Altered motor control strategies in subjects with sacroiliac joint pain during the active straight-leg-raise test.
STUDY DESIGN: An experimental study of respiratory function and kinematics of the diaphragm and pelvic floor in subjects with a clinical diagnosis of sacroiliac joint pain and in a comparable pain-free subject group was conducted. OBJECTIVE: To gain insight into the motor control strategies of subjects with sacroiliac joint pain and the resultant effect on breathing pattern. SUMMARY OF BACKGROUND DATA: The active straight-leg-raise test has been proposed as a clinical test for the assessment of load transfer through the pelvis. Clinical observations show that patients with sacroiliac joint pain have suboptimal motor control strategies and alterations in respiratory function when performing low-load tasks such as an active straight leg raise. METHODS: In this study, 13 participants with a clinical diagnosis of sacroiliac joint pain and 13 matched control subjects in the supine resting position were tested with the active straight leg raise and the active straight leg raise with manual compression through the ilia. Respiratory patterns were recorded using spirometry, and minute ventilation was calculated. Diaphragmatic excursion and pelvic floor descent were measured using ultrasonography. RESULTS: The participants with sacroiliac joint pain exhibited increased minute ventilation, decreased diaphragmatic excursion, and increased pelvic floor descent, as compared with pain-free subjects. Considerable variation was observed in respiratory patterns. Enhancement of pelvis stability via manual compression through the ilia reversed these differences. CONCLUSIONS: The study findings formally identified altered motor control strategies and alterations of respiratory function in subjects with sacroiliac joint pain. The changes observed appear to represent a compensatory strategy of the neuromuscular system to enhance force closure of the pelvis where stability has been compromised by injury.