The Fate of Iliopsoas Muscle in the Long-term Follow-up After Open Reduction of Developmental Dysplasia of the Hip by Medial Approach. Part 1: MRI Evaluation.

Background: There has been little information about the long-term status of the iliopsoas, which is the main flexor of the hip, after iliopsoas tenotomy in the treatment of developmental dysplasia of the hip (DDH). The aim of this study was to assess the status of the iliopsoas muscle and other flexors and extensors of the hip in long-term follow-up with magnetic resonance imaging after complete iliopsoas tenotomy in patients with unilateral DDH treated with open reduction with a medial approach.

Methods: The study included 20 patients who underwent open reduction with a medial approach for unilateral DDH and had long-term follow-up. Magnetic resonance imaging assessment of iliopsoas, rectus femoris, tensor fasia lata, sartorius, and gluteus maximus muscles was applied and the muscles of the hip that was operated on were compared with the unoperated hip. In addition, the iliopsoas muscle was examined for reattachment and the effect of reattachment was evaluated.

Results: The mean age at the time of operation was 10.53±3.61 months (range, 5 to 18 mo), and mean follow-up was 16.65±2.16 years (range, 13 to 20 y). Spontaneous reattachment of the iliopsoas was observed in 18 patients (90%), either in the lesser trochanter (65%) or the superior part of it (25%). There was no significant difference between the hips that were operated on and those that were not with regard to the mean cross-sectional areas (CSA) of the tensor fascia lata, rectus femoris, sartorius, and gluteus maximus muscles. The CSA of the tensor fascia lata, rectus femoris, sartorius, and gluteus maximus muscles showed no significant difference (P>0.05); however, CSA of iliopsoas muscle was significantly reduced in the operated hip (P<0.001).

Conclusions: Although the iliopsoas tendon was atrophied after complete iliopsoas tenotomy, it was reattached in 90% of the patients spontaneously in long-term follow-up. There was no statistically significant compensatory hypertrophy in any muscles in response to iliopsoas atrophy.

Level Of Evidence: Level IV-Therapeutic.