Fractures around the femoral component of a total hip arthroplasty become more common as patients age. These patients usually present to the emergency room and are often managed by trauma surgeons with varying amounts of revision experience. Osteopenic bone, a femoral component that is often loose, and an elderly patient with medical comorbidities all complicate management. The majority of periprosthetic fractures around the stem of a femoral component are associated with a loose femoral implant, for which revision arthroplasty is preferable to internal fracture fixation2-6. The discussion below focuses on the fundamental decision-making and technical aspects of the management of periprosthetic fractures of the femur associated with a loose femoral component.
The Vancouver classification system helps to guide treatment1. It is based on the location of the fracture, the fixation status of the femoral component, and the quality of the remaining bone stock. The classification system is summarized in Table I. Vancouver type-A fractures involve the greater or lesser trochanter and are generally associated with osteolysis-related avulsion fractures (Fig. 1). The mainstay of treatment of these fractures is to address the underlying osteolysis, typically with polyethylene liner exchange. Lytic lesions are bone grafted with allograft, and unstable fractures of the greater trochanter are stabilized with internal fixation. Tension-band techniques using wires or heavy braided suture have been recommended. The bone quality is typically extremely poor as the trochanter has been “hollowed out” by the lytic process. If the greater trochanter fracture fragment is displaced and unstable, we prefer to suture into the abductor tendon with a heavy braided nonabsorbable suture, which provides more robust fixation than suturing into the remaining bone. This technique is analogous to the fixation of tuberosities of proximal humeral fractures in osteopenic patients. Often, wires or cables will slice through the bone. Newer cable plates may offer an advantage by providing broader support to osteopenic greater trochanters. Postoperative abduction bracing and a period of protected weight-bearing are recommended.
Vancouver type-B fractures occur around the tip of the femoral stem and are the most common fractures encountered. Type-B1 fractures occur around a well-fixed implant; type-B2 fractures, around a loose implant with good remaining bone stock; and type-B3 fractures, around a loose implant with poor remaining proximal bone stock. For fractures around a well-fixed implant (type B1), internal fixation with a plate with or without an allograft strut is recommended.
For fractures around a loose implant (Vancouver types B2 and B3), revision of the femoral component is recommended. This strategy addresses both the loose component and the fracture and provides intramedullary stability by virtue of the long femoral stems typically used for revision. Attempting plate fixation of fractures around a loose implant typically leads to fracture nonunion. Knowledge of specific revision techniques is necessary to effectively handle these challenging cases.
Thorough medical optimization is recommended preoperatively. Good-quality orthogonal radiographs are needed to evaluate the status of the acetabular component and the remaining acetabular and femoral bone stock. If possible, the operative note from the original arthroplasty should be reviewed to determine the manufacturer of the component, and one should be prepared to place a new acetabular liner or revise the acetabular components. If the radiographs are equivocal for loosening, prefracture symptoms, such as thigh or groin pain, suggest that the components are loose. Radiographic signs of femoral component loosening include subsidence, cement mantle fractures, and complete or progressive radiolucencies at the bone-cement interface. Sedimentation rates and C-reactive protein values are of unknown assistance in the presence of an acute fracture. We recommend a preoperative aspiration if there is any concern of infection. Generally, a culture result can be obtained within forty-eight hours, while medical optimization is taking place. Skeletal traction may be required for more unstable fracture patterns in some patients. A tibial traction pin is preferred. When infection is not suspected, we obtain an intraoperative frozen section histological evaluation from the membrane around the loose femoral component, not the fracture site itself. With suspicion of infection, all components and residual cement are removed, and an antibiotic cement spacer is placed to provide some stability. We prefer the use of a metal guide pin with a so-called cement nail made with bone cement impregnated with 3 g of vancomycin and 2.4 g of tobramycin per 40 g batch of cement. Cerclage wires can be placed around the fracture fragments and a so-called spacer nail to allow satisfactory alignment of the fracture fragments. If infection is present, organism-specific intravenous antibiotics are given, and the revision arthroplasty is performed in a staged fashion, typically six weeks after explantation.
