RESULTS OF THE C-STEM TOTAL HIP REPLACEMENT SYSTEM

Abstract

Introduction: The C-stem total hip replacement system was devised in Wrightington in 1993 and represented the first triple tapered stem. There is little literature about the follow up outside of Wrightington and therefore we present our data on the C-Stem at a district general hospital.

Methods: This is a prospective radiological follow up of patients between March 2000 and November 2004, 250 primary hips were performed by a single surgeon using a posterior approach. Cemented all polyethylene cups were used. Initial and annual x-rays were reviewed and the following measurements were recorded: cup angle; radiolucent lines in the bone-cement interface of the acetabulum; heterotopic ossification; stem subsidence, radiolucent lines or osteolysis in the femoral component and stem orientation.

Results: Data is available on 206 hips performed on 185 patients. 107 patients were female and 78 patients were male. 72 were left sided, 92 were right sided and 21 were bilateral. The average age was 66yrs (25–89). Average follow up was 41 months (12–68). The average cup angle was 44.7 degrees. 24 patients had 0.5 mm lucencies in zone 1 of the acetabulum and 1 patient had 1mm lucency in zone 1. No lucencies were progressive. There were no lucencies in any of Gruens’s zones. 18 patients had Grade 1 heterotopic ossification, 2 Grade 2 and 1 Grade 4. 17 stems were in varus and 1 stem in valgus. Average stem subsidence was 0.83mm.

Complications were 1 fractured greater trochanter wired intra-operatively and 1 femoral nerve palsy which resolved in 3 months. There were no PE’s, dislocations or deep infections. No hip replacement has required revision.

Discussion: We conclude that at a maximum follow up of 5.5 years the C-Stem is performing to standards required by NICE and is on course to achieve the benchmark of 10% revision at 10 years.