The evaluation of hip muscles in patients treated with one-stage combined procedure for unilateral developmental dysplasia of the hip: part I: MRI evaluation.

Background: To assess the status of hip flexor and extensor muscles with MRI in patients with unilateral developmental dysplasia of the hip (DDH) after walking age who were treated with one-stage combined procedure.

Methods: Twenty-two patients operated upon with one-stage combined procedure for unilateral DDH were included in this study. All patients underwent complete tenotomy of the iliopsoas muscle hindering open reduction. All patients showed excellent results according to the modified McKay criteria of Barrett and type 1 hips according to radiologic criteria of Severin at the latest follow-up. MRI assessment of iliopsoas, rectus femoris, tensor fasia lata, sartorius, and gluteus maximus muscles was performed and muscles of the hip that was operated upon were compared with the hip that was not. In addition, the iliopsoas muscle was examined for reattachment and the effect of reattachment was evaluated.

Results: Mean age was 154.4+/-34.6 (110 to 216) months. Mean follow-up was 112.6+/-32.0 (68 to 159) months. Reattachment of the iliopsoas was observed in 7 (32%) patients, with no significance in terms of age, postoperative follow-up period, or the duration of the postoperative period. Atrophy in the hip that was operated upon was significant in iliopsoas, rectus femoris, tensor fasia lata, and gluteus maximus muscles when compared with the hip that was not. No significance was detected in the sartorius muscle between hips that were operated upon and those that were not. Cross-sectional areas of tensor fascia lata, rectus femoris, sartorius, and gluteus maximus muscles were not significantly different between patients with and without reattachment of iliopsoas. The width of the iliopsoas muscle was significantly lowered in patients without reattachment.

Conclusions: Patients with DDH treated with combined procedures including complete iliopsoas tenotomy do not have hip muscles similar to hip muscles that have not been operated upon, despite excellent radiologic and clinical results. These patients can be affected by muscular changes in the long term. Follow-up by conventional radiologic and clinical criteria alone may not be enough, and patients may have problems, as in our series, that cannot be detected by conventional radiologic and clinical assessments.

Level Of Evidence: Level IV, Therapeutic case series.