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Cartilage repair · UK

MACI cartilage repair, by a specialist knee surgeon.

A NICE-approved two-stage cartilage transplantation for focal defects in the knee and ankle - done by a consultant with a high MACI case volume, in a unit with a proper cartilage MDT, alignment and meniscal-repair pathways in the same room.

A stethoscope on a clinical desk

Indicative pricing

What private MACI cartilage repair costs in the UK.

Indicative ranges across UK units.

In short

MACI of the knee, all-inclusive: £22,000 to £38,000, home the next day.

Procedure Indicative range
MRI knee with cartilage-sensitive sequences £450 to £850
Microfracture (small defect under 2 cm squared) £6,500 to £10,500
Mosaicplasty / OATS (2 to 4 cm squared) £14,000 to £22,000
MACI knee (2 to 10 cm squared, all-inclusive both stages) £22,000 to £38,000
MACI ankle (talus, all-inclusive) £24,000 to £40,000
Fresh osteochondral allograft (large or deep defect) £22,000 to £38,000
Combined MACI plus realignment (HTO / DFO / TTT) +£4,500 to £8,500
Second-opinion review of MRI and surgical notes £250 to £450

Prices vary by unit, by which surgeon does the case, by whether a concurrent osteotomy or meniscal repair is needed, and by defect size and location.

The problem

The right surgeon, the right technique, the right unit.

A focal cartilage defect booked as a routine knee arthroscopy is a wasted operation. We stop that happening - and we stop MACI being done on a knee where alignment or meniscal loss will sink the graft.

  • Is MACI even the right procedure?

    A defect under 2 cm squared often does well with microfracture. A defect over 10 cm squared, deep bony loss or bipolar wear needs a different plan entirely.

  • Worried about the rehabilitation?

    Twelve months to sport, six weeks non-weight-bearing, CPM from day one. Quoted honestly, with a physiotherapy plan, before you consent.

  • Want it done in a cartilage unit?

    A named consultant, a proper cartilage MDT, and realignment and meniscal-repair pathways available in the same room.

When it helps

When MACI is the right step - and when it is not.

The defects we see most, plus the imaging and clinical signs that mean MACI is abandoned in favour of a different cartilage procedure - or, honestly, none at all.

  • Symptomatic focal chondral defect, 2 to 10 cm squared

    Medial or lateral femoral condyle, trochlea or patella. Skeletally mature, 18 to 55 years, with a clear mechanical story.

  • Osteochondral defect on the talus

    Ankle MACI for symptomatic osteochondral lesions of the talar dome - often with a small malleolar osteotomy for access.

  • Failed microfracture

    A previous bone-marrow-stimulation procedure that has not settled symptoms - MACI is the standard second-line option.

  • Osteochondritis dissecans (OCD)

    A stable meniscus, stable ligaments and a repairable OCD fragment - or a defect after loose-body removal.

  • Osteochondral defect deeper than 6 mm

    Sandwich technique - bone graft to restore the subchondral plate, then a MACI membrane over the top.

  • Kissing lesions or bipolar defects

    MACI is not indicated for opposing (bipolar) grade IV lesions - these behave like early OA and belong on a different pathway.

  • Malalignment or maltracking

    Varus for medial defects, valgus for lateral, patella maltracking - correction with HTO, DFO or TTT is done at the same sitting or before.

  • Red flag: established osteoarthritis

    Kellgren-Lawrence grade 3 or 4, joint-space narrowing on standing X-ray or diffuse bipolar wear - MACI will fail. Different conversation.

Procedure options

MACI sits in a family - microfracture, mosaicplasty and allograft.

What each option on the table actually involves - and which fits which defect. Size, depth, alignment and previous surgery all shape the honest answer.

  • Microfracture (BMS)

    Bone-marrow stimulation for small defects under 2 cm squared. Fibrocartilage repair - cheap and quick but durability drops off at five to ten years.

  • DeNovo NT particulated juvenile allograft

    Off-the-shelf paediatric cartilage cells for small to medium defects. Single-stage, no biopsy - useful when MACI is not funded.

  • Mosaicplasty / OATS

    Autologous osteochondral plugs from a non-load-bearing area, transferred into the defect. Best for 2 to 4 cm squared defects with a bony component.

  • MACI (matrix-associated ACI)

    The workhorse for medium and large chondral defects, 2 to 10 cm squared. Two-stage, hyaline-like repair, superior five to ten year durability vs microfracture.

  • Fresh osteochondral allograft

    A size-matched donor osteochondral plug for large (over 4 cm squared) or deep osteochondral defects. Single-stage but donor availability is the bottleneck.

  • Sandwich MACI

    Bone graft to restore subchondral bone, then a MACI membrane on top. For osteochondral defects deeper than 6 mm.

  • Realignment osteotomy (HTO / DFO / TTT)

    High tibial, distal femoral or tibial tubercle osteotomy - offloads the compartment carrying the graft. Unaddressed malalignment causes graft failure.

  • Second-opinion review

    A specialist review of your MRI, arthroscopy images and standing X-rays - sometimes the honest answer is rehabilitation, not surgery.

Safety and recovery

What to expect afterwards - honestly.

MACI is a well-established cartilage procedure. The things worth planning are your anaesthetic, the six-week non-weight-bearing window, the physiotherapy schedule, and the twelve to eighteen months back to sport.

  • Regional or general anaesthetic

    Stage 1 arthroscopy under a short general. Stage 2 implantation typically under general anaesthetic with a femoral or adductor-canal block for post-operative comfort.