The specific femoral revision strategy chosen depends on the quality of the remaining bone stock, the diameter of the femoral canal distal to the fracture, and patient factors, such as age. Many surgical exposures can be used for revision. We prefer a posterior approach because it is widely extensile. The cement, implants, and cement restrictors can generally be removed through the fracture site. If necessary, the proximal fracture fragment is split coronally to access the stem and allow direct visualization of the distal part of the canal for accurate reaming. The acetabular component is exposed after the femoral component is removed. The liner is removed, if modular, and the acetabular component is manually tested for stability. If it is loose, revision is required. A full discussion of acetabular revision methods is beyond the scope of this article; however, in general, the use of a larger uncemented hemispherical acetabular component with multiple screw augmentation is recommended. If the acetabular component is well fixed, the liner is changed and the femoral head size is increased, if possible, to improve hip stability. Anecdotally, we have noted that the acetabular component is stable in the majority of patients. When the manufacturer cannot be identified preoperatively and the proper acetabular liner is not available, a liner from another manufacturer can be cemented into a well-fixed shell with good results.
Once the acetabulum has been repaired, the femur is reconstructed. Several strategies can be effective, but all rely on obtaining secure distal fixation. Most often, an uncemented reconstruction is done.
Several preoperative radiographic findings help to guide the selection of the appropriate uncemented reconstruction, including the endosteal diameter and morphology of the distal femoral fragment. When the distal fragment has parallel endosteal cortices with ≥5 cm of tubular diaphysis (usually with a diameter of <18 mm), an extensively coated, uncemented, monoblock long-stemmed prosthesis is appropriate, and these reconstructions have a good track record7,8. This stem has an excellent long-term survivorship when used for revision arthroplasty or a periprosthetic fracture. The distal canal is reamed, and a trial stem is inserted into the distal fragment. In general, a slight underreaming (0.5 to 1 mm) is appropriate for such stems; however, for longer, curved stems, a line-to-line ream, which provides sufficient prosthetic stability, is recommended, as there is inevitably a slight mismatch in femoral bow. The proximal fragments can then be reduced using the trial implant as a template. We prefer to select a trial implant one size smaller than the definitive implant and to use that trial implant as a guide to proximal fracture reduction. Essentially, the proximal part of the femur is reconstructed around a trial implant a few millimeters smaller than the real implant, after which the slightly larger final trial implant is impacted to obtain a distal press-fit. Cerclage cables are applied, and a trial reduction is performed. If the limb length and stability are acceptable, the trial implant is removed and the final femoral component is impacted. The cerclage cables are then retensioned, crimped, and cut. The appropriate femoral head size and femoral head-neck offset are selected, and the reconstruction is completed.
If the distal diaphysis has divergent endosteal morphology, <5 cm of parallel endosteal cortex, or large endosteal diameters (typically >18 mm), a fluted, grit-blasted, titanium, tapered modular stem can be used effectively. These stems are available in diameters of ≤30 mm and can be useful in large femoral intramedullary canals. It is wise to ream with use of fluoroscopy and “by hand,” especially in osteopenic bone, to avoid anterior femoral cortical perforation. It is helpful to remember that one is reaming a straight cone into a bowed canal, and varus malalignment and anterior cortical impingement or perforation may occur. When axial stability is obtained by diaphyseal reaming, the implant is impacted into place. It is wise to place prophylactic cerclage cables at the mouth of the distal fragment prior to stem impaction. The proximal bodies of the modular implants are then chosen to restore appropriate limb length, offset, and hip stability.
