Mosaicplasty of the Talus - Cartilage Repair Ankle

What is Mosaicplasty of the Talus?

Mosaicplasty of the talus (also known as osteochondral autologous transplantation, OAT) is a surgical procedure used to treat localized cartilage and bone defects of the talus (ankle bone). The talus is a key bone of the upper ankle joint that transfers body weight between the lower leg and the foot. Cartilage damage in this area can cause significant pain and restricted mobility.

During mosaicplasty, small cylindrical cartilage-bone grafts (called plugs) are harvested from a low-weight-bearing region of the knee joint and inserted into the damaged area of the talus. When multiple cylinders are placed side by side, they create a mosaic-like pattern – hence the name of the procedure.

Causes of Cartilage Damage to the Talus

Cartilage defects of the ankle bone can result from various causes:

• Trauma: Twisting or compression injuries of the ankle, commonly seen in athletes
• Osteochondritis dissecans: A condition in which a cartilage-bone fragment loses blood supply, may die and detach
• Chronic overuse: Repeated microtrauma from sports or occupational strain
• Ankle instability: Recurring sprains leading to chronic cartilage damage
• Avascular necrosis: Impaired blood supply to the bone causes tissue death

Symptoms

Patients with a cartilage defect of the talus often report:

• Load-dependent pain in the ankle joint
• Swelling and joint effusion
• Restricted range of motion of the ankle
• Feelings of locking or catching in the joint
• Instability during walking or running

Diagnosis

The following diagnostic methods are used to evaluate cartilage damage of the talus:

• X-ray: Initial imaging to rule out bony changes
• MRI (Magnetic Resonance Imaging): Gold standard for visualizing cartilage and bone changes; allows precise assessment of defect size and depth
• CT (Computed Tomography): Particularly useful for evaluating bony defects
• Arthroscopy: Joint endoscopy allowing direct assessment of cartilage damage and simultaneous therapeutic intervention

When is Mosaicplasty of the Talus Indicated?

Mosaicplasty is indicated for:

• Localized, full-thickness cartilage defects of the talus (Grade III-IV according to ICRS classification)
• Defect size typically between 1 and 4 cm²
• Failure of conservative treatment or initial arthroscopic procedures (e.g., microfracture)
• Young to middle-aged patients with high athletic demands
• Osteochondritis dissecans of the talus with a stable or loose fragment

Surgical Procedure

The procedure is usually performed under general or spinal anesthesia and involves the following steps:

• Graft harvesting: Cylindrical cartilage-bone plugs are harvested from a low-load-bearing zone of the knee joint (typically the lateral femoral condyle) using specialized hollow chisels.
• Defect preparation: The damaged area of the talus is prepared with matching recipient drills.
• Plug insertion: The harvested cylinders are inserted into the prepared drill holes in the talus, aligned as flush as possible with the joint surface.
• Mosaic pattern: For larger defects, multiple plugs are placed side by side, creating the characteristic mosaic pattern.

The procedure can be performed arthroscopically (minimally invasive) or via open surgery (with a malleolar osteotomy for better access to the defect).

Postoperative Care and Rehabilitation

Postoperative management is critical for a successful outcome:

• Weight restriction: Partial or full non-weight-bearing of the operated foot is required for the first 6 to 8 weeks after surgery.
• Physiotherapy: A targeted exercise program to restore range of motion, muscle strength, and proprioception (deep sensory perception)
• Return to sport: Typically after 4 to 6 months, depending on healing progress
• Follow-up checks: Regular clinical and imaging follow-up (MRI) to monitor graft integration

Outcomes and Prognosis

Mosaicplasty of the talus demonstrates good to very good long-term outcomes in clinical studies. Many patients report significant pain relief and restoration of athletic function. Success rates reported in the literature range from 70 to 90 %. Key influencing factors include the size and location of the defect, patient age, and adherence to rehabilitation protocols.

Risks and Complications

As with any surgical procedure, certain risks exist:

• Donor site morbidity at the knee (pain, sensory disturbances)
• Incomplete integration of the transplanted grafts
• Infection or wound healing complications
• Joint effusion or swelling
• In rare cases: early onset osteoarthritis of the ankle joint

References

1. Hangody L, Vásárhelyi G, Hangody LR et al. - Autologous osteochondral grafting -- technique and long-term results. Injury. 2008;39 Suppl 1:S32-9. PubMed PMID: 18313469.
2. Zengerink M, Struijs PA, Tol JL, van Dijk CN. - Treatment of osteochondral lesions of the talus: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2010;18(2):238-246.
3. Murawski CD, Kennedy JG. - Operative treatment of osteochondral lesions of the talus. J Bone Joint Surg Am. 2013;95(11):1045-1054.