Abstract
Introduction: The purpose of this paper is to present the results of a prospective study involving one stem design used in primary total hip arthroplasty with three different surface enhancements to include a simple textured geometry, a plasma sprayed coating and an hydroxyapatite (HA) coating.
Methods: Between 1990 and 1994, 138 patients underwent primary THA using a simple femoral component. Thirty-eight patients received a textured geometry while 50 were implanted with a HA coated stem and 50, a plasma sprayed stem. The hips were evaluated annually both clinically and radiographically. The results are reported using the Harris Hip Score and the Engh radiographic scale to determine the level of bone ingrowth and type of fixation.
Results: The average length of follow up is 8 years 11 months (range: 6 to 10 years). The average postoperative Harris Hip scores were 81.0% for the textured stems, 89.6 for the HA coated stems and 85.7 for the plasma sprayed stems. The revision rates are 13.2% for textured stems, 0% for HA and 5.4 % for plasma sprayed. Radiographic results show that fixation of the 3 surface coatings to be optimal in 100% of HA, 88.2% in plasma sprayed and 84.2% in textured.
Discussion and conclusion: At this point in the study, it is obvious that the coating enhancement of choice is hydroxyapatite. The next step in this research will be to match the HA coated stems with a comparable porous coated stem of the same design for further comparison.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
