Radiology

Subtalar Dislocations

Case

A 24 year-old male presents with right foot pain after falling off of a 12 foot ladder, his foot locked in supination, with obvious deformed (Figure 1). Pulses, sensation, and motor function intact distally. X-rays are ordered (Figure 2).

Figure 1: Right foot physical examination findings.  Pictures: http://westjem.com/articles/subtalar-dislocation.html

Figure 1: Right foot physical examination findings.

Pictures: http://westjem.com/articles/subtalar-dislocation.html

Figure 2: Plain films of right foot.  http://westjem.com/articles/subtalar-dislocation.html

Figure 2: Plain films of right foot.

http://westjem.com/articles/subtalar-dislocation.html

Diagnosis

Subtalar dislocation

Background

This is a rare injury; it accounts for approximately 1 – 2% of all dislocations. This can look similar to an ankle dislocation on examination, but the tibiotalar joint and mortise are intact.

These injuries typically from a high energy mechanism such as a fall from height or high energy motor vehicle collision (MVC). Typically to cause this dislocation, an axial load is applied when the patient has a plantar flexed foot. Patients may get these injuries from lower energy mechanisms such as sport injuries or fall from standing, especially if the patient is elderly or obese. Most injuries tend to be male (3:1 ratio) and in the third decade of life.

Subtalar dislocation is the disruption of the articulation of both the talocalcaneal and the talonavicular joints with an intact ankle joint mortis. This involves disruption of the surrounding ligaments: interosseous talocalcaneal ligament (most important), anterior talocalcaneal ligament, posterior talocalcaneal ligament, lateral talocalcaneal ligament, and medial talocalcaneal ligament.

Approximately 25% of these injuries are open upon presentation to the ED. There is high risk of skin necrosis from tenting over malleolus or talar head, which can convert these injuries to open dislocations.

Types of Subtalar Dislocations

The vast majority of subtalar dislocations are either medial (85%) or lateral (15%). Anterior and posterior dislocations can also occur.

Medial Subtalar Dislocation

This is the most common type of subtalar dislocation. It typically results from an inversion injury with a plantar flexed foot. It is sometimes called “basketball foot” as this is a common mechanism. Another term for this injury is “acquired clubfoot.” On physical exam, you will find that the foot is inverted, the calcaneus is displaced medially, and the foot is locked in supination.

On AP x-ray, the calcaneus will be displaced medially (Figure 3). Lateral x-ray will show that the talar head is superior to the navicular (Figure 4).

Figure 3: AP view of medial subtalar dislocation.   http://www.radpod.org/wp-content/uploads/2011/05/ser000img000011.jpg

Figure 3: AP view of medial subtalar dislocation.

http://www.radpod.org/wp-content/uploads/2011/05/ser000img000011.jpg

Figure 4: Lateral view of medial subtalar dislocation showing that the head of the talus is superior to the navicular.   http://www.orthobullets.com/trauma/1050/subtalar-dislocations

Figure 4: Lateral view of medial subtalar dislocation showing that the head of the talus is superior to the navicular.

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Lateral Subtalar Dislocation

Lateral subtalar dislocations account for around 15% of subtalar dislocations. On physical examination, you will find that the foot is everted, the calcaneus is lateral to talus, and the foot is locked in pronation. AP x-ray will show lateral displacement of the calcaneus (Figure 5). On lateral views, the talar head with be inferior to the navicular (Figure 6). Lateral dislocations tend to result from higher mechanism injuries; therefore, these injuries are more likely to be open and have more associated injuries.

Figure 5: AP view of a lateral subtalar dislocation.  http://www.wheelessonline.com/image3/i1/subdis1.jpg

Figure 5: AP view of a lateral subtalar dislocation. http://www.wheelessonline.com/image3/i1/subdis1.jpg

Figure 6: Lateral view of lateral subtalar dislocation showing the head of the talus is inferior to the navicular   http://www.orthobullets.com/trauma/1050/subtalar-dislocations

Figure 6: Lateral view of lateral subtalar dislocation showing the head of the talus is inferior to the navicular

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Figure 7: Physical exam findings for a lateral subtalar dislocation.   https://faoj.files.wordpress.com/2008/11/tdisfig_1.jpg

Figure 7: Physical exam findings for a lateral subtalar dislocation.

https://faoj.files.wordpress.com/2008/11/tdisfig_1.jpg

Anterior and Posterior Dislocations

There are case reports of anterior and posterior dislocations, but these are exceedingly rare. They account for around 1% of subtalar dislocations.

