EARLY COMPLICATIONS OF HIP RESURFACING ARTHROPLASTY

Abstract

Introduction: A common criticism of the modern hip resurfacing arthroplasty is its high early complication rate, in particular femoral neck fracture, displacement of the acetabular component and avascular necrosis. The overall complication rate varies widely in different published series. The sometimes alarmingly high rate of complications, as much as 22% for femoral neck fractures alone (Mont et al. 2005), has deterred many surgeons from using resurfacing implants. As a specialist elective hip practice we wished to specifically determine the early complication rate of hip resurfacing arthroplasty using the metal-on-metal Cormet 2000 implants. We defined an early complication as any resurfacing procedure which required inpatient readmission and/or further intervention within 12 months of the primary operation.

Material and methods: We assessed 253 consecutive hip resurfacing procedures (226 patients). All procedures were performed by the same surgical team using the same surgical approach (posterolateral). Operations were performed between 2001–2005. The mean operating time for was 51.8 minutes. The mean age of patients was 50 years (27 to76) at the time of surgery. 141 patients (62.4%) were male and 85 (37.6%) were female. The preoperative diagnosis was osteoarthritis for the majority of patients 246 (97.2%), the remainder having avascular necrosis (4 cases, 1.6%), chondrolysis (2 cases, 0.8%) or large osteochondral defects (1 case, 0.4%).

Results: In this series there were two infections (one superficial and one deep), one intraoperative femoral neck fracture (converted to THR), no episodes of avascular necrosis, one revision because of acetabular component loosening and one readmission because of a postoperative haematoma 10 days after surgery. All together two patients needed a further operation within one year of the primary operation (one two-stage revision because of deep infection, one revision to THR because of acetabular component shift). The haematoma was treated conservatively. There was one deep vein thrombosis (DVT), one case of iliopsoas tendonitis, one case of trochanteric bursitis and one patient wore an abduction brace for 6 weeks because of slight instability although there was no dislocation. The patient with DVT was readmitted as an inpatient. The overall complication rate (readmission as an inpatient) was 1.6% (4 patients) with the Cormet 2000 implant. Reoperation rate was 1.2% (3 patients) (including the intraoperative conversion to THR).

Discussion: The Cormet 2000 is a fully uncemented hydroxy-apatite coated hip resurfacing implant. In our series we found a low early reoperation and infection rate. All the reoperations were performed for cases were the primary operation was carried out in the first 6 months of this series. There were no complications associated with the uncemented femoral component of the Cormet 2000 implant.