A periprosthetic femur fracture is a break in the thigh bone that occurs around the hardware or implant used in a total hip replacement. While relatively uncommon, this serious injury requires prompt medical attention and specialized surgical care. The incidence of these fractures is increasing globally due to the rising number of total hip arthroplasties and the overall aging of the population. The prosthetic stem inside the femur significantly complicates diagnosis and treatment.
Understanding Periprosthetic Femur Fractures
The diagnosis and treatment plan for a periprosthetic femur fracture are guided by the Vancouver Classification system. This system evaluates the fracture’s location, the stability of the existing femoral implant, and the quality of the surrounding bone. This classification directs the orthopedic surgeon toward the most appropriate surgical strategy for fixation.
Fracture location is categorized into three main types relative to the hip replacement stem. Type A fractures are located in the trochanteric region at the top of the femur. Type C fractures occur well below the tip of the femoral stem, distant from the implant. Type B fractures are the most common and complex, happening at or near the stem tip.
Type B fractures are further subdivided based on the implant’s stability, determined by imaging. Type B1 fractures occur around a well-fixed femoral stem. Type B2 fractures involve a loose or unstable stem. Type B3 is the most severe, characterized by a loose stem combined with poor quality or severely compromised bone stock in the proximal femur.
Factors Increasing Fracture Risk
Periprosthetic femur fractures result from patient-specific biological factors and mechanical issues related to the implant. In most cases, the fracture is caused by a low-energy mechanism, such as a simple fall from a standing height, in a patient with compromised bone quality. This contrasts with the high-energy trauma required to break a healthy femur.
Advanced age is a primary biological risk factor; patients over 70 years old have a higher risk of sustaining this fracture. Conditions that weaken bone density, such as osteoporosis and osteolysis (the breakdown of bone tissue around the implant), are major contributors. Chronic inflammatory conditions like rheumatoid arthritis and the long-term use of steroids can also impair bone quality.
Mechanical and implant-related issues also increase fracture susceptibility. The long-term presence of a prosthetic stem can cause stress shielding, where the implant absorbs the normal load, leading to bone resorption and weakening of the surrounding femur. Stem loosening over time is particularly important, as it creates concentrated stress areas, predisposing the bone to a Vancouver Type B2 or B3 fracture. Uncemented implants may carry a higher risk of periprosthetic fracture compared to cemented implants.
Surgical Management of Periprosthetic Fractures
Treatment for these fractures is almost always surgical, as the implant prevents stable healing through non-operative management. The surgical approach depends directly on the Vancouver Classification, specifically whether the femoral stem is stable or loose. Non-surgical management is only considered if the patient is medically unfit for surgery.
For Vancouver B1 fractures, where the implant is stable, the standard treatment is Open Reduction and Internal Fixation (ORIF). The surgeon realigns the fracture fragments and secures them with specialized hardware while retaining the original hip stem. Fixation is typically achieved using cerclage cables, screws, and a long plate that spans the fracture site for stability.
If the fracture is Vancouver B2 or B3 (loose implant or significant bone loss), treatment shifts to revision arthroplasty. This complex procedure requires removing the unstable femoral stem and replacing it with a new, much longer stem. The new stem bypasses the entire fracture zone, providing rigid fixation in the healthy bone below the break. This revision often includes additional fixation of the fracture fragments using plates or cables.
The new implant is chosen to provide a strong, stable foundation. Long porous-coated cementless stems are frequently used for B2 and B3 revisions, offering better mechanical stability. The goal of this surgery is to create an immediate, load-bearing construct that compensates for compromised bone, maximizing fracture healing and long-term implant survival.
Recovery Timeline and Long-Term Outlook
Recovery following surgical management of a periprosthetic femur fracture requires dedicated rehabilitation. Radiographic union for these complex fractures is significantly delayed, often extending beyond the typical three-month period for non-prosthetic femur fractures. While the average time for union on imaging is around 15 months, clinical recovery for the patient is much faster.
Patients should expect a recovery period averaging three to six months to regain functional independence. The initial post-operative phase involves strict weight-bearing restrictions, determined by the surgeon based on fixation stability and bone quality. The prescribed weight-bearing status may include a non-weight-bearing period followed by protected partial weight-bearing.
Physical therapy (PT) is a necessary component of the post-operative plan, restoring muscle strength and joint mobility. PT protocols focus on safely increasing the load on the operated leg, improving gait mechanics, and strengthening the hip and thigh muscles. Consistent adherence to therapy is a primary determinant of the patient’s long-term functional outcome.
Even after successful surgery, patients face potential challenges, including nonunion, re-fracture, or continued pain. The long-term prognosis for regaining functional independence is favorable, but the complication rate remains higher than in primary hip replacement surgery. Patients who complete the initial year post-surgery usually achieve a good level of function, though they may not return to their pre-fracture mobility level.