KOAT (Knee Osteoplasty with Augmented Transplantation) is an advanced surgical technique that combines bone reshaping with cartilage augmentation. It is designed for complex defects where both the cartilage surface and the underlying bone architecture need correction. By addressing both layers in a single procedure, KOAT creates a stable, congruent joint surface that supports long-term function. This technique is offered at London Cartilage Clinic for patients where standard cartilage replacement alone may not be sufficient.
Reviewed byProf Paul Lee MBBch, FRCS (Tr & Orth), PhDLast reviewed 1 May 2026
Cartilage sits on the subchondral bone like a surface coating. If the bone beneath is irregular, depressed, or has collapsed, a cartilage graft placed on top will not match the surrounding contour and may fail under load.
KOAT is often considered after a previous cartilage procedure has failed because the underlying bone problem was not addressed at the time of the original surgery.
KOAT is performed as a single-stage operation. The bone is reshaped first, then cartilage tissue is transplanted or augmented onto the prepared surface to create a smooth, load-bearing joint.
KOAT is a specialist procedure offered to a select group of patients. Your surgeon will determine whether this combined approach is appropriate based on imaging, defect characteristics, and prior surgical history.
You may have more options than you think
At London Cartilage Clinic we follow a structured clinical framework across four areas of treatment. Before recommending a single procedure, we assess which combination of approaches gives you the best outcome.
Protect what you have. Slow degeneration and manage symptoms.
Fix specific damage. Torn tissue, unstable joints, structural problems.
Rebuild lost tissue. Biological treatments that stimulate new growth.
When other options are exhausted. Joint replacement as a last resort.
Explore the full range of treatments available for your joint. Each hub page shows every option we offer, organised by clinical approach.
KOAT refers to Knee Osteoplasty with Augmented Transplantation. It is a combined technique that addresses both the bone contour and the cartilage surface in a single procedure.
OATS and OCA focus on replacing cartilage with a plug or graft. KOAT goes further by reshaping the underlying bone (osteoplasty) to create an optimal surface before augmenting it with cartilage tissue. This combination is suited to defects where the bone itself is irregular or depressed.
KOAT is considered for patients with cartilage defects accompanied by subchondral bone irregularity, where a standard cartilage graft alone may not achieve a congruent joint surface. It is particularly relevant after failed previous cartilage procedures or in cases of osteochondritis dissecans with bone involvement.
Recovery is similar to other cartilage transplantation procedures. Protected weight-bearing for six to eight weeks, early range of motion exercises, and a gradual return to activity over six to twelve months. The bone component needs time to remodel alongside cartilage maturation.
Still have more specific concerns?
Free Discovery CallLondon Cartilage Clinic
Clinical updates, cartilage treatment guidance, and recovery-focused articles from our specialist team.
A partial ACL tear spans from mild stretch to high-grade damage affecting most of the ligament; tears involving less than 25% of the cross-section carry a favourable outlook, but those affecting 50–75% carry substantially higher risk of progressing to complete rupture.
Ultrasound-guided hip injection achieves 100% accurate joint placement versus 72% for landmark-guided techniques, essential for ChondroFiller, which gels irreversibly within 3–5 minutes.
MACI involves two phases: chondrocytes cultured on collagen membrane over four to six weeks, then implanted to mature over up to two years within the joint, generating hyaline-like cartilage rather than the fibrocartilage produced by microfracture.
