Biology and augmentation of tendon-bone insertion repair

Abstract

Surgical reattachment of tendon and bone such as in rotator cuff repair, patellar-patella tendon repair and anterior cruciate ligament (ACL) reconstruction often fails due to the failure of regeneration of the specialized tissue ("enthesis") which connects tendon to bone. Tendon-to-bone healing taking place between inhomogenous tissues is a slow process compared to healing within homogenous tissue, such as tendon to tendon or bone to bone healing. Therefore special attention must be paid to augment tendon to bone insertion (TBI) healing. Apart from surgical fixation, biological and biophysical interventions have been studied aiming at regeneration of TBI healing complex, especially the regeneration of interpositioned fibrocartilage and new bone at the healing junction. This paper described the biology and the factors influencing TBI healing using patella-patellar tendon (PPT) healing and tendon graft to bone tunnel healing in ACL reconstruction as examples. Recent development in the improvement of TBI healing and directions for future studies were also reviewed and discussed.

Cationised gelatin and hyaluronic acid coating enhances polyethylene terephthalate artificial ligament graft osseointegration in porcine bone tunnels

“…During this process, mechanical and biological factors are involved in the healing process of the reconstructed tendons [25][26][27][28][29]. In the distal part of the bone tunnel, the mechanical effect was relatively low and the graft-bone healing was influenced mainly by the biological environment.…”

Tuberculosis of the entheses

“…The tendon-bone junction (enthesis) has unique properties of stress dissipation as it is a transition zone between a dense osseous tissue and a more pliable tendinous tissue [4,5]. The tendon-bone junction is a location for constant traction forces and microavulsions occur alongside stress shielding at this interface.…”

Healing of subcutaneous tendons: Influence of the mechanical environment at the suture line on the healing process

“…These regions are characterized by the presence of a unique transitional tissue called "entheses" at the interface, which can effectively transfer the stress from tendon to bone and vice versa through its gradual change in structure, composition and mechanical behavior [21,22] . There are two types of entheses, based on how the collagen fibers attach to bone [14,21,22] .…”

“…These regions are characterized by the presence of a unique transitional tissue called "entheses" at the interface, which can effectively transfer the stress from tendon to bone and vice versa through its gradual change in structure, composition and mechanical behavior [21,22] . There are two types of entheses, based on how the collagen fibers attach to bone [14,21,22] . Direct insertions (also called the fibrocartilaginous entheses), such as the insertion of the Achilles tendon and patellar tendon, are composed of four zones in order of gradual transition: tendon, uncalcified fibrocartilage, calcified fibrocartilage and bone [21,22] .…”

“…There are two types of entheses, based on how the collagen fibers attach to bone [14,21,22] . Direct insertions (also called the fibrocartilaginous entheses), such as the insertion of the Achilles tendon and patellar tendon, are composed of four zones in order of gradual transition: tendon, uncalcified fibrocartilage, calcified fibrocartilage and bone [21,22] . The continuous change in tissue composition from tendon to bone is presumed to aid in the efficient transfer of load between the two materials [22] .…”