Matrix-induced autologous mesenchymal stem cell implantation versus matrix-induced autologous chondrocyte implantation in the treatment of chondral defects of the knee: a 2-year randomized study.

Background: Cell-based strategies that combine in vitro- expanded autologous chondrocytes with matrix scaffolds are currently preferred for full-thickness cartilage lesions of the knee ≥2 cm(2). Although this approach is reasonable, continuing advances in the field of cartilage repair will further expand the options available to improve outcomes.

Hypothesis/purpose: In the present clinical study, we compared the outcomes of matrix-induced autologous mesenchymal stem cell implantation (m-AMI) with matrix-induced autologous chondrocyte implantation (m-ACI) for the treatment of isolated chondral defects of the knee.

Study Design: Prospective, single-site, randomized, single-blind pilot study.

Methods: Fourteen patients with isolated full-thickness chondral lesions of the knee >2 cm(2) were randomized into two treatment groups: m-AMI and m-ACI. Outcomes were assessed pre-operatively and 3, 6, 12 and 24 months post-operatively.

Results: Clinical evaluations revealed that improvement from pre-operation to 24 months post-operation occurred in both groups (p < 0.05). At all follow-up intervals, m-AMI demonstrated significantly better functional outcomes (motion deficit and straight leg raise strength) than did m-ACI (p < 0.05). At all follow-up intervals, m-AMI demonstrated significantly better subjective sub-scale scores for pain, symptoms, activities of daily living and sport and recreation of the knee injury and osteoarthritis outcome score (KOOS) than did m-ACI (p < 0.05). Additionally, m-AMI demonstrated significantly better (p < 0.05) scores than m-ACI for the quality of life sub-scale of the KOOS and visual analog scale (VAS) severity at the 6-month follow-up. The Tegner activity score and VAS frequency were not significantly different between the two groups. Graft failure was not observed on magnetic resonance imaging at the 24-month follow-up. m-AMI and m-ACI demonstrated very good-to-excellent and good-to-very good infill, respectively, with no adverse effects from the implant, regardless of the treatment.

Conclusion: For the treatment of isolated full-thickness chondral lesion of the knee, m-AMI can be used effectively and may potentially accelerate recovery. A larger patient cohort and follow-up supported by histological analyses are necessary to determine long-term outcomes.