The immediate effects of passive hip joint mobilization on hip abductor/external rotator muscle strength in patients with anterior knee pain and impaired hip function. A randomized, placebo-controlled crossover trial.

Background: Anterior knee pain (AKP) is often associated with persistent hip muscle weakness and facilitatory interventions may be beneficial for managing patients with AKP (pwAKP). Physiotherapists often employ passive oscillatory hip joint mobilizations to increase hip muscle function. However, there is little information about their effectiveness and the mechanisms of action involved. Objectives: To investigate the immediate effects of passive hip joint mobilization on eccentric hip abductor/external rotator muscle strength in pwAKP with impaired hip function. Design: A double-blinded, randomized, placebo-controlled crossover design. Method: Eighteen patients with AKP participated in two sessions of data collection with one week apart. They received passive hip joint mobilization or placebo mobilization in a randomized order. Eccentric hip muscle strength was measured immediately before and after each intervention using a portable hand-held dynamometer. Results: An ANCOVA with the sequence of treatment condition as the independent variable, the within-subject post-treatment differences as the dependent variable and the within-subject pre-treatment differences as the covariate was conducted. Patients showed a significant mean increase in eccentric hip muscle strength of 7.73% (p = 0.001) for the mobilization condition, compared to a mean decrease of 4.22% for the placebo condition. Seventeen out of eighteen participants reported having no pain during any of the strength testing. Conclusion: These data suggest that passive hip joint mobilization has an immediate positive effect on eccentric hip abductor/external rotator muscle strength in pwAKP with impaired hip function, even in the absence of current pain.

The immediate effects of passive joint mobilisation on local muscle function. A systematic review of the literature.

BACKGROUND: Passive joint mobilisation is popular among healthcare providers and their patients; however, its effectiveness for improving muscle function is not well researched and the mechanisms of action involved are unclear. OBJECTIVES: To assess the effect of passive joint mobilisations on the function of muscles surrounding the targeted joints in symptomatic as well as asymptomatic individuals. SELECTION CRITERIA: Controlled experimental trials assessing the immediate effect of passive joint mobilisation on outcomes associated with local muscle function. DATA COLLECTION: Two authors independently assessed trial quality and extracted data. MAIN RESULTS: A total of seventeen studies were included, of which ten studies reported data on asymptomatic individuals and seven studies reported data on symptomatic individuals with various conditions. There is a moderate level of evidence that joint mobilisation immediately decreases the activation of superficial muscles during low load conditions in symptomatic individuals. For asymptomatic individuals, there is a low level of evidence that passive joint mobilisation improves maximum muscle strength when compared to sham mobilisation, opposed to a very low level of evidence suggesting no effect in symptomatic individuals. The five studies reporting data on both, changes in muscle function as well as changes in pain, suggest that other, not pain-related mechanisms may play an important role regarding the reported improvement in muscle function. CONCLUSION: Current best evidence suggests that passive joint mobilisation has the ability to immediately alter muscle function. The specific mechanisms of action involved require further basic science investigations. Registration number (PROSPERO): CRD42018117033.