Effects of lumbopelvic manipulation on hip and knee neuromuscular activity, pain intensity, and functional level in people with patellofemoral pain syndrome.
Altered hip and knee muscle activity has been associated with patellofemoral pain syndrome (PFPS). While spinal manipulation has been used to alter muscle activity and to reduce muscle inhibition for extremity dysfunctions, few studies examined the spinal manipulation effects on hip and knee electromyography (EMG) activity. The purpose of phase 1 of the study was to examine the immediate effect of a single lumbopelvic manipulation on EMG amplitude of the hip and knee muscles as well as knee pain intensity in people with PFPS. The purpose of phase 2 of the study was to examine the carry-over effects of lumbopelvic manipulation administered twice within 72 hours on the EMG amplitude of the hip and knee muscle, knee pain intensity, and functional level. Twenty-four participants with PFPS were randomly assigned into two treatment groups: lumbopelvic manipulation group (n = 12) and placebo group (n = 12). EMG amplitude of the gluteus maximus (Gmax), gluteus medius (Gmed), vastus medialis oblique (VMO), and vastus lateralis (VL) muscles was collected during stair-stepping tasks. The visual analog scale (VAS) was used to collect the knee pain intensity and the lower extremity functional scale (LEFS) was used to assess the functional level. For phase 1, EMG data was collected before and immediately, 15 min, 30 min, and 45 min after the intervention. The VAS was collected before and immediately after the intervention. For phase 2, EMG amplitude, the VAS scores and the LEFS scores were collected at baseline and at the 1-week follow-up. The results of phase 1 showed no significant difference (p > .5) for the EMG data or the VAS. The results of phase 2 showed a significant difference of main effect of time for the VMO and Gmed muscles. However, this finding maybe related to a testing effect. The findings suggest no effect of the lumbopelvic manipulation on any of the outcome measures. However, the small sample size, the lack of homogeneity and the low level of knee pain in our participants might have contributed to the lack of significance in our results.