UK Exclusive · ICRS Teaching Centre of Excellence
Single-stage cartilage regeneration that rebuilds your own joint surface — in one operation, for any joint.
STACi rebuilds worn or damaged cartilage using your own cells, grown on a three-dimensional scaffold and placed into the joint in a single operation. It is the next-generation evolution of the original cartilage cell therapies, ACi and MACi — able to treat larger and deeper damage, across the knee, hip, shoulder, ankle and beyond, and it is the only procedure of its kind offered in the UK. It exists for one kind of patient above all: the person who has been told a joint replacement is coming, but who is too young or too active to accept one yet.
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STACi is a single-stage cartilage regeneration operation that uses your own cartilage cells on a 3D scaffold to rebuild damaged joint surface. It treats larger defects than older ACi and MACi techniques, works in any joint, and is available only at London Cartilage Clinic in the UK. It costs from £28,000, all-inclusive, and is designed to help you keep your own joint instead of replacing it.
Cartilage is the smooth, slippery surface that lets a joint glide. Once it is worn or torn, it does not heal on its own — and left alone, a small area of damage tends to spread until the only option offered is to replace the joint. For decades the choices in between were limited. Microfracture (drilling tiny holes in the bone) works for small areas but grows a weaker scar-tissue version of cartilage. Grafting techniques like OATS are capped by how much healthy donor tissue the same joint can spare. The original cell therapies, ACi and MACi, were a real advance — but they were largely confined to the knee, needed two separate operations, and struggled with larger or more complex damage.
STACi fills the gap between the simpler cartilage procedures and joint replacement. For an active patient with significant cartilage loss who wants to keep their own joint, it offers a biological answer where the older techniques run out of road.
Regrowing cartilage is a bit like growing a garden. You cannot just drop seeds on bad ground and hope. Professor Lee plans every STACi around five things the new tissue needs to take hold and last. It is the reason STACi is assessed and tailored to you, rather than sold as a one-size procedure.
Your own cartilage cells (chondrocytes) — the living material that becomes new cartilage.
The 3D scaffold the cells sit in, giving them a structure to grow through, in depth as well as across the surface.
Your own biological boosters (PRF, mFat or BMAC where indicated) that feed the cells and encourage them to build tissue.
A stable, well-prepared joint — the right alignment, a clean defect rim, no ongoing instability — so the graft is not fighting the joint around it.
A staged rehabilitation programme that loads the joint at the right pace, because controlled movement is what tells new cartilage to mature.
Older techniques largely delivered the seed and hoped for the best. STACi is built to get all five right in one plan — which is why it can take on the damage that turned other procedures away.
The original ACi and MACi procedures are two operations several weeks apart. In the first, a surgeon takes a small sample of your cartilage cells. Those cells are sent to a laboratory and grown for four to six weeks. Only then, at a second operation, are they put back into the joint. STACi can compress that into a single operative session: the laboratory step is brought into the theatre. Your cells are harvested and processed while the surgeon prepares the damaged area, then implanted on the scaffold in the same sitting — no second surgery, no weeks of waiting, one recovery instead of two.
ACi and MACi: two operations
Op 1: biopsy
cells taken
Op 2: implant
cells placed
STACi: one operation
One session: harvest, process, implant
the laboratory step is brought into theatre, so there is no second surgery and no wait
Whether STACi is done as a single stage or, in some cases, two, is a clinical decision made for your specific defect — not a fixed rule. Professor Lee confirms the approach after reviewing your imaging.
Being turned down for the older ACi or MACi because a defect was “too big” does not mean STACi is out of reach — it is precisely the situation STACi was designed for. The only way to know is an imaging review.
Recovery is deliberately staged to protect regenerating tissue. Loading the joint too hard too soon is the enemy of new cartilage; patience is part of the treatment.
Day-case or short stay. The scaffold and, where indicated, your own biological augmentation are placed in one session (2.5–4 hours). A brace may be fitted.
Rest to let swelling settle and the graft bed in. Gentle, passive range-of-motion often starts early. Protected weight-bearing with crutches.
Brace and crutches while the implant integrates. Two follow-up reviews with the team. A direct line to the surgical team for any concern.
Progressive return to function with your physiotherapist. Weight-bearing advances as the tissue strengthens.
Return to low-impact activity for most patients. New cartilage continues to mature within the scaffold.
Return to higher-impact sport, confirmed at the twelve-month review — depending on the size and location of the defect.
For the full week-by-week detail, see the STACi recovery timeline.
Expected Outcomes
STACi is a regeneration procedure, not a quick painkiller. The goal is a durable, living cartilage surface — not temporary symptom relief. Evidence for single-stage, scaffold-based cartilage cell therapy of this class (including the INSTRUCT-generation single-stage trials) reports meaningful, lasting improvement in pain and function, formation of hyaline-like cartilage in most patients, good defect fill and integration on MRI, and a safety profile comparable to or better than other cartilage treatments.
