ABSTRACT
Regeneration of rotator cuff tendon-bone interface is crucial in rotator cuff repair. The tendon-bone interface consists of four continuous and gradual regions: the tendon region, the unmineralized fibrocartilage region, the mineralized fibrocartilage region, and the bone region. The development and regeneration of various regions in the tendon-bone interface is regulated by growth factors, inorganic ions, mechanical stimulation, and hypoxic environment. Inspired by factors affecting the development and regeneration of the tendon-bone interface, many researchers have designed gradient scaffold systems that promote regionalized regeneration of the tendon-bone interface. The gradient distribution of these scaffolds includes inorganic ion gradients and growth factor gradients. According to different gradients of the scaffold system, osteogenesis, chondrogenesis and tendon differentiation of cells at the tendon-bone interface are promoted, and the healing of the tendon-bone is synchronously completed to realize the repair and regeneration of the rotator cuff tendon-bone interface. Current studies indicated that gradient multiphase scaffolds had high academic research value and guided significance for future clinical applications in the reconstruction of the tendon-bone interface. In this paper, the factors affecting the development and regeneration of the tendon-bone interface are reviewed, and the effects of these factors on osteogenesis, chondrogenesis and tendon formation of various regions in promoting rotator cuff tendon-bone interface repair are summarized. The properties and effects of reported gradient multiphase scaffolds for rotator cuff injury are discussed, including gradient scaffolds containing inorganic ions and growth factors. Finally, the problems and future development opportunities of gradient multiphase support in rotator cuff repair are summarized.