Driven by market demand, many biological and synthetic scaffolds have been developed during the last 15 years. Both positive and negative results have been reported in clinical applications for tendon and ligament repair. To obtain data for this review, multiple electronic databases were used (e.g., Pubmed and ScienceDirect), as well as the US FDA website and the reference lists from clinical trials, review articles and company reports, in order to identify studies relating to the use of these commercial scaffolds for tendon and ligament repair. The commercial names of each scaffold and the keywords 'tendon' and 'ligament' were used as the search terms. Initially, 378 articles were identified. Of these, 47 were clinical studies and the others were reviews, editorials, commentaries, animal studies or related to applications other than tendons and ligaments. The outcomes were reviewed in 47 reports (six on Restore, eight on Graftjacket, four on Zimmer, one on TissueMend, five on Gore-Tex, six on Lars, 18 on Leeds-Keio and one study used both Restore and Graftjacket). The advantages, disadvantages and future perspectives regarding the use of commercial scaffolds for tendon and ligament treatment are discussed. Both biological and synthetic scaffolds can cause adverse events such as noninfectious effusion and synovitis, which result in the failure of surgery. Future improvements should focus on both mechanical properties and biocompatibility. Nanoscaffold manufactured using electrospinning technology may provide great improvement in future practice.

Identification of functional programmable mechanical stimulation (PMS) on tendon not only provides the insight of the tendon homeostasis under physical/pathological condition, but also guides a better engineering strategy for tendon regeneration. The aims of the study are to design a bioreactor system with PMS to mimic the in vivo loading conditions, and to define the impact of different cyclic tensile strain on tendon. Rabbit Achilles tendons were loaded in the bioreactor with/without cyclic tensile loading (0.25 Hz for 8 h/day, 0-9% for 6 days). Tendons without loading lost its structure integrity as evidenced by disorientated collagen fiber, increased type III collagen expression, and increased cell apoptosis. Tendons with 3% of cyclic tensile loading had moderate matrix deterioration and elevated expression levels of MMP-1, 3, and 12, whilst exceeded loading regime of 9% caused massive rupture of collagen bundle. However, 6% of cyclic tensile strain was able to maintain the structural integrity and cellular function. Our data indicated that an optimal PMS is required to maintain the tendon homeostasis and there is only a narrow range of tensile strain that can induce the anabolic action. The clinical impact of this study is that optimized eccentric training program is needed to achieve maximum beneficial effects on chronic tendinopathy management.

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ATT may be a useful treatment of chronic Achilles tendinopathy.