Abstract
Two hundred and seventeen consecutive patients (238 hips) underwent total hip arthroplasty using the St Michael’s stem and a non-porous screw ring cup. Patients were followed prospectively clinically using the St Michael’s hip score and radiographically. At an average of 11.9 years (10-13.5 years), 55 patients (59 hips) had died, 23 patients (23 hips) were lost to follow-up. The St Michael’s hip score improved from 13.4 pre-operatively to 21.7 (out of a possible 25) at the latest follow-up. Thirty-seven (24%) of the acetabular components have been revised for aseptic loosening and an additional seven components are radiographically loose. No femoral components have been revised. Using Engh’s criteria one femoral component is definitely loose and two femoral components have stable fibrous ingrowth. Significant stress shielding was noticed in 23 hips (17%) without clinical consequences. Minor osteolysis was seen in 13 hips most commonly around the proximal femur and has not caused symptoms. The St Michael’s stem with its large pore size madreporic surface has comparable results to other porous coated stems with smaller pore size.
The St Michael’s stem provided reliable ingrowth and fixation with an acceptable degree of stress shielding. The non-porous screw ring cup had a high failure rate.
The abstracts were prepared by Nico Verdoschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, Universitair Medisch Centrum, Orthopaedie / CSS1, Huispost 800, Postbus 9101, 6500 HB Nijmegen, Th. Craanenlaan 7, 6525 GH Nijmegen, The Netherlands.
