Mid-term outcome of arthroscopic AMIC for the treatment of articular cartilage defects in the knee joint is equivalent to mini-open procedures

Introduction: We present the first retrospective study that compares two various autologous matrix-induced chondrogenesis (AMIC) surgical interventions to repair grade III–IV cartilage defects in the knee. Patients who underwent minimally invasive (arthroscopy) or open (mini-arthrotomy) AMIC were followed up to 2 years to investigate if minimally invasive AMIC is superior to open procedures. Materials and methods: Overall n = 50 patients with focal and contained grade III–IV articular cartilage defects in the knee joint were followed in a consecutive cohort study. 20 patients were treated arthroscopically (female 7, male 13; age: mean 38.2 years, range 18–70 years; BMI: mean 27.0, range 18.7–34.7; defect size: mean 3.1 cm, range 1.0–6.0 cm), and 30 patients via mini-arthrotomy (female 13, male 17; age: mean 34.4 years, range 14–53 years, BMI: mean 23.9, range 18.4–28.7; defect size: mean 3.4 cm, range 1.5–12.0 cm). The primary defect localization was the medial femoral condyle. Results: AMIC led to a significant improvement of VAS pain, KOOS and Lysholm scoring for up to 2 years compared to pre-op. Outcome analysis revealed no significant differences between the two different surgical approaches. Conclusions: Our results suggest that mini-open AMIC is equivalent to the arthroscopic procedure. The anticipatory hypothesis that minimally invasive approaches bring greater patient benefit per se could not be confirmed. Therefore, we recommend to perform AMIC where indicated and suggest that the surgeon’s personal skills profile guide the choice of surgical approach. Level of evidence: III.