  • Graft hypertrophy (5 to 15%)

    Overgrowth of the repair tissue, most often at the patella. Usually managed with a short arthroscopic trim - sometimes symptomless and left alone.

  • Delamination (3 to 8%)

    The membrane lifts off the subchondral bone, usually in the first year. Often a rehabilitation-adherence issue. Revision options are considered.

  • Revision rate at ten years

    Five to fifteen percent - either arthroscopic debridement of scar tissue, revision MACI or conversion to osteochondral allograft.

  • Arthrofibrosis and stiffness

    Scar tissue restricting motion. CPM from day one, early physiotherapy and manipulation under anaesthetic in a small number of cases.

  • DVT and PE

    Standard risks for lower-limb surgery. Chemical and mechanical prophylaxis on the ward, extended prophylaxis on discharge in selected patients.

  • Superficial infection

    Uncommon at under two percent. Deep infection is rare but graft-threatening - a low threshold for review is worth having.

  • Rehabilitation is the operation

    Non-weight-bearing six weeks, full weight-bearing by twelve, running at six to nine months, sport at twelve to eighteen. Skipping the protocol is the commonest cause of failure.

  • Red flags after discharge

    A hot, swollen, painful knee with fever, calf swelling, chest pain or breathlessness - call the unit or go to A&E the same day.

Reading your operation note

Your MACI note in four parts. Read the last one first.

Whichever technique was used, the note the surgeon sends you keeps to the same shape.

A UK orthopaedic surgeon reviewing a MACI operation note

A quiet reminder

Orthopaedic language is precise and can read coldly - ask your care team to explain anything that is unclear.

Ask your care team to explain anything that is unclear.

  1. 01 Header

    Defect site, size and depth

    Where the lesion sits (medial or lateral femoral condyle, trochlea, patella, talus), its area in cm squared, and whether it is chondral or osteochondral.

  2. 02 Technique

    Membrane, glue and closure

    Stage 1 biopsy site, Stage 2 approach, defect preparation to a vertical stable rim, MACI membrane cut to size, sealed with fibrin glue.

  3. 03 Findings

    Concurrent procedures

    Meniscal repair, ACL reconstruction, HTO / DFO / TTT realignment - these are recorded separately as they change the rehab timeline.

  4. 04 Impression

    Rehabilitation and follow-up plan

    Read this first: the weight-bearing timetable, the physiotherapy referral, and MRI review at six and twelve months.

Recognised by major UK insurers

BupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealix

Cover for MACI varies by insurer - often funded when the NICE TA477 criteria are met.

Frequently asked

Everything we get asked about MACI.

Quick answers on eligibility, cost, alternatives, alignment surgery and published outcomes.

  • What is MACI cartilage repair?

    MACI (Matrix-Associated Chondrocyte Implantation) is a two-stage procedure. At Stage 1 a small arthroscopic biopsy of about 200 mg of healthy cartilage is taken from a non-load-bearing part of your knee. Those cells are cultured for four to six weeks at the Vericel laboratory in Massachusetts and seeded onto a porcine Chondro-Gide collagen scaffold. At Stage 2 a mini-open arthrotomy is performed, the defect is prepared to a vertical stable rim and the MACI membrane is cut to size and sealed in place with fibrin glue. It is NICE-approved (TA477) for symptomatic focal defects.

  • Who is a good candidate for MACI?

    The NICE TA477 criteria are: skeletally mature, 18 to 55 years old, a symptomatic focal chondral or osteochondral defect of 2 to 10 cm squared in the knee, intact menisci and stable ligaments, normal mechanical alignment (or malalignment corrected at the same operation), and no established osteoarthritis beyond Kellgren-Lawrence grade 2. Bipolar (kissing) lesions and diffuse wear are not suitable.

  • How much does MACI cost privately in the UK?

    All-inclusive MACI of the knee is £22,000 to £38,000 across UK units, covering both stages, the implant, the anaesthetic, the hospital stay and initial physiotherapy. The implant alone lists at around £14,500. Ankle MACI is £24,000 to £40,000. Adding a realignment osteotomy at the same sitting adds £4,500 to £8,500. Mosaicplasty is £14,000 to £22,000, fresh osteochondral allograft £22,000 to £38,000, and microfracture alone £6,500 to £10,500.

  • What are the alternatives to MACI?

    For small defects under 2 cm squared, microfracture or DeNovo NT particulated juvenile allograft. For 2 to 4 cm squared, mosaicplasty (OATS) or osteochondral allograft are reasonable. For larger defects of 4 to 10 cm squared, MACI or a fresh size-matched osteochondral allograft. For osteochondral defects deeper than 6 mm, a sandwich technique using bone graft plus a MACI membrane is standard.

  • Why is alignment so critical?

    A cartilage graft in an overloaded compartment fails - it is a mechanical problem, not a biological one. Varus alignment loading a medial defect calls for a high tibial osteotomy (HTO). Valgus loading a lateral defect calls for a distal femoral osteotomy (DFO). Patella maltracking calls for a tibial tubercle transfer (TTT). Unaddressed malalignment is the commonest reason MACI does not work.

  • What are the published outcomes for MACI?

    The MACI SUMMIT five-year data show 80% or more good to excellent results, with major improvement in KOOS pain and function scores compared with baseline, and superior durability versus microfracture at five to ten years. Revision rates at ten years are five to fifteen percent, most commonly for graft hypertrophy or arthrofibrosis rather than outright graft failure.

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