1.1 Autologous chondrocyte implantation (ACI) is recommended as an option for treating symptomatic articular cartilage defects of the knee, only if:
the person has not had previous surgery to repair articular cartilage defects
there is minimal osteoarthritic damage to the knee (as assessed by clinicians experienced in investigating knee cartilage damage using a validated measure for knee osteoarthritis)
the defect is over 2 cm2 and
the procedure is done at a tertiary referral centre.
Clinical trial evidence shows that ACI can improve the symptoms of articular cartilage defects of the knee. There is evidence that it is likely to be more successful in people who haven't had any previous knee repair surgery, and in people who have very little osteoarthritic damage in the knee. But, it is unclear how well ACI works in the long term compared with microfracture, the most commonly used alternative treatment.
The consensus among UK clinicians is that ACI is the only effective treatment option for defects that are over 2 cm2 when symptoms persist after non-surgical management.
The most accurate cost-effectiveness estimate for ACI compared with microfracture is uncertain, and is not likely to be under £20,000 per quality-adjusted life year (QALY) gained for everyone who is eligible to have ACI. But the cost-effectiveness estimate is lower in people in whom ACI has a better chance of success. This includes people who haven't had any previous knee repair surgery, and people who have very little osteoarthritic damage in the knee. In these people, the most accurate cost-effectiveness estimate is likely to be under £20,000 per QALY gained.