The Effects of Isolated Hip Abductor and External Rotator Muscle Strengthening on Pain, Health Status, and Hip Strength in Females With Patellofemoral Pain: A Randomized Controlled Trial

STUDY DESIGN: Randomized controlled trial. OBJECTIVES: To examine the effectiveness of isolated hip abductor and external rotator strengthening on pain, health status, and hip strength in females with patellofemoral pain (PEP). BACKGROUND: Altered hip kinematics resulting from hip muscle weakness has been proposed as a contributing factor in the development of PEP To date, no study has examined clinical outcomes associated with isolated hip muscle strengthening in those with PEP METHODS: Twenty-eight females with PEP were sequentially assigned to an exercise (n = 14) or a no-exercise control group (n = 14). The exercise group completed bilateral hip abductor and external rotator strengthening 3 times per week for 8 weeks. Pain (visual analog scale), health status (WOMAC), and hip strength (handheld dynamometer) were assessed at baseline and postintervention. Pain and health status were also evaluated at 6 months postintervention in the exercise group. Two-factor mixed-model analyses of variance were used to determine the effects of the intervention on each outcome variable. RESULTS: Significant group-by-time interactions were observed for each variable of interest. Post hoc testing revealed that pain, health status, and bilateral hip strength improved in the exercise group following the 8-week intervention but did not change in the control group. Improvements in pain and health status were sustained at 6-month follow-up in the exercise group. CONCLUSION: A program of isolated hip abductor and external rotator strengthening was effective in improving pain and health status in females with PEP compared to a no-exercise control group. The incorporation of hip-strengthening exercises should be considered when designing a rehabilitation program for females with PFP. LEVEL OF EVIDENCE: Therapy, level 2b. J Orthop Sports Phys Ther 2012;42(1):22-29, Epub 25 October 2011. doi:10.2519/jospt.2012.3704