Differential Diagnosis for Achilles Pain

The patient presents with bilateral Achilles pain, tightness, and morning stiffness, which has been ongoing for over a month. The symptoms have significantly impacted their ability to run, jump, and even walk comfortably in the mornings. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Achilles Tendinosis/Tendinitis: This condition is characterized by chronic inflammation and degeneration of the Achilles tendon, often due to overuse or repetitive strain. The patient's symptoms of pain, tightness, and morning stiffness are classic for this diagnosis. The bilateral nature could suggest a systemic or biomechanical issue contributing to the condition.

• Other Likely Diagnoses

  • Achilles Tendonitis with Possible Partial Tear: While tendinosis is more chronic, an acute or subacute partial tear could also present with similar symptoms, especially if there was a recent increase in activity level.
  • Plantar Fasciitis: Although the primary complaint is Achilles pain, plantar fasciitis can cause significant heel pain and stiffness, especially in the mornings, and could be considered if the pain radiates or is referred.
  • Overuse Syndrome: This is a broad category but could encompass various musculoskeletal issues related to repetitive stress and overactivity, including but not limited to shin splints, stress fractures, or other tendonopathies.

• Do Not Miss Diagnoses

  • Rupture of the Achilles Tendon: Although the patient's symptoms have been chronic, a complete or partial rupture could present with sudden onset of severe pain and significant disability. This is a critical diagnosis to rule out due to its significant impact on treatment and prognosis.
  • Inflammatory Arthritis (e.g., Rheumatoid Arthritis, Psoriatic Arthritis): These conditions can cause widespread musculoskeletal pain, including tendonitis and enthesitis (inflammation at the sites where tendons or ligaments insert into the bone), and could explain bilateral symptoms.
  • Infection (e.g., Cellulitis, Abscess): Although less likely, infection in the soft tissues around the Achilles tendon could present with pain, swelling, and warmth, and is a medical emergency.

• Rare Diagnoses

  • Seronegative Spondyloarthropathies: Conditions like ankylosing spondylitis can cause enthesitis, which might affect the Achilles tendons, but these are less common and typically associated with back pain and other systemic symptoms.
  • Tumor or Cyst: Rarely, a soft tissue tumor or cyst (e.g., ganglion cyst) near the Achilles tendon could cause chronic pain and stiffness, though this would be an uncommon presentation.