Reduction technique

Reduction should be attempted rapidly due to the threat of skin necrosis if dislocation is prolonged. Reduction should occur prior to obtaining radiographs (either immediately upon presentation to the ED or in the field) if the foot has obvious neurovascular compromise such as absent or thready dorsalis pedis or posterior tibial pulse, decreased capillary refill, or lack of sensation to the bottom of the foot. Obtaining a thorough vascular and sensory exam of the foot before and after any reduction attempts is key. Often procedural sedation is necessary to perform this procedure. The approach to reduction is as follows:

  • Knee bent at 90 degrees to relax gastrocnemius and soleus muscles

  • Apply traction at heel and counter-traction to thigh

  • Accentuate deformity followed by reversal.

    • Medial dislocations: Further invert, pull traction, and then evert

    • Lateral dislocations: Further evert, pull traction, and then invert

  • Apply a splint – short posterior slab splint with side gussets

  • If reduction is successful, then obtain post-reduction x-rays and CT scan of foot and ankle. It is recommended that the patient is non-weight bearing in short leg cast for 4 to 6 weeks.

Associated injuries

Given that most of these injuries occur from a high degree force to the foot, it is not surprising that many of patients have other foot and ankle injuries in addition to the subtalar dislocation. Approximately 55% of medial subtalar dislocations and 72% of lateral dislocations have associated injuries. Common associated injuries include osteochondral lesions of the talus, subtalar debris, ankle fractures, 5th metatarsal fracture, navicular fracture, and cuboid fracture. Given the high percentage of associated injuries and that some of the associated injuries are difficult to see on plain radiographs, it is recommended to get a CT scan of the ankle and foot after reduction. In a case series of 9 patients, CT scan showed additional injuries missed on plain film in 100% of cases, and the CT changed the treatment in 44% of the cases. Fortunately, neurovascular injury and chronic subtalar joint instability are rare complications.

Complications

Approximately 30% of injuries are not reducible by closed means. In medial dislocations, the capsule of the talonavicular joint, peroneal tendons, or the extensor digitorum brevis (EDB) muscle can block reduction. The talar head can “button hole” through the EDB which blocks reduction. In lateral dislocations, the posterior tibialis tendon, flexor halluces longus, or flexor digitorum longus can be interposed into the joint space and block reduction. These injuries are also associated with contusions or lacerations of the posterior tibial artery and nerve.

Open subtalar dislocations have an infection rate of approximately 30% even with aggressive irrigation in the OR. Appropriate antibiotics prophylaxis should be given immediately upon recognizing an open fracture. Cefazolin is sufficient coverage for skin flora in most cases without obvious contamination and with minimal soft tissue damage. If the patient is high risk for MRSA, vancomycin coverage can also be added. For patients with severe soft tissue injury or gross contamination coverage should be expanded to ampicillin-sulbactam, cefoxitin, or cefotetan. If there is exposure to water, then Pseudomonas coverage should be added with an agent like cefepime. If fecal contamination is possible or there is concern for clostridial exposure (agricultural injuries), then high dose penicillin should be used as an adjunct.

Figure 8: Open medial subtalar dislocation.  http://www.orthobullets.com/trauma/1050/subtalar-dislocations

Figure 8: Open medial subtalar dislocation.

http://www.orthobullets.com/trauma/1050/subtalar-dislocations

There also is a risk of avascular necrosis of the talus or navicular after a subtalar dislocation. This is a rare complication more likely to occur after lateral subtalar dislocation. This is more common with tibiotalar dislocation when the ankle mortise is disrupted.

Many patients will go on to have chronic pain in their ankle (30 - 63%); intraarticular debris fragments and open injuries increase the risk of this.

