Stress Fractures: Commonly Affected Bones, Imaging, Clinical Features and Treatment

Stress Fractures are fractures that occur due to small repetitive stresses (minor traumatic incidents)

Repetitive stress lead to osteoclastic resorption of the bone exceeding osteoblastic formation and a zone of relative weakness develops leading to a fracture

Repetitive stress could be a bending force or compressive one or a combination of both

Risk factors

Athletes, dancers and military recruits because they build up muscle power quickly but bone strength slowly
People with osteoporosis or osteomalacia
Patients treated with drugs that affect bone remodeling (corticosteroid, methotrexate or bisphosphonate)
Female gender
Low vitamin D level

Affected bones

Mostly lower extremities
Metatarsals (esp. second metatarsal) are the most commonly affected (march fracture) then comes navicular, calcaneum, fibula, tibia, patella, femoral shaft, femoral neck and pubic rami
Could also affect fifth lumbar vertebra and the shaft of humerus

Clinical features

Healthy patient

History of repetitive strenuous activity
Patient present with insidious onset of pain, starting after exercise initially then pain during exercise then it progresses to pain even without exercise
Patient usually present after the fracture has healed and may complain of a lump which is the callus
On examination: on look the affected site is swollen or red, warm and tender , the callus maybe palpable
Feeling the bone is result in tenderness over the fracture site

Imaging

Early on the fracture is difficult to detect on plain x ray, but if re take the x ray after few weeks it would show the defect with callus formation
Radio scintigraphy will show increased activity at the painful spot
MRI shows the fracture very well even at early stage so it is confirmatory test

Treatment

Elastic bandage and avoidance of painful activity for 2 to 6 weeks
Except in femoral neck stress fracture, if confirmed with MRI , it has to be fixated with screws
Most patients benefit from calcium and vitamin D supplementation