Injection or keyhole surgery
Both use Seed, Soil and Signal. STACi adds surgical Structure when defect preparation or joint mechanics must be addressed before the biology is placed.
Reviewed byProfessor Paul Lee MBBch, FRCS (Tr & Orth), PhDCartilage and joint preservation expertiseNanoACi is the non-arthroscopic Seed, Soil and Signal pathway for a structurally suitable joint. STACi adds Structure because the damage pattern or mechanics require surgery first. That may mean defect preparation, alignment correction, stabilisation or treatment of associated mechanical damage before the same regenerative logic is applied.
The dividing line is not a preference for injections or surgery. It is whether the joint already provides a mechanically credible environment for repair, or whether surgery is needed to create one.
| What to compare | STACi (surgery) | NanoACi (injection) |
|---|---|---|
| How it is delivered | Keyhole day-case surgery, single-stage, under general anaesthetic | A single injection in clinic, under local anaesthetic, in around thirty minutes |
| The biology | Structure first, then patient-derived cartilage Seed, a collagen Soil and platelet-rich fibrin Signal | Your own cartilage cells, a ChondroFiller scaffold and PRF, delivered together by injection |
| Where it happens | Operating theatre, as a day case | Outpatient clinic, no theatre stay |
| Best suited to | Cartilage damage where defect preparation or correction of relevant joint mechanics requires surgery | Cartilage damage where the joint structure is suitable for a non-arthroscopic pathway |
| Alignment correction | Alignment or stability work is included when imaging shows it is required | Does not correct malalignment or instability; structural suitability is assessed before treatment |
| Recovery | Staged rehabilitation over months, with protected weight-bearing | Much lighter; most people are back to light activity the same day |
| Bone-on-bone wear | Widespread end-stage disease may be beyond joint preservation even with structural work | Not decided from the phrase alone; the full pattern and mechanics must be reviewed |
| Core distinction | Surgery is required to create the mechanical environment for repair | The joint can support biological delivery without arthroscopic surgery |
| Also known as | Liquid Cartilage Surgery (LCS) | Injectable cartilage regeneration |
| Available at London Cartilage Clinic | Yes, from £12,500 | Yes, £8,000, or £8,500 all-inclusive |
Both procedures are offered at London Cartilage Clinic; this is a genuine choice about your joint, not a takedown of either.
These are not two products competing for the same patient. NanoACi uses the cartilage Seed, Soil and Signal architecture without arthroscopy. STACi adds Structure, using surgery to create a stable, prepared mechanical environment before the biology is applied. Because Professor Lee offers both, the consultation can start with the scan and the joint rather than working backwards from a preferred treatment name.
STACi is an operative pathway in which Structure is dealt with first—defect preparation and any indicated correction of alignment, stability or associated damage—before Seed, Soil and Signal are placed. NanoACi uses the three biological components without arthroscopy when imaging shows the joint does not need that structural surgery.
Liquid Cartilage Surgery is an earlier description of the single-stage cartilage component. STACi now describes the wider surgical RegenRepair™ plan: Structure, Seed, Soil and Signal. See the full STACi page.
Not necessarily, but it is not evidence by itself that NanoACi or STACi is suitable. The distribution of damage, bone change, alignment, stability and realistic joint-preservation potential all matter. Some joints need a surgical Structure plan; some can use a non-arthroscopic pathway; widespread end-stage disease may call for a different option.
NanoACi is £8,000, or £8,500 all-inclusive, which covers an MRI scan, your consultation, the session and a follow-up. STACi, as a surgical procedure, is from £12,500, all-inclusive. The two prices reflect an outpatient injection versus a day-case operation. See the NanoACi cost page.
Still have more specific concerns?
Free Discovery CallOptions that our doctors may discuss include NanoACi, ChondroFiller, Mytocel MSK, joint replacement, established conservative care or surgery, depending on examination and imaging.
Because both lanes are offered here, the fairest next step is a review of your imaging. Start with a free discovery call, or book your MRI and consultation together so Professor Lee can advise which fits your joint.
London Cartilage Clinic
Clinical updates, cartilage treatment guidance, and recovery-focused articles from our specialist team.
Cartilage MRI reports describe anatomy but rarely include measured lesion area—the figure most determining treatment strategy. Defects below 2–4 cm² are typically managed with bone-marrow stimulation or cartilage grafting; larger injuries favour cell-based implantation.
Inside-knee pain without swelling signals early cartilage damage that progressively widens through ordinary walking unless treated — marking a closing intervention window. ChondroFiller, a collagen scaffold injected under ultrasound, protects the defect and recruits the body's own repair cells.
ChondroFiller injection, an injectable collagen scaffold that recruits progenitor cells to form cartilage-like tissue, delivers functional gains of approximately 30 IKDC points in advanced knee osteoarthritis — meaningful improvement that defers rather than cancels joint replacement.
