Differential Diagnosis for 39 YOM with Calf Injury

• Single most likely diagnosis:
  • Gastrocnemius muscle strain: The patient's description of feeling and hearing a "muscle snap" in the right calf, followed by pain in the mid-calf area that worsens with weight bearing and dorsiflexion of the foot, is highly suggestive of a muscle strain, particularly of the gastrocnemius muscle. The absence of ecchymosis and a negative Thompson test helps to rule out more severe injuries like Achilles tendon rupture.
• Other Likely diagnoses:
  • Soleus muscle strain: Similar to gastrocnemius strain, soleus muscle strain could present with pain in the calf area, especially with activities that involve pushing off or weight bearing. However, the pain might be more pronounced during plantarflexion rather than dorsiflexion.
  • Plantaris muscle rupture: This is another muscle in the calf that could rupture, presenting with a sudden snap and pain. However, it's less common and might be harder to diagnose without imaging.
  • Achilles tendonitis or partial tear: Although the Thompson test is negative, which suggests the Achilles tendon is intact, partial tears or tendonitis could still cause significant pain, especially with dorsiflexion.
• Do Not Miss diagnoses:
  • Deep vein thrombosis (DVT): While less likely given the acute onset of pain after physical activity, DVT is a critical diagnosis not to miss due to its potential for severe complications like pulmonary embolism. The absence of ecchymosis does not rule out DVT.
  • Compartment syndrome: This is a medical emergency that could present with severe pain out of proportion to the injury, especially with passive stretch of the muscles within the compartment. The fact that pain increases with dorsiflexion could be a clue, but other signs like pallor, paresthesia, and poikilothermia would also be expected.
• Rare diagnoses:
  • Popliteal artery entrapment syndrome: This condition involves compression of the popliteal artery and could present with claudication pain in the calf. However, it's rare and usually associated with specific anatomical variations or repetitive activities.
  • Calf tumors or cysts: Although extremely rare as an acute presentation, tumors or cysts in the calf could cause pain, especially if they impinge on surrounding structures or rupture.