What Is AMIC Cartilage Repair Surgery?
Mr Shanmugasundaram Rajkumar is a Consultant Trauma and Orthopaedic Surgeon in Glasgow. He has a specialist interest in knee surgery, joint preservation and lower limb arthroplasty. He assesses patients to determine whether cartilage repair, or another approach, is likely to be the most appropriate option. This page explains what AMIC involves, who it may help, and what the recovery usually looks like. It also covers the risks and limitations that should be discussed before any decision is made.
Articular cartilage is the smooth, glossy tissue that lines the ends of the bones inside the knee. It allows the joint to glide with very little friction and helps to distribute load. Cartilage has a poor blood supply. So once it is damaged by injury or wear, it does not heal reliably on its own. Left untreated, a cartilage defect can remain symptomatic. It may also, in some patients, contribute to further deterioration of the joint over time.
AMIC is a single-stage surgical procedure that combines two steps. First, the damaged cartilage is carefully trimmed back to a stable rim. The underlying bone is then prepared using a bone marrow stimulation technique such as microfracture or nanofracture. This allows blood and bone marrow cells to reach the surface of the defect. Second, a sterile collagen membrane is placed over the prepared area and secured. The membrane acts as a scaffold, holding the blood clot and marrow cells in position. This lets repair tissue develop in a more organised way than with bone marrow stimulation alone.
AMIC is a surgical, restorative treatment rather than a cosmetic or purely diagnostic one. It sits within a wider family of cartilage preservation procedures. These also include microfracture on its own, osteochondral transfer and cell-based techniques such as autologous chondrocyte implantation. NICE has reviewed several of these cartilage repair techniques, and the evidence base continues to evolve. This is why careful patient selection matters.
Who May Benefit From Cartilage Preservation Surgery?
Cartilage repair is not suitable for everyone with knee pain. It tends to be considered for younger and middle-aged, active patients with a focal cartilage defect. The rest of the joint should also be reasonably healthy. Your surgeon will assess the whole knee, not just the damaged area.
You may be considered a candidate if you have:
- Persistent pain localised to one part of the knee, often worse with weight-bearing, stairs, squatting or twisting
- Swelling that recurs after activity
- Catching, clicking or a sensation of the knee giving way
- A known cartilage or osteochondral injury confirmed on MRI or at previous arthroscopy
- Symptoms that have not settled despite physiotherapy, activity modification, weight management or injections
- A stable, well-aligned knee with intact ligaments and adequate meniscal tissue, or a plan to address those problems at the same time
AMIC may be less appropriate where there is advanced, generalised osteoarthritis, significant bone loss, or inflammatory joint disease. It may also be less suitable where malalignment has not been corrected, or where smoking and other health factors are likely to impair healing. In those situations, alternatives such as an osteotomy, partial knee replacement or total knee replacement may be discussed instead. Your clinician will advise based on your assessment.
Conditions and Problems This Procedure May Address
- Focal chondral defects of the femoral condyle, trochlea or patella
- Osteochondral lesions, including some cases of osteochondritis dissecans
- Cartilage damage following a sports injury, patellar dislocation or ligament rupture
- Traumatic cartilage flaps or loose bodies causing mechanical symptoms
- Early, localised cartilage wear that has not progressed to established arthritis
- Ongoing pain and functional limitation after failed conservative treatment
Potential Benefits
Outcomes vary between individuals and no cartilage procedure can guarantee a particular result. That said, where patients are well selected, AMIC may:
- Reduce activity-related knee pain and swelling
- Improve function for walking, stairs and everyday tasks
- Support a return to recreational activity or sport, usually after a structured rehabilitation programme
- Provide biological cover over exposed bone, which may help protect the joint surface
- Be completed as a single operation, avoiding the two-stage approach required by some cell-based techniques
- Preserve the option of joint replacement later in life if it becomes necessary
- Day 0–1: Day case or overnight stay, a brace fitted if needed, and pain managed with medication
- Week 1–6: Protected weight-bearing on crutches, with gentle range-of-motion work and physiotherapy
- Week 6–12: Progressive strengthening, with a gradual return to low-impact activity such as cycling and swimming
- Month 3–12: Continued rehabilitation, with a return to running or pivoting sport considered around six to twelve months
Consultation and Assessment
A thorough assessment is the most important part of the process. At your consultation with Mr Shanmugasundaram Rajkumar, you can expect:
- A detailed discussion of your symptoms, injury history, occupation, sporting goals and previous treatment
- Review of general health, medication, smoking status and body mass index, all of which can influence healing
- A physical examination of the knee, hip and limb alignment, including ligament and meniscal testing
- Weight-bearing X-rays to assess joint space and alignment, and an MRI scan to map the size, depth and location of the cartilage defect
- An honest conversation about the realistic benefits, risks, recovery demands and alternatives, including non-surgical management
If surgery is appropriate, a personalised plan is agreed. This includes whether an additional procedure is needed at the same time, to protect the repair. Such procedures might include meniscal repair, ligament reconstruction or a realignment osteotomy.
How the Procedure Is Performed
AMIC is usually carried out in a hospital operating theatre under general or spinal anaesthetic. This is sometimes combined with a nerve block for pain relief. Many patients are treated as a day case or stay for one night, depending on the extent of surgery and their circumstances.
