Associations between altered movement patterns during single-leg squat and muscle activity at weight-transfer initiation in individuals with anterior cruciate ligament injury

Abstract

BackgroundLittle is known about factors contributing to the altered movement patterns observed in many individuals with anterior cruciate ligament (ACL) injury. We addressed whether altered muscular activity is such a factor.Methods16 participants with unilateral, non-reconstructed ACL rupture were scored for altered movement patterns according to Test for Substitution Patterns (TSP), which includes the single-leg squat (SLS). Surface electromyography (SEMG), was recorded in the lower extremities at initiation of weight-transfer from double-leg to single-leg stance (eyes closed), simulating the initiation of an SLS. Normalised SEMG amplitudes 200–300 ms after weight-transfer initiation were compared between injured and non-injured sides, and correlated to the TSP scores for the SLS. Peak absolute SEMG amplitudes during 5 TSP test movements were also compared between sides.ResultsAt weight-transfer initiation, muscle activity was lower in the tibialis anterior, gastrocnemius and peroneus longus muscles on the injured side. Low muscle activity correlated moderately to worse TSP scores for the SLS for the gluteus medius (rs=−0.56, p=0.03), and gastrocnemius muscles (rs=−0.56, p=0.02). Median peak absolute amplitude during TSP movements was lower in the quadriceps, gastrocnemius and peroneus longus muscles on the injured side.ConclusionsThe altered patterns of muscle activity at weight-transfer initiation, correlations between lower activity at movement initiation and altered movement patterns during SLS and the altered peak amplitudes during TSP movements together indicate alterations in sensorimotor control that may contribute to the observed altered movement patterns. Future studies will determine if exercises targeting muscle activity initiation should complement customary ACL injury rehabilitation.

Single-Joint Type Hybrid Assistive Limb for Knee Training in the Acute Postoperative Phase After Opening Wedge High Tibial Osteotomy: A Feasibility and Safety Trial

“…A decrease in the stiffness of the elastic components could lead to diminished efficiency in the transmission of contractile tension to the bones. Furthermore, human studies have reported changes in the tensile strength of the elastic components following disuse after orthopedic surgery [ 28 ]. Consequently, it is of paramount importance to emphasize targeting the knee extensor mechanism, particularly during the early postoperative period for individuals undergoing OWHTO.…”

Lower limb kinematics of single-leg squat performance in patients with anterior cruciate ligament deficiency

“…The single-leg squat (SLS) test is a physical examination used by many physical therapists for the assessment of patients with lower limb injury, including those with suspected ACL injuries. The test provides information about a patient’s confidence and stability on one leg, as well as information about knee pain and a patient’s pattern of movement that might be considered undesirable or potentially injurious 6 , 7 ) . The dynamic valgus position of the knee during single-leg activities is one movement pattern that has received much attention in the literature and has been associated with higher rates of knee injuries 8 , 9 ) .…”