Abstract
BackgroundIndividuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control. Here, we therefore aimed to assess muscular activity during movements often used in ACL-rehabilitation and to characterize associations between deviations in muscular activity and specific altered movement patterns, using and further exploring the previously developed Test for substitution Patterns (TSP).MethodsSixteen participants (10 women) with unilateral ACL rupture performed Single and Double Leg Squats (SLS; DLS). Altered movement patterns were scored according to TSP, and Surface Electromyography (SEMG) was recorded bilaterally in six hip, thigh and shank muscles. To quantify deviations in muscular activity, SEMG ratios were calculated between homonymous muscles on injured and non-injured sides, and between antagonistic muscles on the same side. Correlations between deviations of injured/non-injured side SEMG ratios and specific altered movement patterns were calculated.ResultsInjured/non-injured ratios were low at transition from knee flexion to extension in quadriceps in SLS, and in quadriceps and hamstrings in DLS. On injured side, the quadriceps/hamstrings ratio prior to the beginning of DLS and end of DLS and SLS, and tibialis/gastrocnemius ratio at end of DLS were lower than on non-injured side. Correlations were found between specific altered movement patterns and deviating muscular activity at transition from knee flexion to extension in SLS, indicating that the more deviating the muscular activity on injured side, the more pronounced the altered movement pattern. “Knee medial to supporting foot” correlated to lower injured/non-injured ratios in gluteus medius (rs = −0.73, p = 0.001), “lateral displacement of hip-pelvis-region” to lower injured/non-injured ratios in quadriceps (rs = −0.54, p = 0.03) and “displacement of trunk” to higher injured/non-injured ratios in gluteus medius (rs = 0.62, p = 0.01).ConclusionsDeviations in muscular activity between injured and non-injured sides and between antagonistic muscular activity within injured as compared to non-injured sides indicated specific alterations in sensorimotor control of the lower limb in individuals with ACL rupture. Also, correlations between deviating muscular activity and specific altered movement patterns were suggested as indications of altered sensorimotor control. We therefore advocate that quantitative assessments of altered movement patterns should be considered in ACL-rehabilitation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0472-y) contains supplementary material, which is available to authorized users.
Highlights
Individuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control
In this study we focused on the movements Single Leg Squat (SLS) and Double Leg Squat (DLS), since these movements have previously been used in standardized assessments in individuals with knee-complaints, have proved to be both valid and reliable and are often used as functional rehabilitative exercises [16,17,18,19]
More pronounced altered movement patterns were observed on participants’ injured than on non-injured side
Summary
Individuals with Anterior Cruciate Ligament (ACL) injury often show altered movement patterns, suggested to be partly due to impaired sensorimotor control. In clinical practice of ACL injury evaluation and rehabilitation, assessments primarily focus on knee stability, muscular strength and/or knee symptoms [4,5,6], and since it has been argued that interventions should be based on functional performance tests [7], assessments of jump performance are often used [8]. Still, none of these tests strongly predict the demonstrated alterations in movement patterns [9,10]. Individuals with ACL injury demonstrate biomechanical instability due to increased knee-joint laxity between tibia and femur, with increased anterior-posterior translations and/or internal-external rotation, which may increase the risk of “giving-way” episodes (abnormal, sudden, painful displacement of tibia relative to femur during weight bearing) [14]
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