The operation typically involves:
- An initial arthroscopy (keyhole inspection) to confirm the size and position of the defect and treat any other findings
- Debridement of unstable cartilage back to a stable border and preparation of the underlying bone
- Microfracture or nanofracture to allow bone marrow cells to reach the surface
- Sizing and placement of a collagen matrix over the defect, secured with fibrin sealant or fine sutures
- Closure and application of a dressing, with a brace fitted where required
Depending on the location and size of the lesion, the membrane may be inserted arthroscopically. Or it may be placed through a small open incision known as a mini-arthrotomy.
Recovery and Aftercare
Rehabilitation after cartilage repair is deliberately protective, because the new repair tissue takes many months to mature. Recovery varies from person to person, but a typical pathway includes:
- Crutches with non-weight bearing or partial weight bearing
- A hinged brace in some cases, particularly for kneecap or trochlear lesions
- Early, gentle range of motion work and muscle activation exercises with a physiotherapist
- Measures to reduce the risk of blood clots, as advised before discharge
- Progressive strengthening from around six to twelve weeks, with gradual return to low impact activity such as cycling and swimming
- Return to running and pivoting sport usually considered somewhere between six and twelve months, only once strength and control targets are met
Follow-up appointments allow wound checks, review of progress and adjustment of the rehabilitation plan. You should seek prompt medical advice if you develop increasing pain, fever or spreading redness. The same applies if you have wound discharge, a hot swollen calf or breathlessness. General guidance on recovery after knee surgery is also available through the NHS.
Risks and Considerations
All surgery carries risk, and cartilage repair is no exception. Possible complications include infection, bleeding, stiffness, persistent swelling, deep vein thrombosis and pulmonary embolism. Other possible complications include numbness around the incisions, anaesthetic complications and, in some cases, ongoing pain despite technically successful surgery.
Specific considerations include the possibility that the repair tissue does not integrate fully, or that symptoms recur. Further surgery may also be needed in the future. Repair tissue is generally more fibrous than the original hyaline cartilage, so it may not behave identically. AMIC does not reverse established arthritis and it will not prevent every patient from eventually needing joint replacement. Adherence to the rehabilitation programme has an important influence on the outcome. Independent guidance on orthopaedic care standards is published by the British Orthopaedic Association.
Why Choose Mr Shanmugasundaram Rajkumar
Mr Shanmugasundaram Rajkumar is a Consultant Trauma and Orthopaedic Surgeon with more than 16 years of consultant experience. His practice covers hip and knee surgery, joint replacement and complex trauma care. He is fellowship-trained in lower limb arthroplasty and knee surgery. He gained experience at Wrightington Hospital, a long-established centre for joint replacement surgery.
- Honorary Senior Clinical Lecturer at the University of Glasgow
- College Tutor for the Royal College of Physicians and Surgeons of Glasgow
- Experienced in knee arthroscopy, cartilage preservation and day-case joint replacement
- Uses ODEP 10A-rated hip and knee implants, with outcomes recorded through the National Joint Registry
- Active researcher involved in randomised controlled trials and UK and European multicentre studies
- Published in peer-reviewed orthopaedic journals and a reviewer and consulting editor for international surgical journals
- National lecturer and medical educator in Trauma & Orthopaedics
His approach combines modern surgical technique with evidence-informed, patient-centred care. The aim is to reduce pain, restore mobility and support a return to an active lifestyle.
Location and Areas Served
Consultations and cartilage repair surgery are available in Glasgow. Patients also travel from Renfrewshire, Paisley and the surrounding areas of the west of Scotland. Both private and appropriately referred patients are welcome.
Frequently Asked Questions
Is AMIC surgery painful?
The procedure itself is performed under anaesthetic, so you will not feel it. Discomfort and swelling are common in the first days afterwards and are managed with pain relief, ice, elevation and early physiotherapy.
How long does the operation take?
Most AMIC procedures take around one to two hours. This depends on the size of the defect and whether any additional procedures are performed at the same time.
How long is the recovery?
Protected weight-bearing usually lasts about six weeks, with strengthening continuing for several months. Many patients feel substantially better by three to six months, although full maturation of the repair tissue takes longer.
Am I suitable for cartilage preservation surgery?
Suitability depends on your age, activity level, and the size and site of the defect. It also depends on limb alignment and the overall condition of the joint. This can only be determined after clinical examination and imaging.
What are the alternatives?
Alternatives may include physiotherapy, activity modification, weight management, injections, microfracture alone, osteochondral transfer or cell-based cartilage repair. Where arthritis is established, osteotomy or partial or total knee replacement may also be considered.
When should I book a consultation?
If knee pain, swelling or locking has persisted for several weeks despite conservative measures, or if a cartilage injury has already been identified on a scan, a specialist assessment is sensible.
At a glance
Anaesthetic
General or spinal, sometimes with a nerve block
Operation time
Typically 1–2 hours
Hospital stay
Day case or one night
Recovery
6 weeks protected weight-bearing; several months to full recovery
Technique
Single-stage AMIC with a collagen membrane scaffold
Fees & insurance
New Consultation
£180
Follow-up
£110
Insurers
Bupa · AXA Health · Aviva · Vitality · WPA
Self-pay
All-inclusive quotation on request
A written quotation is provided before any procedure is booked.
Discuss your knee
Request an appointment at Ross Hall Hospital, Glasgow.