Abstract: INTRODUCTION Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. This method requires a collagen scaffold, derived from the bovine Achilles tendon, which is shaped like the human menisci and enriched with GAG in order to enhance cellular ingrowth, thus leading to gradual regeneration of meniscal tissue.Aims of this study were to assess the early clinical results achieved on 20 patients treated with CMI, and evaluate the evolution of the implant by MRI imaging and histological analysis. MATERIALS AND METHODS Twenty patients (16 male, 4 female), affected by irreparable meniscal lesions, were arthroscopically treated with CMI at the authors’ Institution since March 2001. The average age at the time of surgery was 37.6 years (range, 22 to 53 years). The main indication for CMI was represented by primary meniscal lesions (16 cases), while 4 patients underwent the operation for persistent pain after a previous meniscectomy. The average size of the lesion/defect was 3.8 cm (range, 2 to 4.6 cm). An inside-out technique was adopted in 10 patients, and an all-inside technique in 10 patients. Additional procedures included 6 ACL reconstruction, 1 high tibial osteotomy and 1 matrix-induced autologous chondrocyte implantation (MACI®).The clinical-functional assessment was performed according to the Lysholm II and Tegner activity scales. All the knees were evaluated by X-rays examination and CT-scan or MRI preoperatively.Patients with a longer follow up were studied by MRI (GE and FSE Fat suppressed T2W scans) at 6 and 12 months post-op. A biopsy of the implant was performed in occasion of a second arthroscopic look in two patients, respectively 5 and 7 months after surgery. The specimens, as well as the scaffold before implantation, were studied by light microscopy (LM), TEM, SEM and EDAX microanalysis. RESULTS Follow up averaged 5.4 months (range, 2 to 12 months). Postoperative complications included 2 cases of neurapraxia (1 saphenus, 1 infrapatellar) after inside-out sutures: in one patient symptoms subsided spontaneously, while in the second one surgical neurolysis was required.All the patients with a minimum follow up of 3 months showed an increase in the clinical scores with respect to the preoperative status.A non homogeneous signal of the scaffold was observed at MRI after 6 months, while a more uniform aspect was evident at 12 months. In the two second looks, a 10% bulk reduction of the implant was noted; the newly formed menisci appeared healed to the parameniscus and to the residual meniscal stumps. Good consistency and stability was detected by probing.Histological and ultrastructural analysis of the scaffold showed a parallel arrangement of collagen fibers connected by thinner fibrils (LM, TEM). Orthogonal views at SEM demonstrated at the surface a dense collagen barrier, which prevents cellular invasion, and in the frontal sections a porous meshwork allowing cellular migration.Microscopic observations on the two implant biopsies were similar. Hyalin tissue infiltrated by cells and vessels, surrounded by the scaffold fibers, was evident at LM. Chondroblast-like cells, with newly synthesised collagen fibers, were observed inside the porous meshwork of the scaffold at SEM. Vitality and activity of these cells, as well as the new matrix organization, were clearly shown by TEM.At EDAX microanalysis no calcifications were detected inside the speciments.Statistical analysis of the collagen fibers diameters indicates a trend to lower values in the biopsies, as would be expected in human connective tissue. CONCLUSIONS According to this study, clinical results with CMI are promising. Pain relief cannot be attributed exclusively to the concomitant meniscectomy, since satisfactory outcomes were also achieved in symptomatic knees for previous meniscectomies. Follow up is too short for drawing conclusions, but morphologic observations indicate that the scaffold is progressively infiltrated and remodeled by cells reconstituting a meniscal tissue.
Collagen Meniscus Implant (CMI): early results and histological analysis of the implant.
RONGA, MARIO;
2003-01-01
Abstract
Abstract: INTRODUCTION Collagen meniscus implant (CMI) is a tissue engineering technique for the management of irreparable meniscal lesions. This method requires a collagen scaffold, derived from the bovine Achilles tendon, which is shaped like the human menisci and enriched with GAG in order to enhance cellular ingrowth, thus leading to gradual regeneration of meniscal tissue.Aims of this study were to assess the early clinical results achieved on 20 patients treated with CMI, and evaluate the evolution of the implant by MRI imaging and histological analysis. MATERIALS AND METHODS Twenty patients (16 male, 4 female), affected by irreparable meniscal lesions, were arthroscopically treated with CMI at the authors’ Institution since March 2001. The average age at the time of surgery was 37.6 years (range, 22 to 53 years). The main indication for CMI was represented by primary meniscal lesions (16 cases), while 4 patients underwent the operation for persistent pain after a previous meniscectomy. The average size of the lesion/defect was 3.8 cm (range, 2 to 4.6 cm). An inside-out technique was adopted in 10 patients, and an all-inside technique in 10 patients. Additional procedures included 6 ACL reconstruction, 1 high tibial osteotomy and 1 matrix-induced autologous chondrocyte implantation (MACI®).The clinical-functional assessment was performed according to the Lysholm II and Tegner activity scales. All the knees were evaluated by X-rays examination and CT-scan or MRI preoperatively.Patients with a longer follow up were studied by MRI (GE and FSE Fat suppressed T2W scans) at 6 and 12 months post-op. A biopsy of the implant was performed in occasion of a second arthroscopic look in two patients, respectively 5 and 7 months after surgery. The specimens, as well as the scaffold before implantation, were studied by light microscopy (LM), TEM, SEM and EDAX microanalysis. RESULTS Follow up averaged 5.4 months (range, 2 to 12 months). Postoperative complications included 2 cases of neurapraxia (1 saphenus, 1 infrapatellar) after inside-out sutures: in one patient symptoms subsided spontaneously, while in the second one surgical neurolysis was required.All the patients with a minimum follow up of 3 months showed an increase in the clinical scores with respect to the preoperative status.A non homogeneous signal of the scaffold was observed at MRI after 6 months, while a more uniform aspect was evident at 12 months. In the two second looks, a 10% bulk reduction of the implant was noted; the newly formed menisci appeared healed to the parameniscus and to the residual meniscal stumps. Good consistency and stability was detected by probing.Histological and ultrastructural analysis of the scaffold showed a parallel arrangement of collagen fibers connected by thinner fibrils (LM, TEM). Orthogonal views at SEM demonstrated at the surface a dense collagen barrier, which prevents cellular invasion, and in the frontal sections a porous meshwork allowing cellular migration.Microscopic observations on the two implant biopsies were similar. Hyalin tissue infiltrated by cells and vessels, surrounded by the scaffold fibers, was evident at LM. Chondroblast-like cells, with newly synthesised collagen fibers, were observed inside the porous meshwork of the scaffold at SEM. Vitality and activity of these cells, as well as the new matrix organization, were clearly shown by TEM.At EDAX microanalysis no calcifications were detected inside the speciments.Statistical analysis of the collagen fibers diameters indicates a trend to lower values in the biopsies, as would be expected in human connective tissue. CONCLUSIONS According to this study, clinical results with CMI are promising. Pain relief cannot be attributed exclusively to the concomitant meniscectomy, since satisfactory outcomes were also achieved in symptomatic knees for previous meniscectomies. Follow up is too short for drawing conclusions, but morphologic observations indicate that the scaffold is progressively infiltrated and remodeled by cells reconstituting a meniscal tissue.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
