Association of combined hip-pelvic-lumbar mobility with hip muscle strength and clinical outcomes in patients treated for femoroacetabular impingement syndrome: A case–control study

It is unclear whether hip and pelvic mobility in the sagittal plane are associated with hip function in FAIS. This study aimed to determine whether hip-pelvis-lumbar mobility is associated with preoperative hip function and postoperative outcomes in FAIS. This was a level 3 case–control study. This study included 111 patients who underwent arthroscopic FAI correction and labral preservation between 2015 and 2019. The Hip-Pelvic-Lumbar Mobility Test (HPLMT) was performed preoperatively; hip flexion with the hip adducted and internally rotated was examined in the lateral decubitus position, and a total hip flexion angle of less than 120° was diagnosed as positive. HPLMT-positive patients were classified as cases, and HPLMT-negative patients were classified as controls. Hip muscle strength was measured preoperatively using a hand-held dynamometer. The modified Harris hip score (mHHS), Nonarthritic Hip Score (NAHS), and International Hip Outcome Tool-12 score were obtained preoperatively and postoperatively. The rates of patient acceptable symptomatic state (PASS) achievement for patient-reported outcome scores (PROSs) were compared between groups. The preoperative PROSs for the HPLMT-positive patients were significantly lower than those for the HPLMT-negative patients. HPLMT-positive patients had significantly weaker hip strength on the affected side than HPLMT-negative patients (flexion; p < 0.001, abduction; p = 0.001). HPLMT-positive patients had significantly lower postoperative mHHS than HPLMT-negative patients. HPLMT-positive patients were significantly less likely to achieve a PASS for the mHHS (62% versus 85%) and NAHS (48% versus 71%) than HPLMT-negative patients. Hip-pelvis-lumbar mobility is associated with hip function and clinical outcomes in FAIS patients. The HPLMT is an efficient tool for assessing FAIS patients.