LONG-TERM FOLLOW-UP OF 173 HA-COATED, SCREW-CUP TOTAL HIP ARTHROPLASTIES

Abstract

Introduction: Reports of the results of screw-cup arthroplasties have been disappointing with high revision rates.

Aim: To review our experience of 173 HA-coated screw- cups that have been implanted in 150 patients.

Methods: The patients were followed up at six weeks, three months, six months, again at one year and annually thereafter. The patients were assessed using the Merle D’ Aubigne (MDP) clinical scoring scale and by radiographic review.

Results: The average follow-up was 6.5 years (range 5–9 years). The follow-up rate was 93%. Two patients had revision surgery for recurrent dislocations (1.2%). Two patients were revised for aseptic loosening (1.2%). One patient underwent revision surgery for to deep prosthetic infection (0.6%) and two patients were revised for polyethylene wear without loosening (1.2%). This gave a total revision rate of 4.0%. The average post operative MDP scores were 5.7 for pain, 5.5 for range of movement and 5.4 for function. A radiological review revealed one patient with extensive granuloma formation and two patients with evidence of migration although no cups were revised for migration alone.

Discussion: We believe that the lower revision rate in this series is due to the double advantage of an HA coated cup (which leads to low revision rates for aseptic loosening), and the use of a ceramic head (which produces low polyethylene wear rates). We believe our results convey strong evidence for the advantage offered by HA coating for use with a screw-cup or other prosthesis.