Written by: Justine Ko, MD (NUEM PGY-3) Edited by: Spenser Lang MD (NUEM Alum ‘18 ) Expert commentary by: Matt Levine, MD
“Can’t Miss” Hand and Wrist Injuries in the ED
In the emergency department, orthopedic complaints make up a large percentage of presentations, up to 50% in the pediatric population and close to 33% in the adolescent and young adult population. Many of these injuries are uncomplicated, but an astute clinician can diagnose subtle and uncommon injury patterns. Three less common injuries are reviewed here. If found, these injuries can alter the management and disposition of the patient. Each of these injuries should be carefully assessed for on physical exam and imaging.
DISTAL RADIOULNAR JOINT (DRUJ) INJURIES
What exactly is the distal radioulnar joint and why is it important?
The distal radioulnar joint (DRUJ) consists of both the bony radioulnar articulation as well as the soft tissue components, including ligaments. It has significant contributions to the axial load-bearing capabilities of the forearm. The injury can be an isolated injury or associated with forearm fractures and should be tested for with every forearm injury as its presence can alter the disposition and even functionality of the patient.
When does it occur?
A DRUJ injury may occur, although rarely, in isolation. This is usually related to a fall on outstretched hand (FOOSH). A DRUJ injury is more often associated with a fracture. Common associations include:
Distal radial fracture (DRF)
DRF + DRUJ = Galeazzi fracture (pictured to the right)
Ulnar styloid fracture
How should I assess for a possible DRUJ injury?
Routine AP and lateral views are poor for determining a DRUJ injury. This is largely a CLINICAL DIAGNOSIS.
Piano Key Sign: with the patient’s hand in pronation, push on the dorsal aspect of the ulnar head. Depression and rebound of the ulnar head suggest DRUJ instability
Table Top Test: have patient place hands on a table and apply force. A DRUJ injury will show dorsal depression of the ulna
Grind Test: hyperextend the wrist and axial load the forearm. A positive sign elicits pain over the joint
How does this alter management?
When associated with a fracture, operative management is often indicated and consultation with our orthopedist is warranted. When missed, a DRUJ injury will result in instability of the joint and arthrosis.
PERILUNATE AND LUNATE DISLOCATIONS
It has been reported that these injuries are missed in up to 25% of ED presentations.
How do these injuries occur?
In perilunate and lunate dislocations, the mechanism is usually hyperextension in the setting of trauma. Patients presents with hand and wrist pain/swelling.
How do I distinguish perilunate from lunate dislocations?
Lunate and perilunate dislocations can be easily confused or mistaken for each other. The key to distinguishing these injuries on imaging is the alignment between the metacarpal, carpal, and the radius/ulna bones.
In a normal lateral x-ray, these bones should all align (Figure 1, far left). In a lunate dislocation, the lunate itself is physically removed or out of line with the rest of these bones (Figure 1, far right), resulting in the classic “spilled teacup” appearance on x-ray. In a perilunate dislocation, the lunate sits in line with the radius/ulna, however the capitate/metatarsal bones are dislocated dorsally.
On an AP film, a break in Gilula’s arc/lines may be used to assess for a perilunate or lunate dislocation (Figure 2).
How Are These Injuries Treated?
In the ED, closed reduction can be attempted. If successful, definitive treatment can occur up to 7 days later. If unsuccessful, operative management is indicated. Definitive treatment involves open reduction and internal fixation.
How Would I Reduce These Injuries in the ED?
Usually, the assistance of our orthopaedic colleagues is warranted. Finger traps can be used for traction. The wrist should be extended while placing palmar pressure on the lunate. Then, with continued traction, the wrist should be gradually flexed so that the capitate falls back into place within the concavity of the lunate. Once the lunocapitate joint is reduced, the wrist can be extended in traction again for full reduction.
What is a scapholunate dissociation?
Scapholunate dissociation is caused by injury to the scapholunate ligament. Injury to this ligament can occur with acute FOOSH injury or be caused by degenerative rupture of the ligament.
How do I diagnosis it?
These patients present with radial wrist pain. On imaging, the following signs can aid in diagnosis.
Terry Thomas sign: This is seen on an AP wrist film and is indicated by a gap >3mm between the scaphoid and lunate bones
Cortical Ring sign: occurs when the scaphoid is in a flexed position, making the scaphoid tubercle more prominent. A measure distance less than 7mm between the end of the cortical ring and the proximal end of the scaphoid suggests scapholunate dissociation and instability.
How do I manage it?
In the ED, patients should be placed in a thumb spica cast for stabilization and referred to orthopaedics for follow up. Operative indication includes injury within 3 weeks and associated imaging and physical exam findings. During this time frame, the SL ligament is still viable for repair.
Great choice by Dr. Ko to highlight these injuries that are often subtle, yet important because of the comorbidities associated with missing the diagnosis.
The Galeazzi fracture is a classic EM boards question, because it is important! It was termed by Campbell as the “fracture of necessity” (modern day translation = “this needs surgery!”) in 1942 because nonoperative management was observed to be associated with recurrent ulna styloid dislocations. Hughston confirmed this is 1957, reporting that 35/38 cases treated nonoperatively had unsatisfactory outcomes.
There’s a saying in orthopedics that “the most commonly missed injury is the second injury”. The radial shaft fracture is usually obvious and can distract the clinician from the less dramatic DRUJ injury. DRUJ injury is radiographically diagnosed by:
Fracture at the BASE of the ulna styloid process (not the tip)
A widened DRUJ (a comparison x ray may be necessary), or
>5mm of shortening of the radius relative to the distal ulna.
A subtle clinical finding often associated with the Galeazzi fracture is anterior interosseus nerve injury. It is a branch of the median nerve and is purely motor, so there will be no sensory deficit or paresthesia! It manifests as loss of pinch strength between the thumb and index finger. So have the patient make the OK sign and resist as you try to open it!
Mayfield, Johnson and Kilcoyne described a pattern of carpal injury caused by wrist hyperextension, ulnar deviation and intercarpal supination in 1980. In their original research on cadavers, progressive hyperextension force was applied and resulted in a consistent, sequential, progressively more unstable intercarpal injury pattern known as the four stages of carpal instability:
Perilunate and triquetral dislocation
Acute scapholunate dissociation is the most common pattern of carpal instability. It occurs secondary to a tear of the scapholunate interosseus ligament. Scapholunate dissociation can also be chronic secondary to arthritic changes when there is no history of recent trauma.
X rays in lunate and perilunate dislocations are often not as clear and obvious as the diagrams used to teach these injuries. The key to realizing that there is a carpal bone dislocation is recognizing that the carpal arcs are disrupted on the AP view. The distal and proximal carpal rows should never overlap on this view. If you recognize this, you will heighten your suspicion and won’t miss these injuries, even if you cannot immediately tell the exact diagnosis.
The name perilunate dislocation has always been a pet peeve of mine. There is no perilunate bone, so this nomenclature just introduces confusion. It should simply be called a capitate dislocation, because that it what it really is.
All of these injuries, and more, are further detailed in our Ortho Teaching Files!
Matthew R. Levine, MD
Department of Emergency Medicine
How to Cite this Post
[Peer-Reviewed, Web Publication] Ko J, Lang S. (2019, Aug 19). Can't Miss Hand and Wrist Fractures in the ED. [NUEM Blog. Expert Commentary by Levine M]. Retrieved from http://www.nuemblog.com/blog/cant-miss-hand-and-wrist-fractures-in-the-ed/.
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To learn more about the diagnosis and management of orthopedic injuries from head to toe, check out our Ortho Teaching Files!
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