Background: Autologous osteochondral transplantation (AOT)—the transfer of hyaline cartilage with its underlying subchondral bone—is well established for focal osteochondral lesions, yet evidence for larger (>200 mm²) defects is limited. We assessed clinical and functional outcomes of AOT in patients with osteochondral knee lesions exceeding 200 mm². Methods: In this retrospective cohort study, 52 patients underwent AOT for full-thickness osteochondral defects of the femoral condyles or patellofemoral joint. All lesions were ≥200 mm² and treated with a standardized press-fit technique using one to four overlapping cylindrical grafts. Pain and knee function were evaluated preoperatively and at 3, 6, and 12 months postoperatively with the Visual Analogue Scale (VAS), Tegner–Lysholm Knee Score (TLKS), and Knee Society Score (KSS). Results: Mean defect size was 224.4 ± 84.5 mm². The VAS improved from 6.32 ± 1.1 preoperatively to 0.72 ± 0.6 at 12 months (p < 0.001). The TLKS rose from 58.6 ± 11.4 to 95.0 ± 6.8 and the KSS from 63.8 ± 12.2 to 97.4 ± 4.9 during the same period (both p < 0.001). Most gains occurred within the first 3–6 months and were sustained at 12 months. No major surgical complications were observed, and outcomes were unaffected by age, sex, or graft number/size. Conclusions: AOT is a safe, effective option for large osteochondral knee defects (>200 mm²), offering rapid, durable pain relief and excellent functional recovery while preserving native joint structures. Accurate donor site reconstruction and precise graft placement in the weight-bearing zone appear critical for optimal results. Longer-term prospective studies are needed to confirm durability and refine patient-selection criteria.

Background/Objectives: Large osteochondral lesions of the talus (OLT) pose a major challenge because their size and depth often exceed the indications for bone marrow stimulation, and durable biological repair remains difficult to achieve. However, evidence for autologous osteochondral transplantation (AOT) in extensive talar defects is still limited. Methods: In this retrospective cohort, 40 consecutive patients ≥ 14 years with ICRS grade III–IV lesions of the talar dome were treated with AOT at a tertiary referral center. One to three overlapping cylindrical osteochondral grafts (mean diameter 0.9 cm) were harvested from non-weight-bearing regions of the ipsilateral patellofemoral groove using a water-cooled diamond trephine system and implanted press-fit into the talar dome. Donor sites were refilled with autologous iliac crest bone cylinders and hydroxyapatite substitute. Pain (Numeric Rating Scale, NRS) and function (AOFAS Ankle–Hindfoot Score) were recorded preoperatively and at 3, 6, 9, and 12 months, and changes over time were analyzed using generalized estimating equations. Results: Mean defect size was 137.4 ± 31.9 mm², and 82.5% of lesions were ICRS grade III. NRS pain improved from 5.69 ± 2.52 preoperatively to 0.53 ± 0.98 at 12 months (p < 0.001). AOFAS score increased from 63.79 ± 2.55 to 97.36 ± 2.49 (p < 0.001). Age and graft location significantly influenced postoperative pain, whereas graft size and sex did not. No infections, graft failures, conversions to arthrodesis or arthroplasty, or clinically relevant donor-site symptoms occurred. Conclusions: Multi-plug AOT using a diamond trephine system provides substantial and durable pain relief and functional improvement in patients with large OLT, with low complication and donor-site morbidity rates. These findings support AOT as a joint-preserving option for extensive talar defects and justify further prospective, comparative studies with long-term follow-up.