overuse injury 5-8% 3-5% 1-3%

tendon rupture +8%

0-1%

1

2

3

4

5 67 8 strain (%)

Figure 2: The effect of loading on the behaviour of a tendon. As collagen fibrils are loaded, they realign and undergo elastic deformation, returning to their original structure and length when unloaded unless the forces are too severe. If the load is too great, injury occurs and the original structure will not be regained. With increasing load, rupture occurs. The force level at which this occurs is related to the cross-sectional area and length of the tendon

tenosynovial sheath. Other tendons, such as the Achilles, patellar and rotator cuff tendons, have only a loose connective tissue sheath called the paratenon.

Pathologies can affect the sheath or the tendon proper, or both. Tendons with a tenosynovial sheath can develop a true tenosynovitis, whereas other tendons develop inflammation in the paratenon.

In the tendon proper, although

it is considered that inflammation can occur in acute tendon injuries, in most chronic injuries there is little inflammation but there is a process

9

Figure 4: Magnetic resonance image, showing Achilles tendinosis

THE ACTUAL TENDON ITSELF

of degeneration, in which there is disruption of collagen fibrils and dysfunction of tendon cells (tenocytes), resulting in cell matrix changes, release of chemicals including neuropeptides, and pain. In some tendons there is also neovascularisation, in which new blood vessels form. It appears that these new blood vessels are seen

PATHOLOGIES CAN AFFECT THE SHEATH OR

particularly in more severe, painful tendon injuries. This whole process is called ‘tendinosis’.

Injuries to tendon can be classified according to the specific tendon, the component of the tendon affected, the duration of symptoms, the severity of symptoms (in particular, pain), function, and imaging features such as neovascularisation (Table 1). Imaging findings are important but do not always correlate with the clinical scenario, particularly in athletes. The VISA and VISA-A scores, developed for the assessment and monitoring of patellar and Achilles tendinopathies, are very useful (1,2). These scores assess levels of pain at rest and during functional activities, and the patient’s level of activity at that time.

CAUSES OF TENDON INJURIES

The most common causes of tendon injuries in sport can be subdivided into intrinsic and extrinsic factors (Table 2).

Figure 3: Ultrasound image, showing Achilles tendinosis with neovascularisation 8

DIAGNOSIS OF TENDON INJURES Assessment involves taking a careful history to address the underlying cause(s), past medical, injury and training histories, and the expectations and concerns of the athlete. Examination focuses on general

sportEX medicine 2009;39(Jan):7-11

stress