Long-term results of a soft interface- (Proplast-) coated femoral stem

Background Mid-term clinical results of uncemented femoral components with a Proplast coating have been unfavorable and the low modulus system was abandoned in the mid-1990s. There are, however, still substantial numbers of patients with a Proplast-coated prosthesis in situ. We evaluated the clinical and radiographic results in patients with 8–13 year follow-up.

Methods We evaluated the survival rate, Harris Hip score and radiographic features of 82 hips in 69 patients. Mean age at operation was 58 (35–72) years.

Results With respect to the Harris Hip score (HHS), 21% of the hips were considered to be clinical failures (HHS < 70) at final follow-up, mainly because of excessive thigh pain. Osteolysis was observed in one or more Gruen zones in one-third of the hips. According to the criteria of Engh, 79/82 stems were unstable. 11 hips were eventually revised due to aseptic loosening. Survival of the femoral component of the original cohort at final follow-up was 84% (95% CI: 75–93) in a standard-case scenario.

Interpretation Extensive signs of loosening were observed in almost all hips, while not all hips were considered to be clinical failures. Thus, all patients should be thoroughly screened for radiographic progressive osteolysis or the occurrence of thigh pain. Thigh pain or progressive osteolysis warrants revision of the Proplastcoated femoral stem.