Abstract
Introduction. Periprosthetic femoral fractures (PPF) have become more common as the population at risk, patients with joint arthroplasty, has increased. The choice of treatment depends on the location of the fracture relative to the implant, the residual fixation of the implant and patient factors such as deficient bone stock or osteopenia. The Vancouver classification categorises types of PPF and identifies strategies for its management. However, the Vancouver classification is mainly based and focused on cemented implants. Recently a modified algorithm for the management of PPF based on the Vancouver classification has been published. We analysed PPF with a single type of uncemented hip stem and compared our treatment to the most recent management algorithm.
Methods. From a consecutive series of 619 uncemented proximal hydroxyapatatite coated ABG-I prostheses, 14 patients (2.3%) sustained a PPF after an adequate trauma. The mean time between the index operation and the fracture was 6.9 years(range: 2.0 to 13.7 years). The mean age of the patients at the time of fracture was 79 years (range 59–87). The fracture patterns and state of stem fixation were analysed.
Results. In 5 patients the fracture was limited to the proximal Gruen zones 1 and 7 with the stem still firmly fixed (type A). Fracture treatment was conservative but in one patient the greater trochanter had to be reat-tached. Six B1,two B2 fractures and one B3 fracture were seen. Compared to the Vancouver classification we observed a different pattern in the type B fractures. No fractures at the tip of the stem were seen as common and characteristic in cemented implants. Three B1 fractures were operated due to fracture displacement and three were treated conservately. THe B2 and B3 fractures were managed with long uncemented revision stems because of a disrupted bone-prosthesis interface. Type C fractures were not seen. All fractures healed well.
Conclusion. The ABG-I shows a bone remodelling pattern consisting of mid stem bone condensation and proximal bone resorption, which leads to a high bone density gradient. This gradient acts as a stress riser and thus can be a preferred location for the initiation of a fracture. This pattern is distinctly different from the fracture types observed for cemented implants. . As a result the ABG-I stem was modified to the ABG-II design permitting more proximal and less mid-stem load transfer, smoothening the bone density gradient.
This study confirms that the Vancouver classification and the modified algorithm for the management of PPF are a simple,reproducible classification system also for the uncemented treatment modality. Conservative treatment is a valid option in case of a stable implant, while in case of a loose implant surgical intervention is mandatory.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
