Abstract
Introduction: The double threaded Cone Modular Hip Replacement System has been used in 114 patients as a primary prosthesis in over three years. No patient has been lost to follow up and all patients have been assessed postoperatively for the Harris Hip Score, Pain Score, Dexa analysis as well as plain X-rays.
Method: 114 patients requiring primary hip replacement were entered into a prospective clinical trial over a three year period. The Harris Hip Score, Pain Score and Dexa analysis (Luna 2000 program) and X-rays were assessed at six weeks, three months, six months, twelve months, two years and three years and results were compared with the preoperative figures. Length of hospital stay, discharge details (home or rehabilitation unit) and physiotherapy assessment of time to independent stair climbing was prospectively assessed.
Results: The Dexa analysis indicates a loss of bone at two years at Gruen’s zones one and seven of 25% and at zones two and six of approximately 20% with no increase or loss of bone in zones three, four and five.
The Harris Hip Scores and Pain Scores show a significant improvement comparing preoperative with postoperative results in this series.
One patient required revision of the femoral neck component for recurrent dislocation and three patients have significant rotational thigh pain due to varus implantation of the stem (the pilot has since been shortened and the diameter reduced by 1mm).
Conclusion: The double threaded cone shaped modular hip prosthesis stem allows immediate full weight bearing postoperatively. No prosthesis has loosened or subsided and the locking mechanism has been shown to gain immediate and long term fixation as a primary prosthesis stem.
Clinical assessment, X-rays and Dexa analysis indicate satisfactory results with good incorporation of the prosthesis by the bone.
The abstracts were prepared by Professor Jegan Krishnan. Correspondence should be addressed to him at the Flinders Medical Centre, Bedford Park 5047, Australia.
