Coxa Magna following treatment of developmental dysplasia of the hip: investigation for associated potential factors

Coxa Magna (CM) is defined as a condition in which the horizontal (transverse) diameter of the femoral head is larger on the affected side than on the intact side. CM can occur as a manifestation of avascular necrosis (AVN) following treatment for the developmental dysplasia of the hip (DDH). Alternatively, it can also be secondary to other hip disorders, such as Perthes' disease. This study aimed to determine the prevalence and indicators of CM and AVN of the femoral head that can be detected during follow-up in patients with unilateral DDH treated with closed reduction (CR) or open reduction (OR) surgery. The files of 143 patients treated for unilateral DDH between January 1997 and December 2017 were reviewed retrospectively. A total of 104 patients, including Group 1 (n = 49) patients who underwent CR under general anesthesia and Group 2 (n = 55) patients who underwent OR were included in the study. CM; It was considered as the case where the femoral head was 15% or more larger than the intact side. A total of 104 patients were followed up for 77.27 +/- 13.96 months, with a mean age of 15.43 +/- 7.76 months. When Group 1 and Group 2 were compared, there was no statistical difference in terms of sex, side, adductor tenotomy, and AVN (P > 0.05). CM developed in 22.4% (n = 11) of the patients in Group 1 and in 49.1% (n = 27) in Group 2, and the difference was statistically significant (P = 0.008). When the effect of independent variables on the development of CM is evaluated with the multivariate logistic regression model, the risk of developing CM is 3474 times higher in those who underwent iliopsoas tenotomy compared with those who did not. The primary outcome of this study is that CM is more frequent in patients treated with OR for DDH. CM may be a nonpathological condition that occurs in connection with iliopsoas tenotomy or surgical treatment. Prospective studies with a larger number of cases, designed to minimize confounding factors, are required.