Randomized Evaluation of BST-CarGel Versus Microfracture Alone On Recovery From Distal Femoral Cartilage Lesions

Inclusion Criteria: * requires cartilage repair treatment due to distal femoral cartilage lesion * is 18-55 years of age at the time of surgery * has single, focal cartilage lesion on one of the femoral condyles * has symptomatic cartilage lesion that has failed conservative management * has a single lesion classified as focal, full-thickness grade 3 or 4 according to the ICRS (3A, 3B, 3C, 3D and 4A) * an area of lesion between 1.5-3 cm2 after debridement * has a stable knee (\<5-mm side-to-side difference on Lachman and varus and valgus stress testing and grade 0 or 1 on the pivot-shift test) and an intact meniscal rim * is willing and able to participate in required follow-up visits at the investigational site and to complete study procedures and questionnaires and recommended physiotherapy regimen * has agreed to discontinue the use of all knee pain medication 3 days before the pre-treatment visit and the post-treatment follow-up visits at 3, 6, 9, 12, and 24 months * has consented to participating in the study by signing the IRB/EC approved informed consent form * no deep osteochondral defect ( \< 5 mm bone loss) Exclusion Criteria: * has multiple lesions or kissing (opposing) lesion(s) greater than GII * has clinically relevant compartment malalignment (\>5°) * has bone cyst(s) associated with, or adjacent to, the index lesion * has Osteochondritis Dissecans with bone or bone-cartilage fragment in place * has had ligament treatments in the index knee within the previous 24 months * has had surgical cartilage treatments in the index knee within previous 12 months * has had intra-articular injections in the index knee within the previous 2 months * has diagnosis of an immunosuppressive disorder * has a BMI \> 30 kg/m2 * has concomitant healing bone fractures * has a single lesion classified as focal, full-thickness grade 4B as defined by ICRS * has noteworthy pain in the ipsilateral hip or ankle or contralateral hip, knee, or ankle * has inflammatory arthropathy * has blood clotting disorders, was receiving anticoagulant therapy, or has recurring deep vein thrombosis * has a serious heart condition or liver and/or renal abnormalities diagnosed within the previous 24 months * has chronic infection of the lower joint extremities * has a history of alcohol or drug abuse within the previous 12 months * is facing current or impending incarceration * has a known allergy to shellfish * is pregnant or plans to become pregnant during the course of the study * in the opinion of the PI, has an emotional or neurological condition that would pre-empt their ability or willingness to participate in the study including mental illness, drug or alcohol abuse * chronic knee pain * has a documented medical history of vitamin-D deficiency that is not being managed with supplementation * is entered in another investigational drug, biologic, or device study or has been treated with an investigational product in the past 30 days * requires an open procedure * is known to be at risk for lost to follow-up, or failure to return for scheduled visits