The primary objective of this study is to compare the improvement in subject-reported clinical outcomes for Regenexx SD vs. Exercise Therapy treatment of partial and complete, non-retracted knee ACL ligament tears, from baseline to 3 months, with continued evaluation of efficacy and durability up to 24 months.

Secondary objectives include evaluation of MRI evidence of tendon repair; incidence of post-operative complications, adverse events, re-injections, and surgical intervention; change in pain score and use of pain medications.

Prospective, randomized, controlled to include 25 subjects treated with Regenexx SD and 25 subjects treated with exercise therapy alone with the exercise group crossing over to the injection group at 3 months.

Subjects will have a partial or complete, non-retracted ACL ligament tear as evidenced with MRI.

Subjects will be enrolled within 60 days prior to Regenexx-SD injection or initiation of exercise therapy and take part in follow-up visits for two years following treatment. A preoperative visit will occur at the time of enrollment; follow-up visits will occur at the clinical site at 6 weeks, 3 months, 6 months, 12 months, and 24 months post injection.

The primary endpoint analysis will be conducted once all subjects reach the 3 month endpoint. Subjects will continue to be followed through the 2 year endpoint with data analysis performed at the 1 year and 2 year time points.

Inclusion Criteria:

• Pain, swelling, or functional disability in the affected knee with activity, having failed conservative treatment (e.g. NSAIDs, physician initiated physical therapy) for at least 3 months or unable to return to normal day to day activities by 6 weeks
• Physical examination consistent with lax ACL ligament (Anterior Drawer Test)
• Abnormal Telos Arthrometer measurement
• Positive diagnostic MR imaging of the affected knee with at least 1/3 of the ACL ligament at any area along its length having high signal on MRI PDFS/Fat Sat images.
• Full range of motion of the affected knee (other than restriction clearly due to effusion)
• Normal range of motion of the non-treated knee
• Is independent, ambulatory, and can comply with all post-operative evaluations and visits

Exclusion Criteria:

• A massive ACL tear or one that includes more than 2/3'rds of the ligament that's retracted.
• Previous surgery to the affected ACL (i.e. previous ACL replacement with an autograft or allograft)
• Prior ACL prolotherapy, PRP, corticosteroid injection or other injection therapy within the past three months,
• Concomitant meniscus tear or cartilage injury that occurred at the same time as the as the ACL tear and which is considered a pain generator by the treating physician at the time intake into the study (i.e. a meniscus tear or cartilage lesion associated with an active BML).
• Concomitant PCL or LCL tears
• Inflammatory or auto-immune based joint diseases or other lower extremity pathology (e.g., rheumatoid arthritis, systemic lupus erythematosus, psoriatic arthritis, polymyalgia, polymyositis, gout pseudogout)
• Quinolone or Statin induced myopathy/ tendinopathy
• Kellgren-Lawrence grade 2 or greater knee osteoarthritis
• Significant knee extension lag compared to the opposite knee
• Symptomatic lumbar spine pathology (e.g. radicular pain)
• Severe neurogenic inflammation of the cutaneous nerves about the knee or thigh
• Contraindications for MRI
• Tested positive or has been treated for a malignancy in the past or is suspected of having a malignancy or is currently undergoing radiation or chemotherapy treatment for a malignancy anywhere in the body, whether adjacent to or distant from the proposed injection site
• Condition represents a worker's compensation case
• Currently involved in a health-related litigation procedure
• Is pregnant
• Bleeding disorders
• Currently taking anticoagulant or immunosuppressive medication
• Allergy or intolerance to study medication
• Use of chronic opioid,