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Advanced knee surgery in operating theatre

KOAT

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.

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Prof Paul LeeReviewed byProf Paul LeeLast reviewed 1 May 2026
Interior view of joint during arthroscopic assessment

Why bone shape matters for cartilage survival

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.

  • Osteoplasty reshapes the bone to restore normal joint geometry.
  • Cartilage augmentation is then applied to the prepared, congruent surface.
  • The combined approach addresses the root cause rather than patching over structural problems.

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.

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The procedure and what to expect

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.

  • Protected weight-bearing for six to eight weeks post-operatively.
  • Early physiotherapy to maintain range of motion and prevent stiffness.
  • Return to activity guided by imaging and clinical assessment of graft incorporation.

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.

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Professor Lee discussing surgical options

You may have more options than you think

Most patients have more treatment options than they have been told

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.

Preserve

Protect what you have. Slow degeneration and manage symptoms.

Repair

Fix specific damage. Torn tissue, unstable joints, structural problems.

Regenerate

Rebuild lost tissue. Biological treatments that stimulate new growth.

Replace

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.

Explore Knee Options
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Frequently Asked Questions

What does KOAT stand for?

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.

How does KOAT differ from OATS or OCA?

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.

Who benefits from the KOAT procedure?

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.

What is the recovery after KOAT?

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?

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