Differential Diagnosis for Achilles, Tibialis Anterior, and Extensor Hallucis Tightness During Running

Single Most Likely Diagnosis

• Overuse or Repetitive Strain Injury: This is the most likely diagnosis due to the nature of the symptoms occurring during running, an activity that involves repetitive strain on the muscles and tendons of the lower leg. The fact that the tightness abates when walking suggests that the issue is related to the increased stress and demand on these muscles during running.

Other Likely Diagnoses

• Poor Running Mechanics: Abnormal biomechanics during running, such as overpronation or supination, can lead to increased stress on specific muscles and tendons, causing tightness. Identifying and correcting running form issues could alleviate the symptoms.
• Muscle Imbalances: Strength or flexibility imbalances between different muscle groups in the lower leg can lead to overcompensation and tightness in certain areas, such as the Achilles, tibialis anterior, and extensor hallucis longus muscles.
• Shin Splints (Medial Tibial Stress Syndrome): While shin splints typically present with pain along the medial aspect of the tibia, they can also involve tightness in the surrounding muscles, including the tibialis anterior.

Do Not Miss Diagnoses

• Compartment Syndrome: Although less common, compartment syndrome is a serious condition that can present with muscle tightness and pain, especially during exercise. It is crucial to consider this diagnosis due to the potential for serious complications, including nerve damage and necrosis, if left untreated.
• Stress Fractures: Stress fractures in the lower leg can cause pain and tightness, especially during weight-bearing activities like running. Missing this diagnosis could lead to further injury and prolonged recovery time.

Rare Diagnoses

• Peripheral Nerve Entrapment: Entrapment of nerves supplying the muscles of the lower leg, such as the peroneal or tibial nerves, can cause symptoms including muscle tightness, pain, and weakness. This would be a less common cause of the described symptoms.
• Inflammatory or Autoimmune Conditions: Certain inflammatory conditions, such as rheumatoid arthritis or lupus, can cause muscle and tendon symptoms, including tightness. However, these conditions would typically be accompanied by other systemic symptoms and signs.