Evaluation of the ipsilateral knee more than 40 years after successful closed reduction of DDH

We asked whether the ipsilateral knee of patients treated by closed reduction for developmental hip dislocation (DDH) is affected by osteoarthritis (OA) more than 40 years later.

In total, 61 patients (71 hips) with the diagnosis of DDH were included in the study. The average age at the time of closed reduction was 17.9 months. The follow-up after closed reduction averaged 44.4 years. We determined the following parameters on radiographs, taken in the standing position: minimal joint space width in the medial and lateral compartments of the knee, minimal joint space width of the hip joint, radiological signs of osteoarthritis of the knee and the hip joints (Kellgren and Lawrence), knee alignment, acetabular roof obliquity (AC angle), depth of the acetabulum (ACM angle) and center-edge angle (CE angle) according to Wiberg. All radiographs were measured twice manually with ruler and goniometer by two independent investigators. Interobserver and intraobserver reliability (test-retest) was calculated for all parameters.

We observed that patients with bilateral DDH had significantly more joint space narrowing in the medial compartment of the knee joints than those with unilateral DDH. The length of follow-up correlated with radiological signs of OA in the hip, but not in the knee.

We found a significant difference in medial compartment joint space narrowing between patients with unilateral DDH and those with bilateral DDH. The Kellgren-Lawrence classification, however, showed no significant differences between uni- and bilateral DDH. The knee alignment was always at the threshold of physiological values.