Inclusion Criteria:
* Patients of any gender with an age from ≥ 18 years to ≤ 60 years
* Clinical indication for a surgical cartilage regeneration procedure
* Symptomatic grade III/IV cartilage defect according to ICRS or osteochondral defect with a maximum depth of 3 mm
* A cartilage defect requiring treatment with a defect size of 2-6 cm² on the femoral condyles or patella or trochlea
* Affected and contralateral knee (if known): Kellgren-Lawrence (K/L) osteoarthritis severity \< grade III
* KOOS pain sub-score of ≤ 70 (out of max. 100) in the affected knee joint and \> 80 (out of max. 100) in the contralateral knee joint measured without taking analgesics within the last 24 hours
* BMI \< 35 kg/m²
* Written informed consent of the participant, also regarding alternative procedures such as cartilage transplantation (MACT) or matrix-augmented bone marrow stimulation (BMS, AMIC)
Exclusion Criteria:
* Clinical indication explicitly for a cartilage regeneration procedure other than the intended study treatment
* Known varus or valgus malalignment of the affected leg of ≥ 5°
* Antero-posterior or medio-lateral instability
* Meniscus loss of more than 20% in the affected compartment
* Patella instability
* Simultaneous surgery on other joint structures (cruciate ligament replacement, meniscus suture, partial meniscus resection \> 20%, osteotomy)
* Simultaneous higher-grade (ICRS grade III/IV) cartilage damage on the corresponding joint surfaces to the treated cartilage damage ("kissing lesions")
* Osteoarthritis Kellgren-Lawrence (K/L) grade III or IV
* Arthrofibrosis
* Metabolic arthropathy
* Collagenosis
* Autoimmune disease
* Tumor disease within the last 5 years
* Neuromuscular disease
* Peripheral arterial occlusive disease
* Intra-articular application of hyaluronic acid or glucocorticoids or platelet concentrates within the last 6 months
* Joint replacement in the contra-lateral knee or hip within the last 12 months
* Rheumatoid arthritis or other inflammatory diseases such as autoimmune diseases, seronegative spondyloarthritis, gout, pseudogout
* Previous fracture in the affected knee joint
* Osteoporosis
* Contraindications against the planned operation under general anesthesia
* Relevant secondary diseases that increase the risk of surgery, e.g. cardiac insufficiency, coronary heart disease, coagulation disorders, diabetes mellitus, liver cirrhosis, renal insufficiency, etc.
* History of known hypersensitivity to porcine collagens, human albumin, glucose or components of fibrin adhesives used in orthopaedics or surgery
* Simultaneous participation in another interventional clinical trial (incl. within the last 4 weeks prior to inclusion)
* Addiction or other illnesses that do not allow the person concerned to assess the nature, scope and possible consequences of the clinical trial (lack of capacity to consent)
* Indications that the patient is unlikely to adhere to the protocol (e.g. lack of compliance)
* Persons who are placed in an institution by court or official order
* Persons who are dependent on the sponsor
* Pregnant or breastfeeding women
* Women of childbearing age, except women who meet the following criteria:
1. Post-menopausal (12 months natural amenorrhea)
2. Post-operative (6 weeks after bilateral ovariectomy with or without hysterectomy or bilateral salpingectomy)
3. Presence of a negative pregnancy test (urine, not older than 14 days on the day of surgery) and willingness to regularly and correctly use a contraceptive method with a Pearl Index \< 1 % per year:
3.1 Combined (oestrogen and progestogen-containing) hormonal contraception 3.2 Hormonal contraception containing progestogens (oral, injected, implanted) 3.3 IUD (hormonal IUD, copper IUD)
4. Sexual abstinence
5. Vasectomy of the partner
