Proximal Periprosthetic Femur Fractures: Strategies for Internal Fixation
As the number of patients living with total hip arthroplasty continues to rise, there will be an increase in periprosthetic fractures requiring surgical treatment. Treatment of periprosthetic femur fractures below a well-fixed hip arthroplasty stem presents a unique set of challenges. A review of the existing literature on surgical technique, including plate selection and configuration, proximal fixation options, and use of allograft, can serve to guide treatment of these challenging injuries. While not conclusive, the literature supports using soft tissue preserving techniques, bicortical proximal fixation, and fixation spanning the length of the femur.
Similarly, in Vancouver C fractures there is some evidence that fixation should span the femoral stem, regardless of available bone for fixation proximal to the fracture. Kubiak and colleagues41 found increasing load to failure and decreased cortical strain in a biomechanical model comparing plates that stop short of the femoral stem with those that span the stem.
Clinically, this concept is supported by Froberg and colleagues.12 In their series of 60 Vancouver B1 and C fractures treated with laterally based locked plating, 3 patients went on to refracture. All of these fractures occurred in patients with Vancouver C fractures treated with plates overlapping the preexisting stem by <50%. The fractures all occurred at the high stress area between the tip of the stem and the end of the plate.
Further support of extended plate length comes from Drew and colleagues,8 who demonstrated a significantly decreased risk of reoperation following ORIF of periprosthetic femur fracture when >75% of the length of the femur was spanned compared to <50%. Although in some settings short fixation may produce satisfactory results, consideration should be given to extending the length of fixation, especially in the osteoporotic population.
Interprosthetic Fractures
With a rising number of patients with ipsilateral hip and knee arthroplasty, the rate of interprosthetic fractures is rising. These fractures present additional challenges given preexisting implants above and below the level of the fracture. The use of a single precontoured laterally based locked plate has been reported with good union rates approaching 90%.42,43 In one series, all nonunions occurred in Vancouver B1 fractures,43 again bringing to light the challenging nature of the B1 fracture.
Nonunion
Success in treating periprosthetic femur fractures has improved with improved fixation methods and understanding of technique. However, current rates of nonunion are still reported up to 27% for B1 and C fractures.44
There is limited evidence on the treatment of periprosthetic femur fracture nonunion. However, treatment is difficult and complication rates are high. Crockarell and colleagues45 reported a 52% overall complication rate in their series of 23 periprosthetic femur fracture nonunions.
Nonunions of the femur near a prosthesis can be treated by revision of the fracture fixation using compression and grafting to achieve bone healing vs revision of the joint prosthesis to span the area of the nonunited bone. Case-by-case decision-making is based on the remaining bone stock and the type of revision prosthesis necessary to span the problem area. Given the challenges associated with their treatment, a focus on prevention of nonunion is of paramount importance.
Authors’ Preferred Treatment
Our treatment of periprosthetic femur fractures with a well-fixed hip arthroplasty stem adheres to the principles supported in the literature (Figures 1A-1D and Figures 2A, 2B).
- Soft tissue friendly dissection with limited exposure at the fracture site is preferred as the fracture allows, particularly in cases with comminution where a direct assessment of the reduction is not available.
- Plate fixation strategy is dictated by the characteristics of the fracture. Fracture patterns amenable to anatomic reduction receive interfragmentary compression and absolute stability constructs. Highly comminuted fractures receive relatively stable bridging constructs to encourage callous.
- Locking screws are used rarely in diaphyseal fracture patterns, and when employed, are applied to only one side of the fracture to limit “over stiffening” the construct.
- Liberal use of dual plating, both as a method of maintaining fracture reduction while a structural plate is applied and increasing construct rigidity.
- Proximal fixation relies heavily on bicortical screws placed through the holes of the lateral plate. Cerclage wires and unicortical screws are rarely used in our practice. In the case of larger stems, a bicortical 3.5-mm screw can be placed through a 4.5-mm plate using a reduction washer.
Summary
Techniques for treatment of periprosthetic femur fractures around a well-fixed hip arthroplasty stem are constantly evolving. Several principles have emerged to decrease rates of treatment failure and subsequent reoperation. While there are several methods to do so, it is critical to achieve stable proximal fixation. Long spanning fixation constructs are linked to lower failure and reoperation rates in both B1 and C type fractures. Additionally, the importance of soft tissue management and maintenance of local vascularity should not be underestimated.
