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Rossbach, Björn P.; Guelecyuez, Mehmet F.; Kempfert, Lena; Pietschmann, Matthias F.; Ullamann, Tina; Ficklscherer, Andreas; Niethammer, Thomas R.; Zhang, Anja; Klar, Roland M.; Müller, Peter E. (2019): Rotator Cuff Repair With Autologous Tenocytes and Biodegradable Collagen Scaffold: A Histological and Biomechanical Study in Sheep. In: American Journal of Sports Medicine, Vol. 48, No. 2, 0363546519892580: pp. 450-459
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Abstract

Background: Large rotator cuff tears still represent a challenging problem in orthopaedics. The use of tenocytes on biomaterials/scaffolds for the repair of large rotator cuff defects might be a promising approach in the field of tendon regeneration. Hypothesis: Cultivated autologous tenocytes seeded on a collagen scaffold lead to enhanced histological and biomechanical results after rotator cuff repair in a sheep model as compared with unseeded scaffolds in an acute setting. Study Design: Controlled laboratory study. Methods: At the tendon-bone junction of the infraspinatus tendon of the right foreleg of 24 sheep, a 3.5 x 1.5-cm tendon defect was created. Sheep were randomly allocated to group 1, a defect;group 2, where an unseeded collagen scaffold was implanted;or group 3, which received the implantation of a collagen scaffold seeded with autologous tenocytes. Twelve weeks postoperatively, tendon regeneration was examined histologically and biomechanically. Results: The histology of the neotendons of group 3 showed better fiber patterns, a higher production of proteoglycans, and an increased genesis of collagen III in contrast to groups 1 and 2. Immunostaining revealed less tissue dedifferentiation, a more structured cartilage layer, and homogeneous cartilage-bone transition in group 3 in comparison with groups 1 and 2. Biomechanically, the tensile strength of the reconstructed tendons in group 3 (mean load to failure, 2516 N;SD, 407.5 N) was approximately 84% that of the native tendons (mean load to failure, 2995 N;SD, 223.1 N) without statistical significance. A significant difference (P = .0095) was registered between group 1 (66.9% with a mean load to failure of 2004 N;SD, 273.8 N) and the native tendons, as well as between group 2 (69.7% with a mean load to failure of 2088 N;SD, 675.4 N) and the native tendons for mean ultimate tensile strength. In breaking stress, a significant difference (P = .0095) was seen between group 1 (mean breaking stress, 1335 N/mm(2);SD, 182.7 N/mm(2)) and the native tendons, as well as between group 2 (breaking stress, 1392 N/mm(2);SD, 450.2 N/mm(2)) and the native tendons (mean breaking stress, 1996 N/mm(2);SD, 148.7 N/mm(2)). Again, there was no significant difference between group 3 (mean breaking stress, 1677 N/mm(2);SD, 271.7 N/mm(2)) and the native tendons. Conclusion: Autologous tenocytes seeded on collagen scaffolds yield enhanced biomechanical results after tendon-bone reconstruction as compared with unseeded scaffolds in an acute setting. Biomechanical results and histological outcomes were promising, showing that the use of autologous tenocytes with specific carrier matrices could be a novel approach for repairing rotator cuff tears.