Matthew W. Tetreault
Brandon J. Yuan
Matthew P. Abdel
Periprosthetic fractures around the knee are relatively uncommon.
Management considerations include fracture location and displacement, stability of the prosthesis, bone quality, and patient health.
Classification systems help categorize and guide the treatment of periprosthetic femur, tibia, and patella fractures.
Goals of operative treatment include:
A stable and well-aligned construct that allows early motion and weight bearing
Maximizing implant longevity while mitigating further complications
Supracondylar femur fractures continue to be the most common periprosthetic fractures around a total knee arthroplasty (TKA).
The evolution of locked plating and retrograde intramedullary nailing techniques decreased surgical morbidity and improved union rates in the setting of well-fixed implants.
Revision TKA with diaphyseal-engaging stems or distal femoral replacement may be indicated when the prosthesis is compromised, when adequate fixation and bony union is unlikely, or when a previous attempt at internal fixation has failed.
Nonoperative treatment is rarely indicated given a strong predisposition to stiffness.
Intraoperative periprosthetic tibia fractures are treated according to fracture location and pattern. Postoperative periprosthetic tibia fractures are rare and often associated with loose tibial components; the preferred management in this scenario is revision TKA.
Operative treatment of periprosthetic patellar fractures is associated with a high rate of complications and should be reserved for cases of extensor mechanism disruption and patellar component loosening. That topic is discussed in another chapter.
Sterile Instruments and Implants
Open Reduction Internal Fixation (ORIF)/Intramedullary Nail (IMN)
Routine knee retractors
Fracture reduction instruments (e.g., bone hooks, reduction clamps, Kirschner wires)
Femoral distractor versus sterile external fixator versus sterile skeletal traction to aid in provisional reduction
Metal-cutting, high-speed burr if the need to expand femoral box for IMN is anticipated
Routine knee retractors
A full set of revision TKA instruments to remove well-fixed implants while preserving bone, including:
Reciprocating and oscillating saws
High-speed burrs (e.g., short and long pencil-tip burrs, 6.5-mm round burr)
Cement removal instruments to clean out intramedullary canal
Trephines may be required if stemmed components are in place
Cerclage cables or wires and wire passers
Diaphyseal and metaphyseal reamers and revision TKA cutting jigs
ORIF/Retrograde IMN of the Femur
Periarticular distal femoral locking plates and retrograde intramedullary nails are commonly utilized for fixation of these fractures.
Locking plates amenable to “hybrid” constructs (with locked and unlocked screws) and polyaxial locking screws are favored over fixed-angle locking plates for these often complex fractures with deficient distal bone stock.
Have compatible polyethylene liners (and trials) available when a retrograde IMN is planned, as polyethylene liner removal can facilitate nail placement.
ORIF of the Tibia
Metaphyseal plates, buttress plates, and/or periarticular locking plates (preferred)
Stainless steel wire if fixation of tibial tubercle fracture is planned
Revision TKA system, including:
Tibial and femoral components with cemented stems
Increasing degrees of implant constraint, including varus-valgus constrained implants and rotating-hinge options
Not infrequently, a distal femoral replacement with a rotating-hinge construct is required
Metal augments, sleeves, and/or porous metal cones based on assessment of bone loss
Appropriate polyethylene liners
Patellar component from compatible manufacturer
Cerclage cables and/or Luque wires
Bone cement and cement plugs
ORIF/Retrograde IMN of the Femur
Supine on a radiolucent operative table. Of note, ORIF can also be performed in a lateral position.
In the case of fractures that show significant shortening preoperatively, it may be difficult to restore length off the fracture table. Before preparing the limb, consider the following:
With the patient under anesthesia with full muscle paralysis, an attempted reduction should be performed under fluoroscopy before preparing the limb. If length is difficult to restore manually, a femoral distractor, spanning external fixator, or sterile traction device should be used for the procedure.
The contralateral extremity should be examined to verify normal leg length and rotation. Femoral length can be evaluated using a radiographic ruler and fluoroscopy. Rotational profile can be gauged preoperatively by checking the internal and external rotation of the uninjured hip and by examining the normal resting position of the foot.
For ORIF, a bump under the ipsilateral hip aids in internal rotation of the limb and a sterile thigh tourniquet ensures access to the proximal thigh if needed. The extremity should be draped free from the anterior superior iliac spine to the ankle, with the entire hip included.
