Engineering Biomimetic Tendons

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Engineering of Biomimetic Tendons Tendon tissue is a soft connective tissue which connects muscle and bone allowing movement and increasing joint stability. Tendons are composed of a hierarchical structure of collagen molecules (fibrils, fibre bundles and fascicles) and can be categorised into two types, those that transmit loads (e.g. Achilles and patellar tendons) and those that transmit motions (e.g. flexor tendons). In vivo, tendons support large mechanical loads and because of this, they are frequently injured. Examples of commonly injured tendons are: the rotator cuff, finger flexor tendons, patellar tendons and Achilles tendons. Tendon ruptures are injuries that occur due to accidental laceration or under extreme instantaneous loads. For example, the Achilles tendon can be ruptured in sport under actions requiring explosive acceleration, such as pushing off or jumping. Slow spontaneous healing does occur in the body however this often causes scar tissue formation or disorganised matrix made largely of dense collagen fibres, resulting in the repaired area having poorer mechanical properties than healthy and intact tendons. Because of this, repaired tendons are at greater risk of being re-injured at the repair site and so tendon repair is mostly carried out by surgery. Surgical tendon repair is commonly performed using an autograft or allograft to fill the gap between the two ruptured tendon ends. An autograft is when tendon tissue is taken from one part of the patient’s body and transplanted into the repair site. Allografts use tissue from a donor of the same species. These are used for example in the repair of an Achilles tendon by using the flexor hallicus longus (FHL). The FHL tissue is used to fill the space between the tendon ends rather than bringing them together and shortening the Achilles tendon, increasing the tension and making it more prone
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