Missed Radiologic Injuries
Michelle Lin, MD
Associate Residency Director, UCSF-SFGH Emergency Medicine Residency
Assistant Clinical Professor of Medicine, UC San Francisco
San Francisco General Hospital, Emergency Services
mlin@sfghed.ucsf.edu
MEDICOLEGAL SIGNIFICANCE
1. Missed orthopedic injuries, such as fractures and dislocations, comprise the largest source of
malpractice claims in the emergency department, according to a study conducted by the
American College of Emergency Physicians during the period of 1974-1985. [44%
pelvis / vertebra, 22% extremity, 14% hand]
2. Various studies corroborate that these injuries comprise a significant # of medical claims.
• Pennsylvania Hospital Insurance Company (1977-1981): 19% of 200 ED malpractice
cases were due to “misinterpretation of radiographs.” (Trautlein et al.)
• Chicago (1975-1994): Retrospective study of 18860 malpractice claims showed 12%
involved radiology cases, of which missed diagnoses was the #1 cause of litigation.
(Berlin and Berlin)
• Massachusetts Joint Underwriters Association: Missed fractures comprised 20% (during
1980-1987) and 10% (1988-1990) of malpractice claims. (Karcz et al, 1993)
3. The majority of malpractice claims on misread radiographs are those whose radiographs were
taken during “off” hours.
• 63% malpractice suits occur from incidents during 6 pm-1 am (weekends) and midnight7 am (weekdays)
• ED radiograph interpretations during non-business hours are often provided by EP’s.
• Over 80% acute care hospitals do not have 24/7 radiologist interpretation available.
• Radiographic interpretation discrepancy rate between an EP and radiologist = 2-11%.
(Lufkin et al, Robinson et al, Scott et al)
ERRORS IN RADIOGRAPH INTERPRETATION
Commonly missed, high-risk injuries on radiographs can be
remembered by using my mnemonic “DOH.” (similar
to what your response might be when a patient is
recalled for your incorrect radiology interpretation…)
Ortho Radiography (Lin) 2
Wrist
D islocations
Scapholunate DS
Perilunate DL and Lunate DL
O ccult fracture
Scaphoid
Triquetrum
H alf of injuries missed
Galeazzi
Distal Radius Fx + Carpal Injury
Elbow
Radial head DL
Radial head
Monteggia
Pelvis/ Hip
Hip DL
Femoral neck
Sacrum
Acetabulum
Another ring fracture
Knee
Knee DL
Tibial plateau
Segond
Patella
Maisonneuve
Foot
Lisfranc injury
Calcaneus
Talus
Thoracolumbar + Calcaneus fx
Abbreviations: “DL” – dislocation, “DS” – dissociation, “Fx” – fracture
WRIST
Normal Anatomy
PA View (R Wrist):
 3 smooth arcs
along carpals
 Intercarpal
distance < 3 mm
PA
View
Lateral View (Right Wrist):
 Alignment: Smooth
articulation of distal
radius to lunate, lunate to
capitate, and capitate to
3rd metacarpal
 Scapholunate angle < 3060 degrees
Lateral
View
Ortho Radiography (Lin) 3
D islocation
1. SCAPHOLUNATE DISSOCIATION
Most common and significant ligamentous injury of wrist.
Rotatory subluxation of scaphoid into more transverse
orientation.
Mechanism: Fall on outstretched hand (FOOSH)
Xray:
 PA view: >4 mm widening of scapholunate space
(“Terry Thomas sign”)
 PA view: Scaphoid has “signet ring sign”
 Lateral view: Scapholunate angle > 60 deg
PA View of R Wrist
2. PERILUNATE DISLOCATION
Mechanism: Hyperextension of the wrist
Xray:
 Lateral view: Capitate is not vertically aligned with
the lunate and radius.
 PA view: Smooth middle arc alignment of carpal
bones is disrupted.
