Abstract
Introduction
Optimal results from uncemented total hip arthroplasty (THA) requires the prosthesis to obtain initial stability, restoration of biomechanics, bone contact along the ingrowth surface and uniform stress transfer to the proximal femur. Anatomic variation within the population makes this difficult to reproduce in every patient. To achieve optimal fit and fill of the proximal femur, options are reshaping the canal or creating an implant which precisely fits the patient's anatomy. The former increases bone loss and risks weakening the supporting bone, creating areas of stress concentration or shielding. Computer assisted design-computer assisted manufacture (CAD-CAM) femoral components were designed to overcome these issues. We present the long term results of CAD-CAM femoral components used in primary THA.
Methods
This was a prospective study looking at a consecutive, single surgeon series of THA's. Patients were reviewed pre operatively then at 6 weeks, 3 and 12 months post operatively and then yearly. Clinical as well as radiological review was performed at each visit and Harris Hip Score (HHS), Oxford Hip Score (OHS) and Western Ontario McMaster's (WOMAC) scores were calculated. Kaplan-Meier survival analysis was performed.
Results
One hundred and eleven patients were included (53 men and 58 women). Their mean age was 46.2 years and mean follow-up was 13 years. Pre operative Oxford, Harris and WOMAC hip scores were 43.1, 42.4 and 57.0 respectively. Mean post operative scores at last follow up were 18.2, 90.3 and 11.9 respectively (p< 0.0001 for each score). There were no revisions for aseptic loosening. Worst-case survival at 13.2 years was 98.2%.
Conclusions
CAD CAM femoral components result in pain relief and functional improvement in the long term. These results are comparable with the best long term results for primary THA with any means of fixation.
