For primary uncemented hip arthroplasty, various stem designs are available. The cementless CLS((R)) Spotorno stem has been used for more than 20 years. We re-evaluated a group of patients previously examined for a 10-year follow-up to assess the clinical and radiological stem performance in the long run.
Between 1987 and 1988, a consecutive series of 107 uncemented CLS((R))-Spotorno stems (Zimmer Ltd., Germany) were implanted in 94 patients. The patients' mean age at the time of surgery was 51 years (range 20-77 years); 80 hips out of 107 (86%) were available for a clinical examination [Harris Hip Score (HHS)] after a mean of 17 years (range 15-18 years). In addition, radiographs were available from 74 out of 80 examined hips (92%) and analyzed for radiolucency, stress shielding, stem migration and heterotopic ossification.
Stable stem fixation was present in 64 hips (98.5%). With "non-traumatic loosening" as an endpoint, stem survival was 100% after 17 years. Two stems (3%) showed mild subsidence already in the 10-year follow-up with no progression after 17 years. The HHS described excellent results in 47 hips (59%), good results in 16 hips (20%) and fair or poor results in 7 hips (9%) and 10 hips (13%), respectively. Radiolucency and grades II and III stress shielding were progressive at 17 years compared with the 10-year results. Grade IV stress shielding associated with osteolysis was seen in 9 hips (14%). Thigh pain was present in 20 hips (25%).
The CLS((R)) Spotorno stem allows excellent long-term results in cementless hip arthroplasty, leaving only minimal options for substantial improvements. Our findings on progressive stress shielding point towards a more diaphyseal load transfer of the CLS stem.