decrease significantly
after the initial six months post -surgery, which
suggests that critical early period is key. The
overall 30 -day complication rate is notably
high at 45%, with a concerning 22 % being major
complications and 13 % minor, and a 30 -day mortality
rate of 10%. 10 % mortality in 30 days. Yes.
It's critical to note that significant risk factors
for these adverse outcomes include a patient's
abbreviated mental test score, or AMTS, of 8
out of 10 or less, indicating some level of cognitive
impairment and a delay to surgery of more than
72 hours. So cognition and timing matter hugely.
Absolutely. This underscores the need for rapid
assessment and intervention, as well as comprehensive
geriatric co -management. Functional and radiological
outcome data are somewhat limited, largely due
to the wide diversity of fracture types, the
varied treatment approaches, and the high morbidity
and mortality rates inherent in this patient
population, not to mention characteristics like
those low AMTS scores. However, studies generally
indicate that patients undergoing revision for
periprosthetic fractures tend to have worse functional
outcomes compared to those revised simply for
aseptic THA loosening. Worse function than a
standard revision? Generally, yes. Functional
impairment is common, with studies showing around
41 .9 % of patients may not return to their pre
-injury walking status. That's a truly significant
impact on their quality of life. The most unfavorable
prognosis in terms of both survival and functional
return is typically seen after a B3 fracture,
given the extent of bone loss and surgical complexity
involved. As for arthroplasty longevity after
these revisions, long -term data are rather sparse
due to the high mortality and restricted follow
-up in this frail cohort. Though short - to mid
-term studies generally report high union rates
in stable implants, we need more long -term data.
Beyond the immediate outcomes, infection is always
a major concern in orthopedic surgery, and I
imagine paraprosthetic joint infection, or PJI,
is a critical and potentially devastating complication
here. What's the situation with PJIs in this
context? PGI is indeed a critical complication,
and its incidence is unfortunately rising in
parallel with the increasing number of arthroplasty
procedures globally. This leads to significant
morbidity and mortality, and the cost of treatment
is truly substantial, particularly in regions
with limited health insurance access. It's a
huge burden. A massive burden. Effective management
demands a high level of teamwork, involving a
dedicated multidisciplinary team. That includes
microbiologists, histobiologists, pathophysiologists,
working alongside orthopedic surgeons, often
guided by clear radiological imaging and comprehensive
laboratory results. Diagnosis relies on a combination
of strong clinical evidence and, crucially, identifying
the causative organism. Preoperative testing
typically includes hematological markers such
as ESR and CRP, advanced imaging like x -rays,
maybe PD scans, and synovial fluid analysis looking
at cell counts, leukocyte esterase, and most
importantly, cultures. However, intraoperative
tissue samples, taken from multiple sites within
the joint during surgery, are vital for definitive
diagnosis and identifying the specific pathogen.
Newer methods such as PCR are also becoming more
available, offering quicker and potentially more
sensitive detection. Getting the right bug is
key. Absolutely essential for targeted treatment.
The treatment algorithm for PJI is complex. For
acute infections occurring soon after surgery,
debridement, antibiotics and implant retention,
or DARE, is often considered. However, for infections
older than three weeks, where biofilms have likely
established on the implant surface, a multi -stage
approach, often guided by algorithms like Zimmerle's,
may be necessary. Biofilms make it much harder.
Much harder. In some severe intractable cases,
a salvage operation like arthrodesis, fusion
of the joint, or even amputation might be the
only option left. The most common choice among
surgeons, and generally considered the gold standard
for chronic PGI, is a two -stage exchange. Two
stages? How does that work? The first stage involves
complete removal of the implant, thorough debridement
of all infected and devitalized tissue, and temporary
installation of an antibiotic -impregnated cement
spacer into the joint space. A spacer with antibiotics.
Yes, delivering high local concentrations. After
an interim waiting period, typically two to six
weeks or even longer, allowing systemic antibiotics
to take effect and infection markers to normalize.
The second stage involves implanting a new prosthesis
and taking further tissue biopsies to confirm
infection eradication. Patients usually receive
a prolonged course of oral antibiotics, often
for six weeks or more, following the second stage.
