Background: Focal chondral defects in the knee lead to swelling, discomfort, and mechanical symptoms, resulting in disability and loss of function. Matrix-induced autologous chondrocyte implantation (MACI) has emerged as a viable treatment option, with satisfactory clinical outcomes reported compared with microfracture. Patient and lesion-specific variables associated with MACI after biopsy remain largely underreported. Purpose: To examine patient- and defect-specific characteristics associated with conversion to MACI after biopsy from a single institution. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective chart review of prospectively collected data from June 2018 to March 2025 was performed. Inclusion criteria included patients ≥15 years of age with an arthroscopically confirmed focal International Cartilage Regeneration 95% CI, 1.70-208.50; P = .017) were independently associated with a greater likelihood of conversion to MACI, while concomitant procedures during biopsy (OR, 0.22; 95% CI, 0.06-0.81; P = .022) were associated with a significantly lower likelihood of implantation. Conclusion: MACI was performed in 28.8% of patients undergoing biopsy for symptomatic chondral lesions. Patients with patellar defects exhibited a significantly higher likelihood of MACI, with increased conversion rates associated with previous ipsilateral knee surgery and/or more advanced chondral defects. Patients undergoing concomitant procedures at biopsy were significantly less likely to require MACI, with lower conversion rates associated with a history of preoperative mechanical symptoms.
Knapik et al. (Sun,) studied this question.