Table 1 Inclusion and exclusion criteria

Inclusion criteria

 (1) Males or females aged 18–40 years;

 (2) Anterior cruciate ligament (ACL) injury requiring reconstruction with bone bruising evident on pre-operative magnetic resonance imaging (MRI) scan at screen or within 6 months of initial ACL injury;

 (3) Have undergone unilateral ACL reconstruction surgery within 6 months of injury;

 (4) Clinically stable knee after reconstruction—International Knee Documentation Committee clinical knee examination at time of surgery after reconstruction to be grade normal or nearly normal;

 (5) Willing and able to undertake a standardized rehabilitation protocol as assessed by surgeon;

 (6) ACL graft used was autograft hamstring;

 (7) Willingness to participate in follow-up for 24 months from the time of initial treatment;

 (8) Ability to understand and willingness to sign consent form;

 (9) If a female was of childbearing potential, then she must have confirmed negative urine and serum pregnancy test result at screening, and a negative urine pregnancy test prior to the administration of the study treatment, and agree to use a medically reliable method of preventing conception for the first 6 months after injection of the study treatment;

 (10) Male patients with partners of childbearing potential must be willing to use a medically reliable method of preventing conception for the first 6 months after injection of the study treatment.

Exclusion criteria

 (1) Women who are pregnant or breast feeding or planning to become pregnant during the first 6 months after injection of the study treatment;

 (2) Known sensitivities to bovine (cow), murine (mouse), chicken products, and/or dimethyl sulphoxide;

 (3) Known allergies to products from birds such as feathers, eggs, or poultry;

 (4) Previous allergic reaction to hyaluronan (HA);

 (5) Systemic or local infection at the screen visit or at the time of the study injection;

 (6) History of any autoimmune disease, such as systemic lupus erythematosus, Addison’s disease, Crohn’s disease, or rheumatoid arthritis;

 (7) Treatment with immunosuppression therapy within 6 months prior to screening;

 (8) Chronic (at least 7 consecutive days) of systemic corticosteroids at a dose equivalent to >10 mg/day prednisolone within 14 days prior to screening;

 (9) Acute or chronic infectious disease, including but not limited to human immunodeficiency virus;

 (10) Treatment and/or uncompleted follow-up treatment of any investigational therapy within 6 months before the procedure and/or intent to participate in any other investigational drug or cell therapy study during the 24-month follow-up period of this study;

 (11) Recipient of prior allogeneic stem cell/progenitor cell therapy;

 (12) Undergoing a simultaneous procedure to the opposite knee;

 (13) Injury was work related and covered by workers compensation;

 (14) A medical condition, serious intercurrent illness, or extenuating circumstance that, in the opinion of the investigator, would preclude participation in the study or potentially decrease survival or interfere with ambulation or rehabilitation (e.g., histories of transient ischemic attack, stroke, uncontrolled diabetes, or liver disease);

 (15) Presence of ≥20% anti-human leukocyte antigen (HLA) antibody titres and/or having antibody specificities to donor HLAs;

 (16) History or current evidence of alcohol or drug abuse or was a recreational user of illicit drugs or prescription medications;

 (17) Significant damage to the collateral or posterior ligaments of the knee;

 (18) Meniscal injury requiring more than a 1/3 resection or more than a single suture to reconstruction or a reconstruction that would alter the usual ACL rehabilitation;

 (19) History of prior surgery to the study knee joint;

 (20) History of malignancy (excluding basal cell carcinoma that has been successfully excised);

 (21) Chondral lesions noted at time of surgical reconstruction greater than grade 1a on any surfaces;

 (22) Intra-articular steroid or corticosteroid or HA injections in preceding 3 months to the affected joint;

 (23) Diffuse synovitis at time of surgery for the ACL reconstruction;

 (24) Indwelling metal of any description which precluded MRI examination such as, but not limited to, indwelling pacemaker, cerebral aneurysm clips, or electrical indwelling device such as bone stimulator or anything that would preclude patient from undergoing screening MRI;

 (25) Not willing to return for required follow-up visits or there was a clear demonstration of likely poor compliance;

 (26) Any other medical condition that, in the judgment of the Principal Investigator/Investigator, would prohibit the patient from participating in the study;

 (27) Patient was legally or mentally incapacitated;

 (28) Prisoners or patients who were involuntarily incarcerated;

 (29) Patients who were compulsorily detained for treatment of a psychiatric disorder.