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Forearm and wrist radiology: Part II
Printed rn the USA ??Copyright 0 1989 Pergamon Press plc
TheJournal of Emergency Medicine, Vol. 7, pp. 491-496, 1989
FOREARM AND WRIST RADIOLOGY:
PART II
Douglas A. Propp, MD, FACEP, * 0 and Harold Chin, MD, FACEP, t.5 *Education Director, Division of Emergency Medicine, and *Attending Physician, Division of Emergency Medicine, Lutheran General Hospital, Park Ridge, Illinois; $Assistant Professor of Clinical Emergency Medicine, Reprint
address:
University of Illinois Affiliated Hospitals Emergency Medicine Residency, Chicago Douglas A. Propp, MD, Lutheran General Hospital, 1775 W. Dempster Street, Park Ridge, IL 60068
?? Abstract-The emergency physician must be well versed in diagnosing forearm and wrist injuries. Although many of these injuries are readily apparent, others require more sophistication to appreciate. Careful attention to radiographic findings given the assistance of a well-directed history and physical examination is imperative. Both the more common and the more subtle injuries will be discussed.
0 Keywords-radius; dislocations.
the lateral projection, the distal radius, lunate, capitate, and third metacarpal should form a straight line (2). The concavity of the radius and lunate, along with the convexity of the head of the capitate, form three consecutive Cs along a line (see Figure 2, Figure 1) (3,4). A line drawn through the central axis of the scaphoid should be at an angle of 30” to 60” (average 45”) to the longitudinal line of the wrist.
ulna; carpal bones; carpal
Lunate and Perilunate Dislocations RADIOGRAPHY
OF THE WRIST
Lunate and perilunate dislocations are midcarpal dislocations, occurring between the two rows of the carpal bones. They are the result of violent hyperextension injuries such as falls from heights. Clinical findings may be surprisingly subtle and therefore overlooked. The diagnosis is usually made on the lateral radiograph. In a dorsal perilunate dislocation, the lunate retains its normal position but the capitate and the remainder of the carpus are dislocated dorsally (see Figure 3). The normal longitudinal line through the radius, lunate, and capitate is disrupted. On the PA projection, the capitate and lunate overlap and the normal gap between these bones is obliterated. In lunate dislocations, the capitate and carpus are in normal alignment with the radius while the lunate is displaced volarly. Because it resembles a cup spilling its contents toward the palm, the dislocated lunate has been called the “spilled teacup” sign (5). On the PA projection, foreshortening of the wrist is present,
Routine views of the wrist include posteroanterior (PA), lateral (see Figure l), and oblique projections. The properly positioned PA view has no overlap between the radius and ulna at their distal articulation (1). The carpal bones are anatomically arranged into two rows. The proximal row beginning at the radial aspect consists of the scaphoid (navicular), lunate, triquetrum, and pisiform. The distal row contains the greater multangular (trapezium), lesser multangular (trapezoid), capitate, and hamate. Each row forms a continuous arch on the PA view with uniform 2 to 3 mm joint spaces. Any distortion of the intercarpal spaces suggests ligamentous instability or dislocation. Narrowing with sclerosis and spurring is the result of degenerative arthritis. On an appropriately positioned lateral view, the radial and ulnar styloid processes are superimposed with the posterior cortices of these bones lying parallel. The hand should be in the neutral position. On Radiology-This
section of JEM contains articles of interest and original research related to emergency radiology and is coordinated by Jack Keene, MD, of St. Francis Hospital, Poughkeepsie, NY.
RECEIVED:11 March 1988; FINALSUBMISSION RECEIVED:31 August 1988; ACCEPTED:15 September 1988 491
0736-4679/89 $3.00 + .OO
492
Douglas A. Propp, Harold Chin
(a)
Figure 1. Normal AP and lateral wrist. (a) AP vlew of the wrist: the artlcular surface of the radius normally has a 15’ to 30’ angulatlon relative to the artlcular face of the ulna. (b) Lateral view of the wrlst: the pronator quadratus muscle fat stripe Is usually less than 1 cm from the volar surface of the radius. The artlcular surface of the radius has a volar tilt of lo to 23O.
and the space between the capitate and lunate is obliterated. The normal trapezoid appearance of the lunate is also replaced by a triangular shape. This socalled “piece-of-pie” sign is pathognomonic for a lunate dislocation (see Figure 4).
