Miscellaneous Conditions (Bone tumors)

Melorheostosis

Epidemiology

• Typically discovered around age 40.

Aetiology

• Excessive periosteal bone formation.
• Unknown cause; non-hereditary.

Clinical Features

• Painful.
• Skin changes: erythema, warmth, fibrosis, and induration.
• Commonly affects the lower limb.

Imaging Features

• "Dripping candle wax" appearance: periosteal bone extending along the outer bone surface and crossing joints.

Pathology

• Normal bone features.

Management

• Symptomatic treatment.
• Surgical excision for prominent areas.
• Release joint contractures.

Gorham Disease

Overview

• Also known as Massive Spontaneous Osteolysis or Vanishing Bone Disease.
• No curative treatment.

Gaucher Disease

Aetiology

• Enzyme deficiency: Glucocerebrosidase.
• Autosomal recessive disorder leading to:
  • Pancytopenia.
  • Thrombocytopenia.
  • Osteonecrosis and fractures.

Epidemiology

• Most common in Ashkenazi Jews.

Imaging Features

• Erlenmeyer flask deformity of long bones.
• Subchondral and vertebral collapse.
• Lucent metaphyseal areas.

Management

• Enzyme replacement therapy.
• Symptomatic management.

Neuropathic Arthropathy (Charcot Joint)

Definition

• Joint destruction caused by trauma due to loss of protective sensation.

Aetiology

• Chronic sensory nerve issues:
  • Diabetes (foot and ankle).
  • Alcoholism.
  • Spinal cord anomalies (malformation, tumor).
  • Syphilis (knee).
  • Syringomyelia (shoulder and elbow).

Clinical Features

• Early stages mimic osteoarthritis.
• Late stages resemble infection.

Imaging Features

• Joint subluxations, collapse, and hypertrophic bone formation.

Management

• Treat reversible causes.
• Fusion or reconstruction of joints.
• Total contact casting for ulcers.

Haemophilic Arthropathy

Aetiology

• Haemophilia A: Factor VIII deficiency.
• Haemophilia B: Factor IX deficiency (Christmas disease).
• X-linked recessive inheritance.
• Repeated haemarthroses leading to hypertrophied synovium and cartilage erosion.

Imaging Features

• Squared distal pole of the patella.
• Flattened distal femur.
• Overgrowth of tibia and femur.

Management

• Prevent haemarthrosis.

Pigmented Villonodular Synovitis (PVNS)

Epidemiology

• Middle-aged adults; men = women.

Aetiology

• Benign but locally aggressive synovial proliferation.
• Often associated with prior trauma.

Clinical Features

• Pain, restricted ROM, and swelling.
• Diffuse or nodular form:
  • Nodular: Single nodule in the joint.
  • Diffuse: Recurrent haemarthroses.

Common Locations

• Knee (80%) > hip > shoulder > ankle.

Diagnosis

• X-ray: Bony erosions on both sides of the joint.
• MRI: Dark nodule or nodular proliferation, sometimes with fat signals and haemarthrosis.

Pathology

• Inflamed synovium with haemosiderin deposition.

Management

• Nodular: Excision.
• Diffuse: Total synovectomy (arthroscopic or open).
• Arthroplasty for secondary arthrosis.
• Recurrence rate: ~20% (usually due to incomplete excision).