Introduction: The Centrament® (Aesculap, Tuttlingen, Germany) is modular hip system combined with a range of modular heads and acetabular components, enabling the system to cover a wide range of applications. We looked at medium term results in a district general hospital.

Methods: This is a retrospective cohort study. Information was obtained from patient notes and radiographs.

Results: One hundred and ninety two (n =192) total hip arthroplasties in 178 patients (14 bilateral) were followed up for at least 5 years (mean: 5.8 years; range: 5–9 years). The mean age of the patients at the time of surgery was 71.8 years (range, 38–91 years). The most frequent indication for surgery was osteoarthritis (94%). One acetabular cup was revised for aseptic loosening, and 2 cups were revised for recurrent dislocation. Two stems have been revised (one for aseptic loosening and one for prosthetic fracture). The dislocation rate was 4.2% during the initial fifty arthroplasties that reduced to 0.9% in the subsequent years. For radiological evaluation Gruen zones for the stem and DeLee and Charnley zones for the cup were used. The acetabular cup was satisfactory in 186 hips radiographs and showed asymptomatic non-progressive osteolysis in three cups. Two stems showed signs of osteolysis at nine years but the patients had no symptoms. Using the recommendation of revision as the endpoint, Kaplan Meier Survival Analysis showed a cumulative survival for the prosthesis as 97.3%, with stem survival of 99% and cup survival of 98.5%.

Discussion: In the medium-term, these results are comparable to other cemented hip prosthesis used in the UK.

Tumour necrosis factor-α (TNF) is thought to play a role in aseptic loosening, the major cause of implant failure after total hip arthroplasty (THA). Natural sequence variations at –238 and –308 in the promoter region of the TNF gene are associated with differences in the susceptibility and severity of several TNF-mediated diseases. We tested whether carriage of the [less common] ‘A’ allele at –238 and –308 are associated with aseptic loosening after THA.

481 Caucasians (214 with failed implants versus 267 with radiologically intact implants) were recruited 11.7± 4.1 years after cemented THA for osteoarthritis. Genomic DNA was extracted from peripheral blood and genotyped for the –238 and –308 polymorphisms using the Taqman® 5′ nuclease method. 500 subjects from the local population were also genotyped using Taqman® to establish the background prevalence of the ‘A’ allele at each site.

The carriage rate of –238A was 8.8% in the background population and 10.9% in the THA controls (P> 0.05). –238A carriage in the loosening group was 17.3% (odds ratio 1.72, 95% confidence interval 1.02 to 2.90). Carriage was highest (20.5%) in subjects with loosening of both the femoral and pelvic implant components (odds ratio 2.12; 1.17 to 3.83). The association of –238A with aseptic loosening was independent of age, sex, and amount of implant wear (Cox hazard ratio 1.49 (1.04 to 2.13; P=0.03)). Carriage of –308A was not associated with aseptic loosening.

Genetic, as well as environmental factors, influence implant failure after THA. Whether the –238 polymorphism causes the biological change that predisposes to loosening, or is in linkage disequilibrium with such a locus, is not yet known.