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Objective. To evaluate minimum biosecurity parameters (MBP) for arthroscopic matrix-encapsulated autologous chondrocyte implantation (AMECI) based on patients’ clinical outcomes, magnetic resonance imaging (MRI) T2-mapping, Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, and International Cartilage Repair Society (ICRS) second-look arthroscopic evaluation, laying the basis for a future multicenter study. Design. Pilot clinical study. We analyzed the logistics to perform AMECI to treat focal chondral lesions in different hospitals following strict biosecurity parameters related to tissue and construct transportation, chondrocyte isolation, and cell expansion. Patient progress was analyzed with patient-reported outcome measures, MRI T2-mapping, MOCART, and ICRS arthroscopic second-look evaluation. Results. Thirty-five lesions in 30 patients treated in 7 different hospitals were evaluated. Cell viability before implantation was >90%. Cell viability in construct remnants was 87% ± 11% at 24 hours, 75% ± 17.1% at 48 hours, and 60% ± 8% at 72 hours after implantation. Mean final follow-up was 37 months (12-72 months). Patients showed statistically significant improvement in all clinical scores and MOCART evaluations. MRI T2-mapping evaluation showed significant decrease in relaxation time from 61.2 ± 14.3 to 42.9 ± 7.2 ms (P< 0.05). Arthroscopic second-look evaluation showed grade II “near normal” tissue in 83% of patients. Two treatment failures were documented. Conclusions. It was feasible to perform AMECI in 7 different institutions in a large metropolitan area following our biosecurity measures without any implant-related complication. Treated patients showed improvement in clinical, MRI T2-mapping, and MOCART scores, as well as a low failure rate and a favorable ICRS arthroscopic evaluation at a mid-term follow-up. Level of Evidence. 2b.

Background Complex meniscal lesions often require meniscectomy with favorable results in the short term but a high risk of early osteoarthritis subsequently. Partial meniscectomy treated with meniscal substitutes may delay articular cartilage degeneration.Purpose To evaluate the status of articular cartilage by T2 mapping after meniscal substitution with polyurethane scaffolds enriched with mesenchymal stem cells (MSC) and comparison with acellular scaffolds at 12 months.Methods Seventeen patients (18-50 years) with past meniscectomies were enrolled in 2 groups: (1) acellular polyurethane scaffold (APS) or (2) polyurethane scaffold enriched with MSC (MPS). Patients in the MPS group received filgrastim to stimulate MSC production, and CD90+ cells were obtained and cultured in the polyurethane scaffold. The scaffolds were implanted arthroscopically into partial meniscus defects. Concomitant injuries (articular cartilage lesions or cartilage lesions) were treated during the same procedure. Changes in the quality of articular cartilage were evaluated with T2 mapping in femur and tibia at 12 months.Results In tibial T2 mapping, values for the MPS group increased slightly at 9 months but returned to initial values at 12 months (P> 0.05). In the APS group, a clear decrease from 3 months to 12 months was observed (P> 0.05). This difference tended to be significantly lower in the APS group compared with the MPS group at the final time point (P= 0.18). In the femur, a slight increase in the MPS group (47.8 ± 3.4) compared with the APS group (45.3 ± 4.9) was observed (P> 0.05).Conclusion Meniscal substitution with polyurethane scaffold maintains normal T2 mapping values in adjacent cartilage at 12 months. The addition of MSC did not show any advantage in the protection of articular cartilage over acellular scaffolds (P> 0.05).

Methods Seventeen patients aged 18 to 55 years with symptomatic full-thickness cartilage lesions on either patella or trochlea were treated with matrix autologous chondrocyte implantation (MACI) or microfracture (MF). Both procedures combined with unloading/realigning techniques. Clinical assessment and T2-mapping were evaluated at 48-months.Results Clinically results from pre-op to 48-months improved significantly in MACI and MF for Lysholm (p= 0.001, p= 0.001), IKDC-S (p= 0.001, p= 0.002), KOOS-P (p= 0.000, p= 0.002), KOOS-DLA (p= 0.002, p= 0.003), KOOS-Sports/Rec (p= 0.000, p= 0.004), KOOS-QoL (p= 0.000, p= 0.003), KOOS-symptoms (p= 0.001, p= 0.020), and Kujala (p= 0.000, p= 0.01), respectively. Tegner was significant between baseline and 48 months only for MACI (p< 0.008) compared with MF (p= 0.25). No significant difference was observed between groups for any score at 3, 12, 24, and 48-months (p> 0.05). T2-mapping values improved significantly over time in MACI compared with MF at 24 months (39.35 vs. 50.44, p= 0.007) and 48 months (36.54 vs. 48.37, p= 0.005). When comparing control values to MACI at 12-m (p= 0.714), 24-m (p= 0.175), and 48-m (p= 0.097), no significant difference was found. MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score comparison gave no statistical difference between groups.Conclusions Clinically both techniques improved significantly over time. However, quantitative assessment showed that only newly formed tissue with MACI technique improves significantly since 12-months and maintains stable values compared with native cartilage until 48-month follow-up. MF results were never comparable to those native values. Level of evidence II.