Carpometacarpal fracture-dislocations: a retrospective review of injury characteristics and radiographic outcomes

Key points

1. 01Carpometacarpal dislocations are rare and easily missed; delayed diagnosis can lead to ongoing pain, lost function, and arthritis.
2. 02A blow with a closed fist was the most common cause, but high-energy mechanisms (vehicle accidents, falls, crush) also occurred.
3. 03The fourth and fifth joints were injured most often, frequently with fractures of the metacarpal base or the carpal bones.
4. 04Early closed reduction and percutaneous pinning achieved concentric (anatomical) reduction on x-ray in most patients diagnosed promptly.
5. 05Open surgery was reserved for cases where closed reduction failed or the injury was old, so it cannot be directly judged inferior to pinning.

How it was conducted

Design

Single-center retrospective chart and radiograph review over a 10-year period (2005 to 2015)

Participants

80 patients with 81 involved hands and 165 carpometacarpal dislocations or fracture-dislocations of digits 2 to 5; thumb joint injuries excluded

Treatment

All had initial closed reduction and splinting; closed reduction with percutaneous pinning (CRPP) attempted first, with open reduction reserved for failures

Primary outcome

Adequacy of joint reduction graded 1 (anatomical) to 5 (75 to 100% subluxation) on lateral radiographs at the time of pin removal

Analysis

Descriptive statistics; Student t test for time to surgery; Fisher exact test for infection rate; P less than .05 significant

What they found

• 164 of 165 dislocations were dorsal; only 1 dislocated volarly.
• 17.5% (14/80) of patients presented more than 10 days out from injury.
• Initial management was CRPP in 90.1% (73/81) of hands versus open reduction and internal fixation pinning in 9.9% (8/81); mean time to surgery 6.43 days versus 15.57 days (P = .0027).
• At pin removal, anatomical (grade 1) alignment was achieved in 91.2% (62/68) of the CRPP group versus 33.3% (2/6) of the open-reduction pinning group (P = .0024).
• Mean time to surgery was 6 days for patients with grade 1 alignment versus 14.6 days for those with grade 2 to 4 alignment (P = .03).
• Final follow-up imaging after pin removal (available in 25 of 73 CRPP patients, average 86.2 days) showed maintained reduction in 24 of 25 (96%).
• Infection rates were 10.9% (8/73) for CRPP versus 37.5% (3/8) for open reduction pinning (P = .07); 9 of 11 infections resolved with K-wire removal and oral antibiotics.

Limitations

• Retrospective single-center design subject to selection bias.
• Most patients had minimal follow-up after pin removal, and only radiographic (not functional) outcomes were assessed.
• The radiographic grading system was newly developed with no measure of intraobserver or interobserver reliability.
• Open reduction was used only when closed reduction failed or injuries were chronic, so its poorer results may reflect harder cases rather than an inferior technique.

Why it matters

For patients

If your hand injury followed a punch or high-energy impact and remains painful or swollen, ask whether a carpometacarpal dislocation has been ruled out, because early diagnosis makes a less invasive fix more likely.

For clinicians

Keep a high index of suspicion for carpometacarpal dislocations, scrutinize the lateral radiograph for metacarpal-base or carpal fractures, and favor early closed reduction with percutaneous pinning when an adequate closed reduction can be obtained.

For readers

This large case series describes how these rare injuries occur and reports good early radiographic reduction with prompt pinning, but it offers no long-term or functional outcome data.