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Perilunate dislocation: case studies of a frequently missed diagnosis: delayed treatment adversely affects clinical results.

Article Excerpt
ABSTRACT: If enough force is applied in a wrist ligament injury, a perilunate dislocation may occur. Physicians can readily make the diagnosis, but the injury may be missed in the initial evaluation. With prompt recognition and intervention, the incidence of permanent disability may be lessened. Acute carpal tunnel syndrome may accompany perilunate injuries and frank dislocations. The scapholunate and lunotriquetral ligaments confer significant structural stability and help maintain the anatomical relationships of the carpal bones; when they are compromised, structural integrity is lost.Visual inspection is critical to the physical examination. Neurovascular status should be determined and documented. Radiographic evaluation is recommended for all hand injuries. All perilunate dislocations first need to be closed reduced, followed by surgical treatment. (J Musculoskel Med. 2008;25:390-395)

Wrist ligament injuries usually result from a fall onto an outstretched hand. (1) If enough force is applied, a perilunate dislocation may occur--the carpal ligaments may become severely damaged and the lunate can dislocate from its facet on the distal radius. Fractures and neurological injuries also may occur within the spectrum of perilunate dislocations.

Physicians often can readily make the diagnosis of perilunate dislocations. In some cases, however, these injuries are missed in the initial evaluation.

An estimated 2.5% of emergency department (ED) visits in the United States are for wrist injuries. (2) Of these, about 10% are perilunate dislocations and carpal fracture dislocations. (3) The diagnosis of perilunate and lunate dislocations is missed initially in up to 25% of cases, and the resultant delay of treatment adversely affects clinical results. (4) Long-term outcomes for patients with these injuries can be poor because of damage to the ligamentous architecture of the carpus. With prompt recognition and intervention,however, the incidence of permanent disability may be lessened and patients may approach near-normal hand function. (5)

Acute carpal tunnel syndrome (ACTS) may accompany perilunate injuries and frank dislocations when there is severe trauma to the wrist. (6) The defining features include a rapid onset of numbness and paresthesia in the median nerve distribution. Because unresolved ACTS is an orthopedic emergency, early diagnosis and prompt referral improve clinical results and long-term patient outcomes.

In this article, we describe 2 cases of perilunate dislocation in which the diagnosis was not made initially and the patient presented with neurological signs consistent with ACTS. We provide a schema to facilitate diagnosis that involves recognizing the bony and neurological injuries and describe approaches to management, including referral to an orthopedist for prompt surgical treatment.

CASE PRESENTATIONS

Case 1: Snowboarding

A 17-year-old right hand-dominant adolescent boy sustained an injury to his right wrist while snowboarding. He was executing an extreme jump and landed primarily on his outstretched right upper extremity....

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