When cartilage damage outgrows other repair options

Being told that a donor graft may be needed tends to prompt a specific worry: that the cartilage damage is somehow beyond repair. In practice, it signals something more precise — that the area of damage has grown beyond the footprint that other restorative options can reliably fill.

Cartilage surgery broadly follows a size-stratified logic. Smaller, contained lesions — roughly under 2 cm² — can often be addressed using the patient's own tissue or marrow stimulation techniques. Once a defect climbs past that threshold, those approaches run short: autograft donor sites are limited in what they can yield, and marrow-stimulation techniques tend to produce fibrocartilage rather than the durable hyaline cartilage that load-bearing surfaces need. Cell-based procedures such as MACI or ACI extend the viable range further, suited to defects in the 2–10 cm² bracket.

At the upper end of that scale — and for any defect where no other technique can supply enough healthy hyaline cartilage — a fresh osteochondral allograft becomes the biologically appropriate choice. OCA sits at the top of this hierarchy not as a fallback when everything else has failed, but as the tool that makes true cartilage restoration possible when the scale of damage exceeds what the patient's own body can provide.

What a fresh osteochondral allograft is

An osteochondral allograft is, at its most basic, a composite piece of tissue: the surface layer of hyaline cartilage bonded to the subchondral bone beneath it, taken together as a single biological unit from a deceased donor. Donor tissue is carefully size-matched to the patient's anatomy before implantation — a step guided by pre-operative MRI measurement and tissue-bank co-ordination.

The word 'fresh' in the name is a clinical specification, not a marketing term. Chondrocytes — the living cells responsible for maintaining cartilage integrity — begin to decline in viability soon after procurement. By day 28 post-procurement, viable cell counts typically fall below the accepted 70% threshold. A graft that has crossed that window contains cells that can no longer sustain the tissue once transplanted. Cryopreservation and freeze-drying are not workable alternatives, as both processes damage chondrocytes in sufficient numbers to compromise graft function.

That 28-day window carries a direct practical consequence: surgery must be coordinated with donor procurement within weeks, not months. This restricts OCA to specialist centres with reliable access to a regulated tissue bank, since the logistical chain — from donor harvest through regulatory compliance to theatre — must close in a matter of days. Once implanted, the bone component of the graft integrates progressively with the patient's own subchondral bone, in a process analogous to fracture healing, while the cartilage surface begins serving its load-bearing role immediately.

Extended-storage protocols designed to widen this window are under investigation but are not yet in routine clinical use.

Who typically needs this procedure

Several distinct patient groups reach OCA, though they share a common feature: a defect large enough, or structurally complex enough, that autograft or cell-based approaches cannot adequately address it.

The most common presentation is a large post-traumatic osteochondral defect — an injury that has disrupted both the cartilage surface and the bone immediately beneath it. High-energy impacts, twisting injuries, and patellar dislocations can all produce this pattern, and the combined depth of damage is what places these cases outside the reach of surface-only repair techniques.

Osteochondritis dissecans (OCD) accounts for another significant subgroup: patients in whom a segment of subchondral bone has separated or partially detached, and in whom conservative management or an earlier surgical attempt has not achieved stable healing. The lesion's biological failure to consolidate is the clinical driver, not any single age group.

Avascular necrosis (AVN) — including steroid-induced AVN in patients treated with high-dose corticosteroids for autoimmune disease or malignancy — presents a structurally similar problem. Bone death progresses from below, eventually undermining the overlying cartilage and causing surface collapse that cannot be rebuilt without replacing the affected bone-cartilage unit entirely.

Finally, some patients present following failed prior cartilage surgery, most commonly microfracture. Microfracture was historically first-line for smaller defects, but it carries recognised long-term limitations including fibrocartilage breakdown and, in some cases, changes to the subchondral bone plate that complicate subsequent repair. OCA is the appropriate reconstructive step for these cases — not a reflection of patient failure, but a response to the biology of the original procedure.