Your individual result depends on the size, depth and location of the damage, the surrounding cartilage, and how closely the rehabilitation is followed. We tell you, in writing at consultation, what to expect for your specific defect — and every outcome feeds our ICRS-aligned cartilage regeneration database.
| What to compare | Microfracture | OATS | ACi | MACi | STACi |
|---|---|---|---|---|---|
| What it does | Drills bone to bleed | Moves plugs of your own cartilage | Cells under a shin-tissue flap | Cells on a flat 2D sheet | Cells on a 3D scaffold |
| Tissue quality | Scar-type (fibrocartilage) | Real cartilage, limited supply | Hyaline-like | Hyaline-like | Hyaline-like, in depth |
| Defect size it suits | Small (<2 cm²) | Small–moderate | Up to ~4 cm² | Up to ~4 cm² | Larger & complex defects |
| Operations | One | One | Two | Two | One in most cases |
| Extra tissue harvested | No | Yes (donor plugs) | Yes (shin periosteum) | No | No |
| Joints | Any | Mainly knee/ankle | Mainly knee | Mainly knee | Any joint |
| UK availability | Widely | Specialist centres | Few specialist centres | Branded product withdrawn* | LCC only |
*The branded MACi product’s European authorisation was suspended in 2014; it is now a US product, licensed for the knee only. The matrix-induced ACi procedure it is named after is still performed at some UK specialist centres. See the MACi page.
The pattern across the row is consistent: STACi keeps the strengths of the earlier cell therapies — your own cells, real cartilage regeneration — and removes their limits on defect size, joint and number of operations.
Single-stage scaffold-based cartilage implantation is performed only at LCC in the UK. Patients travel from across the country and internationally for it.
Recognised by the International Cartilage Regeneration & Joint Preservation Society. Cartilage regeneration is the clinic’s principal interest, with one of the largest published outcome databases in Europe.
Consultation, surgery and every follow-up are with Professor Lee — no hand-off to a registrar.
Professor Paul Lee holds a PhD in medical engineering and has authored 80+ peer-reviewed publications cited 1,000+ times. He developed single-stage cartilage implantation within LCC’s regeneration programme.
Pricing
£28,000 all-inclusive at London Cartilage Clinic. Single-stage cartilage implantation at an ICRS Teaching Centre of Excellence. Theatre, scaffold, biological augmentation, consultant anaesthetist and 12-month follow-up included.
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.
This treatment can be applied across multiple joints. Select yours to see the full range of options we offer, organised by clinical approach.
Explore All Treatment Options
STACi stands for Scaffold-based Tissue-engineered Autologous Chondrocyte implantation. It is the next-generation evolution of the original ACi (autologous chondrocyte implantation) technique — using a three-dimensional scaffold to support cartilage cell growth over larger and deeper areas of damage.
ACi seals cartilage cells under a flap of shin tissue; MACi improved on this with a flat collagen sheet. STACi places the cells inside a three-dimensional scaffold that supports growth in depth as well as across the surface — closer to how natural cartilage is built. It can treat larger, more complex defects, works across any joint, needs no shin-tissue harvest, and can be done in a single operation.
Any joint where cartilage is damaged — knee, hip, shoulder, ankle, elbow, foot, hand or wrist. The knee is most common because focal cartilage damage happens there most often. The right approach for your joint is confirmed at consultation.
Patients with significant focal cartilage loss — often larger than 2–4 cm² — who are too young or too active for a joint replacement, and who want to preserve their own joint. It is particularly relevant when a defect is too large for OATS or microfracture.
In most cases, one. STACi brings the laboratory step into the theatre, so cells are harvested, processed and implanted in a single session — removing the weeks-long wait that ACi and MACi require. In some cases a two-stage approach is used; this is decided for your specific defect.
STACi is £28,000 at London Cartilage Clinic, all-inclusive of theatre, the scaffold, your biological augmentation, the consultant anaesthetist, the surgeon’s fee and a 12-month follow-up programme. See the STACi cost guide. The final cost is confirmed after assessment.
No. STACi is a private, UK-exclusive procedure and is not routinely available on the NHS or through UK insurers. We can provide an itemised invoice if you wish to submit a claim independently.
Recovery is staged to protect the new cartilage: protected weight-bearing with crutches for six to eight weeks, early range-of-motion with physiotherapy, return to low-impact activity from four to six months, and higher-impact sport from nine to twelve months depending on the defect. See the full recovery timeline.
It requires specialist surgical expertise, tissue-engineering facilities and a specific regulatory framework. Professor Lee and the LCC team developed the protocols and infrastructure to deliver it, making LCC the only UK centre currently performing STACi.
Still have more specific concerns?
Free Discovery CallIf you want to talk it through first, the discovery call is free and takes fifteen minutes. If you have decided you want to be assessed, book a consultation with the surgeon who will perform the procedure — and read exactly what’s included in the price first.
London Cartilage Clinic
Clinical updates, cartilage treatment guidance, and recovery-focused articles from our specialist team.
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Damaged hip cartilage cannot heal naturally, but ChondroFiller, an injectable collagen scaffold, now enables the patient's own cells to repair the damaged tissue in an outpatient setting, offering an alternative to surgery.
