Regrowth of the psoas tendon after arthroscopic tenotomy: a magnetic resonance imaging study.

Purpose: The purpose of this study was to evaluate whether the psoas tendon regenerates after arthroscopic tenotomy through the central compartment of the hip in patients with internal snapping hip.

Methods: Twenty-seven patients with a snapping hip, aged 18 to 54 years (mean, 37.47 years), underwent arthroscopic tenotomy through the central compartment of the hip; all patients had symptomatic femoroacetabular impingement as well. The degree of regeneration was evaluated by preoperative and postoperative measurements of the tendon perimeter with a magnetic resonance imaging protocol in patients with more than 6 months' follow-up. In addition, function was assessed preoperatively and postoperatively with the Western Ontario and McMaster Universities Osteoarthritis Index score. Postoperative active flexion force was graded clinically between 1 and 5 with the Medical Research Council score.

Results: Eight patients had less than 6 months' follow-up, and they were excluded. The remaining 19 patients were evaluated after a mean follow-up period of 23.16 months (SD, 12.95 months). Tendon regeneration occurred in all patients. Compared with preoperative measurement, the psoas tendon circumference had recovered by 84.3% on average (55.44 ± 5.68 mm v 46.71 ± 6.05 mm, P < .001). Pain improved in all patients, and the mean Western Ontario and McMaster Universities Osteoarthritis Index score fell from 49 ± 15.9 points to 10.74 ± 11.35 points (P < .001). Muscle force recovered completely in all cases.

Conclusions: There is a process of tissular repair after psoas tenotomy, and the findings on magnetic resonance imaging suggest that tendon tissue regrowth occurs.

Level Of Evidence: Level IV, therapeutic case series.