ACL SNNAP Trial: ACL Surgery Necessity in Non Acute Patients

Inclusion Criteria: * Participant is willing and able to give informed consent for participation in the study. * Male or Female, aged 18 years or above. * Symptomatic ACL deficiency of the native ligament1 (instability-episodes of frank giving way or feeling unstable) with ACL deficiency (either partial or complete tear) confirmed using clinical assessment and MRI scan. Exclusion Criteria: * Acute phase of primary ACL injury i.e. not recovered from any acute symptoms relating to their initial ACL injury. * Previous knee surgery (other than diagnostic arthroscopy or partial meniscectomy) to index knee concomitant severe injury to contra-lateral knee. * Meniscal pathology with characteristics that indicate immediate surgery i.e. locked knee, large bucket handle or complex cartilage tear producing mechanical symptoms. * Knee joint status of grade 3 or 4 on the Kellgren and Lawrence scale, * Grade 3 MCL/LCL injury, associated PCL/PLC injury * Inflammatory arthropathy. * Pregnancy.