Foot Fractures Frequently Misdiagnosed as Ankle Sprains
DANIEL B. JUDD, M.D. and DAVID H. KIM, M.D.
Tripler Army Medical Center, Honolulu, Hawaii
<!-- #BeginLibraryItem "/Library/afp_abstract-pdf.lbi" --><TABLE cellSpacing=0 cellPadding=0><TBODY><TR vAlign=top><TD vAlign=center align=left>Most ankle injuries are straightforward ligamentous injuries. However, the clinical presentation of subtle fractures can be similar to that of ankle sprains, and these fractures are frequently missed on initial examination. Fractures of the talar dome may be medial or lateral, and they are usually the result of inversion injuries, although medial injuries may be atraumatic. Lateral talar process fractures are characterized by point tenderness over the lateral process. Posterior talar process fractures are often associated with tenderness to deep palpation anterior to the Achilles tendon over the posterolateral talus, and plantar flexion may exacerbate the pain. These fractures can often be managed nonsurgically with nonweight-bearing status and a short leg cast worn for approximately four weeks. Delays in treatment can result in long-term disability and surgery. Computed tomographic scans or magnetic resonance imaging may be required because these fractures are difficult to detect on plain films. (Am Fam Physician 2002;66:785-94. Copyright© 2002 American Academy of Family Physicians.)
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Ankle injuries are commonly evaluated by primary care and emergency physicians. Most of these injuries do not pose a diagnostic dilemma and can be managed nonsurgically without a prolonged or costly work-up. However, the clinical presentation of some subtle fractures can be similar to that of routine ankle sprains, and they are commonly misdiagnosed as such. Many of these injuries, if left without a definitive diagnosis, result in long-term disability (Table 1).
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Summary and Comparison of Presented Fractures
<HR></TD></TR><TR><TD vAlign=bottom><TABLE class=a10 cellSpacing=0 cellPadding=4><TBODY><TR class=s15 vAlign=bottom><TD vAlign=bottom align=left>Fracture type</TD><TD vAlign=bottom align=left>Mechanism of injury</TD><TD vAlign=bottom align=left>Important physical examination findings*</TD><TD class=s16 vAlign=bottom align=left>Best plain radiograph†</TD><TD vAlign=bottom align=left>Treatment</TD></TR><TR class=s18><TD vAlign=top align=left>Talar dome (lateral) </TD><TD vAlign=top align=left>Inversion with dorsiflexion</TD><TD vAlign=top align=left>Tenderness anterior to the lateral malleolus, along the anterior border of the talus </TD><TD vAlign=top align=left>Mortise view: shallow, wafer-shaped lesion</TD><TD vAlign=top align=left>Stage I or II (see Table 3): NWBSLC for six weeks
Stage III or IV (see Table 3), or persistent symptoms: surgical treatment</TD></TR><TR class=s18 vAlign=top><TD vAlign=top align=left bgColor=#eaf1e2>Talar dome(medial)</TD><TD vAlign=top align=left bgColor=#eaf1e2>Inversion with plantar flexion or atraumatic</TD><TD vAlign=top align=left bgColor=#eaf1e2>Tenderness posterior to the medial malleolus, along the posterior border of the talus</TD><TD vAlign=top align=left bgColor=#eaf1e2>AP view: deep, cup-shaped lesion; initial radiograph can be normal because changes in subchondral bone may not develop for weeks.</TD><TD vAlign=top align=left bgColor=#eaf1e2>Stage I, II, or III (see Table 3): NWBSLC for six weeks
Stage IV (see Table 3): surgical treatment</TD></TR><TR class=s18><TD vAlign=top align=left>Lateral talar process</TD><TD vAlign=top align=left>Rapid inversion with dorsiflexion </TD><TD vAlign=top align=left>Point tenderness over the lateral process (anterior and inferior to the lateral malleolus)</TD><TD vAlign=top align=left>Mortise view; lateral view may show subtalar effusion</TD><TD vAlign=top align=left>Small fragment with <2 mm displacement: NWBSLC for four to six weeks
Large or displaced fragments: operative treatment</TD></TR><TR class=s18 vAlign=top><TD vAlign=top align=left bgColor=#eaf1e2>Posterior talarprocess (lateral tubercle)</TD><TD vAlign=top align=left bgColor=#eaf1e2>Hyperplantar flexion or forced inversion</TD><TD vAlign=top align=left bgColor=#eaf1e2>Tenderness to deep palpation anterior to the Achillestendon over posterolateral talus
Plantar flexion may reproduce pain.</TD><TD vAlign=top align=left bgColor=#eaf1e2>Lateral radiograph (anaccessory ossicle, the os trigonum, may be present)</TD><TD vAlign=top align=left bgColor=#eaf1e2>Minimally displaced fracture: NWBSLC for four to six weeks
Large or displaced fragments or persistent symptoms: operative treatment</TD></TR><TR><TD vAlign=top align=left>Posterior talar process (medial tubercle)</TD><TD vAlign=top align=left>Dorsiflexion with pronation</TD><TD vAlign=top align=left>Tenderness to deep palpation between the medial malleolusand the Achilles tendon</TD><TD vAlign=top align=left>Difficult with standard views; an oblique ankle radiographtaken with the foot placedin 40 degrees of external rotation has been successful.</TD><TD vAlign=top align=left>Similar to lateral tubercle fractures</TD></TR><TR class=s18 vAlign=top><TD vAlign=top align=left bgColor=#eaf1e2>Anterior process of the calcaneus</TD><TD vAlign=top align=left bgColor=#eaf1e2>Inversion withplantar flexion can lead to an avulsion fracture.
Forced dorsiflexion can cause a compression fracture.</TD><TD vAlign=top align=left bgColor=#eaf1e2>Point tenderness over the calcanealcuboid joint (approximately 1 cm inferior and 3 to 4 cm anterior to the lateral malleolus)</TD><TD vAlign=top align=left bgColor=#eaf1e2>Lateral radiograph (an accessory ossicle, the calcaneus secondarium,may be present)</TD><TD vAlign=top align=left bgColor=#eaf1e2>Small nondisplaced fracture:nonweight-bearing with compressive dressing or NWBSLC for four to six weeks
Large or displaced fractures may require operative treatment.</TD></TR></TBODY></TABLE><HR></TD></TR><TR><TD vAlign=top>AP = anteroposterior; NWBSLC = nonweight-bearing, short leg cast.
*--Acutely, most fractures will have symptoms very similar to those of ankle sprains: swelling, ecchymosis, ligamentous laxity, tenderness, and decreased range of motion.
†--All of these fractures can have subtle findings on plain radiograph, and computed tomography or magnetic resonance imaging may be required to accurately confirm or characterize a fracture.
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This article features subtle fractures to facilitate timely diagnosis and treatment of these less-common injuries. These fractures should be considered in the differential diagnosis of any acute ankle sprain, as well as any suspected sprain that does not improve with routine treatment (Table 2).