Assessment of femoral head ossific nucleus growth after medial approach reduction in developmental dysplasia of the hip patients aged 6–18 months

Background
The goal of treatment of developmental dysplasia of the hip in different age groups is aimed at the reduction of the femoral head into the true acetabulum. In younger children below the age of 18 months, a medial approach reduction can achieve concentric reduction and eliminate obvious obstacles in the acetabulum; however, capsulorrhaphy is not possible. The risk of avascular necrosis (AVN) must be considered using this approach due to the proximity of the medial circumflex vessels from the site of capsulotomy. The medial approach is also cosmetically more favorable as a small and hidden incision is only needed.


Objective
It was used to analyze and assess the effect and radiological outcomes of this procedure on the growth of the ossific nucleus of the femoral head and correlate this effect to the incidence of AVN.


Patients and methods
A prospective therapeutic case series study included 20 patients with developmental hip dysplasia treated via medial approach between August 2019 and December 2021 at Kafr El-Sheikh University Hospitals. Cases were followed up for 2 years postoperatively.


Results
The mean preoperative height-width ratio was 0.4±0.14 (0.21–0.75). The mean postoperative height-width ratio was 0.9±0.21 (0.21–1.24) 2 years after the medial approach. Shenton’s arc remained intact at the latest. The mean preoperative acetabular index was 63±4.36° (69–52°) to a mean of 33±3.83° (22–37°) 2 years postoperative. Two hips in the medial approach had radiological evidence of osteonecrosis type II according to the Kalamchi and MacEwen classification.


Conclusion
The medial approach can be a good option for the treatment of developmental dysplasia of the hip patients aged between 6 and 18 months of age achieving concentric reduction, removing possible obstacles of reduction, and with the low rate of AVN.