Research Review by Dr. Shawn Thistle©


May 2006

Study Title:

The role of hip muscle function in the treatment of patellofemoral pain syndrome.


Tyler TF et al.

Publication Information:

American Journal of Sports Medicine 2006; 34(4): 630-636.


Patellofemoral pain syndrome (PPS) is one of the most common causes of knee pain in athletes, weekend warriors, and the general population. PPS normally presents as anterior or retropatellar knee pain (in and around the kneecap) that is aggravated by activities such as prolonged sitting, stair climbing, squatting, running, kneeling, and jumping. Non-operative treatment remains the standard approach for managing this condition.

Common treatment approaches include addressing soft tissue lesions around the kneecap, normalizing patellar tracking via taping or bracing, and strengthening the surrounding musculature, specifically the vastus medialis oblique (VMO).

Unfortunately, successful treatment outcomes are not always obtained using this approach. Recent evidence has suggested that patients with PPS may display significant weakness in their hip flexors. This is proposed to lead to biomechanical aberrations that can proliferate abnormal patellar tracking, destabilize the pelvis during motion, and alter the normal rotation pattern of the femur during gait.

The purpose of this study was to evaluate the efficacy of a rehabilitation program including closed kinetic chain hip flexor strength and flexibility exercises on patients with PPS. It was hypothesized that increases in hip flexor strength and flexibility would contribute to a decrease in patellofemoral pain.

Thirty-five patients (average age 33) with PPS were placed on a six week rehabilitation program (a total of 43 knees were evaluated as 8 patients had bilateral symptoms). At the beginning of the study, measurements of hip flexor, adductor, and abductor strength were taken.

Ober's test and the Thomas test were also done to evaluate the flexibility of the iliotibial band and hip flexor/rectus femoris respectively. Finally, a visual analogue scale (VAS) was used to measure pain intensity, and was included as the final outcome measure.

These tests were all repeated after the six week exercise program. The rehabilitation program included progressive resistance exercises, manual and self stretching, home exercise, and manual therapy directed at the medial and lateral retinaculum. Hip flexor strength and flexibility exercises were a main component of the program.

Pertinent Results:

  • VAS scores decreased significantly after the rehabilitation program, indicating that 21 patients (26 knees) had a successful outcome, and 14 patients (17 knees) had an unsuccessful outcome
  • before treatment, patients with unilateral PPS demonstrated significant weakness of the hip flexors on the involved side
  • hip flexion strength improved 35% on the successfully treated knees, and decreased 1.8% in unsuccessfully treated knees, indicating that it may influence positive results
  • improvement in iliotibial band and hip flexor flexibility was associated with a successful treatment outcome

Conclusions & Practical Application:

Patellofemoral pain syndrome is commonly seen in manual medicine. I thought this study provided some interesting insight into taking a more comprehensive approach to local symptoms. By evaluating and rehabilitating hip strength and flexibility in addition to traditionally used treatment approaches for PPS, patient outcomes seemed positive.

It would be interesting to add other components of a general fitness program such as spinal stability and general conditioning to a program like this to see if results could be further improved.

This study had a relatively small experimental group, and lacked a control group. That being said, it did demonstrate the potential value in a comprehensive rehabilitation approach to treat PPS. Special attention may be warranted to the flexibility and strength of the hip musculature, as the patients in this study did demonstrate deficiencies in these areas, and those that improved hip strength and flexibility had better outcomes.