Image Interpretation: The central portion of the plantar fascia central cord demonstrates a hypoechoic region with loss of volume and fibrillar architecture, consistent with a full-thickness, partial-width tear. There is no associated hematoma, suggesting at least subacute chronicity. The intact medial and lateral portions of the central cord are mildly thickened with partial loss of fibrillar architecture, consistent with underlying fasciosis.
Teaching Pearl: Plantar fasciopathy most commonly involves the proximal one-third of the plantar fascia, with the central cord more commonly affected than the lateral and medial cords. Hypoechogenicity and loss of fibrillar architecture is a hallmark feature of fasciopathies, with accompanied diffuse thickening (greater than 4 mm in the central cord origin) suggestive of degenerative fasciosis, while fascia thinning/volume loss signals high-grade tearing. Hematoma/fluid is a helpful sonographic finding, delineating an acute plantar fascia tear, but is typically not present in subacute or chronic tears. Although plantar fascia rupture is uncommon, it has been associated with corticosteroid injection, and clinicians should consider this diagnosis even in the absence of a clear injury mechanism.