Differential Diagnosis for Aching Pain in the 5th Phalanx PIP Joint of the Foot

• Single Most Likely Diagnosis
  • Osteoarthritis: Given the location and nature of the pain, osteoarthritis is a common cause of aching pain in the joints of the foot, especially in the PIP joints. The absence of trauma or systemic symptoms makes this a plausible diagnosis.
• Other Likely Diagnoses
  • Stress Fracture: Although the patient denies trauma, stress fractures can occur without a significant traumatic event, especially in individuals with repetitive stress on the foot, such as runners.
  • Tendinitis: Inflammation of the tendons surrounding the PIP joint could cause aching pain, especially if the patient has recently increased activity levels or has poor footwear.
  • Bursitis: Inflammation of the bursae around the joint can cause pain and swelling, which might be considered given the location of the pain.
• Do Not Miss Diagnoses
  • Infection (Septic Arthritis): Although less likely, an infection in the joint is a medical emergency that requires prompt treatment to prevent long-term damage. The absence of fever or significant swelling does not rule out this diagnosis.
  • Tumor: Both benign and malignant tumors can present with localized pain in a joint or bone. While rare, missing a diagnosis of a tumor could have significant consequences.
• Rare Diagnoses
  • Psoriatic Arthritis: This condition can cause joint pain and swelling, especially in the feet, but it is typically associated with skin changes of psoriasis.
  • Rheumatoid Arthritis: Although more commonly affecting the hands, rheumatoid arthritis can also affect the feet and cause similar symptoms.
  • Sesamoiditis: Inflammation of the sesamoid bones under the first metatarsal head can cause pain, but the location described (5th phalanx PIP joint) makes this less likely.