It's also important to consider special patient
conditions, like immunosuppression or cognitive
decline, and country -specific challenges, such
as delayed presentation due to financial constraints
or limited access to certain antibiotics in developing
nations, all of which complicate effective management.
That's a comprehensive yet daunting approach
to managing a potentially devastating complication.
Given all these challenges, what proactive prevention
strategies are being implemented? And what does
the future hold for this field? Prevention is
absolutely crucial for patients' success and
to mitigate the rising burden of these fractures.
It starts long before surgery and continues long
after. Patient education, for instance, isn't
just handing them a leaflet. It's a deep dive
into realistic expectations, the absolute necessity
of compliance with rehabilitation protocols,
and a clear understanding of their physical limitations
and risks. We often involve physical therapists
in preoperative counseling to design personalized
home exercise programs, emphasizing not just
strength, but balance and proprioception to prevent
falls. Preventing the falls in the first place.
Exactly. And it's not just about what they do
after surgery. It's about optimizing their overall
bone health, now ensuring adequate calcium and
vitamin D intake, maybe even considering anti
osteoporotic medications like bisphosphonates
or teraparitide, if indicated. We also stress
environmental modifications, simple but critical
things like securing rugs, improving home lighting,
installing grab bars and bathrooms. It's a holistic
approach to fall prevention, recognizing that
one bad fall can undo all the surgical success.
Simple things can make a big difference. They
really can. Preoperative assessments are also
essential to identify high -risk patients. those
with atypical anatomy, significant fixed deformities,
or leg length discrepancies allowing us to tailor
prophylactic measures or choose specific implant
designs to minimize risk. During surgery, meticulous
implant positioning and fixation, maintaining
an impeccably sterile environment, and early
controlled mobilization are key to reducing post
-operative complications. Looking to the future,
the evolution of orthopedic implants continues
at a rapid pace, providing more surgical options.
However, there's a clear and ongoing need for
even more specially designed implants that can
better address the vast majority of paraprosthetic
fractures, particularly those with complex geometry
and significant bone loss. Better tools for the
job. Exactly. New concepts in fracture fixation.
such as plates with far cortical locking, which
offer unique biomechanical advantages by engaging
the opposite cortex. And active plating, where
the plate itself provides dynamic compression,
are emerging. These will require robust clinical
evidence and long -term studies to thoroughly
evaluate their outcomes in practice. The significant
remaining challenge is the limited robust data
on long -term functional outcomes and implant
longevity following revision surgery for periprosthetic
fractures. This is critical, especially as their
incidence is projected to continue rising. Interprosthetic
and periprosthetic acetabular fractures, while
currently less common, represent growing challenges
that demand further dedicated research and evidence
-based guidelines. Ultimately, the substantial
financial burden these complex injuries place
on healthcare systems globally highlights an
ongoing and pressing need for more effective,
predictable solutions. and perhaps a potential
move towards specialized regional centers to
provide optimal cost -effective care for these
highly complex cases. So, what does this all
mean for us as medical professionals? The management
of paraprosthetic hip fractures remains one of
the most complex and critical areas in orthopedic
surgery today. It's abundantly clear that successful
outcomes hinge on a deeply individualized approach.
One that seamlessly combines highly advanced
surgical skills with comprehensive patient assessment,
rigorous risk stratification, and meticulous
post -operative care. As the number of total
hip arthroplasties continues to rise globally,
so too will the incidence of these challenging
fractures, meaning this will remain a focal point
for decades to come. The ongoing need for innovation
in implant design, refined surgical techniques,
and robust long -term data for our decision -making
simply cannot be overstated. If you found this
deep dive valuable, please do take a moment to
rate and share this deep dive with a colleague
who might benefit. Join us next time on the deep
dive as we continue to explore the cutting edge
of medical knowledge. This raises an important
overarching question for all of us in the field,
doesn't it? How can we further collaborate across
disciplines and national borders to standardize
best practices, share learnings, reduce complications,
and ultimately improve not just survival, but
the meaningful quality of life for this increasingly
frail and complex patient population? The journey
of mastering paraprosthetic fracture management
is an ongoing one, a continuous learning curve
for us all.