RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Treatment of Periprosthetic Femoral Fractures above a Total Knee Arthroplasty

Introduction

  • Periprosthetic fractures remain problematic complications after total knee arthroplasty. The number of knee arthroplasties performed worldwide continues to increase, and with the ever-growing elderly population, the number of periprosthetic fractures will continue to increase as well.

  • Approximately 300,000 primary knee arthroplasties are performed annually in the United States, and this number continues to increase.

  • It is estimated that 0.3–2.5% of patients will sustain a periprosthetic fracture as a complication of total knee arthroplasty (Ayers, 1997; Engh and Ammeen, 1998; Mulvey et al., 2000).

  • Patient-specific risk factors such as rheumatoid arthritis, osteolysis, osteopenic bone, and frequent falls, which are common in the elderly population, and technique-specific risk factors such as anterior femoral cortical notching have all been implicated as potential causes of periprosthetic fractures.

  • The economic impact and disability associated with these fractures is substantial, thus, having an effective strategy to manage these challenging injuries is important.

     

    P ITFALLS

    • Bony defects, areas of osteolysis, osteopenia, and short periarticular fragments all pose challenges to a successful revision arthroplasty in the case of a loose implant.

     

    Indications

  • Decision making regarding the treatment of periprosthetic fractures around a total knee arthroplasty is divided according to whether the fracture occurred in the distal femur or the proximal tibia and whether the implant is well fixed or loose.

    • Typically, fractures occur in the supracondylar area of the femur above a well-fixed total knee

      Controversies

      • There has been recent interest in the minimally invasive osteosynthesis of these injuries using fixed angled, locked, percutaneously inserted plates for the treatment of fractures of the distal femur. Early clinical and biomechanical data are encouraging.

       

      arthroplasty (Ayers et al., 1997; Healy et al., 1993) (Fig. 1A and 1B).

    • Fractures of the tibia are much less common and are frequently associated with implant loosening (Felix et al., 1997; Healy, 1996).

  • Typically patients with fractures around loose implants are considered candidates for revision total knee arthroplasty.

  • Fractures of the distal femur above a well-fixed arthroplasty are typically treated with some form of open reduction and internal fixation (ORIF). Various methods of internal fixation have been described for the treatment of these injuries (Ayers et al., 1997; Chen et al., 1994; Healy et al., 1993; Mulvey et al., 2000; Sanders et al., 1989). Revision arthroplasty in

     

     

     

    Periprosthetic Femoral Fractures

     

    A B

    FIGURE 1

     

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    this setting can be very demanding, with a unique set of technical challenges.

    • In elderly patients, distal femoral replacement “megaprostheses” are often required to reconstruct massive bony defects.

    • Attention to specific technical details is necessary for a successful result, and the surgeon undertaking such reconstructions should be experienced in both arthroplasty and fracture management techniques.

       

      P EARLS

      • Older implant designs may not offer varying degrees of constraint, augmentations, polyethylene insert sizes, and so forth, and thus compatibility issues may necessitate complete arthroplasty revision.

       

      Examination/Imaging

    • Patients with fractures around asymptomatic, well-fixed implants do not usually require an infection workup.

    • In patients with a loose implant or a history of prefracture knee pain, the routine preoperative evaluation should include a complete blood count with manual differential, sedimentation rate, C-reactive protein serologies, and a knee aspiration to exclude occult infection. Medical optimization for these frequently frail elderly patients is recommended.

    • High-quality radiographs are necessary to evaluate the fixation status of the arthroplasty and the amount and quality of remaining periarticular bone stock.

    • History and physical examination should focus on prefracture knee symptoms such as pain, instability, or stiffness.

       

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    • If available, the operative notes from the original arthroplasty should be obtained. This is especially important if isolated component revision is contemplated.

    • Previous incisions and the status of the soft tissues should be circumferentially evaluated.

    • The neurovascular status of the limb should be carefully documented.

      OPEN REDUCTION AND INTERNAL FIXATION OF SUPRACONDYLAR PERIPROSTHETIC FRACTURES

    • The most common clinical situation the orthopedic surgeon will encounter is the supracondylar femur fracture above a well-fixed, well-functioning total knee arthroplasty in an elderly patient.

    • Minimally displaced, stable fractures and those impacted in good alignment may be candidates for nonoperative treatment. In the author’s experience, these situations are quite rare. Long-leg casting with incorporation of a hip guide brace to control leg rotation is recommended.