A radiolucent triangle, sterile towels, or sheets under the distal metadiaphyseal region of the femur create a bump to aid in reduction and facilitate imaging of the knee.
At least 40° of knee flexion is needed for intramedullary nailing.
One may consider preparing the well leg and including it in the operative field so that it may be elevated during lateral imaging of the operative femur.
Intraoperative fluoroscopy should come in from the uninjured side.
ORIF of the Tibia
Supine on a radiolucent operative table
Bump under ipsilateral hip to aid in internal rotation of limb
Sterile thigh tourniquet
Stack of towels or Bone Foam Ramp under the distal leg can facilitate imaging
Intraoperative fluoroscopy should come in from the uninjured side
Supine on a standard operative table
Nonsterile tourniquet placed high on upper thigh
Intraoperative radiographs in orthogonal planes should be obtained intraoperatively with trials in place. The x-ray machine will come in from the well side.
ORIF of the Femur
Exposure of the distal femur for ORIF is typically achieved through a lateral approach.
The exposure should be consistent with the planned reduction and fixation method. For comminuted fractures, the goal is a functional, indirect reduction and no direct exposure of the fracture site is necessary. As long as an acceptable reduction is obtained, only the distal aspect of the lateral exposure need be performed, and proximal screws may be placed percutaneously. For relatively simple fractures when direct reduction is planned, an extensile lateral incision with a subvastus approach to the femur is performed.
The distal aspect of the incision is curvilinear and centered over the lateral femoral epicondyle to Gerdy tubercle.
The incision can be extended proximally along the posterior aspect of the femur.
Effort should be made to maximize the skin bridge between the lateral incision and the anterior TKA incision.
Superficial dissection proceeds through the subcutaneous fat, and the iliotibial band is incised in line with its fibers and the skin incision.
The vastus lateralis is reflected anteriorly off the intermuscular septum to provide direct visualization of the periosteum.
The extent of dissection depends on the fracture pattern, the components in place, and the surgeon’s comfort level with percutaneous fixation techniques.
Minimization of soft tissue and periosteal stripping is paramount.
Perforating vessels that cross the field are coagulated or ligated; deliberate dissection is advised as transection of the perforating vessels can cause them to retract, making hemostasis difficult and blood loss substantial.
Exposure of the medial aspect of the distal femur is occasionally needed and can be achieved through an anteromedial approach.
A longitudinal incision is made over the interval between the vastus medialis and the rectus femoris.
Distally, the extensor mechanism is incised using a medial parapatellar arthrotomy.
This approach can be extended proximally as needed.
With proximal dissection, the vastus intermedius is incised in line with its fibers and elevated to expose the femoral shaft.
Care is required in the distal one-third of the medial thigh given the proximity of the femoral vessels within the adductor hiatus.
Retrograde IMN of the Femur
The starting point for a retrograde IMN can be accessed through the prior anterior knee incision.
A medial parapatellar arthrotomy is advised to allow subluxation of the patella and removal of the polyethylene liner (if a replacement liner is available) to facilitate access to the intercondylar notch.
ORIF of the Tibia
The proximal tibia can be accessed through an anterior exposure by extending a prior longitudinal TKA incision distally or through a separate medial or lateral approach (depending on fracture location).
Be mindful of spacing if using a separate incision given the potential for skin bridge necrosis.
Incisions should be medial or lateral to the tibial tubercle and not directly over this bony prominence.
An extensile longitudinal incision over the anterior knee that incorporates a prior TKA incision is favored for revision TKAs.
If several scars are present, incorporation of the most laterally based incision that will allow extensile exposure proximally and distally is preferred to preserve blood supply to the overlying skin.
Conservative, full-thickness skin flaps also help to minimize the insult to skin perfusion.
A medial parapatellar arthrotomy is most often utilized.
Mobilization of the patella can be difficult in the revision setting owing to scarring and patella baja.
Fastidious release of scar tissue in the suprapatellar pouch, the medial and lateral gutters, and behind the patellar tendon can help to mobilize the patella.
Mobilization of the patella can be further aided by proximal extension of the incision, lateral retinacular release, and a quadriceps snip. A low threshold to utilize a quadriceps snip in this setting is recommended given the exposure benefits and lack of need to modify postoperative rehabilitation.1
Removing the polyethylene insert helps relax the extensor mechanism.
