Autologous Chondrocyte Implantation Versus Microfracture in the Knee: A Meta-analysis and Systematic Review

Purpose: To compare clinical outcomes among patients with fractures of knee cartilage who were treated with autologous chondrocyte implantation (ACI) or microfracture (MF). Methods: A systematic review was made of randomized controlled trials of articular cartilage lesions of the knee treated with ACI or MF that were published between January 2000 and November 2018 and catalogued in 4 major databases. The outcomes of clinical score, quality of life (QoL), pain relief score, and failure rate were assessed. Results: A final group of 12 randomized controlled trials were included that enrolled a total of 659 patients with knee cartilage lesions: 332 patients had received ACI and 327 patients had undergone MF. Patients ranged in age from 25 to 41 years, and the majority were male. Lesion size ranged from 2.3 to 10.0 cm(2). Pooled analysis found no significant difference in the improvement in International Knee Documentation Committee and Lysholm scores or overall Knee Injury and Osteoarthritis Outcome Score measures between patients in the ACI and MF groups at 1-year, 2-year, and 5-year follow-up examinations or in failure rate at 2-year, 3-year, and 5-year follow-up timepoints. However, patients treated with ACI had a significant benefit in activities of daily living at follow-up of 5 years or less compared with patients treated with MF. ACI treatment also showed better improvement in QoL and pain relief than MF at 5-year and 2-year follow-up examinations, respectively. Conclusions: The pooled analysis found no significant difference in the improvement in International Knee Documentation Committee or Lysholm scores or overall Knee Injury and Osteoarthritis Outcome Score measures between patients in the ACI and MF groups at 1 to 5 years of follow-up. Patients treated with ACI may have a significant benefit in activities of daily living, QoL, and pain relief compared with patients treated with MF, although clinical relevance may not be achieved.