Stress fracture in lower back9/5/2023 ![]() ![]() The role of gender, age, and race in determining risk of developing stress fractures has also been discussed. 1-2 Those most at risk for BSI include runners who rapidly increase mileage and duration and those who average over 30-40 miles per week, ballet dancers, military recruits, athletes who participate in track and field or gymnastics, and those who exercise for over five hours per day. 1,2,8-10 Extrinsic factors are related to training variables and other elements that affect how stresses are applied to bone including type of sport, training intensity/duration and technique, equipment utilized, training surface, and environmental factors. 1-2 Intrinsic factors are those related to the individual athlete, including anatomic alignment, poor biomechanics, other structural variations (such as small tibial width), conditioning, insufficient blood supply, and endocrine (hypoestrogenism) and/or nutritional abnormalities (negative energy balance). Risk factors for stress fracture are divided into intrinsic and extrinsic factors. ![]() 7 The incidence of sacral or pubic stress fractures is unknown, however they may be under-recognized. 6,7 More specifically, femoral stress fractures account for 2.5% to 5% of all BSIs. 7 They have been found to be most prevalent in military recruits and endurance runners. 6,10 While stress fractures are typically more common in the distal lower extremities, stress fractures of the hip and pelvis are becoming increasingly recognized in the literature. Stress fractures comprise up to 20% of athletic injuries and 80% of stress fractures occur in the lower limb. 1,3,4-5 Epidemiology including risk factors and primary prevention 1-5 Insufficiency or pathological fractures include those that occur in bone weakened by infection, tumor, or various processes producing low bone mineral density. 1,5 Insufficiency fractures occur when normal loading is applied to bone in which new bone formation is impaired, producing reduced mechanical strength. 7 Fatigue fractures occur when continued repetitive loading exceeds the process of remodeling. Stress fractures are often multifactorial and common risk factors include high volume of activity, anatomic changes, poor preparticipation fitness, low bone mineral density, and prior history of stress fracture. 1-4 Stress fractures of the femoral shaft, pubic ramus, sacral ala, and compression side of the femoral neck are considered lower risk fractures. 8Tension-sided fractures are considered high-risk due to their tendency to displace if they progress to complete fracture, which results in increased likelihood of delayed healing and complications including avascular necrosis. 6,7įNSFs can be divided into those that occur on the tension side (superior aspect) and more commonly those that occur on the compression side (inferior aspect). ![]() Early identification of femoral neck stress fracture (FNSF) in particular is important to avoid long-term complications of complete, displaced FNSF. 1-5 Locations where femoral and/or “hip” stress fractures occur include femoral shaft, femoral diaphysis, femoral neck, pubic ramus, and sacral ala. Stress fractures can be further broken down based upon whether they occur as the result of excessive and repetitive strain placed on structurally normal bone (fatigue reaction) or normal stress applied to structurally abnormal bone (insufficiency reaction). BSI initially starts as a stress reaction which can progress to stress fracture and finally a complete bone fracture. BSI represents the inability of bone to withstand repetitive loading leading to structural fatigue and microarchitectural discontinuities. They are part of a continuum of injuries which is broadly classified as bone stress injury (BSI). Stress fractures are common injuries that tend to occur in athletes or other people who participate in activities that place repetitive and excessive stress on bone. ![]()
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