Effect of muscle strengthening on perceived pain and static knee angles in young subjects with patellofemoral pain syndrome

The purpose of this pilot study was to determine the effects of strength training of the knee muscles on perceived pain and static knee angles in young subjects with patellofemoral pain syndrome (PFPS). Ten patients, 100% female (mean age, 18.2±3.8 years), with unilateral PFPS (anterior knee pain for at least 3 months), received muscle strengthening of the hip and knee (10 sessions over a period of 3 weeks). The outcome measures were perceived pain (visual analogue scale, VAS) and static knee angles (knee rotation measurer). All measures were collected at pre-, postintervention, and at 1-month follow-up (VAS). Muscle strengthening reduced perceived pain after intervention in 90.8% in subjects and this result was maintained at 1-month follow-up (all, P=0.001). Regarding changes in static knee angles, no significant improvements were found in internal and external rotation; valgus and varus; flexion and recurvatum (all, P>0.05). There was no significant difference between the symptomatic and healthy sides (all, P>0.05). Analyses of the correlation coefficients indicated no significant associations between changes in perceived pain and static knee angles. The current study found that muscle strengthening addressed to the symptomatic knee reduced pain; however, perceived pain was not associated with static knee angles in young subjects with unilateral PFPS.