-w-w
A
When the lunate is dislocated, it is pushed into the carpal tunnel, frequently causing a median nerve neuropathy. Complications of perilunate or lunate dislocations also include scaphoid injuries. Since the scaphoid is attached to both the lunate and capitate, it must either fracture or rotate as a consequence of midcarpal dislocations. When a scaphoid fracture accompanies a perilunate dislocation, it is referred to as a transscaphoid perilunate dislocation. Whereas an attempt may be given to closed reduction, early open reduction for lunate and perilunate dislocations is usually necessary.
Rotatory Subluxation of the Scaphoid
Flgure 2. Normal relationship of carpal bones on lateral proJectlon. The f-ad/us, lunate and capltate should lie along a Ilnear axis (A). The concavity of the radius and lunate, and convexity of the capltate form 3 Cs along this axis. A llne drawn along the axis of the scaphold (B) should fall at 30° to 60 ’ to axls A.
Rotatory subluxation or scapholunate dissociation is an injury involving the ligaments supporting the scaphoid, usually due to forceful hyperextension of the wrist. Although this injury is frequently associated with a perilunate dislocation, it may occur alone. On the PA radiograph, the scaphoid may appear shortened with a dense ring-shaped image around its
493
Forearm and Wrist Radiology
Figure 3. Lateral view of perilunate dislocation: the carpal bones are dorsally displaced to the normally sltuated lunate.
(a)
W Figure 4. AP and lateral view of lunate dislocation. (a) Anteroposterior view of the w&t. The displaced lunate appears as a “piece of pie” (arrow). (b) Lateral view of the wrist. The dislocated lunate forms the “spilled teacup” sign (arrow).
494
Douglas A. Propp, Harold Chin
distal perimeter (“ring sign”). This represents the scaphoid seen in an axial projection after volar rotation. A gap between the lunate and scaphoid greater than 3 mm is pathognomonic. This has been called the “l&y Thomas” sign, after the British comedian with a wide gap between his front teeth (6). On the lateral projection, the scaphoid may appear perpen-
Figure 6. AP view of navicular fracture.
(a)
dicular to the longitudinal axis of the wrist (see Figure 5). These injuries are treated with closed reduction and percutaneous pinning or open reduction.
Scaphoid Fractures
(b) Figure 5. AP and lateral view of rotary subluxation of the navlcular. (Photo courtesy of Dr. Sonnenberg. Mercy Hospltal, Chicago, Illinole) (a) Anteroposterior radiograph of the wrist rhowlng the shortened acaphold wlth the rlng sign (arrow) and wldenlng of the scapholunate joint. (b) The lateml view of the wrist shows the longitudinal axis of the scaphold to be at almost 90° to the longitudinal line of the wrist (normal 30° to 60”).
