Hip Flexion Weakness following Transpsoas Interbody Fusion

Objective The present work evaluated the motor deficit resulting from the psoas muscle access through the extreme lateral interbody fusion (XLIF) approach. Methods This was a prospective, non-randomized, controlled, single-center study with 60 patients, with a mean age of 61.8 years old. All of the subjects underwent a lateral transpsoas retroperitoneal approach for lumbar interbody fusion with electroneuromyographic guidance and accessing 1 to 3 lumbar levels (mean level, 1.4; 63% cases in only 1 level; 68% cases included L4-L5). The isometric hip flexion strength in the sitting position was determined bilaterally with a handheld dynamometer (Lafayette Instrument, Lafayette, IN, USA). The mean value of three peak force measurements (N) was calculated. Standardized isometric strength tests were performed before the procedure and at 10 days, 6 weeks, 3 months and 6 months postsurgery. Results Ipsilateral hip flexion was diminished (p < 0.001) at the early postoperative period, but reached preoperative values at 6 weeks (p > 0.12). The mean hip flexion measures before the procedure and at 10 days, 6 weeks, 3 months and 6 months after surgery were the following, respectively: 13 N; 9.7 N; 13.7 N; 14.4 N; and 16 N (ipsilateral); 13.3 N; 13.4 N; 15.3 N; 15.9 N; and 16.1 N (contralateral). Neither the level nor the number of treated levels had a clear association with thigh symptoms, but hip flexion weakness was the most common symptom. Conclusions Patients in the early postoperative period of transpsoas access presented hip flexion weakness. However, this weakness was transient, and electroneuromyography use is still imperative in transpsoas access. In addition, patients must be thoroughly educated about hip flexion weakness to prevent falls in the immediate postoperative period.