| Objective: To sum up therapeutic effects of minimally invasive metal on metal total hip arthroplasty in the treatment of adult hip joint disease.Method: Between Nov 2004 and Feb 2008,13 total hip arthroplasty were performed in 11 patients admitted in China-Japan Union Hospital of JiLin University,including 7 males (8 hips) and 4 females(5 hips). Their average age was 44 years (range,36~56). The case included aseptic necrosis of femoral head in 9 hips, acetabulum dysplasia in 3 hips,traumatic arthritis in 1 hip. The metal on metal total hip prosthes was produced by Corin Group.Cementless Heads were available in 4mm increments from 40mm to 52mm outside diameter, and were manufactured to exacting standards, ensuring optimum sphericity and surface finish. Acetabular cups were available in 2mm OD increments from 46mm to 60mm, with two cup sizes for each head size, providing surgical flexibility. All cups and cementless heads are bi-coated? with a plasma sprayed porous titanium coating overlaid with hydroxyapatite, which provides excellent primary and long-term fixation. The clinical and radiographic followup were performed at average 7.4 months(rang,1~36) postoperatively.Hip joint function was evaluated according to Harris classification:excellent: 90~100scores; good:80~90 scores;fine:70~79 scores;bad:<70 scores.The surgery was defined as a success_if Harris scores>80.The anterior and posterior film of pelvis and the lateraI film of hip joint were pictured in each patient.Clinical evaluation consisted of assessment of pain and function. Patients were asked to state whether or not they were satisfied with the operation.Results: The mean length of the skin incision was 8.3cm.The mean time of operation was 60 min (40~110mins).Neither systemic nor local complications had occurred.94 days later, all patients in this group could walk without support after operation.During the short followup period,there were no dislocation, infection,component loosening and toxicity.The average time of clinical followup and examination was 7.4 months (range,1~36). Radiographs showed that all patients were satisfied with 13 hips.of both the femoral and acetabular components satisfied the radiographic criteria.The Harris score rose from preoperative 46(32~55) to postoperative 93(86~96). According to Harris system,9 hips were excellent,4 hips were good.The satisfactory effect rate was 100 % .Imaging analysis indicated good location of prosthesis.Their postoperative radiographs showed a neck shaft angle of 140°.Conclusions: Minimally invasive total hip arthroplasty through small skin incision has the advantages of less tissue damage,less blood loss and quick postoperative recovery.It is feasible with strict indication and high demanding in operative technique.The metal on metal total hip arthroplasty is a useful treatment to hip joint disease.Large diameter heads are more resistant to dislocation than small diameter heads and improve the stability of THA.Compared to conventinal total hip arthroplasty,the optimom large diameter total hip arthroplasty allows a greater range of motion,permitting patients to return to high activity levels. Optimal sphericity, surface roughness and diametrical separation of the components result in enhanced lubrication of the bearing, which reduces wear, as well as providing effective function and longevity. Metal on metal total hip arthroplasty are not only highly successful in relieving the pain of arthritis and improving quality of life in older patients, but also they can meet the increased demands of the younger, more active patient. |
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