Summary

Atelocollagen-associated autologous chondrocyte implantation provided satisfactory clinical, radiological, and histological outcomes for the repair of large-sized and full-thickness cartilage defects of the knee at a minimum follow-up period of 3 years.

Abstract

Introduction

Autologous chondrocyte implantation using atelocollagen gel (A-ACI) in three-dimensional culture is the only ACI procedure covered by Health Insurance in our country since 2013. This is the first study reporting the results of the A-ACI in patients with cartilage defects >4 cm2 caused by trauma or osteochondritis dissecans (OCD). The purpose of this study was to evaluate midterm clinical results after A-ACI for the treatment of large-sized and full-thickness cartilage defects of the knee.

Methods

Thirteen consecutive patients (11 men, 2 women; mean age 34 years, range 15-52) who underwent A-ACI between 2014 and 2018 had been prospectively enrolled. The causes of the cartilage defect were trauma in 10 knees and OCD in 3 knees. The total number of cartilage defects was 15, with a mean size of 5.3 cm2 (range, 4.0-10.5 cm2). The mean follow-up period was 51 months (range, 36 to 84 months). Each knee was clinically and radiologically evaluated over time using Lysholm score, Knee injury and Osteoarthritis Outcome Score (KOOS) and Magnetic Resonance Observation of Cartilage Repair Tissue 2.0 (MOCART 2.0) score. Seven of 13 patients underwent second-look arthroscopy at a mean of 22 months (range, 8-41 months) after A-ACI procedure. The arthroscopic results were graded with the Oswestry Arthroscopy Score (OAS) and the International Cartilage Repair Society (ICRS) score. During second-look arthroscopy, a needle biopsy was taken. Histological sections were scored using the ICRS II score. Friedman test followed by Wilcoxon t-test with Bonferroni correction was used to compare the values at each time point with the preoperative scores. Spearman’s rank test was used to assess the correlations. Statistical significance was set at p = 0.05.

Results

The median Lysholm scores at 24 months (93.0 points) after the implantation and at the final follow-up (94.0 points) were significantly (p=0.029 and p=0.008, respectively) higher than that at preoperative value (74.0 points). The KOOS subscale scores of ADL and QOL improved significantly (p=0.003 and p=0.002, respectively) from 12 months. The subscale scores of symptoms, pain, and Sport/Rec improved significantly (p=0.003, p<0.001, and p=0.001, respectively) from 24 months. Age had a tendency to negatively affect clinical outcomes and a significant negative correlation with the KOOS QOL subscale (r=-0.557, p=0.048). The MOCART 2.0 score at the mean final follow-up of 38 months (67.5 points) was significantly higher than that at 2 months postoperatively (55.0 points) (p=0.014) The mean scores of OAS and ICRS were 7.9 ± 2.1 and 10.1 ± 3.6, respectively. The implanted tissues were stained with safranin-O in 5 specimens. According to the ICRS II scale, the median overall assessment of the repaired tissue was 75. Five patients (38%) had to undergo revision arthroscopy because of symptomatic graft hypertrophy or partial graft detachment.

Conclusions

The A-ACI significantly improved clinical scores based on Lysholm score and KOOS at a minimum of 3 years follow-up. The clinical, radiological, and histological outcomes of A-ACI in our study were comparable to those reported for A-ACI for lesions <4.0 cm2 and other types of ACI for lesions >4 cm2.