Differential Diagnosis for Thumb Pain and Swelling

The patient's presentation of thumb pain, swelling, and loss of motion after a fall onto the thumb, along with specific radiographic findings, guides the differential diagnosis.

• Single Most Likely Diagnosis

  • A. Bennett fracture: This is the most likely diagnosis given the patient's history of a fall onto the thumb, immediate onset of symptoms, and the radiographic finding of a 2-component, proximal first metacarpal fracture with intra-articular extension. A Bennett fracture is an intra-articular fracture of the base of the first metacarpal bone, which matches the description provided.

• Other Likely Diagnoses

  • B. Boxer fracture: Although less likely than a Bennett fracture due to the specific radiographic findings, a boxer fracture (a fracture of the fifth metacarpal neck) could present with similar symptoms if the patient had punched something during the rugby game. However, the location and intra-articular extension point more towards a Bennett fracture.
  • D. Gamekeeper thumb fracture: This refers to a fracture of the ulnar collateral ligament of the thumb, which could result from a similar mechanism of injury. However, the radiographic findings of a 2-component fracture with intra-articular extension are more indicative of a Bennett fracture.

• Do Not Miss Diagnoses

  • C. Colles fracture: Although a Colles fracture (a fracture of the distal radius) is common in falls onto an outstretched hand, the specific symptoms and radiographic findings localized to the thumb make this less likely. However, given its frequency and potential for similar presentation (especially if the patient fell in such a way that both the thumb and wrist were injured), it's crucial not to miss this diagnosis.
  • E. Jones fracture: A Jones fracture is a specific type of fracture to the fifth metatarsal bone in the foot, which would not apply to this case of thumb injury. However, mentioning it here emphasizes the importance of considering all potential fractures in the differential diagnosis, even if they seem unlikely based on the presentation.

• Rare Diagnoses

  • Other rare diagnoses might include various types of fractures or dislocations not commonly associated with the described mechanism of injury or radiographic findings. These could potentially include fractures of other carpal bones or more complex injuries involving multiple bones and ligaments in the hand. Given the specific findings, these would be less likely but could be considered if the initial diagnoses do not fully explain the patient's symptoms and radiographic results.