Codman, Ann Surg 1905 - The Diagnosis and Treatment of Fracture of the Carpal Scaphoid and Dislocation of the Semilunar Bone: With a Report of Thirty Cases. Part II. Dislocation of the Semilunar Bone with or without Fracture of the Carpal Scaphoid - Article Summary

The Diagnosis and Treatment of Fracture of the Carpal Scaphoid and Dislocation of the Semilunar Bone: With a Report of Thirty Cases. Part II. Dislocation of the Semilunar Bone with or without Fracture of the Carpal Scaphoid

Codman, Chase·Ann Surg·1905·15 citations·Case series

Codman and Chase report twelve cases of anterior (volar) lunate dislocation, with or without scaphoid fracture. They describe the injury mechanism, clinical presentation, and reduction technique. The series compares outcomes across closed reduction, open reduction, and excision at varying times after injury.

Key Findings

Volar lunate dislocation is caused by forced hyperextension, which tears the posterior horn ligaments and squeezes the lunate forward. Because the mechanism is hyperextension, reduction must be by hyperflexion: hyperextend first to seat the lunate on the radius, then use thumb pressure while an assistant flexes the wrist.
The injury classically produces a palmar tumor beneath the flexor tendons that compresses the median nerve, causing pain and numbness in the median distribution. This palmar prominence, plus a dorsal os magnum bump, creates a silver-fork appearance easily mistaken for Colles fracture.
Nearly every case was initially misdiagnosed as Colles fracture or sprain. The authors insist the X-ray is the only reliable way to confirm the dislocation and to detect an associated displaced scaphoid fragment.
Closed reduction succeeded even over a month after injury and gave near-perfect results (Cases 9 and 10). This supports attempting bloodless reduction before any open procedure, even with significant delay.
When lunate dislocation combines with a displaced fractured scaphoid and closed reduction fails, excising both the lunate and the scaphoid fragment (Case 11) gave better motion than excising only the fragment and reducing the lunate (Case 8).
The volarly dislocated lunate must be reached through an anterior incision between the flexor tendons. The dorsal approach used for scaphoid excision cannot access it.
A scaphoid fragment excised at 7 weeks showed almost no healing, only a thin fibrous layer over the trabeculae, illustrating the poor union tendency of the proximal fragment.
All 12 patients were male, mostly aged 20 to 50, injured by high-energy falls and occupational trauma.

Board PearlVolar lunate dislocation results from hyperextension and is reduced by hyperflexion; it mimics Colles fracture and demands X-ray for diagnosis.

Supplemental

The Diagnosis and Treatment of Fracture of the Carpal Scaphoid and Dislocation of the Semilunar Bone: With a Report of Thirty Cases. Part II. Dislocation of the Semilunar Bone with or without Fracture of the Carpal Scaphoid.