Tibia stress fractures in athletes : an investigation of possible predisposing factors

Sammanfattning: This study indicated that posteromedial and anterior tibia stress fractures are two entities with different etiology, pathoanatomy and natural course. In both cases clinical examination and bone scintigram were conclusive for the diagnosis. Whereas the posteromedial fracture was found to be a benign entity, the anterior tibia stress fracture was a threat to the career of an elite athlete. No consensus on treatment can be stated for the anterior injuries. Posteromedial stress fractures were treated with adjustments in training only. In the literature, different extrinsic and intrinsic factors are discussed as etiologic factors. However, there may be an anatomical predisposition to tibia stress fractures in some individuals. Great variations in type and size of muscle origin, length of attachments and overlap of the deep plantar flexor muscles were found in 36 dissected tibiae. Furthermore, muscle fibers and/or connective tissue attached the muscle to the periosteum or directly to the cortical bone in varying pro portions. Excessive local bone deformation has been suggested as another important factor contributing in the occurrence of a stress fracture. A method for measuring local bone deformation was validated by in vitro experiments. An in vivo study re vealed different local deformations at two sites of the tibia during different conditions. The clinical implication of this finding must be further elucidated. Precursors of injury may not only be based upon orthopaedic and biomechanical factors, but also upon the individual's ambition to achieve more than the body can tolerate. The results indicated that the injured runners, especially the women, scored higher than the non-injured runners on a number of the trait inventories used. In summary, this thesis explores a number of factors claimed to be associated with tibia stress fractures.