Abstract
Objective: To review medium-term outcomes of 34 patients who underwent total hip arthroplasty (THA) or bipolar hip prosthesis (BHP) using the Mayo conservative prosthesis (Mayo stem) in young patients.
Methods: Records of 40 hips in 7 men and 27 women aged 30 to 65 (mean, 52.7) years who underwent THA for osteoarthritis secondary to dysplastic hips or BHP for idiopathic osteonecrosis of the femoral head or femoral neck fracture, and had been followed up for a mean of 7.2 (range, 5-9.7) years, were retrospectively reviewed. The outcomes of Mayo stem were evaluated in size, alignment, contact point, bone reaction (stress-shielding, radiolucent line, increased bone density, and neocortex), and complications (loosening, intraoperative fracture, subsidence and thigh pain).
Results: Four hip procedures used overly small sized stems, and 2 hip procedures used overly large sized stems. Alignment was evaluated by measuring the angle between the tail line of the stem and the lateral cortex of the femur in the anteroposterior view. The mean angle was 0.6 degrees. Multi contact points were identified in the intraoperative radiographic images. Grade 2 stress-shielding (Engh classification) were identified in 18% of the hips. Radiolucent lines were demonstrated in zones 1 (37%), 2 (8%), and 7 (5%), respectively. All of the hips showed increased density (zone 2) and neocortex (zone 6). In 8 patients, intraoperative femoral fracture at the site of the implantation was found, but there were no differences in clinical outcomes. There was no subsidence of more than 2 mm, implant loosening, or thigh pain.
Conclusion: In this study, we demonstrated satisfactory medium-term outcomes of Mayo stem in young patients.
