ABSTRACT
PURPOSE: To confirm the effect of the frog leg lateral radiographs for determining the clinical indication of total hip arthroplasty for high riding dislocation and to discuss its theoretical background. MATERIALS AND METHODS: A consequent series of reconstructive THA were studied in 28 recent tuberculous hips. Twenty-three hips (17patients) with developmental dysplastic hip were compared. Preoperatively, frog-leg lateral radiographs were performed in all the patients, which were enhanced using a 2-dimensional computer model to predict the reattachment of the greater trochanter. RESULTS: The modified scores of Merle d'aubigne and Postel improved from a mean of 2.6 points preoperatively to a mean of 5.1 points. Sciatic nerve palsies occurred in three cases. In two cases, they fully recovered, but in one case, it did not. We confirmed that old high dislocation of the hip could be adopted in type 1 and 2 categories of frog leg lateral position. The reconstruction of hip was relatively simple in type 3, however, further study is necessary in type 5 due to unsuitable abduction contracture. CONCLUSION: We confirm that frog leg lateral radiography is effective for determining the operative indication of high riding dislocation. However irreducible frog leg lateral position is absolutely contraindirated for total hip arthroplasty.