The knee — particularly the femoral condyle — is the most common and best-evidenced treatment site. OCA is also performed in the ankle, hip, shoulder, and elbow where donor tissue can be appropriately sized and surgical experience supports it.

What the operation involves

Choosing between the two graft constructs is one of the first decisions made at the planning stage, and it depends almost entirely on the shape of the defect.

For contained condylar lesions — roughly circular defects on the femoral condyle measuring between 15 and 35 mm across — a cylindrical press-fit plug is the standard choice. The circular core is cut to match defect depth and diameter, then seated firmly into a prepared recipient socket. In most condylar cases, the interference fit itself provides mechanical stability; supplemental screws or pins are not routinely required.

When the defect is ovoid, involves the posterior condyle, or extends across the tibial plateau, a shell allograft is used instead. This is a custom-shaped section of donor tissue, contoured to match the anatomy of the target area rather than a standard circular footprint. Larger or geometrically complex shell constructs may require internal fixation to hold position during the early healing phase.

Pre-operative MRI — including advanced quantitative sequences where the defect depth or bone quality warrants closer characterisation — is used to measure the lesion precisely and guide donor tissue sizing from the tissue bank. This is open surgery rather than keyhole: theatre time is approximately two to three hours, giving the surgeon direct access to seat and verify the graft under full visualisation.

Recovery, survivorship, and what the evidence shows

The first month after surgery is the most demanding: patients remain on touch-down weight bearing for four to six weeks while the graft begins to integrate, with early physiotherapy focused on reducing swelling and recovering range of motion rather than loading the joint.

Taken together, the survivorship data suggest that OCA can provide durable joint preservation — not indefinite, but measurable in years to decades for appropriately selected patients. In condylar OCA series, Kaplan-Meier analysis shows approximately 82.6% graft survival at five years and 69.6% at ten years. A separate long-term cohort — in which 44 of 65 grafts remained in situ and functioning at a mean follow-up of 12.9 years — reported 95% survivorship; the difference between these figures most likely reflects variation in patient selection and surgical era across different study populations rather than any contradiction in the underlying biology. For patellofemoral OCA, published series report approximately 87.9% survival at five years and 77.2% at ten years, with mean IKDC scores rising from roughly 41.8 before surgery to 68.1 at follow-up.

Functional outcomes follow a similar pattern. In a cohort of 149 knees followed for a mean of six years (with some cases tracked to 15.8 years), 75.2% of patients returned to sport or recreational activity; 71% rated their knee function as very good to excellent, and 79% could participate in high-level activity. Roughly 45% of that cohort were highly competitive athletes before injury, which gives those percentages meaningful context.

Most outcome data comes from specialist-centre registries rather than randomised trials, so direct head-to-head comparisons with ACI or MACI remain limited; published follow-up beyond fifteen years is also thinner for patellofemoral and tibial plateau sites than for the femoral condyle.

Getting assessed for OCA in London

Few NHS or private hospitals carry the tissue-bank relationships and surgical volume needed to manage the procurement logistics that OCA demands; the narrow viability window means only centres with established donor-tissue pathways can reliably schedule the procedure.

Assessment begins with standard MRI to characterise defect size and depth, supplemented where necessary by quantitative sequences to clarify subchondral involvement. That imaging, alongside clinical examination and a review of any prior cartilage surgery, gives the specialist the information needed to determine whether OCA is the most appropriate option or whether a different restorative approach better fits the defect.

London Cartilage Clinic, at 66 Harley Street, offers OCA assessment and surgery across the knee, ankle, hip, and other joints. Professor Paul Lee — whose centre holds ICRS Teaching Centre of Excellence status — leads the programme. All-in pricing is £28,000, covering donor tissue, regulatory compliance, theatre, anaesthetist fees, and a twelve-month follow-up programme; the figure reflects the genuine cost of sourcing and implanting human tissue under UK Human Tissue Authority regulations.

For patients who have reached this decision point, the more important question is rarely whether the damage can be addressed — the published evidence suggests it usually can, in the right hands — but whether a specialist with the right infrastructure is available. To arrange an assessment, visit londoncartilage.com.