Purpose: To assess the clinical and radiological performance of the Ultima THR.

Material-Methods: Between January 1991 and July 1994, 147 consecutive patients (154 hips) underwent a primary THR using an all-polyethylene cemented cup and the Ultima Ti alloy smooth, collarless, double tapered, straight stem. 65% were females and primary diagnosis was OA or RA in the majority. The average age at operation was 66.4 years. At average follow-up of 76 months, 34 patients (35 hips) were dead and 5 were lost. Patients were annually assessed clinically (HSS) and radiologically. Radiographs were digitized and migration analysis and cup wear was performed using the EBRA method.

Results: There were 9 aseptic failures (5 stems, 1 cup and 3 both components). Cup migration analysis was possible in 106 cases. Migration was detected in 62 of them (18 proximal, 15 medial, and 29 combined). Proximal migration ranged from 0.8 mm-4.0 mm and medial migration from 1.0 mm–3.5 mm. The average cumulative linear cup wear was 0.2 mm. Stem migration analysis was possible in 114 cases. At 2 years, 35 stems subsided less than 1.5 mm. Migration of more than 1.5 mm was observed in 16 stems. Early subsidence of more than 1.5 mm was highly predictive for later revision.

Conclusions: Ti-stems have been criticised for high failure rate but the exact mechanism of loosening is multifactorial. Our revision rate and the low incidence of focal osteolysis, even in the presence of a small degree of stem subsidence, indicate that a smooth double tapered Ti-alloy cemented stem may offer a durable long-term solution.

Cemented Ti-6Al-4V components were used to resurface ten femoral heads in nine young adult patients with osteonecrosis of the femoral head (average age 32 years; range 20 to 51). There were eight hips at Ficat stage III and two at stage IV. Five hips have maintained satisfactory function for an average period of 11.2 years (10 to 12.2) with no radiographic evidence of component loosening or osteolysis; five have been revised after an average period of 7.8 years (3.3 to 10.3) for pain caused by deterioration of the acetabular cartilage. No component required revision for loosening and the specimens retrieved at revision showed no evidence of osteolysis despite burnishing of the titanium bearing surface and the presence of particulate titanium debris in the tissues.

We report the results of imaging with labelled white cells in 52 patients before the revision of 54 cemented joint prostheses at which the diagnosis of infection was made from biopsies. Twenty-five hips were imaged with 111In-oxine-labelled cells; 20 hips and 11 knees were imaged with 99mTc-hexamethylpropylene-amineoxime-labelled cells. Of these, 13 hips and five knees proved to be infected. The scans taken together had an accuracy of 82%, a sensitivity of 44% and a specificity of 100%. Indium scans gave 37% sensitivity, 99mTc labelling 50% sensitivity. Infected arthroplasties with positive scans had presented significantly earlier than those with negative scans, the time after the original insertion being 1.1 years for the true-positive scans and 6.1 years for the false-negative scans. The value of labelled white-cell scans in the detection of infection in failed joint replacements is dependent on the activity of the infection. There is reduced sensitivity to the more insidious infections which affect arthroplasties and aspiration under controlled conditions remains an important investigation.

We describe a simple, retroperitoneal approach for the removal of acetabular components that have migrated into the pelvis. The dense fibrous tissue layer which surrounds the implant protects the iliac vessels during removal of the cup by this method.