Take Home Points

  • Subtalar dislocations often occur after a high mechanism injury to the foot while it is plantar flexed

  • Medial subtalar dislocations are more common

  • Lateral subtalar dislocations are more likely to be open and to have other associated injuries

  • Open dislocations have very high infection risk even with prompt and appropriate care

  • Fast reduction is key. Put the knee at 90 degrees, apply traction, recreate the injury and then reverse it

  • Get appropriate antibiotics on board quickly for open fractures

  • Approximately 30% of the time, closed reduction is impossible as the dislocated bone is caught on adjacent structures

  • Get a CT scan after reduction to look for other injuries

Faculty Reviewer: Dr. Mark Greve


References:

  1. Bryant, J. and Levis, J.T. 2009. Subtalar dislocation. Western Journal of Emergency Medicine, 10(2).

  2. Bibbo, C., Lin, S.S., and Abidi, N. 2001. Missed and associated injuries after subtalar dislocation: the role of CT. Foot and Ankle International, 22(4).

  3. DeLee, C. 1982. Subtalar dislocation of the foot. The Journal of Bone and Joint Surgery, 64(3): 433-437.

  4. Gustilo RB, Anderson JT. 1976. Prevention of infection in the treatment of one thousand and twenty-five open fractures of long bones: retrospective and prospective analyses. J Bone Joint Surg Am, 58:453.

  5. Gustilo RB, Gruninger RP, Davis T. 1987. Classification of type III (severe) open fractures relative to treatment and results. Orthopedics, 10:1781.

  6. Horning, J. 2009. Subtalar dislocation. Orthopedics, 32(12): 904.

  7. Melenevsky, Y., Mackey, R.A., Abrahams, B., and Thomson, N.B. 2014. Talar fractures and dislocations: a radiologist’s guide to timely diagnosis and classification. Retrieved 7/29/17 from http://pubs.rsna.org/doi/full/10.1148/rg.2015140156

  8. Schmitt, SK. 2018. Osteomyelitis associated with open fractures in adults: preventative antibiotics after open fractures. UpToDate, retrieved on 1/24/19 from https://www.uptodate.com/contents/osteomyelitis-associated-with-open-fractures-in-adults?search=open%20fracture%20antibiotics&sectionRank=1&usage_type=default&anchor=H7&source=machineLearning&selectedTitle=1~150&display_rank=1#H7

  9. Weatherford, B. 2017. Subtalar dislocations. Retrieved on 7/29/17 from http://www.orthobullets.com/trauma/1050/subtalar-dislocations

  10. Weir, A. 2015. MR:EM subtalar dislocation. Retrieved on 7/29/17 from https://www.youtube.com/watch?v=GG3ni7fR__s

  11. Wheeless, C.R. 2012. Wheeless’ Textbook of Orthopaedics: Sub Talar Dislocation. Retrieved on 7/29/17 from http://www.wheelessonline.com/ortho/sub_talar_dislocation

  12. Yoder, W., Nelson, P., Bowen, M., and Frania, S. 2011. Chapter 11: Talocalcaneal navicular dislocation. Retrieved on 7/29/17 from http://www.podiatryinstitute.com/pdfs/Update_2011/2011_11.pdf


Orbital Floor Blowout Fracture

CASE

A 16-year-old male presents with head trauma. The patient was in gym class when another classmate ran into him, kneeing him in the left eye. There was no loss of consciousness. On presentation, the patient complains of headache, dizziness, nausea, visual disturbance, and photophobia. He has vomited several times. On review of systems, the patient also endorses double vision and numbness over the left cheek. The patient’s mother notes he is alert but is slow to respond to questions.  He has no prior history of facial fractures.

Physical Exam

BP 130/70, HR 58, RR 20, SpO2 99% on RA, Temp 98.6 F

The patient is alert and oriented.  He appears uncomfortable but is in no acute distress.

HEENT exam with left periorbital ecchymosis and edema, with tenderness to palpation. Diminished sensation to light touch over cheek and upper lip. Nasal bridge swelling and tenderness, with subtle nasal deviation to the right. No septal hematoma. Symmetric smile.

