Comparison of high, medium and low mobilization forces for reducing pain and improving physical function in patients with hip osteoarthritis: Secondary analysis of a randomized controlled trial.

Background: Long-axis distraction mobilization (LADM) of the hip has been shown to reduce pain and improve physical function in hip osteoarthritis (OA). The optimal intensity of mobilization force necessary to reduce pain and improve physical function is unknown.

Objective: To compare the effects on pain and physical function of three different intensities of LADM mobilization force in hip OA patients.

Design: Randomized controlled trial.

Methods: Sixty patients with unilateral hip OA were randomized to three groups: low, medium or high force mobilization group. Participants received three treatment sessions of LADM. Pressure pain thresholds (PPT) at hip, knee and heel, physical function (Western Ontario and McMaster Universities physical function subscale, timed up and go and 40 m self-placed walk test) and pain after the physical function tests (visual analogic scale) were assessed before and after the intervention.

Results: The three treatment groups showed significant improvements in pain and in physical function (p < 0.05). The low-force group showed the largest effects size for pain (d = 2.0) and the greatest mean percentage increase in PPTs (hip = 30.3%, knee = 34.6%, heel = 25.6%). The high-force group showed the largest effects size for physical function (d = 0.5-0.7).

Conclusion: A low-force LADM produced the largest reduction in pain and a high-force LADM the largest improvement in physical function in hip OA patients. The improvements in pain and physical function after LADM in hip OA patients appear to be modulated by the intensity of the mobilization force.