The scaphoid (navicular) is the most frequently fractured carpal bone (see Figure 6). The mechanism is typically a fall on the outstretched hand with forceful dorsiflexion of the wrist. Oblique and scaphoid views may be helpful in delineating subtle fractures. The distortion or obliteration of the thin radiolucent line that normally lies parallel to the scaphoid can be a subtle clue to a fracture (7). Initial radiographic diagnosis may be difficult; 10% of these fractures are not visible on the initial radiograph (8). A presumptive diagnosis of a fracture of the scaphoid can be made on clinical grounds. Well localized tenderness in the anatomical snuffbox is diagnostic for a scaphoid fracture. Pain referred to the anatomic snuffbox when the patient’s hand is supinat-
495
Forearm and Wrist Radiology
ed and pronated against resistance is also considered strong evidence for this injury (9). If these tests are positive, the patient should be treated as if a fracture is present. This treatment includes immobilizing the wrist in a short-arm thumb spica cast and reexamining in 10 days to 2 weeks. Repeat radiographs may demonstrate bone resorption at the fracture site. Displaced fractures often require open reduction and fixation. Failure to diagnose the fracture and inadequate immobilization may lead to delayed union, malunion, or avascular necrosis of the proximal fragment. Lunate Fracture Lunate fractures occur due to an impact on the heel of the hand or a dorsiflexion injury. Fractures of the lunate are frequently overlooked on routine radiographs. Diagnosis depends on finding well-localized tenderness and swelling over the middorsum of the wrist. Radiographic confirmation often requires the use of tomography or a bone scan. If clinical suspicion exists, these injuries should be treated with a thumb spica cast and later re-evaluation. Failure to diagnose and adequately immobilize these fractures may lead to avascular necrosis of the proximal segment (Kienboch’s disease). Triquetrium Fractures This is the second most frequently fractured carpal bone. The fracture usually results from either hyperextension with ulnar deviation or a direct blow to the dorsum of the hand. The majority of these injuries are minor, involving small dorsal chip fractures, best seen on the lateral film (see Figure 7). Treatment generally requires splinting the wrist for three to four weeks.
(a)
Pisiform and Hamate Fractures Fractures of both the pisiform (see Figure 8) and hamate (see Figure 9) present with pain over the base of the hypothenar eminence. These injuries usually result from a fall on the outstretched hand. Fractures of the hook of the hamate may present with the history of a painful grip after an improperly hit shot with a tennis racquet, golf club, or baseball bat (10). Fractures of either of these bones are generally not visible on routine radiographs. Oblique and carpal tunnel vieys may be helpful. The deep branch of the ulnar nerve lies directly between these bones and is frequently injured when they are fractured. These in-
W Figure 7. AP and lateral vlew of triquetrium fracture. (a) Anteroposterior view of wrist failing to demonstrate an obvious fracture. (b) Lateral view of wrist showing dorsal chip fracture of the triquetrium.
496
Douglas A. Propp, Harold Chin
Figure 8. Schematic representation of fracture of pisiform.
juries are treated with immobilization. Surgical excision of the fracture fragments may be necessary if ulnar neuropathy is present.
Figure 9. Schematic representation of fracture of hook of hamate.
lous review of the radiographs with an understanding of the normal anatomy and pathologic signs will assure proper diagnosis. Accurate diagnoses and proper treatment are crucial to maintaining function in wrist and forearm fractures.
CONCLUSION A thorough history and physical examination will usually pinpoint wrist and forearm fractures. Meticu-
authors wish to express their appreciation to Dorothy Bissell and the Lutheran General Medical Group for their help in preparing this manuscript.
1. Hudson T, Cargo1 W, Kaye J. Isolated rotatory subluxation of the carpal navicular. Am J Roentgenol. 1976;126:601. 2. Green D. The sprained wrist. Am J Fam Pratt. 1979;19:114-22. 3. Sonnenberg J. The metacarpals and carpals: fractures, dislocations and instabilities. Trauma Quarterly. 1985;1:61-73. 4. Hamlin D. Diagnosis of wrist injuries. Emerg Med Clin North Am. 1985;3:311-17. 5. O’Brien E. Acute fractures and dislocations of the carpus. Orthop Clin North Am. 1985;15:237-57. 6. Frankel V. The Terry Thomas sign. Clin Orthop. 1978;135:
311-12. 7. Terry D, Ramin J. The navicular fat stripe. Am J Roentgenol. 1975;124:25-8. 8. O’Dell M, Moore J. Scaphoid fracture of the wrist. Am J Fam Pratt. 1984;29:189-94. 9. Waeckerle JF. A prospective study identifying the sensitivity of radiographic findings and the efficacy of clinical findings in carpal navicular fractures. Ann Emerg Med. 1987;16:733-7. 10. Bryan R, Dobyn J. Fractures of the carpal bones other than lunate and navicular. Clin Orthop. 1980;149:107-11.