Pupils are equal, round, and reactive to light. No hyphema or subconjunctival hemorrhage. Left eye with decreased up-gaze as compared to the right. Extraocular movements of the left eye are painful.

The neck has normal range of motion. There is no cervical midline tenderness to palpation.

The patient’s history and examination are significant for trauma to the left eye and face. His examination reveals bony tenderness, with decreased sensation to light touch, and evidence of inferior rectus entrapment as evidenced by abnormal extraocular movements. These findings are concerning for orbital blow-out fracture. There is also concern for nasal bone fracture given nasal bridge swelling, tenderness, subtle deviation, and epistaxis. Given patient’s nausea, vomiting, dizziness, and slowed responses to questions (as per patient’s mother), intracranial injury was also considered.

The patient underwent a CT of the brain and face, with thin (1mm) cuts through the orbits (Figure 1).

Figure 1: Axial CT of the face (bone window) with fracture through the left orbital floor, with herniation of the orbital fat (“teardrop” sign) and inferiorly displaced inferior rectus muscle

Figure 1: Axial CT of the face (bone window) with fracture through the left orbital floor, with herniation of the orbital fat (“teardrop” sign) and inferiorly displaced inferior rectus muscle

DISCUSSION

Figure 2: Anatomy of the orbit (https://en.wikipedia.org/wiki/File:Orbital_bones.png)

Figure 2: Anatomy of the orbit (https://en.wikipedia.org/wiki/File:Orbital_bones.png)

The orbit is composed of six bones. The frontal bone forms the superior orbital rim and the roof of the orbit. The sphenoid bone and the zygomatic bone form the lateral wall of the orbit. The maxilla and the zygomatic bone form the infraorbital rim and floor of the orbit. Finally, the maxilla and ethmoid bones form the medial wall of the orbit (Figure 2).

Housed within, or within in close proximity to the bony orbit are the globe, six extra-ocular muscles, the infraorbital and supraorbital nerves, lacrimal duct system, medial and lateral canthal ligaments, and 4 pairs of sinuses (Neuman).

A blowout fracture is a fracture through any of the orbital walls, with an inferior fracture through the floor being the most common (Knipe). It is caused by direct force to the orbit. In children, nearly 50% of these injuries occur during sports, with the direct blow usually coming from a ball or another player (Hatton).

A trap door fracture is a sub-type of the orbital floor fracture. It is a linear fracture that inferiorly displaces and then recoils back to near-anatomic position. With this movement there is concern for entrapment of orbital fat and inferior rectus muscle, resulting in ischemia, restriction of ocular movement, and visual disturbance (Hacking). The trap door fracture is predominantly seen in the pediatric population, owing to increased elasticity of the orbital floor (Chung, Grant).

Clinically, a patient will present with periorbital edema and ecchymosis. Altered sensation or numbness over the cheek, upper lip, and upper gingiva is suggestive of infraorbital nerve injury. Proptosis of the eye is suggestive of orbital hematoma. A posteriorly displaced globe (enophthalmos) is suggestive of increased orbital volume secondary to fracture. An inferiorly displaced globe (orbital dystopia) is a result of muscle and fat prolapse into the maxillary sinus. Restricted and/or painful extraocular movements are suggestive of muscle entrapment (Neuman).

In children, a phenomenon called the oculocardiac reflex can occur. Stimulation of the ophthalmic division of the trigeminal nerve due to traction or pressure on the extraocular muscles or globe results in excitation of the vagus nerve, leading to bradycardia, nausea, and syncope. In severe cases, asystole can occur (Sires).

CT of the face, with thin (1mm) cuts through the orbit is the primary modality used for identification of orbital blowout fractures. Plain radiographs of the face and orbits are no longer the gold standard as they have poor sensitivity and specificity.  Trap door fractures may be occult, but any evidence of soft tissue herniation into the maxillary sinus (also known as the “teardrop” sign) should raise suspicion for a clinically significant fracture.

