By Jordana Bieze Foster
Six weeks of lower extremity strengthening in runners with patellofemoral pain (PFP) leads to improvements in pain and function that are retained six months later, regardless of whether the rehabilitation focuses on the knee or the hip, according to research presented in late June at the National Athletic Trainers Association (NATA) annual meeting in Las Vegas.
Two oral presentations and two posters at the NATA meeting analyzed early findings from a long-term multicenter study comparing knee and hip exercise programs in patients with patellofemoral pain. The 202 patients (135 women) analyzed to date represent the study populations from two of the four research sites.
All participants had experienced patellofemoral pain symptoms for at least four weeks but not longer than one year. Patients were randomly assigned to a knee rehabilitation program that focused on vastus medialis oblique strengthening or to a hip rehabilitation program that primarily involved open-chain exercises for hip adduction, flexion, external rotation, and balance. A successful rehabilitation was defined as an improvement of 3 cm on a 10-cm visual analog pain scale (VAS) and/or eight points on the 100-point anterior knee pain scale (AKPS).
Patients who had achieved success after six weeks discontinued the program at that time; those who were unsuccessful after six weeks continued for another two weeks. Successful patients were allowed to continue moderate levels of running for the next six months but were discouraged from using anti-inflammatories or any other intervention. Unsuccessful patients were counseled to discontinue running and rest for the next six months.
Immediately after discontinuing the program, 141 of the 202 patients were classified as successful—70 in the hip program and 71 in the knee program. Both groups demonstrated significant improvements in VAS and AKPS scores, but the degree of improvement did not differ significantly between groups for either outcome. A separate analysis found that strength gains for knee extension, hip extension, hip adduction, and hip external rotation did not differ between groups.
“We have rehabilitation programs that we thought were different enough to see differences between groups, but there may be too much overlap between the exercises,” said Reed Ferber, PhD, ATC, director of the Running Injury Clinic at the University of Calgary in Canada, who presented the six-week and six-month results at the NATA meeting.
However, the researchers did find that the VAS and AKPS improvement occurred about a week earlier in the hip rehab group than in the knee rehab group (at three weeks vs four weeks).
Six months after completing the rehabilitation, analysis of 105 successful patients and 26 unsuccessful patients revealed that the between-group differences in VAS and AKPS were similar to what they had been at six weeks.
“That tells us that the benefits of exercise are being maintained in the successful group, and the unsuccessful patients, who are resting, are not getting better,” Ferber said.
In 185 of the first 202 patients, the researchers also looked for effects of gender on outcomes. Although they found no statistically significant differences between genders for VAS, AKPS, or strength in any of the four muscles tested, they did find that women were more likely than men to experience hip extension strength gains, while men were more likely to experience hip external rotation strength gains.
The study will continue to follow patients and reassess them at 12, 18, and 24 months. The results of further analysis will be presented in September at the International Patellofemoral Pain Research Retreat in Vancouver, Canada, Ferber said.
Ferber R, Bolgla L, Earl-Boehm J, et al. Optimal rehabilitation protocols for the treatment of patellofemoral pain syndrome: an outcome-based RCT study. Presented at the National Athletic Trainers’ Association 64th Annual Meeting and Clinical Symposia, Las Vegas, June 2013.
Earl-Boehm J, Bolgla L, Emery CA, et al. Strength changes following quadriceps or hip focused rehabilitation in patients with PFP: an outcome-based RCT study. Presented at the National Athletic Trainers’ Association 64th Annual Meeting and Clinical Symposia, Las Vegas, June 2013.
Hamstra-Wright KL, Earl-Boehm J, Bolgla L, et al. Prospective pain and function outcomes after 6-weeks of rehabilitation for patellofemoral pain syndrome. Presented at the National Athletic Trainers’ Association 64th Annual Meeting and Clinical Symposia, Las Vegas, June 2013.
Bolgla LA, Earl-Boehm J, Emery CA, et al. Pain, function, and strength outcomes for males and females with patellofemoral pain who participate in either a hip- or knee-based rehabilitation program. Presented at the National Athletic Trainers’ Association 64th Annual Meeting and Clinical Symposia, Las Vegas, June 2013.