Enhancement of tendon-bone healing following rotator cuff repair using hydroxyapatite with TGFβ1

The formation of fibrocartilage at the healing site following a rotator cuff tear repair is a major problem in the field of tendon‑bone healing. The present study aimed to enhance the healing of the tendon‑bone interface following rotator‑cuff tear repair by the interposition of hydroxyapatite (HA) encapsulated with transforming growth factor β1 (TGFβ1). Using an acute rotator cuff repair model, rats were divided into three groups: i) Repair only (control); ii) HA group; and iii) HA‑TGFβ1 group. Animals were sacrificed at 2, 4 and 8 weeks following surgery. Micro‑computed tomography (CT), histomorphometric analyses and biomechanical tests were used to evaluate the supraspinatus tendon‑bone complex. The micro‑CT images revealed notable novel bone formation in the groups treated with HA‑TGFβ1. The histomorphometric analyses demonstrated improved fibrocartilage formation and collagen organization at the tendon‑bone interface. The HA‑TGFβ1 combination significantly improved the area of fibrocartilage, particularly at early time points (2 and 4 weeks). There was a significantly greater load‑to‑failure force achieved in the HA and HA‑TGFβ1 groups compared with the control group at 4 and 8 weeks. Augmentation of the ceramic powder with HA‑TGFβ1 at the tendon‑bone interface was demonstrated to strengthen the healing entheses, increase bone and fibrocartilage formation and improve collagen organization compared with surgical repair alone. Local application of HA‑TGFβ1 demonstrates potential in improving tendon‑bone healing following rotator cuff repair.