MSK Session Recap

Hi Everyone,

Thank you to everyone for joining us at our most recent session. Please see below the summary of the papers discussed.

Ultrasound for the Diagnosis of Giant Cell Arteritis

European Journal of Rheumatology, Alarcon et al., 2024

• Giant Cell Arteritis (GCA) is a medical emergency due to the risk of irreversible visual loss and stroke, both preventable with prompt diagnosis and treatment.
• GCA is a systemic vasculitis affecting external cranial branches of the aorta. Risk factors include:
  • Age >50 years
  • Female gender
  • Caucasian ethnicity
  • Associated conditions like Polymyalgia Rheumatica
• Clinical Presentation:
  • Acute, unilateral temporal headache
  • Jaw claudication
  • Visual disturbances
• Diagnosis:
  • Ongoing debate between imaging and biopsy.
  • EULAR Guidelines recommend ultrasound (US) of temporal ± axillary arteries as the first-line imaging modality.
    • Reduces time to diagnosis and avoids unnecessary treatment when performed with high expertise and appropriate equipment.
• Key Ultrasound Findings:
  • Halo Sign: Homogeneous, hypoechoic thickening of the vessel wall (sensitivity 43–77%, specificity 89–100%).
  • Compression Sign: Persistent hypoechogenic area during probe compression, indicating vessel wall inflammation.
• Pros of Ultrasound:
  • Non-invasive, quick, and cost-effective.
  • High specificity with experienced operators.
• Limitations:
  • Lower sensitivity in early or mild disease.
  • Operator-dependent with variability based on equipment quality.

Radiological Findings in Paget’s Disease

• Paget’s Disease (Osteitis Deformans) is a chronic inflammatory bone remodelling disorder first described in 1877. It is characterised by bony thickening, enlargement, and structural weakness due to accelerated turnover.
• Epidemiology:
  • Affects 3–4% of people over 40 and up to 11% over 80.
  • Higher prevalence in the UK, with slight male predominance.
• Etiology:
  • Genetic Factors: Mutations in SQSTM1 gene increase risk.
  • Environmental Triggers: Possible link to early viral infections and low childhood calcium intake.
• Pathophysiology:
  • Three phases:
    1. Osteolytic Phase: Intense bone resorption by abnormal osteoclasts.
    2. Mixed Phase: Simultaneous bone resorption and disorganised bone formation.
    3. Sclerotic Phase: Thickened, brittle bone with mosaic patterns on biopsy.
• Clinical Features:
  • Asymptomatic in many cases, diagnosed incidentally via imaging.
  • Symptoms include bone pain, deformities (e.g., bowing of long bones), hearing loss (cranial nerve compression), and pathological fractures.
• Radiological Findings:
  • Skull:
    • Cotton Wool Appearance—mixed lytic and sclerotic lesions.
    • Tam o’Shanter Sign—cranial thickening.
  • Spine:
    • Ivory Vertebra—diffuse vertebral sclerosis.
    • Picture Frame Sign—thickened cortical margins of vertebrae.
  • Pelvis:
    • Brim Sign—sclerosis along pelvic brim.
    • Shepherd’s Crook Deformity—varus angulation of the femur.
  • Long Bones:
    • Blade of Grass/Candle Flame Sign—advancing lytic lesions.
    • Banana Fractures—transverse fractures in weakened bone.
• Complications:
  • Fractures, osteoarthritis, cranial nerve deficits, high-output cardiac failure, and rare malignant transformation to osteosarcoma.
• Management:
  • Pharmacological: Bisphosphonates (1st-line), analgesia for pain management.
  • Non-Pharmacological: Physiotherapy, orthotic support.
  • Surgical: Fracture fixation, joint replacements, decompression for nerve involvement.

Thank you again for your participation. We look forward to seeing you at the next session!