Tissue Engineering of Tendons

Rupture of tendons due to either high load or laceration is a common injury, especially for the hand. Tendon disorders are traditionally treated by reducing inflammation, restoring flexibility, and, if necessary, performing surgical repair. It has been estimated that hand surgeons repair nearly one-third of a million digital flexor tendon injuries per year in the United States. Despite the fact that surgery of tendons is a common procedure, its outcome is often unsatisfactory. Recovery after tendon surgery can take months. At best, the restored tendon is about half of its initial mechanical properties, so surgeons often face patients’ dissatisfaction. On the other hand, if left untreated, healing tendon is not as good as original structure from a mechanical point of view. Moreover, the related pain is difficult to treat. Several factors may explain these unsatisfactory results such as the difficulty to anchorage the tendon in muscle, the high mechanical constraint on the repair structure, or the unavailability of ideal tendon grafts (currently, tendon grafts are either auto, allo, or synthetic). It has been shown that early mobilization following tendon surgery gives superior results. The repaired tendon should then be able to support immediate loading. However, suturing techniques to joint split ends of tendons, while providing sufficient mechanical strength to limit gapping, are inadequate to carry normal loads. Based on the shortcomings of the actual tendon surgery, tendon tissue engineering may offer an alternative approach. The objective in developing an engineered tendon will then be the reconstruction of the injured structure with structural and functional properties as good as the original. Moreover, an engineered tendon could reduce the rate of secondary problems by making the surgical procedure less extensive. This article gives first some general details on anatomy and physiological properties of tendons, followed by a list of requirements for an ideal engineered tendon. A review of the actual state of the art in tendon replacement is then performed, and finally, some remarks on the future of tissue engineering of tendons are proposed.