After trial reconstruction is complete, the components are assembled and the hip is reduced. The proximal fragments are then reduced with cerclage cables around the body of the implant (Figs. 2 through 3-D). Essentially, the stem serves as an endoskeleton for the fragments while providing stable distal fixation. We find this strategy effective for type-B2 and even most type-B3 fractures; however, concerns remain about the durability of the modular junction of such stems without proximal osseous support. The advantages of these modular constructs include the independent control of the distal diameter, limb length, offset, and femoral anteversion that make such reconstructions very time efficient and clinically effective. Berry demonstrated excellent results and favorable proximal osseous remodeling with this technique7.
The use of a cemented long-stemmed femoral component for revision is rarely recommended, but it can be used when the patient has extremely osteopenic bone with a large femoral intramedullary canal, as obtaining press-fit stability in such hips is difficult. When a cemented long-stemmed femoral component is used, the fracture is initially reduced and fixed with cerclage cables. The polymethylmethacrylate is pressurized gently to minimize extravasation. After cementation, intraoperative radiographs are made to determine if any problematic cement extravasation has occurred, and extravasated cement is removed.
Rarely, the proximal femoral bone is extremely osteoporotic such that a modular proximal femoral replacement (a so-called tumor prosthesis or megaprosthesis) is necessary. Cemented distal fixation is recommended in this situation. Preserving a sleeve of remaining proximal bone can provide some soft-tissue attachment and assist in maintaining a stable hip. A coronal split of the proximal part of the bone facilitates femoral stem removal. The implant is cemented into the distal fragment, and the proximal sleeve of remaining bone and soft tissue can be circumferentially fixed around the body of the prosthesis with cable or heavy braided suture. If the hip abductors are deficient, the construct should generally include a constrained acetabular liner to minimize the risk of postoperative dislocation. If the acetabular component is of sufficient diameter and a compatible constrained liner is not available, some surgeons have recommended cementing a constrained liner into a well-fixed acetabular component9. Adequate containment of the constrained liner by the acetabular component is required, and cup position should be acceptable to prevent impingement. Contouring the backside of a smooth liner to be cemented is recommended to allow cement interdigitation. We prefer to routinely add antibiotics to any cemented reconstructions in this setting, with use of 1 g of vancomycin powder for 40 g of cement.
After revision or internal fixation, patients are mobilized as soon as possible. We allow initial partial weight-bearing with a walker and, at six weeks, progression to full weight-bearing. After revision arthroplasty, an abduction brace with a 70° flexion stop is used if necessary to avoid hyperflexion and adduction, which may compromise greater trochanteric fixation.
Orthopaedic complications include dislocation, infection, limb-length discrepancy, abductor muscle deficiency, limp, and mechanical failure or nonunion of proximal fragments. With modern modular stems, limb length and stability can be optimized through adjusting proximal body height, femoral head-neck offset, and version. Abductor mechanism problems, however, have no good solution. Careful attention to detail and understanding the principles of revision arthroplasty are necessary for optimal outcomes.
Acetabular fractures are rare compared with femoral fractures. They occur in two general scenarios: early, during cup impaction, and late, as a result of osteolytic involvement of the underlying bone with loss of cup fixation and fracture.
Intraoperative Acetabular Fractures
Various risk factors have been documented for intraoperative acetabular fracture, including poor bone quality, posttraumatic arthritis, underreaming, and the use of elliptical monoblock components. In general, we prefer to ream by 1 or 2 mm less than the true size of the shell to be impacted. It is important to know true diameters, since some manufacturers “build in” some press-fit by the elliptical nature of the shell. For example, a shell labeled as 54 mm may actually measure 55.5 mm at the rim. If a fracture occurs, acute revision to a so-called multihole shell is recommended if the component is unstable. If the impacted cup is stable, no further treatment is necessary. Multiple screws are used to provide fixation, and bone obtained from reaming is placed along the fracture line. The outcomes of such a strategy have been generally satisfactory10-16. For more unstable fractures, the addition of a posterior column plate may be necessary.
