Radiographic findings of the fatigue fracture depend on the location of involvement and chronicity of the injury. Compressive forces pass through the medial shaft whereas, tensile forces act upon the lateral aspect when one bears the weight – the latter is substantially lesser relieved by the iliotibial tract and vastus lateralis action – in contrast of dynamics of vastus medialis, adductor longus and brevis increasing medial compression force. 9 The medial aspect is at risk and commonly affected due to biomechanical forces exerted on it during weight-bearing and muscle exertion. 8 The femoral neck (50%), the condylar area (24%) and the proximal shaft (18%) are commonly affected anatomical sites and can be bilateral (9% cases). The femur is the fourth common bone affected by stress injuries accounting for approximately 7.2% cases in athletes. Frequent in young, suboptimally conditioned individuals who abruptly engage in strenuous activities such as weekend-warriors with limited physical fitness, military recruits, and athletes who abruptly intensify their training regimen, 6 they are also common after orthopaedic surgery in lower limbs, foot in particular where altered gait and osteopaenia following guarded mobility in post-surgical period implied as causative factors. These are focal fractures in the normal bone due to repetitive stress following sustained microdamage exceeding the bone’s ability to heal employing physiological remodelling. (c) T1 coronal MRI image showing aggressive lesion replacing the normal marrow fat at the fracture site with a large adjacent soft tissue component. (b) Lateral view of the knee joint including the distal femur demonstrating a pathological fracture through the lesion. Pathological fracture/ (a) AP radiograph of the femur demonstrating a lucent lesion in the distal femur with permeative pattern of bone destruction suggesting an aggressive lesion. By the same definition, fracture through osteomyelitis is regarded as a pathological fracture. Pathological fractures are insufficiency fractures occurring in a bone weakened by benign or malignant neoplastic lesion affecting its trabecular integrity ( Figure 1). 3 The term “Fragility fracture” is exclusive for insufficiency fractures in osteoporosis following single minimally traumatic event. 2 Such fractures can be of two types: fatigue fractures – from abnormal repetitive stress causing temporal mechanical failure – in a normal and insufficiency fractures – owing to normal stress on an abnormally weakened bone. Stress fractures, partial or complete, usually result in bones unable to withstand subthreshold stress applied in a rhythmical and repeated manner. 1 This broad category includes pathological, stress, fatigue, insufficiency and atypical femoral fractures. Terminologies used to describe atraumatic fractures are confusing and often overlap.Ītraumatic fracture term donates a fracture caused by a relatively low-energy mechanism that usually considered incapable of producing a fracture. In the end, we will outline to approach these fractures. We will describe non-traumatic femoral fractures, their imaging features and differentials in the article. Atraumatic fractures, contrary to those following trauma, present with vague symptoms, occult on imaging posing challenges during diagnosis. In addition to traumatic injuries, the femur is susceptible to fractures even without significant trauma under certain clinical conditions e.g. ![]() ![]() The femur is the largest weight-bearing bone providing attachments to powerful antigravity muscles and a few of the strongest ligaments and tendons of the body and endures considerable biomechanical forces. Atraumatic femoral fractures are frequently encountered in clinical practice.
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