title: Predictors of treatment response to strengthening and stretching exercises for patellofemoral pain: An examination of patellar alignment.
abstract: BACKGROUND
  Closed kinetic chain and quadriceps strengthening, combined with flexibility exercises of the lower limb musculature, is a common treatment for patellofemoral pain syndrome (PFPS). The effectiveness has been well documented; however, very little is known about which factors predict treatment success.
  
  
  METHODS
  A total of 43 female subjects with PFPS participated in an eight-week progressive leg press (LP) strengthening and stretching exercise program. A decrease of 1.5 cm on a 10 cm visual analog scale (VAS) score was used as an indicator for treatment success. The baseline patellar tilt angle difference (PTA-d) due to quadriceps contraction prior to treatment was evaluated as a predictor of treatment success. The logistic regression and receiver operating characteristics (ROC) curve analysis were performed to investigate the predictive value of PTA-d.
  
  
  RESULTS
  PTA-d could significantly predict the treatment success of LP strengthening and stretching exercises. The odds ratio (OR) for having an unsuccessful outcome was 1.19 (95% confidence interval (CI), 1.03-1.39, P<0.021) per degree increment of PTA-d. The most optimal cut-off value for the clinical discrimination of treatment success after LP strengthening and stretching exercise was -1.5° of PTA-d (sensitivity=0.74, specificity=0.71). The area under the ROC curve was 0.73 (standard error=0.08).
  
  
  CONCLUSIONS
  Female patients with PFPS whose quadriceps contraction reduced the lateral patellar tilt prior to LP strengthening and stretching exercise treatment are more likely to experience pain relief. It seems clinically important to check dynamic patellar tilt characteristics before treatment to aid in clinical decision making.
authors.affiliation: Department of Physical Education, Chinese Culture University, No. 55, Hwa-Kang Road, Yang-Ming-Shan, 11114 Taipei, Taiwan.
authors.forename: Hsien-Te
authors.initials: HT
authors.lastname: Peng
authors.affiliation: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Third Floor, No.17, Xuzhou Road, Zhongzheng District, 100 Taipei, Taiwan. Electronic address: qqbudingdog@yahoo.com.tw.
authors.forename: Chen-Yi
authors.initials: CY
authors.lastname: Song
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D010147:Pain Measurement; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology / Q000534:rehabilitation*; D052097:Quadriceps Muscle / Q000503:physiopathology*; D055070:Resistance Training / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Exercise; Patella; Patellofemoral pain; Quadriceps