34th Annual Scientific Meeting proceedings

Not all fatigue fractures are the same and it’s good to know the differences since they require different approaches and treatment strategies.

Stress fractures as such are not rare and occur due to significant overload in otherwise healthy bones. Especially athletes are at risk. Early diagnosis is the key but unfortunately this is not the rule. Rest is the traditional basic treatment. To promote healing and shorten healing time, ESWT may be useful. On the other hand, literature and experience provide no evidence that bone stimulation methods may be effective. Surgery offers the best option in refractory and ‘time’ cases.

Traditional stress fractures have to be distinguised from insufficiency fractures who occur under normal stress on fragile bone and is typically seen in osteoporosis, rheumatoid artritis and cortisone use. The priority is to make the correct diagnosis in order to be able to treat the underlying bone disease. In addition, pain control is important, and mobilisation within comfort limits is promoted as much as possible because of the risks of muscle atropy and thromboembolic disease. Bifosphonates and bone-anabolic medication such as parathyroid hormone may be very helpful. Unstable or displaced fractures require surgery.

A special type of insufficiency fracture is SONK (Spontaneous Osteonecrosis of the Knee), which is known today not to be a vascular problem but mainly an osteoporosis based insufficiency fracture. A name change is proposed from SONK to SIFK (Spontaneous Insufficiency Fracture of the Knee). In horses a similar condition exists and is named ‘subchondral bone lesion’ with the same the same pathology. Treatment is based on rest and tackling the associated osteoporosis.

Pathological fractures are the result of normal stress on pathologic bone on one single spot (benign or malignant tumors, metabolic disease) and these fractures are often the first sign of the underlying disease. Treatment should be individualized and depends entirely on the nature and localization of the fracture.

Atypical fractures occur spontaneously or after minor trauma in cases of chronic use of bisfosphonates in the femoral diaphysis. Xray shows a typical transversal fracture line. Bifosphonates need be stopped, and if pain persists despite parathyroid therapy, intramedulary nailing has to be performed.

Finally, Medial Tibial Stress Syndrome (MTSS) - with his analogue of Bucked Shins of the cannon bone in horses - stands for diffuse microfractures over a longer lenght on the medial tibia due to mechanical overload. In humans pulling forces of Tibialis Posterior and Soleus play a major role, in horses the mechanism is not yet defined but probably similar. Besides rest, both ESWT and bone stimulation have been shown to be efficient adjuvants in therapy. Surgery with periosteal stripping has been proven to give good results in resistant human cases.