Bioinductive collagen implants facilitate tendon regeneration in rotator cuff tears

PURPOSE: To evaluate the clinical outcomes, MRI imaging and histological characteristics of biopsy samples of the tendon from patients in whom rotator cuff repair was previously performed with a bioinductive type I bovine collagen implants. METHODS: Prospective study of 30 patients with partial or complete rotator cuff tears who underwent arthroscopic repair and augmentation with a resorbable type I bovine collagen implant. Preoperatively and at 6 and 12 months after surgery, the VAS, ASES and Constant-Murley scores were evaluated and an MRI study was performed. At 6 months, biopsies of the resulting tissue were obtained and examined histologically. RESULTS: Patients experienced statistically significant and sustained improvement from baseline for all scores and the mean tendon thickness increased by 1.84 mm. Magnetic resonance imaging evidence of complete healing was found in 27 patients and a considerable reduction in defect size, greater than 50%, was shown in 3. In all samples obtained, the new tissue generated had the histological appearance of a tendon, and was indistinguishable from the native tendon. There was no evidence of any remaining collagen implant. CONCLUSIONS: Biopsies of tissue formed from bioinductive type I bovine collagen implants showed, six months after surgery, the generation of a neotendon indistinguishable from the native one. Histology and MRI imaging, revealed complete integration of the implant and absence of inflammatory or foreign body reactions. The clinical parameters, thickness and MRI signal of the tendon improved significantly at 6 months, regardless of the type and size of the tear, and remained unchanged until 12 months. LEVEL OF EVIDENCE: Level IV, case series.