Stress fractures and fracture classification

Fatigue and pathological fractures

Stress fractures (fatigue injuries) result from cumulative microtrauma. They occur in runners and military recruits, affecting weight-bearing sites: the tibia, metatarsals, pelvic ring, and the pars interarticularis of the vertebral arch (pars interarticularis). MRI is the imaging modality of choice for early detection or definitive exclusion of the injury. Radiographs may show pronounced periosteal reaction.

If normal stress is applied to structurally compromised bone (osteoporosis, osteomalacia, pelvic radiation therapy), insufficiency fractures occur. They typically present as multiple, symmetric pelvic lesions. Pathological fractures develop against the background of tumors (metastases, myeloma) or Paget's disease, necessitating bone scintigraphy to confirm the underlying diagnosis.

Fractures of the immature skeleton

The pediatric skeleton is elastic, which determines specific morphological types of trauma:

• Plastic deformation: The bone bends without forming a discrete fracture line.
• Torus (buckle) fracture: An elastic-plastic injury with compression (buckling) of the cortex on the concave side of the bone. Typical of the radius after a fall on an outstretched hand.
• Greenstick fracture: Compression on the concave side with a simultaneous cortical break on the convex side.

Epiphyseal plate injuries are described using the Salter-Harris classification (Salter-Harris). The prognosis worsens as the type number increases:

1. Type I: Isolated tear through the growth plate. Initial radiographs often appear normal; the diagnosis is confirmed after 10 days by widening of the physis and bone callus formation.
2. Type II: The fracture line extends through the growth plate and metaphysis. A metaphyseal fragment is displaced along with the intact epiphysis.
3. Type III: An intra-articular fracture extending through the growth plate and epiphysis.
4. Type IV: The fracture line crosses all three structures: metaphysis, growth plate, and epiphysis (e.g., triplane fracture of the tibia).
5. Type V: Compression crush injury of the growth plate. The worst prognosis due to a high risk of premature physeal closure and angular deformity.

Avulsion fractures and biomechanics

Avulsion fractures (avulsion fractures) occur strictly at the attachment sites of joint capsules, ligaments, or tendons. Comminuted and depressed injuries are not included. Avulsion due to muscle contraction is most likely in muscles crossing two joints (rectus femoris, hamstrings). Since ligaments do not contract, their avulsion requires extreme stretching or angular joint displacement. Chronic avulsion fractures (e.g., of the ischial apophysis) have clear margins and ossification; due to their location, they can easily be mistaken for bone tumors.

Proximal femur injuries

Femoral neck fracture is a common injury in elderly patients with osteoporosis. Diagnostics utilize an AP view of the pelvis and a specialized "shoot-through lateral view" to avoid painful hip movements.

According to localization, they are divided into:

• Intracapsular fractures (subcapital, transcervical). They carry a high risk of damage to the ascending cervical branches of the arterial ring closely adhered to the femoral neck. This leads to avascular necrosis of the femoral head in 15–35% of patients, especially with fragment displacement (assessed using the Garden classification). Treatment in the elderly generally involves hemiarthroplasty or total hip arthroplasty.
• Extracapsular fractures (intertrochanteric, subtrochanteric). The risk of femoral head ischemia in these cases is minimal.

It is important to remember that about 15% of femoral neck fractures remain occult. Key markers of an impacted fracture are a sclerotic line and interruption of the trabecular pattern. When in doubt, CT or MRI is mandatory.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Radiological evaluation and modified views in shoulder joint dislocations
• Diagnostic tactics for occult and impacted proximal femur fractures
• Differential diagnosis of physeal growth plates and fractures in adolescents
• Garden classification of femoral neck fractures

Other topics in the "Musculoskeletal System" section

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