Effect of general anesthesia on preoperative hip range of motion in patients undergoing hip arthroscopy

The purpose of this study was to investigate the effect of general anesthesia on preoperative passive hip range of motion (ROM) in patients undergoing hip arthroscopy for various indications. A total of 260 consecutive patients undergoing hip arthroscopy were included in this study. Passive hip ROM was evaluated bilaterally in the clinic and subsequently under general anesthesia immediately preoperatively. Demographic variables, including age, height, weight, and clinical diagnosis, were recorded for all patients. Hips with pincer-type femoroacetabular impingement (FAI) and hips with acetabular dysplasia showed a mean increase of 4° and 6°, respectively, in hip external rotation at 90° of hip flexion (ER-90) with induction of anesthesia (P=.018 and P=.021, respectively). In contrast, a statistically significant reduction in hip abduction (2°) and hip flexion (4°) was observed following induction of anesthesia in healthy contralateral hips of patients presenting with unilateral hip pathology (P=.01 and P<.001, respectively). Hip ROM does not change to a clinically significant extent with induction of general anesthesia. Small increases in external rotation in patients with FAI or acetabular dysplasia are within the standard error for ROM measurements.