Tendinopathy: injury, repair, and current exploration

Abstract

Both acute and chronic tendinopathy result in high morbidity, requiring management that is often lengthy and expensive. However, limited and conflicting scientific evidence surrounding current management options has presented a challenge when trying to identify the best treatment for tendinopathy. As a result of shortcomings of current treatments, response to available therapies is often poor, resulting in frustration in both patients and physicians. Due to a lack of understanding of basic tendon-cell biology, further scientific investigation is needed in the field for the development of biological solutions. Optimization of new delivery systems and therapies that spatially and temporally mimic normal tendon physiology hold promise for clinical application. This review focuses on the clinical importance of tendinopathy, the structure of healthy tendons, tendon injury, and healing, and a discussion of current approaches for treatment that highlight the need for the development of new nonsurgical interventions.

Keywords: healing; tendinopathy; tendon injury; tendon repair.

Figure 1

Hierarchical structure of tendon. Notes: Collagen alignment is based on organization into fascicles, fibers, and fibrils. Tenocytes, terminally differentiated from tenoblasts, are the main cellular component of tendons. Though the exact location of tendon stem cells is unknown, their presence has been confirmed. Blood vessels and nerves are also present within the structure, but are not shown. Data from Docheva et al and Nourissat et al.

Figure 2

Representation of the interaction between tendon extracellular matrix and cellular signal transduction. Note: With a predominance of type I in the healthy tendon, collagens interact with growth factors (such as TGFβ) and proteoglycans (such as SLRPs and COMP) that regulate their synthesis and architectural organization. Data from references.– Abbreviation: SLRPs, small leucine-rich proteoglycans.