These injuries can be severe, and are often more significant in the pediatric population than the adult population, owing to associated soft tissue and muscular injuries. Almost half of children with this injury will require surgery, most frequently due to entrapment. Nearly half of pediatric patients will have ocular injuries (globe rupture, hyphema, retinal tear) and nearly one third of patients will have a second facial fracture (Hatton). 

Urgent ophthalmology and facial surgery consultations are indicated for orbital floor fractures with concern for entrapment (Chung).

Symptomatic treatment includes:

  • Head of bed elevation

  • Ice

  • Sinus precautions: no nose blowing, sneeze with the mouth open, no straw use or sniffing

  • Analgesia and anti-emetics as needed

 

For orbital fractures with extension into a sinus, the use of prophylactic antibiotics has limited data and often varies by institution (Neuman).

Corticosteroids are recommended for patients with diminished extraocular movements to reduce swelling and expedite improvement in diplopia (Neuman).

For orbital blowout fractures with evidence of entrapment and/or oculocardiac reflex, repair should be performed within 24-48 hours. Delayed repair (more than 2 weeks after injury) can be considered if mild-moderate diplopia is not spontaneously improving, or patient has worsening of enopthalmos > 2mm after initial edema and inflammation has resolved.  Other indications for surgical repair include large fracture (involvement of greater than 50% of the orbital floor) or multiple fractures (Chung).

 

CASE CONCLUSION

The patient was admitted for observation overnight in the setting of persistent nausea, vomiting, borderline bradycardia, and diplopia. He was placed on oral prednisone, as well as anti-inflammatory medication. Overnight his symptoms and heart rate improved, although he had persistent diplopia, with diminished upward gaze of the left eye. He was discharged home on hospital day 1, with plan for ophthalmology and facial surgery follow-up for operative planning.

Faculty Reviewer: Dr. Jane Preotle

 

REFERENCES & FURTHER READING

  1. Chung, Stella Y., and Paul D. Langer. “Pediatric Orbital Blowout Fractures.” Current Opinion in Ophthalmology, vol. 28, no. 5, 2017, pp. 470–476., doi:10.1097/icu.0000000000000407.

  2. Grant, John H., et al. “Trapdoor Fracture of the Orbit in a Pediatric Population.” Plastic and Reconstructive Surgery, vol. 109, no. 2, 2002, pp. 490–495., doi:10.1097/00006534-200202000-00012.

  3. Hacking, Craig. “Trapdoor Fracture.” Radiopaedia.org, radiopaedia.org/articles/trapdoor-fracture.

  4.  Hatton, Mark P., et al. “Orbital Fractures in Children.” Ophthalmic Plastic and Reconstructive Surgery, vol. 17, no. 3, 2001, pp. 174–179., doi:10.1097/00002341-200105000-00005. 

  5. Knipe, Henry, and Frank Gaillard.  “Orbital Blowout Fracture.” Radiopaedia.org, radiopaedia.org/articles/orbital-blowout-fracture-1.

  6. Neuman, Mark, and Richard G Bachur. “Orbital Fractures.” UpToDate, www.uptodate.com/contents/orbital-fractures.

  7. Sires, Bryan S. “Orbital Trapdoor Fracture and Oculocardiac Reflex.” Ophthalmic Plastic & Reconstructive Surgery, vol. 15, no. 4, 1999, p. 301., doi:10.1097/00002341-199907000-00014.

  8. Soll, D. B., and B. J. Poley. “Trapdoor Variety of Blowout Fracture of the Orbital Floor.” Plastic and Reconstructive Surgery, vol. 36, no. 6, 1965, p. 637., doi:10.1097/00006534-196512000-00017. 

Thrower’s Fracture of the Humerus: A Case Report

CASE REPORT:


A 35-year-old, right-handed male presented to the emergency department with complaint of right upper arm pain. He was a member of an amateur baseball team; just prior to arrival he threw a ball and immediately felt a pop and sharp pain in his right upper arm. Since that time, he had been unable to move his arm due to pain. He reported no prior injury to the arm but did state that over the last several weeks he had been having an ache in that arm. He was otherwise healthy, took no medications, denied weakness, numbness and tingling in his right arm. He was a non-smoker and an occasional drinker. He used no drugs.

