Stability of internally fixed femoral neck fractures augmented with resorbable cement. A prospective randomized study using radiostereometry

Abstract

Background and aims: Internal fixation of displaced femoral neck fractures is associated with a high risk for complications such as non-union or avascular necrosis. A stable fracture fixation can improve prognosis although stability is often counteracted by weak osteoporotic bone. The aim with this study was to evaluate whether augmentation with resorbable calcium-phosphate cement could improve fracture stability during the early period after surgery as shown in biomechanical studies.

Material and methods: 40 ambulatory patients with a displaced femoral neck fracture were randomized to treatment with cannulated screws alone (controls) or screws combined with calcium-phosphate cement for augmentation (augmented). All patients were allowed unrestricted weight bearing after surgery. Fracture movement was measured with radiostereometry (RSA) at 1 and 6 weeks.

Results: At 1 week the augmented fractures had moved on average 1.9 +/- 1.0 mm while movement in the controls was 5.5 +/- 3.4 mm (p < 0.0001). The average total movement at 6 weeks was 6.9 +/- 2.9 mm and 10.9 +/- 5.1 mm, respectively (p < 0.005). Varus angulation and distal migration of the femoral head were the most common movements for both groups although augmented fractures had moved significantly less at both 1 and 6 weeks. There were no significant differences in angulation between groups around the longitudinal and transversal axes or in migration along the transverse or sagittal axes.

Conclusion: Augmentation with calcium-phosphate cement improved the stability of internally fixed femoral neck fractures during the first six weeks after surgery, with improvement being less pronounced at six weeks compared with at one week.