EFFECTS OF ISOMETRIC HOLD EXERCISE WITH PASSIVE TERMINAL KNEE EXTENSION IN RESTORING QUADRICEPS FUNCTION AFTER ACL RECONSTRUCTION — RESEARCH DESIGN AND METHODS

Background: Inhibition of the quadriceps muscle activity and reduced knee extension strength in terminal extension is observed in most cases following anterior cruciate ligament (ACL) injuries and reconstruction. Quadriceps lag (QL), if it persists, can lead to limitation of functional and performance skills. The loss of quadriceps power may be due to reduced voluntary activation of the quadriceps muscle due to arthrogenic muscle inhibition (AMI). The possibility of physiotherapeutic intervention to reduce the AMI must be considered to decrease the QL, and improve muscle strength and functional recovery. There is a need to develop a specific exercise addressing arthrogenic muscle inhibition (AMI), to achieve complete knee extension at the early phase of rehabilitation. The trial is aimed to evaluate the effect of IEPTE in patients with quadriceps lag following anterior cruciate ligament reconstruction (ACLR). Methods: Randomized, Parallel Group Trial, including 36 patients ([Formula: see text] = 36) aged 18–50 years with ACLR, will be randomly allocated to isometric hold exercise with passive terminal knee extension (IEPTE) and ACL conventional exercise group (CG). The primary outcome for quadriceps lag and the secondary outcome of motor unit action potential (MUAP), pain and knee function will be evaluated. The IEPTE technique is developed by the author, who combined passive terminal knee extension with the isometric hold exercise to knee extensors. The effects of the exercise protocol will be evaluated using outcome measures at 0 (baseline), 2nd, 4th, 8th, 24th weeks. General linear mixed model for repeated measures with effect size tested using Cohen’s d will be used to analyze primary and secondary outcomes to investigate confounding interaction between groups and time. A statistically significant was set to [Formula: see text] < 0.05 (95% CI). The study results are expected to be completed by December 2023 and the results by 2024. Discussion: The exercise developed addresses the AMI and achieves knee extension at the early phase of rehabilitation. If proven to be effective, the early activation of the quadriceps may improve the knee function. This developed exercise (IEPTE) thus can be used in the ACL rehabilitation program and results will help to explore further to frame new guidelines and protocol.