Extensile exposures such as a tibial tubercle osteotomy or a V-Y quadriceps turndown are very rarely, if ever, utilized.
Exposure is facilitated by avoiding patella eversion with knee flexion. After the patella component is addressed in knee extension, the patella can be translated into the lateral gutter and retracted safely.
Key factors in determining the appropriate management of periprosthetic fractures around the knee include fracture location and displacement, stability and alignment of the current prosthesis, bone quality, associated functional deficits, and patient health. As such, a thorough clinical history, physical examination and radiographic review are paramount.
Mechanism and timing of injury
Soft-tissue envelope, including prior incisions or open wounds
Competence of extensor mechanism
Status of compartments
Avoid missing compartment syndrome, particularly with higher energy mechanisms of injury or in patients found down.
Orthogonal full-length radiographs of the injured extremity are needed.
Radiographs should include a complete knee series (anteroposterior [AP], lateral, and patellar views) and full-length AP and lateral views of the femur and tibia to evaluate the joint above and below the fracture.
Evaluation of the stability of the TKA components is key. In particular, the surgeon should evaluate for:
Radiolucency around implants
Change in component positioning or alignment
Fractured cement mantle
Comparison to preinjury radiographs
Make note of patellar height as this can provide insight regarding the integrity of the extensor mechanism.
Observe bone loss and quality of remaining host bone.
Note alignment and rotation of the implants, overall mechanical alignment of the limb, and other hardware or deformity that may affect operative planning.
Take care to screen for contributory pathologic lesions in this often older patient population, particularly in the setting of low-energy fractures (Figure 70.1A and B).
A computerized tomography scan may be warranted for periprosthetic fractures when the fracture pattern is poorly understood, to better assess bone stock around the implants, or when component stability remains in question after plain radiographs. This study can have the added benefit of providing insight into the rotation of components.
Figure 70.1 ▪ Anteroposterior (A) and lateral (B) hip radiographs of an interprosthetic fracture (knee replacement not pictured) revealing a moth-eaten cortex at the fracture site, which proved to be metastatic carcinoma on biopsy.
Figure 70.2 ▪ Illustration (A) and anteroposterior radiograph (B) of a Lewis and Rorabeck type I periprosthetic femur fracture (arrow). (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)
Fracture Classification and Treatment Options
The ideal classification scheme (1) facilitates communication between clinicians, (2) includes only relevant variables, (3) guides management, (4) has prognostic capabilities, and (5) is simple to use.2 We thus prefer the following classification schemes for periprosthetic fractures about the knee.
Lewis and Rorabeck3
Accounts for fracture displacement and integrity of the implant
Accounts for fracture location, integrity of the implant, and timing of the fracture (Figure 70.5)
Type I: Plateau
Type II: Adjacent to stem
Type III: Distal to stem
Type IV: Tibial tubercle
A: Well-fixed prosthesis
B: Loose prosthesis
Operative Planning and Templating
Every effort should be made to obtain the operative report and implant stickers for the index TKA, with particular focus on the surgical approach and components in place.
Full-length femur and tibia radiographs are crucial to detect any bony abnormalities (e.g., deformity) or other implants that may affect treatment.
We provide classification-based treatment considerations for femur and tibia fractures in the following text.
Type I: Nondisplaced fractures of the distal femur with a stable prosthesis may be treated nonoperatively or operatively. Nonoperative intervention consists of casting and restricted weight bearing with close radiographic follow-up. Disadvantages of nonoperative management include a fairly high
risk of malunion, nonunion, and posttreatment functional loss.5 Operative intervention in the form of plate and screw fixation or a retrograde IMN allows for earlier mobilization and range of motion, but with the inherent risks of surgery.
Type II: Treatment of displaced distal femur fractures with a stable implant can be approached in several ways. Considerations include fracture pattern, comminution, position and design of the femoral component (cruciate retaining or posterior stabilized), amount of bone attached to the femoral component, quality of host bone, and timing relative to the index procedure. Fractures that occur intraoperatively during the index TKA can usually be managed with use of a stemmed femoral component that bypasses the fracture site with or without supplemental fixation (cerclage cables or wires, plate and screws or lag screws; Figure 70.6A and B).
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