Background: Since 1987, when (M)ACI was first mentioned, the technique have been used all over the world to treat osteochondral lesions in the knee. Nevertheless, the actual effectiveness of this relatively new treatment option is under question: clinical evidence based on controlled trials and long-term follow-up are still missing. For these reasons (M)ACI is being reimbursed in most countries only under research conditions.

Methods: systematic literature search in Medline via Ovid, Embase, Cochrane Library, NHS-CRD-HTA (INAHTA), ISI WEB of Science, WHO Health Evidence Network and Clinicaltrials.gov was complemented by a hand search. Inclusion criteria: Controlled clinical studies with more than 20 patients and a follow-up period of at least one year.

Results: The effectiveness analysis is based on 9 comparative clinical trials and 6 systematic reviews. Within the studies all together 566 patients were treated with mosaicplasty vs. ACI, microfracture vs. ACI, and ACI vs. ACI. The result show consistency and confirm earlier (international) reviews. There is no evidence that ACI or MACI leads to better outcomes in the treatment of osteochondral lesions than any of the alternative treatments. ACI is not superior; at best equal, at much higher cost. The short term (1-2 years) and mid-term (5 years) non-inferiority in highly selected active patients is proven. Long-term data are lacking.

Conclusion: (M)ACI methods must be considered – though often applied - as experimental techniques. The risks of cultivated chondrocyts cannot be ignored, and have to be seen as a risk.