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Journal of the American Academy of Physician Assistants:
doi: 10.1097/01.JAA.0000430340.10272.a5
Case Report

Acute perilunate dislocation in a pediatric patient: Learn to recognize this uncommon but potentially devastating carpal injury.

Barbee, Major George A. DScPA-EM, PA-C; Berry-Cabán, Cristóbal S. PhD; Jacobs, Brandy R. BSBA

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Author Information

At Womack Army Medical Center in Fort Bragg, North Carolina, Major George Barbee is a PA in the department of emergency medicine and Cristóbal Berry-Cabán is a clinical researcher in the department of clinical investigation. Brandy Jacobs is a PharmD/MSCR candidate at Campbell University's School of Pharmacy and Health Sciences in Buies Creek, North Carolina, and an intern at Womack Army Medical Center. The authors have indicated no relationships to disclose relating to the content of this article.

Disclaimer The views expressed herein are those of the authors and do not reflect the official policy of the Department of the Army, Department of Defense, or US government.

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Abstract

ABSTRACT: Lunate and perilunate dislocations are rare in children, but should be suspected in patients with significant wrist swelling and decreased range of motion after trauma or falls on an outstretched hand.

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CASE

A 5-year-old male patient presented to the emergency department with a chief complaint of left wrist discomfort. The patient stated, “I was running on all fours and I heard a pop in my wrist.” This event occurred 4 hours before arrival at the ED, and the patient's mother corroborated the account. The patient had no acute pain or distress but noted decreased range of motion in the left wrist.

His vitals on presentation were: temperature, 99.1°F; pulse, 107; BP, 112/66 mm Hg; respirations, 20; and an SpO2 of 100% on room air.

History The patient had no prior injuries to his left wrist and denied any other injuries. His past medical history was unremarkable, with no history of past surgeries.

Physical examination The patient's general survey was unremarkable. He was right hand dominant. Examination of the left wrist revealed moderate soft tissue swelling and mild tenderness to palpation over the radial-dorsal aspect of the wrist. There was an overt, palpable deformity noted over the carpus. His wrist extension was limited to 2 degrees of dorsiflexion and palmar flexion to 50 degrees (normal range, 75 degrees for both). Examination distal to the injury showed no neurovascular compromise and good range of motion of the digits.

Radiographs of the left wrist were obtained and showed a perilunate dislocation. Figure 1 (the lateral view) shows volar displacement of the distal carpal row with respect to the lunate, and Figure 2 (frontal view) shows that the capitate and lunate were overlapped. No fractures were observed.

Figure 1
Figure 1
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Figure 2
Figure 2
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Initial treatment Once a diagnosis was reached, the orthopedic PA and surgeon were consulted. Longitudinal traction under C-arm fluoroscopy was attempted in the ED to reduce the dislocation, but was unsuccessful. The patient was then placed in a sugar-tong splint and transferred to a Level 1 trauma center after consultation with the receiving pediatric orthopedic surgeon. The patient subsequently underwent a successful open reduction of the dislocation followed by occupational therapy for rehabilitation.

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DISCUSSION

Lunate and perilunate dislocations (dislocation of the carpus) are unusual injuries of the wrist joint. This type of injury usually results from excessive radiocarpal extension and ulnar deviation with intercarpal supination. Although wrist injuries account for 2.5% of all ED visits in the United States, fractures and dislocations of the carpus are extremely rare in children.1 Suspect this injury pattern when a patient has significant wrist swelling and decreased range of motion after a motor vehicle accident, trauma sustained during contact sports, or fall onto an outstretched hand.1–3

Patients with this type of injury often present with pain and swelling about the dorsum of the wrist, inability to move the wrist without pain, and only slight finger flexion.3 Patients also may experience numbness in the fingers and loss of sensation in the median nerve distribution secondary to acute carpal tunnel syndrome. This dysfunction presents in 25% of these injuries.1 Patients also may experience initial pain or numbness that may resolve before diagnosis can be made.4

Perilunate dislocation is inherently a severe injury as all ligamentous attachments to the lunate, including the scapholunate and lunotriquetral ligaments, have been severed. Refer the patient to a hand surgeon; prompt surgical intervention is needed to re-establish anatomic alignment and reduce the long-term risk of avascular necrosis.1

