The study was terminated early due to a change in business strategy at the sponsor, unrelated to any safety concerns with the medical device.

Multi-center, prospective, concurrently controlled, non-randomized, double-blind (patient and assessor). Treatment of large chondral lesions in the knee with microfracture plus the Chondro-Gide® ACC is non-inferior to treatment of small chondral lesions treated with microfracture alone.

The study evaluates the investigational treatment for treating large chondral lesions of the knee to the control treatment of microfracture alone for treating small lesions.Eligible patients with a large lesion will be treated with microfracture plus the Chondro-Gide® ACC and compared to patients with small lesions that are treated with microfracture alone. Outcome measures to be assessed include patient reported outcomes and freedom from certain adverse events.

Inclusion Criteria:

1. Signed written informed consent
2. One symptomatic knee with cartilage defect on the medial femoral condyle, lateral femoral condyle, or trochlea, identified MRI or arthroscopy
3. Between 18 and 55 years of age
4. Subject is willing and able to comply with all study procedures, including visits, diagnostic procedures, and the rehabilitation protocol

Exclusion Criteria:

1. BMI ≥ 30 kg/m2
2. Symptomatic contralateral knee
3. Diagnosis of radiographic osteoarthritis with Kellgren-Lawrence grade 3 or more
4. Prior surgical treatment of the cartilage using microfracture, mosaicplasty, or autologous chondrocyte implantation (debridement and lavage are acceptable if the procedure was at least 3 months prior to enrollment)
5. Patella dysplasia
6. Chronic inflammatory arthritis or infectious arthritis
7. History of autoimmune disease or immunodeficiency
8. History of connective tissue disease
9. Intra-articular steroid use within the 3 months prior to enrollment
10. Other intra-articular injections (e.g. hyaluronic acid) within 3 months prior to enrollment
11. The patient is currently being treated with radiation, chemotherapy, immunosuppression or systemic steroid therapy with a dose equivalent to more than 5 mg prednisolone
12. Pregnancy or lack of adequate contraceptives if a female of child-bearing potential
13. Enrolled in another study, involved in the study (as a researcher/investigator/sponsor), or relative of someone directly involved in the study
14. Active infection of the index knee
15. Previous diagnosis of osteoporosis as diagnosed by DEXA, bone densitometry or CT scan
16. Any disorder or impairment that would interfere with evaluation of outcomes measures, such as neurological, degenerative muscular, psychiatric, or cognitive conditions
17. History or current substance or alcohol abuse as defined by the DSM-V
18. Any other medical condition that the investigator determines would interfere with the validity of the study
19. Known allergy to porcine collagen
20. Symptom duration greater than 36 months