Biomechanics of periarticular knee muscles after ACL surgery in young patients - comparison of autograft reconstruction and suture-tape augmented primary repair.

: Last years brought a growing interest in suture-tape augmented ACL repair techniques instead of ACL reconstructions with autografts due to their limited success rates. However, there is a lack of experimental studies comparing the infl uence of both procedures on knee periarticular muscles biomechanics. The aim of the study was to analyze periarticular muscles torq ue and their activity during movement for young patients after ACL repair (IB) and ACL reconstruction (ACLR), compare them with each other and with a healthy subjects (Controls). : Isokinetic torques of knee flexors and extensors and their EMG activity during gait and drop vertical jump (DVJ) were measured in 48 patients (IB - 20, ACLR - 28) at least one year after surgery and in 25 healthy controls. : The muscle torques in the operated limb were lower in both group of patients comparing to Controls, but IB scored the lowest values (79% of Controls for extensors, = 0.005; 74% for flexors, = 0.001). Decrease of muscle torques in the contralateral limb occurred only in IB group (84% of Controls for both extensors ( = 0.045) and flexors). Increased hamstrings activity were noticed for ACLR comparing to IB and Controls. The balance between activity of muscles actin g on the medial and lateral side of the knee for ACLR tilts more towards the lateral side. : Increased hamstrings activity and changes in balance between laterally and medially located muscles indicate on the increased need for muscle support of kn ee stability in ACLR patients.