Complications: Median nerve injury, SLAC
Lateral View of R Wrist
3. LUNATE DISLOCATION
Mechanism: Fall backwards on outstretched hand
Xray:
 Lateral view: Lunate is rotated out of alignment into
“spilled teacup” position
 PA view: Smooth proximal arc of carpal bones is disrupted
 PA view: Lunate appears triangular (rather than
quadrilateral)
Complication: Median nerve injury, SLAC
Lateral View of R Wrist
O ccult Fracture
1. SCAPHOID FRACTURE
2nd most common fractured bone of the wrist [#1=distal radius]
At a teaching hospital ED, the “miss rate” was greatest for
scaphoid fractures (13%) (Freed and Shields)
Mechanism: FOOSH
Exam: Tenderness to “snuffbox” area of wrist
Xray:
 Normal in up to 20% cases (Waeckerle)
 Consider obtaining additional scaphoid views
Ulnar deviated AP View
of R Wrist
Ortho Radiography (Lin) 4
 Teaching Pearl: Apply thumb spica splint to all wrists
with snuffbox tenderness regardless of normal xrays
Complication:
 Avascular necrosis (AVN)
 Nonunion rate increases 5-45% when treatment is delayed > 4 weeks (Langhoff and
Andersen)
 SLAC (Scapholunate Advanced Collapse) – Scaphoid and/or lunate undergoes AVN and
collapses
2. TRIQUETRUM FRACTURE
Accounts for 10% of carpal bone fractures
Mechanism: FOOSH
Exam: Tenderness to ulnar aspect of dorsal wrist
Xray: Most easily seen on lateral since triquetrum is most
dorsal carpal bone
Oblique View of R Wrist
Oblique View of R Wrist
H alf of Injuries Missed
1. GALEAZZI FRACTURE
Distal-third fracture of the radius AND disruption of distal radioulnar joint (DRUJ)
Mechanism: FOOSH with forearm hyperpronated
Signs of DRUJ:
 Lateral view: Ulna does not overlie radius
 Lateral view: Ulnar styloid is not aligned with dorsal triquetrum
 PA view: Ulnar styloid fracture
 PA view: Widening of DRUJ
Complication: Chronic disability when DRUJ disruption is
missed > 10 wks
Lateral view
of R forearm
2. DISTAL RADIUS FX + CARPAL INJURY
Because of the same FOOSH mechanism of injury, scapholunate dissociation may also be
present. In a small retrospective study of 52 patients, 69% of distal radius fractures were
associated with scapholunate dissociation (Lee et al.)
Radial styloid fractures are associated with scaphoid / lunate fractures & ligamentous injury.
Ortho Radiography (Lin) 5
ELBOW
Normal Anatomy
Capitellum: Portion of distal humerus which articulates with the radial head
LATERAL VIEW
Fat pads: Collections of fat tissue
adjacent to elbow joint capsule
(appears black on xrays)
 Anterior fat pad
 Can be normal
 If displaced and elevated, is
pathologic (sail sign)
 Posterior fat pad
 Always abnormal if visualized
AP VIEW
Lines: Misalignment of normal
structures can be a subtle
indicator of a fracture or
dislocation
 Radiocapitellate line: On both
the AP and lateral views, a
longitudinal line drawn
through the midshaft radius
should bisect the capitellum.
An abnormal alignment
suggests a radial head
dislocation.
 Anterior humeral line: On the
lateral view, a longitudinal line
drawn along the anterior
aspect of the humerus should
bisect the capitellum. An
abnormal alignment suggests a
supracondylar fracture.
Ortho Radiography (Lin) 6
D islocation
RADIAL HEAD DISLOCATION
When identified, must look for a proximal ulnar fracture (see “Monteggia Fracture”)
O ccult Fracture
RADIAL HEAD FRACTURE
At a teaching hospital ED, the “miss rate” was 2nd
greatest for elbow fractures at 10.8%. In adults,
these fractures were primarily missed radial head
fractures. (Freed and Shields)
Mechanism: FOOSH
Lateral view
of R elbow
Xray:
 Cortical break in the radial head may be very subtle or even absent in a nondisplaced fx
 Large anterior fat pad (“Sail sign”)
 Any posterior fat pad
 In the study by Freed and Shields: >80% had an associated fat pad and >40% had ONLY
a fat pad sign as indicator of a fracture.
Pearl: Sling patients with elbow pain and abnormal fat pads despite no obvious fracture.
H alf of Injuries Missed
MONTEGGIA FRACTURE
Proximal ulna fracture AND radial head dislocation
Missed in 50% pediatric population – importance of
alignment of radiocapitellate line (Gleeson
and Beattie)
Mechanism: FOOSH with rotational forces
Xray:
 Obvious proximal ulna fracture
 Misalignment of radiocapitellate line
Pearl: Beware of diagnosis of isolated proximal ulna fx!
Lateral view of R elbow
Ortho Radiography (Lin) 7
PELVIS / HIP
Normal anatomy
AP View
D islocation
HIP DISLOCATION
Most commonly posterior from dashboard injuries in MVA’s.
Posterior: Affected leg is shortened and internally rotated
Anterior: Aftected leg is shortened and externally rotated
Since hip dislocations are associated with femoral head /
acetabular fx’s, consider a CT for unsuccessful reduction
to assess for intraarticular bone fragments.
AP view of L Hip
O ccult Fracture
1. FEMORAL NECK FRACTURE
Most commonly missed hip fracture
Sometimes elderly patients can weight-bear despite a fx.
Mechanism: From direct blunt trauma (fall)
Xray:
 Can be very subtle
 Cortical disruption or impacted hyperlucency
 Loss of smooth cortical transition from femoral
neck to head.
 Trabecular disruption
AP view of R hip
Delay in Diagnosis:
 Radiographically occult hip fx’s occur in 2-9%.
 One study had 16/825 missed hip fractures. 15/16 were initially nondisplaced but
became displaced secondary to the delayed diagnosis. (Parker)
Additional Imaging: Consider MRI (CT is ok alterative, but less sensitive) if still clinically
suspicious because of the risk of missing a nondisplaced fracture and having the patient
return with a displaced fracture. MRI sensitivity and specificity = 100%.
