Biomechanical Analysis of Dynamic Tasks and Muscular Strength Following Anterior Cruciate Ligament Reconstruction

Background Anterior cruciate ligament (ACL) injuries are one of the most common sporting injuries of the knee. ACL reconstruction (ACLR) has become one of the most common surgical procedures in an attempt to increase joint stability and facilitate athletes to return to sport (RTS). Although ACLR is considered a relatively successful procedure, dynamic control risk factors and strength and power deficits in the involved limb are still present after patients return to sport. Dynamic multi-plane, multi-joint actions such as jumping, landing, change of direction cutting, have been shown to be common mechanisms of injury for the ACL in field sports . Returning to multidirectional sports requires a proficiency and efficiency of movement when carrying out these tasks. There is a lack of standardized, objective criteria to accurately assess an athlete's ability to safely RTS. Therefore, there is a need for research that simultaneously analyses sport specific dynamic tasks (3D motion analysis) and muscular strength/power deficits that may explain poor outcomes following ACLR. This study aims to further investigate movement patterns, limb asymmetry and muscle strength deficit in patients post-surgery to identify risk factors for re-injury and criteria for RTS. The purpose of this study was to: 1. Analyse kinematic (movement descriptors) and kinetic (forces that cause movement) during sports specific dynamic tasks at different time-points (6 and 9 months) following ACLR. 2. To explore the association of those findings with those who re-injure, those who have persistent knee pain or with those who fail to return to sport. 3. To compare the ACLR participants with age and gender matched healthy multidirectional athletes. It is hypothesised that biomechanical analysis will identify clear risk factors for poor outcomes following ACLR. Analysis of ACLR athletes' biomechanics during sports specific tasks will aid in the identification of athletes who are not yet ready to return to sport and will inform the clinician of what must be targeted in specific rehabilitation protocols before return to sport is considered. Brief protocol Participants will be recruited from patients who are scheduled to undergo anterior cruciate ligament reconstruction at the Sports Surgery Clinic, Ireland. Healthy participants will be recruited from local multidirectional teams. Participation will be voluntary and after obtaining informed consent patients will be asked to complete pre-operative questionnaires to ascertain injury information, and the function of their knee. During surgery the surgeon will fill out an intra-operative questionnaire. Items recorded will include graft type, laxity, involvement of other ligamentous structures, type of femoral and tibial fixation, meniscal or chondral pathology. Biomechanical assessment takes place at 6 and 9 months post surgery for the ACL group while the healthy participants will be tested on one occasion. The 3D testing session will include capturing of jumping, landing, hopping and cutting mechanics through the use of three dimensional motion capture technology and force plates. Here reflective markers are placed on the skin at anatomical landmarks. These markers are picked up by the infrared cameras and tracked at 200 frames per second. Participants will make contact with a force plate with their foot on undertaking the movements. Force and marker data will be combined to calculate joint angles and moments. Participants will also perform a muscle strength test using equipment called an isokinetic dynamometer. Both the operated and non-operated limbs will be tested. Participants will also be asked to fill out validated questionnaires to monitor self reported knee function, their confidence in their knee and also collect data on any continuing adverse symptoms such as locking, giving way, swelling or pain. Participants will also be asked if and when they return to sport. Questionnaires will be administered to participants at pre-op, 3, 6, 9, 12, 24 months, 5 and 10 years post operatively.