Late Periprosthetic Fractures of the Acetabulum
These fractures are generally associated with severe osteolysis of the acetabulum14. If a preoperative computed tomography (CT) scan leads to this diagnosis, a jumbo cup with allograft bone and multiple screws generally are used. For more severe defects or discontinuities, a posterior column plate may be necessary. Modular trabecular metal augments are available and can be customized to provide defect fill and component stability. Rarely, so-called custom triflange components are necessary for massive combined osseous deficiencies.
Supracondylar Distal Femoral Fractures
Although most periprosthetic fractures around a femoral stem require revision because the femoral component is loose, most fractures of the distal part of the femur occur above a total knee replacement that is well fixed and has been functioning well prior to the fracture. Internal fixation is therefore indicated for the majority of periprosthetic distal femoral fractures. Both locked plates and retrograde intramedullary nails can provide good outcomes. The amount of available distal bone stock and the intercondylar notch access influence the fixation device selection. Regardless of the device chosen, secure distal fragment fixation must be achieved for predictable healing1,17-21.
Revision arthroplasty is recommended for fractures around loose implants. In our experience, loose implants are rare, occurring primarily in elderly patients with massive distal osteolysis who sustain a distal femoral fracture. An effective way to manage this problem is to use a distal femoral replacement megaprosthesis1. These patients can be mobilized immediately without protected weight-bearing. The role of such prostheses in fractures above a well-fixed total knee replacement is controversial. The majority of periprosthetic fractures above a total knee replacement heal with internal fixation; therefore, such megaprostheses should probably be reserved for fractures above a loose total knee replacement, nonunion, or patients in whom internal fixation is likely to fail because of very poor distal bone stock (Figs. 4-A, 4-B, and 4-C). An alternative strategy for the management of a fracture and a loose femoral prosthesis is to use a long-stemmed femoral component to stabilize the fracture. We have not found this strategy to be effective as the distal bone stock typically is insufficient after component removal so the femoral stem carries an excessive load. If revision arthroplasty is contemplated, traditional revision implants and distal femoral replacements should be available.
Fractures Around a Tibial Component
Periprosthetic fractures around a tibial component almost always occur around a loose tibial component so revision arthroplasty is usually indicated1,22,23. Poor bone quality and varus malalignment are risk factors for tibial fracture. Felix et al. proposed a classification for tibial periprosthetic fractures22. Metal augmentations, stepped sleeves, or trabecular metal cones can be used to manage osseous defects. A tibial component that has a stem long enough to extend distal to the fracture should be used in all cases. Both cemented and press-fit stems are effective and have good long-term data to support their use (Figs. 5-A through 5-D)23. Restoration of a neutral mechanical axis is important.
Fractures of the Patella
Patellar fractures remain the most challenging periprosthetic fractures to manage as poor results and complications are common1. Ortiguera and Berry proposed a classification system to guide treatment on the basis of the integrity of the extensor mechanism and the stability of the patellar component24. Revision is indicated for loose components. Often, the residual bone stock will not support a new patellar button; therefore, simple resection of the loose component and patelloplasty is indicated. If the button is loose and the extensor mechanism is disrupted, some form of fixation is necessary to restore extensor mechanism integrity. The preferred fixation depends on the quality of the remaining bone and soft tissue. For example, if sufficient patellar bone stock remains, tension-band techniques or cannulated screw techniques can be effective. If remaining bone stock is poor, partial patellectomy may be considered. In some patients, the remaining tissues are too attenuated and cannot be repaired effectively. In these situations, an extensor mechanism allograft is used. We prefer an Achilles tendon allograft with a calcaneal bone block that is press fit and wired into the proximal part of the tibia. It is wise to evaluate the fixation status and rotational relationships of the femoral and tibial components concurrently, since a malrotation may have contributed to patellar fracture. Complication rates remain high, and patients should be counseled about the generally poor outcomes of treatment of this fracture. Nonunion, loss of fixation, and hardware-related problems are common24.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.