Umbilical cord stem cells could mend Worn-Out knees

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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