1.1 Autologous chondrocyte implantation (ACI) using chondrosphere is recommended as an option for treating symptomatic articular cartilage defects of the femoral condyle and patella of the knee (International Cartilage Repair Society grade III or IV) in adults, 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) and
the defect is over 2 cm2.
Why the committee made these recommendations
Current surgical treatments for symptomatic articular cartilage defects of the knee include microfracture, ACI and mosaicplasty.
Clinical trial results show that ACI using chondrosphere is as effective in the short term as microfracture, which is the most commonly used surgical option. But it is unclear how well chondrosphere works in the longer term compared with microfracture, because there are little data available beyond 2 years. Chondrosphere has greater benefit in articular cartilage defects larger than 2 cm2.
The most plausible cost-effectiveness estimate for chondrosphere compared with microfracture is £4,360 per quality-adjusted life year (QALY) gained. However, this is likely to be an underestimate because it does not accurately consider the long-term effects of microfracture, which are uncertain. Defects larger than 2 cm2 are often treated by best supportive care. The cost-effectiveness estimate for chondrosphere compared with best supportive care is likely to be lower than £20,000 per QALY gained, for defects larger than 2 cm2.