Acknowledgment-The
TheJournal of Emergency Medicine, Vol. 7, pp. 491-496, 1989
FOREARM AND WRIST RADIOLOGY:
PART II
Douglas A. Propp, MD, FACEP, * 0 and Harold Chin, MD, FACEP, t.5 *Education Director, Division of Emergency Medicine, and *Attending Physician, Division of Emergency Medicine, Lutheran General Hospital, Park Ridge, Illinois; $Assistant Professor of Clinical Emergency Medicine, Reprint
address:
University of Illinois Affiliated Hospitals Emergency Medicine Residency, Chicago Douglas A. Propp, MD, Lutheran General Hospital, 1775 W. Dempster Street, Park Ridge, IL 60068
?? Abstract-The emergency physician must be well versed in diagnosing forearm and wrist injuries. Although many of these injuries are readily apparent, others require more sophistication to appreciate. Careful attention to radiographic findings given the assistance of a well-directed history and physical examination is imperative. Both the more common and the more subtle injuries will be discussed.
0 Keywords-radius; dislocations.
the lateral projection, the distal radius, lunate, capitate, and third metacarpal should form a straight line (2). The concavity of the radius and lunate, along with the convexity of the head of the capitate, form three consecutive Cs along a line (see Figure 2, Figure 1) (3,4). A line drawn through the central axis of the scaphoid should be at an angle of 30” to 60” (average 45”) to the longitudinal line of the wrist.
ulna; carpal bones; carpal
Lunate and Perilunate Dislocations RADIOGRAPHY
OF THE WRIST
Lunate and perilunate dislocations are midcarpal dislocations, occurring between the two rows of the carpal bones. They are the result of violent hyperextension injuries such as falls from heights. Clinical findings may be surprisingly subtle and therefore overlooked. The diagnosis is usually made on the lateral radiograph. In a dorsal perilunate dislocation, the lunate retains its normal position but the capitate and the remainder of the carpus are dislocated dorsally (see Figure 3). The normal longitudinal line through the radius, lunate, and capitate is disrupted. On the PA projection, the capitate and lunate overlap and the normal gap between these bones is obliterated. In lunate dislocations, the capitate and carpus are in normal alignment with the radius while the lunate is displaced volarly. Because it resembles a cup spilling its contents toward the palm, the dislocated lunate has been called the “spilled teacup” sign (5). On the PA projection, foreshortening of the wrist is present,
Routine views of the wrist include posteroanterior (PA), lateral (see Figure l), and oblique projections. The properly positioned PA view has no overlap between the radius and ulna at their distal articulation (1). The carpal bones are anatomically arranged into two rows. The proximal row beginning at the radial aspect consists of the scaphoid (navicular), lunate, triquetrum, and pisiform. The distal row contains the greater multangular (trapezium), lesser multangular (trapezoid), capitate, and hamate. Each row forms a continuous arch on the PA view with uniform 2 to 3 mm joint spaces. Any distortion of the intercarpal spaces suggests ligamentous instability or dislocation. Narrowing with sclerosis and spurring is the result of degenerative arthritis. On an appropriately positioned lateral view, the radial and ulnar styloid processes are superimposed with the posterior cortices of these bones lying parallel. The hand should be in the neutral position. On Radiology-This
section of JEM contains articles of interest and original research related to emergency radiology and is coordinated by Jack Keene, MD, of St. Francis Hospital, Poughkeepsie, NY.
RECEIVED:11 March 1988; FINALSUBMISSION RECEIVED:31 August 1988; ACCEPTED:15 September 1988 491
0736-4679/89 $3.00 + .OO
492
Douglas A. Propp, Harold Chin
(a)
Figure 1. Normal AP and lateral wrist. (a) AP vlew of the wrist: the artlcular surface of the radius normally has a 15’ to 30’ angulatlon relative to the artlcular face of the ulna. (b) Lateral view of the wrlst: the pronator quadratus muscle fat stripe Is usually less than 1 cm from the volar surface of the radius. The artlcular surface of the radius has a volar tilt of lo to 23O.
and the space between the capitate and lunate is obliterated. The normal trapezoid appearance of the lunate is also replaced by a triangular shape. This socalled “piece-of-pie” sign is pathognomonic for a lunate dislocation (see Figure 4).
