FEMORAL HEAD AUGMENTATION WITH METAL-ON-METAL HIP RESURFACING IS EFFECTIVE FOR SEVERE DYSPLASIA

Abstract

Metal-on-metal hip resurfacing (MOMHR) is a good surgical indication for young active patients. However, it cannot be used in patients with severe CDH and in particular a too short head/neck. To address these cases, a new surgical technique consisting of augmentation of the femoral head with impacted morcellized bone grafts has been developed.

32 osteoarthritis patients following severe congenital insufficiency of the femoral head/neck were treated with MOMHR combined with femoral head augmentation. The required amount of augmentation was calculated on preoperative X-rays and confirmed during surgery. Using special instrumentation, bone chips produced while reaming the socket and trimming the head were impacted on the head to achieve the desired reconstruction and lengthening. Finally, the femoral component was cemented.

Mean patient age was 49+ 9 years (18–66). Median head lengthening was 12+ 2 mm. Mean follow up is 4.2 years (3–6). Mean preoperative Harris hip score (HHS) was 58 and at follow-up 95 (p < 0.05). Mean leg lengthening was 2.2 cm (p = 0.001). In all Gruen zones, bone mineral density (BMD) decreased during the first 3 months. At 2 years in zone 1 mean BMD increased to 96.8% (p = 0.009) and in zone 7 to 102.1% (p = 0.05). A correlation was found between valgus positioning of the femoral components and increased BMD (p = 0.005).

This impaction bone grafting technique expands the use of MOMHR to patients with severe congenital hip dysplasia leading to a more anatomical reconstruction with a full recovery of function and BMD.