A tendon is made to resist to load. Tendon injury is usually the result of overloading or repetitive straining (overuse injuries) of the tendon. If the load is too much, the tendon has a subsequent “over”-reaction and is not inflammatory but rather degenerative in nature. A tendon injury can progress through three stages and, if not dealt with, can ultimately lead to tendon rupture. The injured tendon reacts differently in each stage of injury where it tries to protect itself against the forces and leads to changes in the tendon. These tendon changes can be referred to as tendinopathies. The management of tendinopathies are therefore different for each stage, which highlights the importance of primarily determining the stage of a tendon injury with a physiotherapist, before taking action to managing it.
Stage 1 – Reactive Tendinopathy
The first stage of injury to a tendon is called a reactive tendinopathy and is more common in young athletes, for example, where they initially start training, increase their training load or start training again after a rest period. In this case the achilles tendon, for example, responds to an acute overload by temporarily thickens and stiffens to try and cope with the excessive load. This thickening is due to an increase in cellular activity and production of a certain protein which absorbs water and pushes the fibres of the tendon apart. It is not due to inflammation as previous thought. During this first stage it is fairly easy for the tendon to return to normal structure if the load is decreased. The athlete should therefore reduce the load of training by having more frequent rest days, shortening distances or decrease the pace of a run. This reactive phase may settle within approximately 5 – 10 days. Once the reaction is settled, training should be slowly progressed to prevent a relapse.
Stage 2 – Tendon Dysrepair
The second stage of tendon injury appears in chronically overloaded tendons (repetitive strain) and is not age specific. This can appear, for example, if the athlete carries on loading the achilles tendon during training in the reactive phase. The tendon keeps attempting healing by increasing blood and nerve supply and lays down new foundations for fibres to be repaired. These foundation are weaker and more irregular in pattern than the load resisting fibres. Therefore the healing process fails due to the athlete not allowing enough time for the foundations to become stronger and the new fibres to form. The tendon is unable to adaptively strengthen before the athlete loads it again. These structural changes limits the capacity of the tendon for full repair. The swelling and thickening of the tendon leads to a disorganization of the fibres’ alignment which subsequently decreases the tendon’s ability and capacity to take load. This stage is therefore called tendon disrepair due to its inability to heal properly. Anti-inflammatory medication may be beneficial in this stage to reduce the abnormal healing response with leads to the abnormal tendon changes.
Stage 3 – Degenerative Tendinopathy
The last stage is a progression of the disrepair stage, with large changes of cells and more irregular patterns and in some areas of the tendon, deaths of cells may appear. The structure of the tendon is progressively changed as the increase in fluids within the tendon start separating the fibres from each other. During this stage the tendon is being referred to as a degenerative tendon. This is more commonly seen in older patients or mid-aged recreational athletes, but also appears in the young, elite athlete with a chronically overloaded tendon. If this stage is left to progress, it can ultimately lead to tendon rupture. To stimulate tendon restructuring, exercise may be beneficial in this stage. Emphasis has been put on eccentric exercises where the tendon gently needs to control lengthening, such as heel drops for the achilles tendon.