Periprosthetic femoral fracture after a well-fixed revision total knee arthroplasty treated with in situ effective lengthening of prosthesis

A clinical study of the rotational alignment of the femoral component in total knee arthroplasty

[Purpose] The reasons for femorotibial rotational malalignment after total knee arthroplasty (TKA) were analyzed to provide evidence for clinical knee joint surgery and to reduce complications. [Subjects and Methods] Ninety knees of 60 patients were selected and randomly divided into two groups (n=30). For one group, rotational alignment of the femoral component was determined by the transepicondylar axis and TKA was performed. For the other group, rotational alignment of the femoral component was conducted through 3° external rotation of the posterior femoral condyles. Knee joint specimens were operated with TKA and various biomechanical indices were measured. [Results] The femoral epicondylar axis was a constant, reliable reference for femoral component rotational alignment. When the femoral component was rotated by 0° versus the epicondylar axis, the peak contact pressure on the patellofemoral joint was optimal. When the femoral component was arranged in parallel with Whiteside's line, the peak contact pressure on the patellofemoral joint varied largely. The patellofemoral contact areas of the two groups were similar. [Conclusion] Axial rotational alignment of the femoral component influenced the contact pressure of patellofemoral joints in TKA more significantly than external rotation of the femoral condyles. It is more reliable to use the femoral epicondylar axis as the reference for the rotational alignment of the femoral component.

Challenge of managing distal femur fractures with long-stemmed total knee implants

OBJECTIVE

Treatment of distal femur fractures by long-stemmed total knee arthroplasty (TKA) is challenging, because of poor bone stock, decreased blood supply, history of multiple knee surgeries and an absence of standard treatment. Few published studies are available concerning this. The purpose of this study was to share surgical technique and better describe our patients' comorbidities, which add to the challenge of managing individuals with these fractures.

METHODS

Between August 2008 and September 2013, seven patients presented to our level I trauma center with distal femoral fractures associated with long-stemmed TKA implants. Their average age was 68.71 years (range, 52-81 years).The most common mechanism of injury was fall (five patients), followed by a traumatic fracture of the femur while walking (one patient), and being lifted out of bed (the one nonambulatory patient). This retrospective study reports a treatment protocol, including surgical technique, and short-term outcome in seven patients in whom locking compression plates (LCP) were used.

RESULTS

Six fractures were classified as Rorabeck type II, and one as type III. The average time to full-weight-bearing was 5.5 months. At this institution, good short-term results have been achieved by using an LCP with screws placed proximal to the long-stem and distal to the fracture. The six patients all achieved full-weight-bearing,taking an average of 5.5 months (range, 3-7 months).

CONCLUSIONS

LCP is an effective form of management of distal femur fractures around long stem TKAs. An individualized operative approach possibly incorporating bone-graft substitutes, cerclage wire and a post-operative bone stimulator is recommended.

PERIPROSTHETIC FRACTURES IN TOTAL KNEE ARTHROPLASTY

The increasing number of total knee arthroplasties, in combination with the population's longer life expectancy, has led to a greater number of long-term complications. These add to the poor bone quality of elderly patients and often culminate in periprosthetic fractures. This complex orthopedic problem has a great diversity of clinical presentation. It may affect any of the bones in the knee and, because of the difficulty in finding solutions, may lead to disastrous outcomes. Its treatment requires that orthopedists should have broad knowledge both of arthroplasty techniques and of osteosynthesis, as well as an elaborate therapeutic arsenal including, for example, access to a bone bank.