Identification and treatment of potentially destabilizing Vancouver B-lesser trochanter periprosthetic fracture ("New B2"): A 33-case series

Abstract

Introduction: A new type of periprosthetic fracture, between Vancouver-SoFCOT types A and B, was recently described and labeled "new B2". It occurs intraoperatively or in the early postoperative period, on cementless implants, and features a posteromedial cortical fragment around the lesser trochanter. The main aim of the present study was to report clinical and radiological results in a series of 33 cases of what is better called Vancouver B-lesser trochanter (VB-LT) fracture. The secondary objective was to identify risk factors. The study hypothesis was that VB-LT fracture might occur in the late postoperative course.

Material and method: A2 single-center retrospective study included all patients with postoperative periprosthetic VB-LT fracture diagnosed on standard X-ray. Treatment was operative or non-operative depending on femoral implant subsidence and the patient's general health status.

Results: There were 33 VB-LT fractures out of 445 periprosthetic femoral fractures (7.5%), in 27 women and 6 men; all were postoperative, at a mean 47 months (range, 1 day to 20 years). Mean subsidence of the femoral stem was 8.8mm, in 73% of cases (24 out of 33 implants). The 9 VB-LT1 fractures (without subsidence) were treated non-operatively, without secondary displacement. Thirteen of the 24 VB-LT2 fractures (with subsidence) were managed by stem exchange and cerclage; 3 other patients had isolated stem exchange, 2 had isolated internal fixation by cerclage, and 6 in poor health were managed non-operatively. At a mean 28 months' follow-up (range, 6-48 months), mean PMA score was 15.5 (range, 10-18), Harris Hip score 72.4 (range, 43-100) and Parker score 7.2 (range, 4-9). All cases showed osseointegration and implant stability; there was 1 case of non-union, without impact on stability.

Conclusion: Postoperative Vancouver B-lesser trochanter fracture seemed specific to cementless implants and did not occur exclusively in the early postoperative period. Non-operative treatment gave good results when there was no implant subsidence (type VB-LT1).

Level of evidence: IV, retrospective.

Keywords: Hip implant revision; New B2 fracture; Periprosthetic fracture; Total hip replacement; Vancouver classification.