No abstract

The key rationale for a nonmodular flexible press-fit cup was to maximize long-term stability with a cementless, porous metal-coated cup that is low in stiffness (no metal shell) and to achieve fixation solely through biradial eccentricity between the cup and the acetabular cavity. We asked whether the promising results achieved at 5 and 10 years would be maintained at 15 years. We reviewed 261 patients who received the first 280 Morscher Press-Fit Cups. One hundred twenty patients (126 hips) died. One hundred one patients (112 hips) had a clinical and radiographic followup after a minimum of 13.5 years (mean, 14.7 years; range, 13.5-17.0 years). Twenty-four patients with 26 hips were clinically examined or interviewed by telephone. Three of the 101 patients were lost to followup. We judged the results excellent or good in 96% of the hips. The 15-year overall survivorship was 95.3% and with the end point of aseptic loosening, the survivorship was 97.5%. Wear was greater in cups with an inclination greater than 45 degrees and in metal-polyethylene pairings compared with ceramic-polyethylene pairings. This cup design performs well over the long term.

The Morscher-Spotorno (MS-30) femoral stem is a stainless-steel, straight, three-dimensionally tapered, collarless implant for cemented fixation in total hip replacement. We report the results at ten years of a consecutive series of 124 total hip replacements in 121 patients with the matt-surfaced MS-30 stem and an alumina ceramic head of 28-mm diameter. All the stems were fixed with Palacos bone cement with gentamicin using a modern cementing technique. They were combined with an uncemented, press-fit cup. The mean period of observation was 10.2 years (8.3 to 12.1) and no patient was lost to follow-up. Twenty-seven patients (22%) died with the implant in situ. Nine could only be interviewed by telephone. We included 85 patients with 88 hips in the clinical and radiological follow-up examinations. None of the stems or cups had been revised. The Harris hip score was excellent or good in 97% (85 hips) and moderate in 3% (three hips). Radiologically, six hips (6.8%) had osteolysis adjacent to the stem, mostly in Gruen zone 7. Twenty (22.7%) showed one or more radiolucent lines. Twenty-two stems (25%) had subsided by 2 mm to 5 mm. In these cases two showed osteolysis (9.1%) with subsidence and four without (6.1%). Radiolucent lines were seen in seven with migration (31.8%) and in 13 without (19.7%). No infections and no acetabular osteolysis were observed. The clinical results were excellent with survivorship after ten years of 100% and only a slightly statistically non-significant higher rate of osteolysis and radiolucency in cases of subsidence.

At the Orthopaedic Department of the University of Basel, a total of 540 cemented Müller titanium alloy (Ti6Al7Nb) Straight Stems were inserted between 1989 and 1993. A cohort of 120 consecutive patients (66 women, 54 men) with 126 prostheses operated on between March and December 1989 were followed clinically and radiologically in a prospective manner for a mean observation time of 9.1 years. In all cases, the Müller titanium alloy Straight Stem was combined with the senior author's (E.W.M.) Press-Fit Cup. The mean age of the patients at surgery was 66 (range 43-93) years. Fourty patients (41 hips) died, 9 were interviewed by telephone, none was 'lost to follow-up'. Seventy-one patients with 76 hip replacements were available for the follow-up. Four hips had been revised: two of them due to aseptic loosening of the femoral component, one because of a late infection--all after 9 years--and one owing to a periprosthetic fracture after 6 years. The 9-year overall survivorship is 96.8%, and for aseptic loosening of the stem 98.4%. None of the cups had to be revised for aseptic loosening. The clinical result (according to Merle d'Aubigné) was excellent and good in 88%, moderate in 8%, and poor in 4%. The radiological analysis showed no osteolysis or radiolucent lines in 59 prostheses (78%). Nine stems (12%) showed a radiolucent line. Focal osteolysis was detected in 8 cases (10%) in one or more Gruen zones. The distribution of the osteolyses shows that predominantly zones VII, VI, V, and II are affected in decreasing frequency. No osteolysis was detected on the acetabular side. Our results do not confirm the high rate of osteolysis and revisions with the Müller titanium alloy Straight Stem presented by some other institutions. The verdict on a specific endoprosthetic implant must be made by combined assessment of the design, the implant surface condition, the material, the cement, the cementing procedure and the operative technique. The statement made in earlier publications that cemented titanium alloy should not be used as a femoral stem prosthesis should be reconsidered.