Total Hip Arthroplasty With a Fully Hydroxyapatite-Coated Stem: A Cohort Study During 23-28 Years

Long-term results of a hydroxyapatite (HA)-coated stem are sparse. We have followed a cohort of patients operated with a grit-blasted titanium stem designed for press-fit insertion and entirely plasma-sprayed with HA up to 28 years.

In the years 1988-1993, we performed 323 primary total hip arthroplasties in 276 patients (189 women). Their mean age was 48 (15-79) years. During the following years, 83 patients with 88 hips have died, and 18 patients did not attend the follow-up examination, but had no major symptoms according to telephone interviews and control examination. Thus, 212 patients (255 hips) were followed up for more than 20 years.

Three patients were revised because of late periprosthetic infection, 1 because of a fall with periprosthetic fracture, and 2 stems were revised due to mechanical failure. Osteolysis was significantly associated with wear, and wear was significantly associated with the size of the femoral head. We found a small amount of proximal bone loss and a low incidence of distal hypertrophy of the bone. The bone changes confirmed a well-fixed femoral component in asymptomatic patients.

Our findings indicate an essentially physiological weight distribution from the stem to the femoral bone with no significant thigh pain. The changes in the bone confirmed that the femoral component was well-fixed, and we conclude that a fully HA-coated titanium stem designed for press-fit insertion lasts for 23-28 years.