FRACTURE-DISLOCATION OF THELUNOTRIQUETRAL COALITION

Cato T. Laurencin, MD, PhD, Robert S. Cummings, MD, Timothy R. Jones, and Linda Martin, MD, MPH

Philadelphia, Pennsylvania

Bony fusions involving the carpus have a much higher prevalence in blacks relative towhites. This article describes a case of lunotriquetral coalition fracture-dislocation in anAfrican American. This lesion is best treated through open reduction and pin fixation. (J NailMed Assoc. 1 998;90:779-78 1.)

Key words: carpal coalition* wrist fracture-dislocation * wrist pain

Carpal coalitions are rare, asymptomatic entitiesthat most often present as incidental findings. Themost common coalition is of the lunotriquetral type,which, in one study, represented 88.9% of all carpalfusions, followed by the capitohamate coalition at5.60/o.1

The vast majority of carpal fusions show no func-tional deficit in range of motion; however, it has beensuggested that the absent intra-articular cartilage inpatients with incomplete carpal cavitation predispos-es them to degenerative arthritic changes secondaryto poor stress loading tolerance or trauma.2Cockshott3 reported that the prevalence of carpalfusions in blacks may be as high as 100 times greaterthan that of whites. Fractures through these coalitionsare extremely uncommon, and there are few reportsin the literature concerning these findings.

This article reports a case of a fracture-dislocationof the lunotriquetral coalition and its successful treat-

From the Department of Orthopaedic Surgery, MCP-HahnemannSchool of Medicine, and the Department of Chemical Engineering,Drexel University, Philadelphia, Pennsylvania. Requests for reprintsshould be addressed to Dr Cato T. Laurencin, Dept of ChemicalEngineering, Drexel University, Philadelphia, PA 19104.

ment with open reduction, pinning, and the applica-tion of a thumb spica cast.

CASE REPORTA 37-year-old, right-hand dominant African-

American man sustained a closed-head injury in amotor vehicle accident in which he was the driver.He was not wearing a seatbelt. The initial physicalexamination failed to detect any extremity injury,and it was not until 2 weeks after the accident that thepatient began to complain of left wrist pain. He alsocomplained of decreased sensation in the mediannerve distribution of the left hand.An examination at that time demonstrated mild

swelling on the volar aspect of the wrist, with pointtenderness over the lunate. The lunate was palpableand prominent, and motor function was intact.Preoperative radiographs revealed a lunate disloca-tion in the volar direction with no evidence of frac-ture (Figure 1).

The patient underwent open reduction of thelunate dislocation through a volar approach withcarpal tunnel release. Following reduction, fluoro-scopic radiograph revealed a reduction of the lunatedislocation and reduction of a fracture through a pre-viously undiscovered lunotriquetral coalition. TwoK-wires were placed through the scaphoid andthrough the lunotriquetral coalition for fixation. A

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CASE REPORT

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Figure 1.Preoperative AP (top) and lateral (bottom) radiographs ofthe left wrist.

third wire was placed from the radius into the lunateand hamate for further stabilization.

Postoperatively, the patient's left upper extremitywas placed in a short-arm thumb spica cast with thewrist in neutral position (Figure 2). Eight weeks aftersurgery, the splint and wire pins were removed, anda physical therapy program was initiated. By 12weeks postoperatively, the patient had regained full

Figure 2.Postoperative AP (top) and lateral (bottom) radiographs ofthe left wrist.

motion at his left wrist Radiographs at that timedemonstrated complete healing of the lunotriquetralcoalition (Figure 3).

DISCUSSIONWhile often described as carpal fusion, carpal

coalition more accurately represents a failure of cavi-

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Figure 3.Postoperative AP (top) and lateral rcldiographs (bottom) ofthe left wrist taken at the 12-week follow-up examination.

the fourth to eighth week of intrauterine life.4 Thespectrum of symptoms a patient may present withcan be attributed to the chronological stage at whichthe osseous differentiation arrested. Complete fusionof the affected carpal bones provides for no relativemotion between the structures and hence no pain.

However, deficient cartilage formation betweenincompletely separated carpal bones may result insymptoms analogous to that of degenerative arthritis.2

Case reports of fractured carpal coalitions areuncommon and have been described for lunotrique-tral and trapezoid-capital coalitions.3'5'6 Only onereport appears in the literature describing the occur-rence and treatment of lunate dislocation in the set-ting of lunotriquetral coalition.7

Mechanistically, lunate dislocation can bedescribed using the staging of Mayfield et a18 whoreproduced perilunate dislocation in the laboratoryby forcing cadaver wrists into extension and apply-ing a load to the thenar eminence. The sequence ofdisruption that ensued was described in stages (I-IV)of progressive perilunar instability. For dislocationof the lunate to occur in the aforementioned casereport, fracture through a lunotriquetral coalitionwould be predicted by their model.89 Treatment ofa fracture through a lunotriquetral coalition, in asso-ciation with a lunate dislocation, includes openreduction and wire pin fixation to correct the patho-mechanics of the injury.

Literature Cited1. Delaney TJ, Eswar S. Carpal coalitions. JHand Surg Am.

1992;17:28-31.2. Gross SC, Watson HK, Strickland JW, Palmer AK,

Brenner LH. Triquetral-lunate arthritis secondary to synostosis.JHand Surg Am. 1989;14:95-102.

3. Cockshott WP. Carpal fusions. Am J Roentgenol.1963;89: 1260-1271.

4. Moore KL. The Developing Human. 4th ed. Philadelphia,Pa: WB Saunders Co; 1988:355-357.

5. Peyton RS, Moore RJ. Fracture through a congenitalcarpal coalition.JHand Surg Am. 1994;19:369-371.

6. McGoey PF. Fracture-dislocation of a fused triangularand lunate (congenital).JBoneJoint Surg. 1943;25:928-929.

7. Auerbach DM, Collins ED. An unusual fracture disloca-tion pattern in a patient with an os lunatotriquetrum. AmJ Orthop.1995;24:714-6.

8. MayfieldJK,Johnson RP, Kilcoyne RK. Carpal disloca-tions: pathomechanics and progressive perilunar instability. JHand Surg Am. 1980;5:226-241.

9. Kozin SH. Perilunate injuries: diagnosis and treatment. JAm Acad Orthop Surg. 1998;6:114-120.

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