    • Close radiographic follow-up is indicated, with early surgical intervention if fracture instability is noted. Prolonged attempts at managing unstable fractures with casting may result in further erosion of distal bone stock and potentially compromise the success of any future reconstruction.

      Treatment Techniques

    • The goals of treatment of these injuries include obtaining bony union and maintaining correct limb alignment, length, and rotation while avoiding complications.

      • Surgical challenges to achieving these goals include the often short, osteopenic distal bony fragments, fracture comminution, areas of osteolysis, and parts of the femoral component such as lugs, boxes, and stems that can make obtaining stable distal fixation difficult.

      • Such fractures usually require an internal fixation device that provides coronal plane stability to avoid deformity (typically varus collapse) that can occur during the healing process.

         

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        Periprosthetic Femoral Fractures

         

        Blade Plates and Condylar Screws

        • In the past, devices such as the 95° angled blade plate and dynamic condylar screw have been used with mixed results (Bolhofner et al., 1996; Chen

          et al., 1994; Cordeiro et al., 1990; Healy et al., 1993; Sanders et al., 1989).

        • Due to the extremely distal nature of these fractures, often the blade of the blade plate or the lag screw of the dynamic condylar screw must be inserted more proximally to avoid portions of the femoral component, and thus distal fixation is often suboptimal.

        • The traditional condylar buttress plate offers more freedom of angulation of distal screws but offers no coronal plane stability. Unacceptable rates of varus collapse have been reported when this device is used for unstable fractures (Cordeiro et al., 1990; Davison, 2003).

          Intramedullary Nailing

        • Intramedullary nailing has been used successfully in many series to manage these fractures and offers the advantage of soft, tissue-friendly, minimally invasive stability for complex periprosthetic fractures (Ayers, 1997; Chen et al., 1994; Engh and Ammeen, 1998; Healy et al., 1993; Henry, 1995; Henry et al., 1995).

        • The challenges to successful union with intramedullary techniques include the marginal distal fixation provided by locking screws for the typically comminuted, osteopenic distal bony fragments. Additionally, intramedullary nailing is not practical with implants that substitute for the posterior cruciate ligament because the femoral housing precludes access to the intramedullary canal.

        • The author currently reserves intramedullary

          techniques for fractures above cruciate-retaining designs with sufficient distal bone that allows purchase with a minimum of two distal locking screws. Also, recent biomechanical evidence suggests that, in the presence of medial comminution, retrograde intramedullary nails may be mechanically more stable than laterally placed locking plates.

        • Occasionally antegrade femoral nailing can be used for periprosthetic distal femur fractures as well, if a sufficiently long distal fragment is present. In the author’s experience, such fractures are extremely rare.

           

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          Periprosthetic Femoral Fractures

           

      • The main challenges for antegrade techniques are obtaining appropriate alignment and stable distal fixation.

      • Additionally, with antegrade techniques, an area of high stress concentration is created between the distal end of the nail and the femoral component.

        Locking Plates

    • Recently, locking plate technology has gained popularity for the management of complex periarticular fractures about the knee (Koval et al., 1997; Kregor et al., 2001b; Krettek et al., 2001; Marti et al., 2001; Schandelmaier et al., 2001; Schütz et al., 2001). Threads on the screw heads are threaded into corresponding threads in the plate holes, forming a fixed-angle construct and providing coronal plane stability (Frigg et al., 2001).

    • These devices have been used with excellent results

      for the management of complex periarticular injuries and have an excellent track record for providing reliable distal fixation. Additionally, such devices allow multiple locked screws to be placed around and between portions of the femoral component, improving distal fixation (Haidukewych, 2003)

      (Fig. 2A and 2B).

    • Kregor et al. (2001a) reported a series of 38 periprosthetic fractures treated with the LISS device (Synthes, Paoli, PA). There were only two failures (5%): one patient required revision knee arthroplasty and one required bone grafting to achieve solid union. Ultimately 37 of 38 fractures (97%) healed. Medical and orthopedic complications were uncommon. Leaving metaphyseal comminution undisturbed, thereby preserving vascularity to the fragments, is critical to the predictable healing with this technique.

    • In addition to providing excellent mechanical stability, several locked plating designs also offer the added theoretical biologic advantage of allowing percutaneous insertion (Kregor, 2002).

      • Percutaneous insertion minimizes the need for additional large incisions around the knee, and potentially minimizes soft tissue complications and stiffness associated with traditional exposures used for ORIF (Haidukewych, 2003).

      • Many commercially available locked plating designs offer the surgeon the option of either open or percutaneous insertion.

