Comparative 5-Year Results of Short Hip Total Hip Arthroplasty with Ti- or CoCr-Neck Adapters

This prospective study investigated revision after modular short stem implantation. Results are presented for 2 different types of neck adapters (titanium and cobalt-chromium [CoCr]). Eighty-five patients with titanium adapters and 87 patients with CoCr adapters underwent follow-up examination after an average of 5.7 and 5.2 years, respectively. Mean patient age was 57 years in both groups. Indications were primary osteoarthritis (80%), cup dysplasia (14%), and other (6%). Mean Harris Hip Scores were 98 and 99 points (titanium and CoCr groups, respectively). Ninety percent and 96% of patients were very satisfied or satisfied (titanium and CoCr groups, respectively); 3% of patients in both groups were dissatisfied. Pain decreased from visual analog scale score 7 and 6 preoperatively to 0.37 and 0.15 postoperatively for the titanium and CoCr groups, respectively. No joint dislocation occurred. Six patients needed revision within the first year (2 for infection, 1 for via falsa position, and 2 for aseptic loosening in the titanium group, and 1 for aseptic loosening in the CoCr group). Nine revisions occurred due to neck adapter failure (titanium group). Primary standard stems were used in all revisions. Excluding material-related adapter failures in the titanium group, the 5-year survival rate was 94.8% (95% confidence interval [CI], 88.9-97.6 for titanium) and 99% (95% CI, 93.7-99.8 for CoCr). No radiographic signs of loosening were seen at last follow-up. Fine sclerotic lines were detected in Gruen zones 1 (17.2%) and 2 (14%), hypertrophies in zone 3 (4.3%), and periprosthetic cancellous bone compressions in zone 6 (75.8%). No adapter fractures occurred for CoCr components. The treatment and anchoring system of the short stem studied yielded good results and allowed revision using standard stems in all patients.