A damaged tendon will go through different stages in order to heal. During each stage we have the ability to influence the final outcome of healing.
The first stage is the inflammatory phase. This begins immediately after injury and will last the first few days after injury. Blood flow to the area is increased. Platelets release growth factors and pro-inflammatory signals, and a fibrin clot forms a temporary framework for the tissue to stabilise the injury.
In this stage rest, support and anti-inflammatory treatment are important. It is known that initial injury size can get bigger in the first 1-2 weeks as a result of mechanical “pulling” on the affected area. With this in mind horses are rested and often supported with bandages during this stage.
The problem is that even when just standing the tendons will still be pulled and the injury can/will get worse. bandages are not able to give enough support to avoid this “pulling”.
With this in mind we advice the use of our Dynamic Support System (DSS) from an early stage (high support setting) so that excessive pulling can be avoided. (read here more about DSS)
Regular use of ice and other anti inflammatory treatments is advisable in order to avoid excessive inflammation and avoidable tissue damage.
The proliferative stage starts in the first week after injury and will lead to forming of blood clots and filing of the damaged area with scar like tissue. It is very important that we realise, and accept, that tendon cells don’t grow back. This means that the scar tissue needs to be “trained” in order to act like tendon tissue later on.
Towards the end of this stage the active trigger to healing is reduced by the body and the availability of natural stem cell activity and other growth promoting factors are getting less. In this stage it is often advisable to reactivate the healing response by introducing substances like PRP, Stem-cells, and other biological regenerative treatments.
A low amount of loading on the tendon in this stage is advisable, but can only be done safely if the peak load on the tendon is controlled. Traditional protocols leave horses during this stage on complete rest, but this will further reduce healing ability and increase forming of inferior scar tissue.
During the last stage remodeling of scar tissue takes place. During this stage the first fibrils are formed (particularly type I collagen fibers) which become aligned in the direction of strain on the tendon. During maturation, the scar tissue gradually changes to scar like tendon tissue and depending on the protocol followed this stage can take up to 12 months. Traditionally the focus is on “filling the hole in the tendon”, but filling with poor quality scar tissue leafs to very poor results (industry average shows that only about 20% of horses return to previous level of exercise)
Several studies (P. Eliasson 2011, M. Hammerman, et.al 2018) have shown that Ruptured tendons heal faster if they are exposed to mechanical loading. Early loading creates organisation of the matrix and will lead to early fibre forming and less “unorganised scar tissue”. Early loading will lead to a better functioning tendon with a better long term outcome.
Appropriate loading is needed to increase the quality of the healing tendon without inducing microdamage and alter the inflammation in the tissue. This is hard enough to achieve in human patients, but how can we do this in equine patients?
The first step is to be able to assess the fibre content and composition in the tendon. Conventional ultrasound is very limited in producing this information. The use of Tendon Tissue Characterisation technology (UTC) makes it possible to collect the required information of the tendon in order to establish best possible loading off the tendon.
UTC will show us whether the exercise (loading) of the tendon is not enough (leading to inactive scar tissue), too much (leading to micro trauma) or appropriate for achieving optimal healing.