-w-w
A
When the lunate is dislocated, it is pushed into the carpal tunnel, frequently causing a median nerve neuropathy. Complications of perilunate or lunate dislocations also include scaphoid injuries. Since the scaphoid is attached to both the lunate and capitate, it must either fracture or rotate as a consequence of midcarpal dislocations. When a scaphoid fracture accompanies a perilunate dislocation, it is referred to as a transscaphoid perilunate dislocation. Whereas an attempt may be given to closed reduction, early open reduction for lunate and perilunate dislocations is usually necessary.
Rotatory Subluxation of the Scaphoid
Flgure 2. Normal relationship of carpal bones on lateral proJectlon. The f-ad/us, lunate and capltate should lie along a Ilnear axis (A). The concavity of the radius and lunate, and convexity of the capltate form 3 Cs along this axis. A llne drawn along the axis of the scaphold (B) should fall at 30° to 60 ’ to axls A.
Rotatory subluxation or scapholunate dissociation is an injury involving the ligaments supporting the scaphoid, usually due to forceful hyperextension of the wrist. Although this injury is frequently associated with a perilunate dislocation, it may occur alone. On the PA radiograph, the scaphoid may appear shortened with a dense ring-shaped image around its
493
Forearm and Wrist Radiology
Figure 3. Lateral view of perilunate dislocation: the carpal bones are dorsally displaced to the normally sltuated lunate.
(a)
W Figure 4. AP and lateral view of lunate dislocation. (a) Anteroposterior view of the w&t. The displaced lunate appears as a “piece of pie” (arrow). (b) Lateral view of the wrist. The dislocated lunate forms the “spilled teacup” sign (arrow).
494
Douglas A. Propp, Harold Chin
distal perimeter (“ring sign”). This represents the scaphoid seen in an axial projection after volar rotation. A gap between the lunate and scaphoid greater than 3 mm is pathognomonic. This has been called the “l&y Thomas” sign, after the British comedian with a wide gap between his front teeth (6). On the lateral projection, the scaphoid may appear perpen-
Figure 6. AP view of navicular fracture.
(a)
dicular to the longitudinal axis of the wrist (see Figure 5). These injuries are treated with closed reduction and percutaneous pinning or open reduction.
Scaphoid Fractures
(b) Figure 5. AP and lateral view of rotary subluxation of the navlcular. (Photo courtesy of Dr. Sonnenberg. Mercy Hospltal, Chicago, Illinole) (a) Anteroposterior radiograph of the wrist rhowlng the shortened acaphold wlth the rlng sign (arrow) and wldenlng of the scapholunate joint. (b) The lateml view of the wrist shows the longitudinal axis of the scaphold to be at almost 90° to the longitudinal line of the wrist (normal 30° to 60”).
