Probleemstelling:

A tendinopathy of the lower extremities is a common sports injury, which non-athletes are frequently confronted with. This disabling, often chronic, pathology is characterized by pain, swelling and dysfunction of the tendon, leading to difficulties in ADL activities. Despite the high prevalence of tendinopathies, there are still many unresolved questions regarding etiopathogenesis and effective therapies. This results in frequent treatment failure. Traditionally, tendinopathies have been believed to be a result of excessive stress. However, several recent scientific papers provide theoretical evidence that compression is also present in the areas where Achilles tendinopathies occur and that this factor is at least as important, if not more important, in the development of tendinopathies. In addition, an increased intratendinous resting pressure, due to the large increase of glycosaminoglycans (Hyaluronan) in the Achilles tendon, could be important for the maintenance of tendinopathies. The associated swelling can, on the one hand, disrupt blood circulation and, on the other hand, contribute to more intratendinous pressure when the tendon is stretched. This is a prominent reason why some researchers advise against intratendinous (therapeutic) infiltration because of the hypothetical negative effect on internal tendon pressure. The importance of internal tissue pressures has already been demonstrated in peripheral neuropathies, but not yet in tendons. Proving this hypothesis could therefore open doors to new insights regarding adequate therapies.

Doelstelling:

We have and will continue to perform experiments on cadaver tendon (Achilles and patella) while being subjected to mechanical strecting in a mechanical tensile apparatus or in a fully controlled knee rig where cadaver lower limbs can be subjected to highly controlled kinematics. In these experiments, intratendinous pressure is monitored while injecting different volumes of (different) liquids under varying loading conditions (see picture where methylene blue is injected in Achilles tendon). Results, however, are not always easily interpretable.

The aim of this thesis is to provide a theoretical biomechanical basis for the role of intratendinous pressure in tendinopathy to complement the above described experiments, with the development of a computational biomechanics model of tendon. An essential element in the model is the incorpration of the biphasic nature of tendon to account for the interaction between the solid and fluid phase in the tissue, e.g. by using a poro-elastic material model.