Description
Objectives: Autologous chondrocyte implantation utilizing atelocollagen (A-ACI) as a scaffold for cultured cartilage is the only insurance-covered regenerative therapy for knee cartilage defects larger than 4 cm 2 in Japan since 2013. The collagen membrane (type I/III collagen) has been available as an alternative to periosteum since 2019 for this A-ACI to cover the cultured cartilage. However, its clinical efficacy remains unclear. The purpose of this study is to compare the clinical outcomes of A-ACI using the collagen membrane to those using the periosteum.
Methods: We conducted a prospective study on 26 knees in 26 cases who underwent A-ACI for knee cartilage defects caused by trauma or osteochondritis dissecans. Between 2014 and 2018, the periosteum was covered (Group P), and from 2019 onwards, the collagen membrane was covered (Group C) for patching the cultured cartilage. Each group comprised 13 knees, with no significant differences in terms of patient demographics, lesion site, or size (Table 1). Clinical and radiological evaluations were performed one year postoperatively. Biopsy tissues obtained from some cases (Group P: 7 knees, Group C: 4 knees) were subjected to histological evaluation with hematoxylin-eosin and safranin-O staining. Statistical analyses utilized the Mann-Whitney U test, Wilcoxon signed-rank test, Fisher’s exact test, and Levene test with a significance level set at p=0.05.
Results: The mean postoperative Lysholm score were 86 and 83 points in Group P and C, respectively, with no significant difference (Fig. 1). There was also no significant difference in any of the KOOS subscales between the two groups. In Group P, all KOOS items, except for Symptoms, showed significant postoperative improvement (p<0.02). In Group C, Lysholm score and all KOOS subscales showed significant postoperative improvement (p<0.03). In the post-operative KOOS subscales of Pain and QOL, there were significant less variabilities in Group C (p=0.004 and p=0.025, respectively). Regarding the compilation rate, Group P was significantly greater than Group C (p=0.03). MRI revealed graft hypertrophy in 4 knees and cartilage delamination in 2 knees in Group P, requiring arthroscopic partial resection in total 6 cases. In Group C, a large subchondral bone cyst formed in one knee, which was treated with autologous osteochondral transplantation. Histological evaluation revealed cartilage-like tissue staining strongly with Safranin-O in 4 out of 7 knees in Group P and in all 4 knees in Group C (Fig. 2). One case in Group P consisted only of fibrous tissue with blood vessel formation.
Conclusions: There was no significant difference in the one-year postoperative clinical outcomes after A-ACI using either the periosteum or the collagen membrane. Both groups showed significant postoperative clinical improvement. However, collagen covered A-ACI was significantly less in the complication rate than periosteum covered A-ACI. The long-term follow-up is needed due to the different observation periods.