The scaphoid (navicular) is the most frequently fractured carpal bone (see Figure 6). The mechanism is typically a fall on the outstretched hand with forceful dorsiflexion of the wrist. Oblique and scaphoid views may be helpful in delineating subtle fractures. The distortion or obliteration of the thin radiolucent line that normally lies parallel to the scaphoid can be a subtle clue to a fracture (7). Initial radiographic diagnosis may be difficult; 10% of these fractures are not visible on the initial radiograph (8). A presumptive diagnosis of a fracture of the scaphoid can be made on clinical grounds. Well localized tenderness in the anatomical snuffbox is diagnostic for a scaphoid fracture. Pain referred to the anatomic snuffbox when the patient’s hand is supinat-
495
Forearm and Wrist Radiology
ed and pronated against resistance is also considered strong evidence for this injury (9). If these tests are positive, the patient should be treated as if a fracture is present. This treatment includes immobilizing the wrist in a short-arm thumb spica cast and reexamining in 10 days to 2 weeks. Repeat radiographs may demonstrate bone resorption at the fracture site. Displaced fractures often require open reduction and fixation. Failure to diagnose the fracture and inadequate immobilization may lead to delayed union, malunion, or avascular necrosis of the proximal fragment. Lunate Fracture Lunate fractures occur due to an impact on the heel of the hand or a dorsiflexion injury. Fractures of the lunate are frequently overlooked on routine radiographs. Diagnosis depends on finding well-localized tenderness and swelling over the middorsum of the wrist. Radiographic confirmation often requires the use of tomography or a bone scan. If clinical suspicion exists, these injuries should be treated with a thumb spica cast and later re-evaluation. Failure to diagnose and adequately immobilize these fractures may lead to avascular necrosis of the proximal segment (Kienboch’s disease). Triquetrium Fractures This is the second most frequently fractured carpal bone. The fracture usually results from either hyperextension with ulnar deviation or a direct blow to the dorsum of the hand. The majority of these injuries are minor, involving small dorsal chip fractures, best seen on the lateral film (see Figure 7). Treatment generally requires splinting the wrist for three to four weeks.
(a)
Pisiform and Hamate Fractures Fractures of both the pisiform (see Figure 8) and hamate (see Figure 9) present with pain over the base of the hypothenar eminence. These injuries usually result from a fall on the outstretched hand. Fractures of the hook of the hamate may present with the history of a painful grip after an improperly hit shot with a tennis racquet, golf club, or baseball bat (10). Fractures of either of these bones are generally not visible on routine radiographs. Oblique and carpal tunnel vieys may be helpful. The deep branch of the ulnar nerve lies directly between these bones and is frequently injured when they are fractured. These in-
W Figure 7. AP and lateral vlew of triquetrium fracture. (a) Anteroposterior view of wrist failing to demonstrate an obvious fracture. (b) Lateral view of wrist showing dorsal chip fracture of the triquetrium.
496
Douglas A. Propp, Harold Chin
Figure 8. Schematic representation of fracture of pisiform.
juries are treated with immobilization. Surgical excision of the fracture fragments may be necessary if ulnar neuropathy is present.
Figure 9. Schematic representation of fracture of hook of hamate.
lous review of the radiographs with an understanding of the normal anatomy and pathologic signs will assure proper diagnosis. Accurate diagnoses and proper treatment are crucial to maintaining function in wrist and forearm fractures.
CONCLUSION A thorough history and physical examination will usually pinpoint wrist and forearm fractures. Meticu-
authors wish to express their appreciation to Dorothy Bissell and the Lutheran General Medical Group for their help in preparing this manuscript.
1. Hudson T, Cargo1 W, Kaye J. Isolated rotatory subluxation of the carpal navicular. Am J Roentgenol. 1976;126:601. 2. Green D. The sprained wrist. Am J Fam Pratt. 1979;19:114-22. 3. Sonnenberg J. The metacarpals and carpals: fractures, dislocations and instabilities. Trauma Quarterly. 1985;1:61-73. 4. Hamlin D. Diagnosis of wrist injuries. Emerg Med Clin North Am. 1985;3:311-17. 5. O’Brien E. Acute fractures and dislocations of the carpus. Orthop Clin North Am. 1985;15:237-57. 6. Frankel V. The Terry Thomas sign. Clin Orthop. 1978;135:
311-12. 7. Terry D, Ramin J. The navicular fat stripe. Am J Roentgenol. 1975;124:25-8. 8. O’Dell M, Moore J. Scaphoid fracture of the wrist. Am J Fam Pratt. 1984;29:189-94. 9. Waeckerle JF. A prospective study identifying the sensitivity of radiographic findings and the efficacy of clinical findings in carpal navicular fractures. Ann Emerg Med. 1987;16:733-7. 10. Bryan R, Dobyn J. Fractures of the carpal bones other than lunate and navicular. Clin Orthop. 1980;149:107-11.
Acknowledgment-The