 

 

 

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Periprosthetic Femoral Fractures

 

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FIGURE 2

  • When possible, the author performs the internal fixation percutaneously to take advantage of the mechanical stability provided by these devices as well as the theoretical biologic advantages that percutaneous insertion allows (Farouk et al., 1999).

  • When percutaneous techniques are used with a locking plate design, vigilance is required to avoid malalignment, typically valgus and hyperextension of the distal fragment (Haidukewych, 2003).

    • More modern, polyaxial designs allow screw angulation prior to end point locking, and these can be very useful if femoral component lugs or the like are encountered during drilling. Recent data have demonstrated that polyaxial designs allow more fixation versatility with no apparent mechanical complications or varus collapse; therefore, polyaxial plates are the author’s implant of choice for periprosthetic fractures (Haidukewych et al., 2007).

       

      Bump

       

       

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      Periprosthetic Femoral Fractures

       

      FIGURE 3

       

      Positioning

    • The patient is positioned supine on a radiolucent table. Intravenous antibiotics are given. Excellent muscle relaxation and fluoroscopic images are essential.

    • Prepping both legs in the operative field can make it easier to obtain a lateral view of the fractured extremity by lifting the normal extremity out of the C-arm beam (Fig. 3).

      Procedure: Percutaneous Technique of ORIF of the Distal Femur Using Locked Plating

      Step 1

    • A lateral incision is made at the flare of the lateral condyle.

    • A plate of appropriate length is then inserted in a submuscular, extraperiosteal fashion under fluoroscopic control (Fig. 4).

       

       

       

      Periprosthetic Femoral Fractures

       

      FIGURE 4

       

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  • The plate is positioned as distal as possible on the distal fragment and provisionally held with a guide pin.

  • It is critical to place this guide pin parallel to the knee joint to assure excellent alignment. One often has to extrapolate the trajectory of the guide pin as it emerges medially past the femoral component on fluoroscopy.

  • Limb length and rotation are then adjusted, and a second guide pin is placed proximally into the femoral shaft.

    Step 2

    • Leaving metaphyseal comminution undisturbed by “bridging” this area is critical to the success of this technique.

  • A combination of gentle manual traction and a small bump under the fracture site can assist with closed reduction, the most difficult portion of the procedure.

 

Bump

 

 

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Periprosthetic Femoral Fractures

 

A

 

Bump

 

 

B

FIGURE 5

 

  • There is a strong tendency for the distal fragment to tip into hyperextension due to the pull of the gastrocnemius muscles. Moving the bump under the knee more proximally will allow the distal fragment to tip into more flexion (Fig. 5).

  • With first-generation locking plates, it is critical to have the plate positioned accurately, and to have all aspects of the reduction complete prior to placing any locking screws. These screws will not “pull” the plate down to bone, nor will they allow fine adjustments of alignment once they are inserted. Newer locking plate designs offer “hybrid” fixation, allowing the surgeon a choice of either locked, traditional unlocked, or polyaxial locked screws.

    • Specialized clamps are now available to facilitate reduction (Fig. 6).

       

       

       

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      Periprosthetic Femoral Fractures

       

      FIGURE 6

       

       

      Step 3

      • Distal fixation should be optimized by placing as many distal screws as possible.

        • Typically screws can pass just posterior to the anterior flange of the femoral component or just above the “box” of a posterior stabilized housing.

        • The author currently attempts to use all distal screws and at least four proximal screws (Fig. 7).

      • It is critical to understand that the metaphyseal comminution is bridged, that is, left undisturbed to preserve vascularity.

        • Stable fixation is obtained above and below this zone (Fig. 8).

        • No allograft struts, cables, or medial plates or grafts are indicated.

        • Dissection in this area is discouraged.

           

           

           

           

          FIGURE 7

           

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          Periprosthetic Femoral Fractures

           

          FIGURE 8

           

    • Fracture stability is assessed intraoperatively, testing flexion and varus/valgus stability under live fluoroscopy.

    • The wound is closed in a routine layered fashion over a suction drain.

      Postoperative Care and Expected Outcomes

    • Typically, a hinged knee brace is used postoperatively and knee motion is started when the wound is dry.

    • Toe-touch weight bearing is maintained until healing is evident, typically at 12 weeks.

