Abstract
Purpose: Since the establishment of the principle of weight-bearing methods of treatment in Legg-Calvé-Perthes disease (LCPD), lateral displacement of the femoral head has become an important prognostic factor.
Material and Methods: In order to establish reliable boundary lines between orthotopic and subluxated hip, the migration percentage (MP) and the medial joint space (MJS) were determined retrospectively: a) on 166 normal hip radiographs; b) on bilateral arthrograms and radiographs from 37 patients with unilateral LCPD.
Results and Conclusion: the mean upper normal values for MP and MJS on normal radiographs were 20.8 and 11.5 respectively. on arthrograms, the corresponding values were 31 and 5.7.
The MP is easy to determine on both radiographs and arthrograms, and is recommended for detecting and measuring subluxation in cases with LCPD. MJS is of no advantage for detecting containment in LCPD but may be used in other diseases such as coxitis simplex.
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