Aseptic necrosis of the femoral head

Medical Information

The etiology remains unclear; vascular risk factors due to subcritical vascular supply at the age of predilection, constitutional influences, and possible multiple bone infarcts are discussed.

The disease occurs particularly in humans and domestic dogs. The exact causes are not fully understood; femoral head necrosis occurs more frequently in cases of diabetes mellitus and alcoholism. Long-term treatment with anticoagulants can also lead to femoral head necrosis.

Femoral head necrosis can appear after an injury to the femoral head, known as post-traumatic femoral necrosis. Typically, this necrosis occurs following a shear injury of the femoral head in a traumatic hip dislocation.

Without an apparent cause, such as an accident, a hip suddenly begins to ache. Joint mobility becomes limited, primarily internal rotation and extension. A normal X-ray may not show pathological changes in the first stage; only an MRI (also with contrast) reveals the change in the metabolic state of the affected bone in the early stages.

Medical classification according to ARCO staging

• Stage A0:

  Hip pain without verifiable signs on X-ray, CT scan, scintigraphy, or MRI.

• Stage A1:

  Normal X-ray and CT; MRI shows a change in the medial part of the femoral head involving less than 15% of the surface area.

• Stage A2:

  No crescent sign; X-ray shows sclerosis, osteolysis, and focal porosis; the affected area is 15% to 30%.

• Stage A3:

  Crescent sign visible on X-ray; more than 30% of the surface is affected on MRI and CT.

• Stage A4:

  Osteoarthritis; signs of osteoarthritis on X-ray, narrowing of the joint space, changes in the acetabulum, and joint destruction.

Clinical History

• Specific history: knee pain, limping, reluctance to walk, fatigability, pain episodes, alcohol consumption, metabolic pathologies, medication history, sickle cell anemia.

• General history: family history, hip dysplasia, infections.

Diagnosis

• Diagnostic imaging: see previous section.

• Differential diagnosis: bacterial coxitis, tumor diseases, coxarthrosis.

Therapy

Objectives: Preservation of the femoral head, absence of pain, and maintenance of mobility.

Conservative Therapy:

• Iloprost infusion therapy

• Analgesics

• Non-steroidal anti-inflammatory drugs (NSAIDs)

• Physiotherapy

• Gait training

• Range of motion exercises, especially abduction and internal rotation

• Load reduction

• Orthotic adaptation to relieve the joint

• Hyperbaric oxygen therapy (HBOT)

• Extracorporeal Magnetotransduction Therapy (EMTT)

Surgical Therapy:

• In stages I and II: decompression via core drilling

• In stages III and IV: joint replacement, hip arthroplasty

Shockwave Therapy (ESWT)

• Indication:

  Must be indicated by a specialist physician.

• Before therapy:

  • Spatial requirements: Medical practice certification criteria, e.g., hygiene plan and emergency management available according to DIN standards.

  • Patient preparation: Differentiated and documented information and education.

• Physician and assisting staff:

  Extracorporeal Shockwave Therapy (ESWT) must be performed personally by the physician, duly qualified through specialized knowledge.

• Execution of the therapy:

  • Treatment under general anesthesia or conduction anesthesia.

  • Patient positioning with exposure of the affected area (external rotation and extension).

  • Visualization of the previously MRI-localized area (with gadolinium) using an X-ray image intensifier.

  • Localization of neurovascular bundles.

• Post-treatment follow-up:

  Weight-bearing discharge for 6 weeks with crutches, physiotherapeutic mobilization, and movement exercises. Subsequently, progressive load increase until reaching high-performance sports activities, provided there are no symptoms.

  MRI control immediately in case of worsening; otherwise, not before 6 to 12 months, as MRI may continue to show alterations for a long time even if the patient is symptom-free.

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