In perilunate dislocations, the carpus is usually dorsally displaced and the lunate remains in its normal position.5 Lunate dislocation occurs when the hand is close to the body during injury, directing the force against the fingers and metacarpal bones and causing extreme hyperextension of the hand. Additionally, dislocation may occur when longitudinal force is delivered to the palm while the wrist is in hyperextension and in full ulnar deviation. Usually during this instance, a Colles fracture in adults or an epiphyseal fracture in children occurs. If the force exceeds the range of dorsiflexion allowed by the ligaments, the distal radius gives way, resulting in the above fractures.3

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Assessment of associated scaphoid and distal radius fractures should be performed through examination and radiographic studies.1

Frontal and lateral radiographic views of the wrist can usually be used to make the diagnosis of perilunate dislocations. The key to recognition on the radiograph is disruption of the radius-lunate-capitate axis on the lateral view. On the frontal view, any disruption of radiocarpal row, midcarpal row, or distal carpal row indicates a carpal fracture or dislocation.1

Pediatric orthopedic surgery consultation is mandatory in the ED for the management of carpal dislocation injuries.2 These types of dislocations are sometimes treated by closed reduction with general anesthesia, in which the bone is forced back into place without opening the skin and performing surgery.3,6 In closed reduction, traction is applied and the health care provider presses a thumb against the os capitates and forces the hand into flexion. Following closed reduction, dorsal plaster slab and rehabilitation help retain the wrist's range of motion.3

In addition to closed reduction, percutaneous fixation for several weeks may be used. The dorsal approach has the advantage of permitting the assessment of the wrist dorsal ligaments.6 The failure rate for closed reduction is considerably high secondary to ligamentous disruption.7

Open reduction followed by carpal bone relationship restoration and intercarpal ligament repair may be the best method of treatment. Open reduction is performed with general anesthesia and a tourniquet with a dorsal approach. In open reduction, an incision is made in the skin and the bones are set and held in place with screws and plates, if necessary.8 Emergent carpal tunnel release combined with open reduction and stabilization is indicated for any presentation of progressively worsening median nerve dysfunction or acute carpal tunnel syndrome.7

Multiple follow-up visits after surgery are critical as perilunate dislocations may have late complications such as instabilities, degenerative joint disease, and avascular necrosis.7

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CONCLUSION

This case represents an uncommon but potentially devastating carpal injury. The history, physical examination, and radiographs were pertinent to arriving at the correct diagnosis. If perilunate dislocation is unrecognized, the long-term sequelae are disability and chronic pain. These cases may be mistaken for “wrist sprains” or “chipped bones.” Early diagnosis is critical, especially in the pediatric population, to ensure that the patient undergoes treatment necessary to regain range of motion and sensation.7 Early recognition with subsequent pediatric orthopedic intervention is the key to management of this injury.

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REFERENCES

1. Kannikeswaran N, Sethuraman U. Lunate and perilunate dislocations. Pediatr Emer Care. 2010;26:921–924.

2. Rettig AC. Athletic injuries of the wrist and hand, part I: traumatic injuries of the wrist. Am J Sports Med. 2003;31(6):1038–1048.

3. Peiro A, Martos F, Mut T, Aracil J. Trans-scaphoid perilunate dislocation in a child. Acta Orthop Scand. 1981;52:31–34.

4. Sochart DH, Birdsall PD, Paul AS. Perilunate fracture-dislocation: a continually missed injury. J Accid Emerg Med. 1996;12:213–216.

5. Pappas N, Steinberg DR, Ring D. Perilunate injuries: in brief. Univ. of Pennsylvania Orthop J. 2010;20:58–61.

6. Ji JH, Shafi M, Moon CY, Park SE. Trans-scaphoid perilunate dislocation with fractured carpal bones in a child. Chirurgie de la Main. 2010;29:32–35.


8. Zonoozi E, Mazhar FN, Khazai M, Nejadgashti N. Bilateral volar lunate dislocation-–a rare case report. J Res Med Sci. 2009;14(3):187–190.

Keywords:

perilunate; dislocation of the carpus; pediatric injury; orthopedic; radius-lunate-capitate axis

© 2013 American Academy of Physician Assistants.

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