Is mirror gait retraining an effective intervention for patellofemoral pain and does it transfer to other functional tasks?
Patellofemoral pain (PFP) is a fairly common diagnosis treated by physical therapists. It is seen in a variety of athletes but is especially common in runners. PFP can be attributed to abnormal hip mechanics including excessive contralateral pelvic drop, hip adduction, and hip internal rotation. Lately research has focused on strengthening the primary stabilizers of the hip joint (gluteus medius and maximus) for treatment of PFP. Clinically, this strengthening begins with open chain tasks and moves to closed chain. Clinicians often utilize visual and verbal feedback to correct abnormal hip mechanics during closed chain activities. What does the literature say about visual feedback for gait retraining and does gait retraining with a mirror transfer to other functional tasks?
A study by Noehren, et al. looked at gait training via real-time kinematic feedback to address abnormal hip mechanics (hip adduction, hip internal rotation, and contralateral pelvic drop) in ten male and female runners (ages 18-45) suffering from PFP. Runners were provided with the hip adduction angle during each stance phase of treadmill running in real time. They were asked to match their hip angle to a normative target range given on the monitor. Subjects completed a total of eight sessions and feedback was gradually removed over the last four sessions. Following this training, subjects had a significant decrease in hip adduction and contralateral pelvic drop while running. Subjects also demonstrated a decrease in hip adduction during single leg squat, though it was not found to be significant. There were significant improvements in pain on a verbal analogue scale and scores on the lower-extremity functional scale (LEFS). Improvements in running mechanics, pain, and function were maintained at a 1-month follow-up.
Most physical therapy clinics cannot afford a real-time motion analysis system. So, will visual feedback via a full-length mirror produce the same results? Willy, et al. investigated the use of mirror gait retraining for the treatment of PFP in female runners. The methods used in this study are similar to those used by Noehren, et al. Ten female runners (ages 18-40) with PFP underwent eight sessions of treadmill running with mirror and verbal feedback regarding lower extremity alignment. The feedback was progressively removed throughout the last four sessions. Verbal feedback was scripted and consisted of cues such as, “run with your knees apart with your kneecaps pointing straight ahead” and “squeeze your buttocks.” An instrumented gait analysis was performed pre and post intervention during treadmill running as well as single leg squat and step downs. Pain rating and LEFS were also assessed. Peak hip adduction and contralateral pelvic drop during running were both significantly reduced post-intervention. While reductions in hip adduction were not maintained at 1 month and 3 month follow-up, contralateral pelvic drop was maintained at both follow-ups. The decrease in hip adduction during running transferred to SLS but contralateral pelvic drop still occurred. Both the decrease in hip adduction and contralateral pelvic drop were demonstrated during step-downs and maintained at months 1 and 3. Both pain and LEFS scores improved post-intervention and maintained at both follow-up sessions.
The study by Willy, et al. is promising in that it can easily be utilized in clinics everywhere. Because this intervention relies on both visual and verbal feedback, it is important to consider both the biomechanical assessment skills and communication skills of the treating therapist. If they are unable to provide adequate feedback to the patient, the intervention may not be effective. It’s also necessary to note that both of the above studies were done on runners ages 18-45. Patellofemoral pain affects a variety of individuals and this intervention may not be effective in all populations. Although physical therapists don’t often have patients run on a treadmill, they commonly utilize step-down and single-leg-squat activities in the clinic. It would be interesting to see if mirror training during these activities transferred to lower extremity mechanics during gait. It would also be beneficial to investigate if mirror training during treadmill walking was as effective as mirror training during treadmill running. Based on the studies by Noehren, et al. and Willy et al., mirror gait retraining is supported by the literature for correction of abnormal hip mechanics in runners with patellofemoral pain. In general, the improved hip mechanics, decreased pain, and improved LEFS were maintained through three months post-intervention.
Noehren, B., J. Scholz, and I. Davis. “The Effect of Real-time Gait Retraining on Hip Kinematics, Pain and Function in Subjects with Patellofemoral Pain Syndrome.” British Journal of Sports Medicine 45.9 (2010): 691-96. PubMed. Web. 20 Aug. 2015.
Willy, Richard W., John P. Scholz, and Irene S. Davis. “Mirror Gait Retraining for the Treatment of Patellofemoral Pain in Female Runners.” Clinical Biomechanics 27.10 (2012): 1045-051. PubMed. Web. 20 Aug. 2015.