Traumatologists speak of tendinosis when referring to a degenerative pathological condition of the tendons with an absence of inflammatory changes. The difference with tendinitis is that tendinitis involves an inflammatory process. However, both terms define an alteration in the tendon structure and should therefore be used only after histological confirmation, which usually does not occur.
Thus, the name we should use to indicate an abnormal clinical condition in tendons, with pain and pathological changes, is tendinopathy, which is not the same as enthesopathy, a pathological condition affecting the insertion of the tendon into the bone.
It is necessary to know that tendon injuries due to overuse are a major problem in sports and occupational medicine, and account for approximately 200,000 surgical interventions together with ligament injuries per year in the USA.
To diagnose a diseased tendon it is necessary to perform an ultrasound scan, in which the following alterations can be seen: hypoechoic areas, global thickening or a maximum thickening in the Achilles tendon of more than 8 mm or more than 7 mm in the patellar tendon.
How to treat tendinopathies
The big difference between the repair phases in muscle and tendon injuries is the time factor, because while muscle injuries generally evolve in about 4 weeks, the repair of a tendon injury usually extends for at least 4 months.
Pain in a disrupted tendon is usually due to reactive activation of a degenerative focus. That an asymptomatic degenerative tendinopathy becomes painful is generally due to an imbalance between the load-bearing capacity of the tendon and the load applied to it, taking into account that degenerative tendons are less load tolerant. Training the tendon may cause a slight thickening of the tendon and increase its stiffness.
Keep in mind that a tendon – just like a muscle – is trainable and metabolically active.
The tendon responds immediately to both load and rest. Thus, mechanical load causes protein synthesis and collagen degradation, and without a sufficient rest period, at least 24 hours, after exercise, a negative balance will occur, leaving the tendon more vulnerable.
Complementary tests in tendinopathies
It is well known that the relationship between imaging and clinical findings is very poor in tendon injuries, but although imaging alone does not confirm the origin of the pain, decisions made in the management of tendinopathy must be based primarily on clinical findings, supported by ultrasound, which is the diagnostic test of choice.
Changes in tendon ultrastructure are associated with pain on palpation and on movement. Also that tendon thickening and hypoechogenicity are associated with pain and, therefore, is an objective parameter of the severity of Achilles tendinopathy. In this tendon neovascularization is directly associated with severity. Therefore, a decrease in pain is associated with a decrease in pain on palpation, which is the method of clinical follow-up.
The degenerated tendon may rupture without pain, which occurs if there are not enough intact fibers to withstand a given type of load.
It is not known exactly why tendons hurt. There are several models that attempt to answer this question, such as the biochemical model, which is based on the idea that pain is produced by chemical irritation; however, the model that seems to have more strength is the vasculonervous model, according to which repeated microtrauma to the tendon gives rise to a process of repeated ischemia that favors the release of neural growth factor and substance P, which produce pain.
The circle that occurs in a tendon injury begins with an increase in tendon thickness, which can be associated with an increase in vascularization. This results in an increase in nerve endings, leading to pain and a decrease in tendon function with smaller collagen fibers. There is evidence that the sympathetic nervous system acts indirectly to generate pain through neurogenic inflammation (new nerve endings growing next to the neovessels).
Therefore, a normal tendon that suffers excessive load can produce a reactive tendinopathy and, with it, a tendon alteration in the form of tendon degeneration. On the contrary, an optimal load produces an adaptation that leads to an increase in its resistance.
There must therefore be a balance between the load capacity of the tendon and the load applied to it. The load should always be similar to what is required for the sporting activity. Conversely, lack of loading decreases the mechanical properties of the tendon and the ability of the tendon to tolerate the load.
In conclusion, the treatment of tendinopathies does not require rest but rather improving the tendon’s loading capacity to determine what type of loading is detrimental to it. Early action is needed to change and adapt the load when the tendon begins to show pain or structural changes. In addition, it has been studied in recent years that tendinopathies during periods of loading respond better to isometric work than to eccentric work.
The management of tendinopathy therefore includes:
- knowing the state of the tendon (reactive or degenerative)
- quantifying symptoms and function
- modifying the workload. In phases of sports rest with eccentrics and during loading phases with isometrics
- try to maintain strength and power.
The aim of rehabilitation during periods of loading is to maintain or improve muscle function, unload the affected tendon and avoid its overuse by controlling the load. This is achieved by decreasing the frequency and duration of the loads on the tendon, as well as by decreasing the load in training