       

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      Periprosthetic Femoral Fractures

       

      REVISION ARTHROPLASTY OF SUPRACONDYLAR FRACTURE OF THE DISTAL FEMUR

      • The need for revision total knee arthroplasty secondary to periprosthetic fracture has become less common in the author’s practice with the advent of improved internal fixation devices such as locked plates. Typically, revision arthroplasty is reserved for fractures around a loose prosthesis, fractures with inadequate bone stock to allow for stable internal fixation, or recalcitrant supracondylar nonunions, which require resection and megaprosthesis implantation.

      • Surgeons who treat periprosthetic fractures around total knee arthroplasty must have the expertise and technical support to be able to perform either long-stem revision total knee arthroplasty or revision to a megaprosthesis, as one is often unable to determine which reconstructive option is necessary until the fracture has been exposed in the operating room.

      • Bony defects secondary to comminution, multiple previous procedures, the presence of broken hardware, and the presence of deformity all may present technical challenges to a successful outcome.

        Intramedullary Femoral Stems

      • The ideal indication for long-stem revision total knee arthroplasty would be the presence of adequate bone stock in the face of a supracondylar fracture with a grossly loose femoral component (Ayers, 1997; Engh and Ammeen, 1998).

      • Revision total knee arthroplasty with intramedullary femoral stems that engage the diaphysis and simultaneously stabilize the fracture can be used. Cemented stems may be used, but care must be taken to prevent extrusion of cement into the fracture site.

      • Allograft struts with cerclage wiring can be used to reinforce the stability provided by a long-stem

        prosthesis. It is very unusual, however, to have distal femoral bone stock that is inadequate for internal fixation yet adequate for formal revision.

         

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        Periprosthetic Femoral Fractures

         

    • Most of the clinical data evaluating the outcomes of a simultaneous revision arthroplasty with intramedullary stem fixation of a supracondylar fracture have been gathered from the treatment of distal femoral nonunion in this situation. Kress et al. (1993) reported a small series of nonunions about the knee treated successfully with revision and uncemented femoral stems with bone grafting that achieved union in 6 months.

      Replacement Megaprostheses

    • Distal femoral replacement megaprostheses have been used for salvage of failed internal fixation of supracondylar periprosthetic femur fractures.

    • The long-term results of the kinematic rotating hinge prosthesis for oncologic resections about the knee have been good, with a 10-year survivorship of approximately 90%.

    • As their success becomes more predictable, the indications for megaprostheses are expanding. Elderly patients with refractory periprosthetic supracondylar nonunions or those with acute fractures with bone stock inadequate for internal fixation are reasonable candidates for megaprostheses.

  • Davila et al. (2001) have reported a small series of supracondylar distal femoral nonunions treated with a megaprosthesis in elderly patients. They have shown that a cemented megaprosthesis in this patient population permits early ambulation and return to activities of daily living.

  • Freedman et al. (1995) performed distal femoral replacement in five elderly patients with acute fractures and reported four good results and one poor result secondary to infection. The four patients with good results regained ambulation in less than 1 month and had an average arc of motion of 99°. All patients had some degree of extension lag.

     

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    Periprosthetic Femoral Fractures

     

    Allograft Prosthetic Composite

    • For a younger, active patient, an allograft prosthetic composite may be a better alternative. Distal femoral reconstruction with an allograft prosthetic composite, providing a biologic interface, can help restore bone stock and potentially make future revision easier (Engh and Ammeen, 1998; Clatworthy et al., 2001).

    • Kraay et al. (1992) have reported a series of allograft prosthetic reconstructions for the treatment of supracondylar fractures in patients with total knee arthroplasties.

      • At a minimum 2-year follow-up, the mean Knee Society score was 71 and the mean arc of motion was 96°. All femoral components were well fixed at follow-up.

      • Results of this study indicate that large segmental distal femoral allograft prosthetic composites can be a reasonable treatment method in this setting.

Conclusions

  • Periprosthetic fractures around total knee arthroplasty remain challenging injuries to treat. With the ever-growing elderly population, the incidence of these fractures will undoubtedly increase.

  • Decision making regarding ORIF or revision arthroplasty is based on the fixation status of the implant, the remaining bone quality, the physiologic age of the patient, and the location and stability of the fracture.

  • Recent advances in locked plate technology show promise for improved fixation of such complex fractures with minimal additional soft tissue trauma. More data are needed to fully define the role of this exciting new technology alongside traditional techniques of internal fixation of these fractures.

  • Revision arthroplasty frequently requires modular distal femoral replacements, metal or allograft augmentation of bony deficiency, and long stems to bypass deficient bone. These reconstructions are demanding and are fraught with complications.

Attention to specific technical details is essential for a successful result.