The Hyalex Early Feasibility Study (EFS)

Inclusion Criteria (Phase 1):

1. 21-70 years.

2. Body Mass Index (BMI) ≤ 38.

3. Singular treatable joint surface lesion, ICRS Grade 3 or 4, located on the medial orlateral femoral condyle.

4. One implant to treat a single symptomatic lesion with up to 3.8cm2 total lesionarea.

5. Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale score between 20and 65.

6. Stable knee.

7. Failure of non-operative treatment (e.g., physical therapy, physician-directed athome exercise program, intra-articular injections, bracing) for at least 4 weeksprior to consideration for participation in the study.

Inclusion Criteria (Phase 2):

1. 21-70 years.

2. Body Mass Index (BMI) ≤ 38.

3. Up to three treatable joint surface lesion(s), ICRS Grade 3 or 4, located on themedial or lateral femoral condyle(s).

4. Up to 3 implants to treat up to 3 individual symptomatic lesions with a totalsummative area up to 10cm2.

5. Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale score between 20and 65.

6. Stable knee.

7. Failure of non-operative treatment (e.g., physical therapy, physician-directed athome exercise program, intra-articular injections, bracing) for at least 4 weeksprior to consideration for participation in the study.

Exclusion Criteria:

HYALEX Implant, Surgical Technique, and Lesion Site Exclusions:

1. Known allergy to polyurethanes, bone cement, acrylic, or titanium.

2. Lack of 2mm of healthy cartilage (ICRS Grade 0 to 2) and 2mm of vital bone wall onall sides of the implant site.

3. Osteochondral defect affecting subchondral bone more than 11mm in depth fromadjacent non-defect articular surface.

4. Bipolar cartilage lesions involving patellar or tibial lesions ICRS Grade 3 - 4opposite the lesion intended for treatment.

5. Insufficient bone stock or bone density determined intra-operatively preventingimplant press fit.

Patient Orthopaedic Health Exclusions:

1. Kellgren and Lawrence (KL) grade 3 or 4 on standing radiographs.

2. Hip-knee-ankle (HKA) angle of greater than +/- 8 degrees (varus or valgusmalalignment > 8 degrees) on standing X-ray.

3. Lack of normally functioning contralateral knee that restricts activity.

4. Insufficiency fracture of the femoral condyle or tibial plateau.

5. Recent Osteochondritis Dissecans within 1 year.

6. Diagnosis of a concomitant knee injury which the investigator believes may interferewith study participation or confound effectiveness assessment.

7. Untreated ACL and/or PCL deficiency or complex ligamentous instability of the studyknee according to IKDC Grade C (abnormal) or D (severely abnormal).

Previous Surgery and Intervention Exclusions:

1. Previous surgical cartilage treatment in the index knee within the last 6 months

2. Previous intra-articular injections, including HA and steroids, within the last 3months prior to the date of surgery.

Patient Overall Health and Health History Exclusions:

1. Any known history of inflammatory arthropathy or crystal-deposition arthropathy.

2. Current cigarette smoker or user of other nicotine products.

3. Known Type 1 or Type 2 insulin-dependent diabetes mellitus.

4. Currently undergoing immunosuppressive therapy or long-term steroid use (corticosteroid, excluding inhalers) or within 3 months prior to surgery.