What is the term for calcification in the small arteries of the feet?

Mönckeberg's Medial Calcific Sclerosis: Calcification in Small Arteries of the Feet

The calcification in the small arteries of the feet is called Mönckeberg's Medial Calcific Sclerosis (MMCS), which represents calcification of the media layer of arteries rather than the intimal layer that occurs in atherosclerosis. 1

Characteristics and Pathophysiology

• MMCS specifically affects the media layer of arteries, causing "pipe-stem" calcification that is radiographically visible as radiopaque arteries on foot and ankle radiographs 2
• It is characterized by calcification of the arterial media in the absence of atherosclerotic plaque, macrophages, or lipid deposits 3
• The calcification process appears to be mediated by vascular smooth muscle cells that undergo phenotypic modification and express bone-associated proteins 3
• MMCS is more widespread in the lower abdominal region and lower limbs, particularly affecting the peripheral arteries 4

Prevalence and Risk Factors

• MMCS is commonly found in patients with diabetes, particularly those with diabetic neuropathy 5, 2
• Studies show that 40.6-57.1% of patients with foot infections have MMCS, with significantly higher prevalence in people with diabetes compared to non-diabetics 2, 6
• People with diabetes are 8.9 times more likely to have MMCS than those without diabetes 2
• MMCS has been associated with autonomic neuropathy of peripheral vessels, as demonstrated by its increased prevalence following sympathectomy 5

Anatomical Distribution

• MMCS commonly affects both the dorsalis pedis and posterior tibial arteries (29.8-85.0% of cases) 2, 6
• The calcification can extend from the ankle to the toes, with distribution reported as:
  • Hindfoot/ankle: 16.5-40.6% of cases 2, 6
  • Metatarsals: 24.1-34.3% of cases 2, 6
  • Toes: 19.3-59.4% of cases 2, 6

Clinical Significance and Diagnostic Challenges

• MMCS interferes with standard vascular assessment techniques, particularly ankle-brachial index (ABI) measurements 1
• In patients with MMCS, arteries become rigid and non-compressible, resulting in falsely elevated ABI values (>1.3) 1
• The presence of MMCS predicts risk of cardiovascular events and leg amputation in diabetic patients 3
• MMCS is significantly associated with peripheral type of vascular disease 5

Diagnostic Considerations

• When MMCS is suspected (ABI >1.3), alternative diagnostic methods should be used 1:
  • Toe-brachial index (TBI) measurements (normal ≥0.75) 1
  • Doppler waveform analysis of ankle arteries (triphasic waveforms typically exclude significant PAD) 1
  • Transcutaneous oxygen pressure (TcPO2) measurements 1
  • Skin perfusion pressure measurements 1
• Color-Doppler vascular ultrasound can help differentiate between MMCS and atherosclerosis-related lesions 4
• Radiographs can visualize the characteristic "pipe-stem" calcification pattern 2, 6

Clinical Implications

• MMCS makes traditional arterial Doppler studies unreliable in high-risk patients with diabetes 6
• The high prevalence of MMCS raises questions about the reliability of conventional segmental arterial Doppler studies to diagnose peripheral arterial disease 2
• Patients with MMCS require special attention during vascular assessment to avoid misdiagnosis of their perfusion status 1, 6
• Regular clinical examination is particularly important in elderly and diabetic patients to detect early signs of tissue loss 1

MMCS represents an important clinical entity that complicates vascular assessment and may contribute to poor outcomes in patients with diabetes and foot problems. Understanding this condition is crucial for proper diagnosis and management of peripheral vascular disease.