Causes / typical injury mechanism: Anterior tibialis tendon rupture is a rare condition that may occur spontaneously or be caused by acute trauma. Spontaneous rupture is typically seen in older patients with underlying chronic medical conditions and is caused by underlying degeneration of the anterior tibialis tendon. Acute rupture is not commonly seen in younger patients; when it occurs, it may be due to sports injuries. Tibial fracture, laceration, and traumatic force against a dorsiflexed foot are other causes of acute rupture of the anterior tibialis tendon.

Classic history and presentation: Older patients with spontaneous anterior tibialis tendon rupture will typically not report a major traumatic event but instead a mild stumble or fall. They may or may not remember the event. They have pain and swelling at the ankle but may believe it was an ankle sprain. This pain and swelling are likely to subside over time, but the patient will continue to experience a foot drop that impedes normal ambulation. It is not uncommon for patients to present weeks after the injury due to a "mass" or "lump" at the anterior ankle at the stump of the anterior tibial tendon that is evident once the swelling improves.

Younger patients with acute anterior tibialis tendon rupture will often present after the sudden onset of pain and swelling due to a sports-related or traumatic injury.

Prevalence:

• Age – Older patients (aged 50-70 years) or younger athletes.
• Sex / gender – 75% of cases occur in men.

Risk factors:

• Diabetes
• Inflammatory arthritis
• Rheumatoid arthritis
• Gout
• Impingement due to underlying exostosis
• Steroid injection history
• Current fluoroquinolone use

Pathophysiology: Anterior tibialis tendon rupture is caused by underlying tendon degeneration or acute injury.