Ortho Radiography (Lin) 8
2. SACRAL FRACTURE
In one study: 72% of sacral alar fractures were missed
initially. (Jackson et al.)
Xray: Subtle break in smooth sacral alar lines
Additional Imaging:
 Pelvic “outlet views” improve visualization of the
sacrum and rami.
 CT required to assess severity of sacral fracture and
additional fx’s.
AP view of sacrum
3. ACETABULAR FRACTURE
Anterior acetabular fracture: Detected by break in iliopubic line
Posterior acetabular fracture: Detected by a break in the
ilioischial line; look specifically “behind” superimposed
femoral head
Additional Imaging:
 Can get additional Judet views to assess for clinically
suspicious cases
 Requires CT assessment to assess severity and because 40%
of associated intraarticular bone fragments and 50% of
femoral head fractures are missed initially. (Lipman)
AP View of R hip
H alf of Injuries Missed
PELVIC RING DISRUPTION
Because of the inflexible, ring-like structure of the pelvis, pelvic bone injuries are often
found in multiples. In addition to the already mentioned injuries, also beware of subtle rami
fractures and sacroiliac dissociation.
Ortho Radiography (Lin) 9
KNEE
Normal Anatomy
AP
View
Lateral
View
Ortho Radiography (Lin) 10
D islocation
KNEE DISLOCATION
Not a subtle clinical or radiographic finding
40% have associated popliteal artery injury
regardless of pedal pulses and reducibility.
Requires angiography
Lateral view of
R knee
O ccult Fracture
1. TIBIAL PLATEAU FRACTURE
32% of all knee fractures
Mechanism: Valgus force with axial load (knee vs. car bumper)
Sensitivity of radiographs: 79% for 2-view, 85% for 4-view
(Gray et al.)
Pearl: When a patient with knee pain from blunt trauma can not
walk, be sure that oblique views are obtained to assess for a
tibial plateau fracture. Consider CT despite radiographically
negative findings in a patient.
Additional Imaging:
 Oblique views (plain radiographs), CT to assess for severity
2. SEGOND FRACTURE
Small proximal lateral tibial avulsion fx
Often associated with an ACL tear
AP view of R knee
3. PATELLA FRACTURE
40% of all knee fractures
Additional Imaging: “Sunrise” view
AP View
of L knee
Lateral
View
of R knee
H alf of Injuries Missed
MAISONNEUVE FRACTURE
 Proximal fibula fracture AND medial malleolus (or deltoid ligament) fracture
 Mechanism: Abduction and external rotation of ankle
PLUS
AP View of R Knee
AP View of R Ankle
Ortho Radiography (Lin) 11
FOOT
Normal Anatomy
Lateral View
PA
View
PA View: The medial edges of the 2nd
metatarsal and 2nd cuneiform should align.
Lateral View:
 Bohler’s angle (generated by a line
bordering the superior aspect of the
posterior calcaneal tuberosity and a
line connecting the superior subtalar
articular surface and superior aspect
of the anterior calcaneal process)
normally is 20-40 degrees.
 A Bohler’s angle < 20 degrees
implies an occult calcaneal fracture.
Oblique
View
Oblique View: The medial edges of the 3rd
metatarsal and 3rd cuneiform should align.
Ortho Radiography (Lin) 12
D islocation
LISFRANC INJURY
Tarsal-metatarsal (MT) fracture/dislocation pattern
20% are initially missed (Goossens and DeStoop)
LisFranc ligament: Attaches 2nd MT base to 1st cuneiform.
Xray: Fracture of 2nd metatarsal base or Lisfranc
ligament and subsequent dislocation of MT #2-5
from the midfoot
Pearl: An avulsion fracture of the 2nd metatarsal base alone
is a LisFranc fracture DESPITE a normal alignment of
the metacarpals with the tarsal bones, because the
LisFranc ligament inserts at its base.
Complications: Compartment syndrome
AP view of R foot
O ccult Fracture
1. CALCANEUS FRACTURE
At a teaching hospital ED, the “miss rate” was 3rd greatest for
calcaneal fractures at 10%. (Freed and Shields)
Most commonly fractured tarsal bone
Mechanism: Often from fall on heels from a height
Xray:
 A Bohler’s angle < 20 degrees suggests a fracture.
Additional Imaging:
 Consider obtaining a “calcaneal view”
 Often requires CT imaging to assess fragments
Complication: Compartment syndrome
Lateral View of L foot
2. TALUS FRACTURE
Second most commonly fracture tarsal bone
The neck is the most common location of a talar fracture.
Mechanism: Excessive dorsiflexion of ankle
Xray: Can be subtle cortical break on lateral view
Complications of neck fracture: Avascular necrosis,
subchondral collapse, and degenerative arthritis
Lateral View of R foot
H alf of Injuries Missed
CALCANEUS FRACTURES:
10% associated with THORACOLUMBAR FRACTURE
because of load on axial skeleton when landing on the heels
Lateral View of
Lumbar Spine
Ortho Radiography (Lin) 13
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