Evidence-based status of second- and third-generation autologous chondrocyte implantation over first generation: a systematic review of level I and II studies

Purpose: The purpose of this study was to examine the Level I and II evidence for newer generations of autologous chondrocyte implantation (ACI) versus first-generation ACI and to establish whether the newer generations have overcome the limitations associated with first-generation ACI.

Methods: A literature search was carried out for Level I and II evidence studies on cartilage repair using the PubMed database. All the studies that dealt with ACI were identified. Only Level I and II studies that compared newer generations against earlier generations were selected, whereas studies that compared ACI against other methods of cartilage repair were excluded.

Results: A total of 7 studies matched the selection criteria. Two studies compared periosteum-based autologous chondrocyte implantation (P-ACI) against collagen membrane-based autologous chondrocyte implantation (C-ACI), whereas one study each compared membrane-associated autologous chondrocyte implantation (MACI) against P-ACI and C-ACI. One study on C-ACI compared results related to age, whereas 2 studies evaluated postoperative rehabilitation after MACI. There was weak evidence showing that C-ACI is better than P-ACI and that MACI is comparable with both P-ACI and C-ACI. The weak evidence is because of studies with short durations of follow-up, small numbers of patients, medium-sized defects, and younger age groups. There is good evidence favoring an accelerated weight-bearing regimen after MACI. There is currently no evidence that supports scaffold-based ACI or arthroscopic implantation over first-generation ACI.

Conclusions: The hypothesis is thus partly proved in favor of C-ACI/MACI against P-ACI with weak evidence, in favor of accelerated weight bearing after MACI with strong evidence, and not in favor of arthroscopic and scaffold-based implantations because of unavailable evidence. LEVEL OF EVIDENCE: Level II, systematic review of Level I and II studies.