EVALUATION OF THE BIOMECHANICS OF THE HIP FOLLOWING A TRIPLE OSTEOTOMY OF THE INNOMINATE BONE

The biomechanics of the hip joint were evaluated in seventeen patients (twenty-two hips), twelve to forty-one years old (mean, twenty-four y ears old), who had a triple osteotomy of the innominate bone for treat ment of symptomatic dysplasia of the hip, The duration of follow-up ra nged from 2.2 to 13.8 years (mean, 6.8 years), Hip load, the area of t he weight-bearing surface, and stress were determined from measurement s on pelvic radiographs that were made preoperatively, postoperatively , and at the time of the latest follow-up; the values were compared,vi th those in twenty-one hips from control subjects, The Harris hip-rati ng system. was used for clinical assessment, According to the biomecha nical analysis, there was significantly less relative stress on the hi p after the triple osteotomy and at the time of the latest followup (p < 0.001 for both) than there had been preoperatively, The decrease in stress was a direct result of a significant increase in the area of t he weight-bearing surface of the hip (p < 0.001). The load on the hip was not altered significantly, with the numbers available, The functio nal outcome was improved substantially when the biomechanical goals we re achieved, Through the application of basic biomechanical principles , we were able to demonstrate the biomechanical efficacy of a triple o steotomy of the innominate bone, We recommend the use of biomechanical analysis as an adjunct to the clinical decision-making process in the treatment of a dysplastic hip.