Conservative lower back treatment reduces inhibition in knee extensor muscles: A randomized controlled trial

Background: Knee-joint pathologies, such as anterior knee pain (AKP), are a ssociated with strength deficits and reduced activation of the knee extenso rs. which is referred to as muscle inhibition (MI). MI is thought to preven t full functional recovery, and treatment modalities that help to reduce or eliminate MI appeal necessary fur successful rehabilitation. Clinical obse rvations suggest that AKP is typically associated with sacroiliac (SI) join t dysfunction. It is unknown whether SI-joint dysfunction contributes to kn ee-extensor deficits and whether correction of SI-joint dysfunction allevia tes MI. Objective: The objective of this study was to assess whether conservative l ow back treatment reduces lower limb MI. Study Design: In a randomized, controlled, double-blind study the effects o f conservative lower back treatment on knee-extensor strength and MI were e valuated in patients with AKP. Methods: Twenty-eight patients with AKP were randomly assigned to either a treatment or a control group. After a lower back functional assessment the treatment group received a consen ative treatment in the form of a chiropra ctic spinal manipulation aimed at correcting SI-joint dysfunction. The cont rol group underwent a lower back functional assessment but received no join t manipulation. Before and after the manipulation or the lower back functio nal assessment, knee-extensor moments, MI, and muscle activation during ful l effort, isometric knee extensions were measured. Results: Patients showed substantial MI in birth legs. Functional assessmen t revealed SI-joint dysfunction in all subjects (23 symptomatic and 5 asymp tomatic). After the SI-joint manipulation, a significant decrease in MI of 7.5% was observed in the involved legs of the treatment group. MI did not c hange in the contralateral legs of the treatment group or the involved and contralateral legs of the control group. There were no statistically signif icant changes in knee-extensor moments and muscle activation in either grou p. Conclusions: The results of this study suggest that SI-joint manipulation r educes knee-extensur MI. Spinal manipulation may possibly be an effective t reatment of MI in the lower limb musculature.