Total hip arthroplasty with the Lord prosthesis. A long-term follow-up study.

BACKGROUND

The Lord prosthesis has been used rather extensively for total hip arthroplasty. In 1981, we began a prospective study for the purpose of determining the long-term results associated with the use of this prosthesis. In the present report, we describe the results for the living patients after a mean duration of follow-up of 17.5 years (range, fifteen to twenty years).

METHODS

One hundred and two patients (116 hips) with a mean age of sixty-two years at the time of the index arthroplasty were included in the study. Eighty-nine hips were in women, and twenty-seven were in men. The Lord femoral prosthesis (with a 32-mm head) and the Lord threaded cup were used in all patients. The protocol included radiographic analysis, recording of complications, and a clinical evaluation. The patients were evaluated at one to four years, five to nine years, and fifteen to twenty years.

RESULTS

One patient (one hip) refused to participate and forty-two patients (forty-five hips) died with the femoral component in place, leaving fifty-nine patients (seventy hips) available for clinical assessment. One femoral component was revised because of mechanical loosening, and one was revised because of a stem fracture. One stem appeared to be loose radiographically. Kaplan-Meier survivorship analysis with revision of the femoral component because of mechanical loosening, stem fracture, or radiographic loosening as the end point revealed a cumulative survival rate of 98% (95% confidence interval, 95.3% to 100.7%) (with twenty-eight hips at risk) at 17.5 years. Seventeen acetabular components were revised because of mechanical loosening, and sixteen were considered to be radiographically loose. Kaplan-Meier survivorship analysis with revision of the acetabular component because of mechanical or radiographic loosening as the end point revealed a cumulative survival rate of 65% (95% confidence interval, 53% to 72%) (with twenty-two hips at risk) at 17.5 years.

CONCLUSIONS

We believe that the survival rate of the Lord femoral component after 17.5 years of follow-up was excellent. However, there was a substantial rate of proximal femoral bone loss. The results associated with the threaded cup were rather poor, and many patients had a loose implant but few symptoms. We recommend that patients with these implants be followed closely so that revision can be performed before substantial destruction of the acetabulum has occurred.

LEVEL OF EVIDENCE

Therapeutic study, Level II-1 (prospective cohort study). See Instructions to Authors for a complete description of levels of evidence.