What makes a patient suitable for NanoACi

Suitability is never a single answer

For many people, the question arrives quietly, somewhere between a course of physiotherapy and a conversation about joint replacement: is there anything left that doesn't involve a major operation? It is a reasonable question, and the answer depends on far more than a single scan result or a symptom score.

Professor Paul Lee's NanoACi™ — a surgeon-led, non-arthroscopic, needle-delivered, one-stage autologous chondrogenic injection technique — exists precisely in that space. It is designed for patients whose joint still has something worth protecting, and for whom the right biological conditions align with the right clinical picture. But whether those conditions align for any individual patient is a specialist determination, not a self-assessment.

Suitability is shaped by several interacting clinical variables: the pattern and extent of cartilage damage, the accuracy of the underlying diagnosis, the quality and recency of imaging, the alignment of the joint, its structural stability, the character of symptoms, and the patient's own treatment goals. Each of those dimensions is examined before a pathway is confirmed. The sections that follow address each one in turn.

Joint condition and the cartilage damage pattern

Cartilage has no blood supply and no nerves — when it is damaged, there is no bleeding to start a healing response and no pain signal to alert the joint early. Chondrocytes, the cells responsible for maintaining cartilage, are locked inside a dense matrix and cannot travel to an injured area. This biological limitation is why diagnosis must be precise and delivery must be targeted: the joint has no intrinsic mechanism to do the work on its own.

NanoACi sits in a specific part of the treatment pathway — past the point where conventional focal repair tools remain viable, and before joint replacement becomes necessary or accepted. The archetypal candidates are patients with focal chondral damage or chondromalacia, and those with more advanced wear who are not yet ready, or not yet willing, to exchange the joint they were born with.

Where the picture changes is at diffuse osteoarthritis. When cartilage loss is widespread and no healthy margins remain around the damaged area, the biological rationale shifts: NanoACi requires some surviving tissue architecture to build upon, in the same way that a road repair needs sound edges to work against. Diffuse disease without those margins limits what the technique can offer.

The degree of wear also shapes which components are appropriate. For earlier or less extensive damage, a single element — Mytocel MSK, a collagen scaffold that provides a physical structure for tissue repair — may be the right first step. The full NanoACi protocol adds autologous ear cartilage micrografts (the cell source, taken from a small sample of the patient's own ear) and platelet-rich fibrin (a concentrated preparation of the patient's own growth factors) to meet the fuller biological challenge of more advanced cartilage loss.

Why imaging comes before every other decision

Before any pathway is confirmed, a recent MRI is required — if a patient does not have one from the last six months, the clinic arranges the scan first. This is the starting point, not a formality.

What specialist imaging reveals goes well beyond what symptom history can establish. Pain and functional loss indicate that something is wrong; they cannot reliably map the exact defect site, characterise the quality of the cartilage margins surrounding it, assess the condition of the subchondral bone beneath, or show whether the broader joint environment is sound enough to support a biological approach. Cartilage's avascular, aneural character — covered in the previous section — means that diagnostic lag is often significant: damage can be well advanced by the time a patient notices it consistently. Imaging closes that gap.

Professor Lee reviews the MRI personally before confirming suitability. That reading, combined with a clinical examination, determines whether NanoACi is appropriate, which components are indicated, and where precisely delivery should be targeted. Imaging is not presented as proof that the technique will succeed — it is the information needed to decide whether to proceed and how to plan.

It also functions as a procedural map. For most patients who clear the assessment gate, the session can proceed on the same day as the consultation; the scan that established suitability becomes the guide for delivery.

How alignment and joint stability factor in

Alignment and joint stability are not straightforward pass/fail criteria — they are variables that change the role NanoACi plays rather than simply deciding whether it proceeds at all.

If malalignment is directing abnormal load onto the damaged cartilage surface, that mechanical pressure does not disappear because a biological repair has been placed there. A corrective procedure — such as an osteotomy to redistribute weight-bearing forces — may need to come first, or alongside, before a cartilage-focused approach can be expected to hold. Conversely, minor tracking variance may not materially alter the plan; the distinction lies in whether the mechanical environment is hostile enough to undermine repair.

Ligamentous instability works similarly. When joint mechanics are disrupted by insufficient ligament support, the repaired surface faces abnormal shear and rotational forces; resolving that instability may be a prerequisite rather than an optional extra.

The NanoACi suitability assessment routes cases with mechanical problems toward structural repair 'with possible NanoACi support' — which reflects this logic directly. NanoACi may still form part of the pathway, but as an adjunct to structural correction rather than a standalone intervention. Specialist review determines which of those two configurations applies.

Precise published thresholds — acceptable degrees of malalignment, specific instability grades — have not yet been defined for the NanoACi protocol; the NanoACi 100 programme is building the combined-protocol data that will inform these boundaries. Suitability in this dimension currently rests on clinical judgement: the specialist who can read the imaging, conduct the examination, and weigh the patient's goals together.

Symptoms, goals and what the patient is trying to preserve

Symptoms carry more information than their intensity alone suggests. A patient who has worked through physiotherapy, tried load management, and modified activity to accommodate a failing joint is telling the specialist something about timing: the conservative window has likely closed, and biological intervention is being considered at a stage when the joint has not yet deteriorated past the point of return. That trajectory — symptoms persistent despite best conservative care, function declining but the joint not globally worn — describes one of the better-timed starting points for a procedure oriented toward preservation.

Treatment goals shape fit just as directly. NanoACi's design philosophy centres on native joint preservation over the long term — envisioning 'small, spaced, preserving touches over a lifetime, rather than one dramatic intervention.' A patient who wants to protect what the joint can still do, and to delay or avoid replacement, aligns naturally with that intent. A patient whose priority is immediate return to high-impact loading at any cost, or who needs a single definitive structural outcome, may find that a different pathway — ACI/MACI, or where wear is severe, joint replacement — is a fairer match for those aims. Neither is dismissed; they address different situations and different definitions of a good result.

Goals and symptom history are active clinical inputs, weighed alongside imaging findings and mechanical assessment. They are part of why Professor Lee's review of each case is individual rather than protocol-driven.

What the specialist assessment actually involves

The assessment that brings all of these variables together is a single clinical review — not a sequence of independent gates that a patient passes through one at a time. Professor Lee considers the cartilage damage pattern, the joint mechanics around it, and the patient's symptom history and goals as an integrated picture: a finding that looks containable in isolation can read differently once alignment and instability are weighed alongside it, and goals that seem straightforward may shift when imaging tells a more complex story.

For patients who clear the combined imaging and examination review, the transition to treatment is often the same day. Preparation, tissue sampling, combination and delivery all take place at point of care in a single planned sitting — there is no second appointment required once suitability is confirmed.

The same clinical framework applies regardless of which joint is being assessed. NanoACi is used in the knee, hip, shoulder and ankle at the same protocol, so patients presenting with cartilage damage in any of those joints go through the same multi-variable specialist review rather than a joint-specific pathway.

Individual suitability can only be determined through a specialist consultation that reviews imaging alongside the full clinical picture.