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

3D Biomechanical testing involves the following progressive neuromuscular challenge tests: * Single leg countermovement jump - Vertical jump as high as possible off one leg. * Single leg drop jump- Hop from a 20cm height onto one leg and jump as high as possible with as little time spent on the ground * Double leg drop jump- Hop from a 30cm height onto one leg and jump as high as possible with as little time spent on the ground * Hurdle hop - Lateral hop over a 15cm hurdle followed by a hop back to the starting position and a hold for 2sec * Single Leg Hop for distance - maximal jump for horizontal distance on one leg while sticking the landing * Pre-planned change of direction cut - Sprint for 5 metres, make a 90 degree change of direction pre-determined by the tester and sprint for a further five meters to the finish * Indecision cut - Sprint for five meters then react to a light stimulus and make a 90 degree cut to the left or right for a further 1.5metres Patient Registry Patient data will be inputted into the Sports Surgery Clinic medical data management software. Captured data will include: 1. Patient information - Date of Surgery, Surgeon, Side of ACLR, confirmative Magnetic Resonance Imaging 2. Pre-Operative data collection * Pre-Operative Questionnaire- Date of injury, Activity undertaking when injury occurred, level of sporting activity, Injury mechanism, limb dominance, previous ACL injury or surgery. * Marx Activity Questionnaire. * ACL return to sports after injury (RSI) questionnaire- measures the athlete's emotions, confidence in performance, and risk appraisal in relation to return to sport after an ACL injury. 3. Intra-Op data collection \- Operative notes are recorded in theatre using a standardised in theatre questionnaire. This form was developed under consensus with all surgeons who complete ACL reconstructive surgery at the Sports Surgery Clinic. Included are graft type, laxity, involvement of other ligamentous structures, type of femoral and tibial fixation, meniscal or chondral pathology. 4. 6 Month and 9 months post op data collection * Marx Activity Questionnaire * ACL RSI * International Knee Documentation Committee (IKDC) form- The IKDC subjective form is a reliable and valid measure to monitor symptoms and function in daily living activities in those with knee disorders. * Cincinnati Questionnaire - a valid and reliable measure of patient reported outcome after ACL injury * Sports Surgery Clinic return to performance questionnaire- asks whether the participant has returned to sport, have they injured the operated knee or contralateral knee and asks whether they still experience pain and rate that pain on a numerical rating scale. * 3D test battery findings 5. 12 and 24 months post op data collection * Marx Activity Questionnaire * ACL RSI * IKDC * Sports Surgery Clinic return to performance questionnaire Quality assurance plan * Weekly cross-checking will be undertaken by two members of staff to ensure data entered onto the registry is correct and contemporaneous. * A six-monthly audit of the registry will be undertaken by external auditors. Registry standard operating procedures * Basic patient contact details are inputted by administration staff. * Physiotherapists and biomechanists input physical examination findings on medical data software. * Self-reported questionnaires are completed on site using a tablet device and uploaded automatically to the registry once the questionnaire is completed. * During theatre, the surgeon fills out the standardised intra-operative form, which is uploaded to the registry following surgery. * For analysis or auditing purposes, data is downloaded from the Sports Surgery Clinic medical data management software and placed into Microsoft excel. Patient names are de-identified. Sample size * Suggested sample size = 1000 * Sample size calculation was carried out based on current numbers presenting to the clinic. Clinical numbers indicate a re-rupture rate of either the ipsilateral or contralateral ACL of 5%. * This study aims to recruit 1000 participants and follow them over 24 months. With a likely re-rupture rate of 5%- it is hypothesized that 50 re-ruptures will occur over the 24 month period. This is a conservative number allowing for dropouts, and a split between contralateral and ipsilateral ACL injuries, which will be analysed separately. * It is also aimed to recruit 50 healthy volunteers from multidirectional field sports teams. Plan for missing data * Checklist to flag missing data at the end of every week * Participants with missing data may be excluded from the data analysis. Statistical analysis plan * Variables of interest include kinematics, kinetics, power, and vertical ground-reaction force at the pelvis, hip, knee and ankle at specific time points during different jumping, landing and cutting manoeuvres. * Differences between involved and uninvolved legs will be calculated, and used to assess for asymmetry. Two group comparisons will be conducted using the Student t test or Kruskal-Wallis test for normal and non-normally distributed variables, respectively. * Multivariable logistic regression, using variables with P values of \</=0.05 from 2-group comparisons (those who go on to suffer a 2nd ACL injury and those who don't), will be used to identify the most predictive variables of the second ACL injury. * A multivariable logistic regression analysis will also be conducted to identify the most predictive variables of patient reported subjective knee function (IKDC) and pain. * Associations between intra-operative findings and outcome measures of re-injury pain and return to sport will be explored, also using regression analysis.