Inclusion Criteria:  Clinical evidence of an acute unilateral ACL tear (full-thickness, complete tear) will be recruited. This age range is chosen to ensure participants have fully developed adult bone structures and to exclude participants with menopause as this could affect study results. Participants with combined ligament deficiencies (posterior cruciate, medial and/or lateral collateral) or meniscal injury will be included. Participants must be able to fully extend the knee while supported at the time of the baseline measurement in order to conduct the HR-pQCT scan. Participants with a serum calcium level in the normal range (2.1-2.55 mmol/L) and a creatinine level above 50 (reported as eGFR) will be included.  Exclusion Criteria:  Individuals with contraindications to zoledronic acid (see below) Prior knee ligament and/or meniscus tears, and/or intra-articular fractures. Females who are pregnant or planning pregnancy within a year will not be eligible. The research team will recommend participants who are planning to become pregnant within the next five years to withdraw their participation. Individuals with knees larger than the CT scanner's circular field of view. Individuals with a history of disease and/or treatment affecting bone turnover in the past 12 months. Individuals with injuries or implants that are not MRI-safe.  Zoledronic acid is contraindicated for:  Patients who are hypersensitive to this drug or to any ingredient in the formulation, or to any bisphosphonates or component of the container. Severe renal impairment with creatinine clearance <35 mL/min and in those with evidence of acute renal impairment. For this study, participants with a creatinine clearance <50 mL/min may be excluded. Non-corrected hypocalcaemia at the time of infusion. Pregnant and nursing mothers. Patients who are already taking another bisphosphonate (ex. for osteoporosis).