Hip strengthening prior to functional exercises reduces pain sooner than quadriceps strengthening in females with patellofemoral pain syndrome: a randomized clinical trial.
Dolak KL, Silkman C, Medina McKeon J, Hosey RG, Lattermann C, Uhl TL. J Orthop Sports Phys Ther. 2011 Aug;41(8):560-70. Epub 2011 Jun 7.
The Effects of Isolated Hip Abductor and External Rotator Muscle Strengthening on Pain, Health Status, and Hip Strength in Females With Patellofemoral Pain.
Khayambashi K, Mohammadkhani Z, Ghaznavi K, Lyle MA, Powers CM. J Orthop Sports Phys Ther. 2011 Oct 25. [Epub ahead of print]
While several articles have reported associations between hip strength/kinematics and knee pain, including studies that suggest hip strengthening may improve knee pain (see Related Posts below), few have been randomized controlled trials assessing the benefits of isolated hip strengthening on patellofemoral pain. Recently, two randomized controlled trials assessing hip strengthening among females with patellofemoral pain have been published in JOSPT. Khayambashi et al performed a randomized controlled trial to assess the effectiveness of isolated hip abductor and external rotation strengthening among 28 females with bilateral patellofemoral pain. Participants were placed in an alternating order into one of two groups; isolated hip strengthening (n = 14) or no exercises (n = 14; placebo treatment = daily omega-3 and calcium supplements for 8 weeks). The isolated hip strengthening group performed standing hip abduction and seated hip external rotation with elastic tubing resistance (progressed in 2 week intervals for 8 weeks). In contrast to this, Dolak et al conducted a comparative effectiveness study to evaluate the effects of hip strengthening to quadriceps strengthening prior to introducing weight-bearing (functional) exercises to the rehabilitation program. Female participants with patellofemoral pain were randomized to either 4 weeks of hip strengthening (13 finished the study) or 4 weeks of quadriceps strengthening (13 finished the study; full rehabilitation protocol is available online). After the initial four weeks, both groups performed functional exercises for 4 weeks. Khayambashi et al found that isolated hip strengthening for 8 weeks led to improved self-reported knee pain, health status (via a knee-specific questionnaire about symptoms and function), and hip strength, while the placebo control group showed no improvement (the strength assessor was not blinded to group assignment). Dolak et al had similar findings suggesting the hip strengthening group had significantly less self-reported pain after the first 4 weeks of rehabilitation, compared to their pain before treatment and to the quadriceps strengthening group at 4 weeks. In contrast, the quadriceps group did not have a significant improvement in pain after the first 4 weeks but showed significant improvement in pain after 8 weeks of rehabilitation, which included 4 weeks of functional exercises. Both groups had similar improvements in self-reported pain at 8 weeks, as well as, improvements in lower extremity function over time.
Both studies support the implementation of hip strengthening into rehabilitation programs for females with patellofemoral pain. Khayambashi et al demonstrated the benefit of two strengthening exercises relative to no exercises. These exercises could be easily implemented into a rehabilitation program but it is unclear if adding these 2 exercises to a standard regimen improves symptoms more than the standard program. Meanwhile, Dolak et al showed the early implementation of hip strengthening leads to quicker pain relief compared to early use of quadriceps strengthening. It will be interesting to see similar studies performed with male patients, as well as, a larger population. This may be particularly relevant if Dierks et al (link to SMR post) are correct, and different patient subgroups with patellofemoral pain (i.e., weak hip abductor group, weak hip and trunk group, weak hip internal rotator group) exist. Are you already implementing hip strengthening into your patellofemoral rehabilitation? If not, do these articles provide sufficient evidence to implement them among some patients?
Written by: Jeffrey Driban
Reviewed by: Kyle Harris
Dolak KL, Silkman C, Medina McKeon J, Hosey RG, Lattermann C, & Uhl TL (2011). Hip strengthening prior to functional exercises reduces pain sooner than quadriceps strengthening in females with patellofemoral pain syndrome: a randomized clinical trial. The Journal of Orthopaedic and Sports Physical Therapy, 41 (8), 560-70 PMID: 21654093