Carpal Boss

Carpal Boss

 

Summary

Carpal bossing is a benign condition characterised by a bony prominence overlying the dorsal aspect of the carpometacarpal joints, typically the second and third. This can be idiopathic, or can occur as a result of previous injury to or degenerative change of these joints.

Presentation

• History
  • Atraumatic onset of swelling over the dorsal aspect of the wrist.
  • Usually asymptomatic.
  • If very large, can cause mechanical symptoms due to displacement of the extensor tendons.

Examination

• Look/feel
  • Firm, bony mass overlying the dorsal surface of the carpometacarpal joints.
• Move
  • General assessment of hand function
  • Assess the integrity of the extensor tendons by observing the posture of the hand, and the tenodesis effect.

Investigation

• Bloods
  • Typically not required
• Imaging
  • Plain radiographs can confirm the diagnosis

Differentials

• Extensor tenosynovitis (softer mass, which moves on flexion and extension of fingers)
• Dorsal wrist ganglion

Management

Conservative

• The vast majority of cases are treated conservatively with analgesia and activity modification
• Adjuncts to conservative treatment can include a brief period of splinting

Operative

• In refractory cases surgical excision of the underlying bony exostosis can be considered.
• Reports in the literature following surgical excision are limited to small case series, due to the rarity of the injury and the fact that the majority do not require surgical treatment.
• Risks include scar tenderness, recurrence, and damage to local structures (cutaneous nerves or extensor tendons).

When to Refer

• Patients who have attempted conservative treatment but have progressive symptoms.

Prognosis/Managing Expectations

No malignant potential. A benign and self-limiting condition.