The Stability of Fixation of Vancouver B2 Periprosthetic Femoral Fractures: Effect of Implantation Technique.

INTRODUCTION: Due to increasing volume of total hip arthroplasties, periprosthetic femoral fractures have become a common complication with increased revision burden and perioperative morbidity. The objective of this study was to evaluate the fixation stability of Vancouver B2 fractures treated with two techniques.

METHODS: A common B2 fracture was created by reviewing 30 type B2 cases. The fracture was then reproduced in 7 pairs of cadaveric femora. The specimens were divided into two groups. In Group I ("reduce-first"), the fragments were reduced first, followed by implantation of a tapered fluted stem. In Group II ("ream-first"), the stem was implanted in the distal femur first, followed by fragment reduction and fixation. Each specimen was loaded in a multi-axial testing frame with 70% of peak load during walking. A motion analysis system was used to track the motion of the stem and fragments.

RESULTS: The average stem diameter in Group II was 16.1±0.4 millimeters (mm), versus 15.4 ±0.5mm in Group I. The fixation stability was not significantly different in the two groups. After the testing, the average stem subsidence was 0.36±0.31mm and 0.19±0.14mm (P=0.17), and the average rotation was 1.67±1.30° and 0.91±1.11° (P=0.16) in Group I and II, respectively. Compared to the stem, there was less motion of the fragments, and there was no difference between the two groups (P>0.05).

CONCLUSIONS: When tapered fluted stems were used in combination with cerclage cables for treatment of type B2 periprosthetic femoral fractures, both the "reduce-first" and "ream-first" technique showed adequate stem and fracture stability.