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.
METHODS
Randomized controlled trial.


OBJECTIVE
To examine the effectiveness of isolated hip abductor and external rotator strengthening on pain, health status, and hip strength in females with patellofemoral pain (PFP).


BACKGROUND
Altered hip kinematics resulting from hip muscle weakness has been proposed as a contributing factor in the development of PFP. To date, no study has examined clinical outcomes associated with isolated hip muscle strengthening in those with PFP.


METHODS
Twenty-eight females with PFP 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.


CONCLUSIONS
A program of isolated hip abductor and external rotator strengthening was effective in improving pain and health status in females with PFP 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.


METHODS
Therapy, level 2b.
College of Physical Education and Sport Sciences, University of Isfahan, Isfahan, Iran.
Khalil
K
Khayambashi
Zeynab
Z
Mohammadkhani
Kourosh
K
Ghaznavi
Mark A
MA
Lyle
Christopher M
CM
Powers
D000203:Activities of Daily Living; D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016001:Confidence Intervals; D005081:Exercise Therapy; D005260:Female; D006304:Health Status; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness; D010147:Pain Measurement; D046788:Patellofemoral Pain Syndrome / Q000534:rehabilitation*; D026741:Physical Therapy Modalities; D011859:Radiography; D057566:Self Report; D013997:Time Factors; D016896:Treatment Outcome