Physical exam was non-focal except for the right upper extremity. His right upper arm was swollen and tender to the touch. He had decreased range of motion in his elbow and his shoulder secondary to the pain. He had an obvious deformity of the right bicep region. Distally the patient was neurovascularly intact with normal range of motion and light touch sensation intact in the wrist and hand. He had a 2+ radial pulse and capillary refill was less than 3 seconds.

The patient was given pain medication and sent for an x-ray of his right humerus. The x-ray demonstrated a displaced spiral fracture of the humerus (fig 1). The patient was placed in a coaptation splint and prior to discharge, reexamination revealed no evidence of radial nerve palsy or radial artery injury. The patient followed up with the orthopedic doctor on-call and underwent open reduction and internal fixation of his injury within 1 week (fig 2).

Figure 1. AP and oblique radiographs of the right humerus demonstrating a spiral fracture

Figure 1. AP and oblique radiographs of the right humerus demonstrating a spiral fracture

Figure 2: Right Humerus status post open reduction and internal fixation

Figure 2: Right Humerus status post open reduction and internal fixation

DISCUSSION:

This patient's presentation is consistent with a well described, but rarely observed phenomenon known as a 'Thrower's Fracture.' First reported in 1930 [1], cases have been reportedly related to everything from a baseball [2, 3], to a cricket ball [4], to a dodge ball [5], and hand grenades [6]. As with our patient, many patients who present with this injury are amateur athletes who have likely not developed adequate cortical strength of their bones as compared to professional athletes [7]. The injury is often preceded by several weeks to months of aching in the region of the humerus, which is thought to represent a stress fracture [2, 4, 8]. The complexity of the throwing motion and related transfer of forces, results in significant torque being applied to the humeral shaft, leading to a fracture, most commonly in the mid to distal third of the diaphysis.

These patients can have similar complications to any mid-shaft, spiral humeral fracture including damage to the radial artery and radial nerve [9, 10]. In these cases, given the active nature of these athletes, and if underlying complications have occurred, surgeons may elect to repair this injury surgically [2, 4, 10], though this is not always necessary given the fracture morphology.

Faculty Reviewer: Dr. Kristy McAteer

REFERENCES:

  1. Wilmoth, C., Recurrent fracture of the humerus due to sudden extreme muscular action. Journal of Bone and Joint Surgery, 1930. 12: p. 168-169.

  2. Miller, A., C.C. Dodson, and A.M. Ilyas, Thrower's fracture of the humerus. Orthop Clin North Am, 2014. 45(4): p. 565-9.

  3. Perez, A.Z., C.; Atia, H., Thrower's fracture of the humerus: An otherwise healthy 29-year-old man presented for evaluation of acute onset of severe right arm pain. Emergency Medicine, 2016. 48(5): p. 221-222.

  4. Evans, P.A., et al., Thrower's fracture: a comparison of two presentations of a rare fracture. J Accid Emerg Med, 1995. 12(3): p. 222-4.

  5. Colapinto, M.N., E.H. Schemitsch, and L. Wu, Ball-thrower's fracture of the humerus. CMAJ, 2006. 175(1): p. 31.

  6. Chao, S.L., M. Miller, and S.W. Teng, A mechanism of spiral fracture of the humerus: a report of 129 cases following the throwing of hand grenades. J Trauma, 1971. 11(7): p. 602-5.

  7. Ogawa, K. and A. Yoshida, Throwing fracture of the humeral shaft. An analysis of 90 patients. Am J Sports Med, 1998. 26(2): p. 242-6.

  8. Reed, W.J. and R.W. Mueller, Spiral fracture of the humerus in a ball thrower. Am J Emerg Med, 1998. 16(3): p. 306-8.

  9. Curtin, P., C. Taylor, and J. Rice, Thrower's fracture of the humerus with radial nerve palsy: an unfamiliar softball injury. Br J Sports Med, 2005. 39(11): p. e40.

  10. Bontempo, E. and S.L. Trager, Ball thrower's fracture of the humerus associated with radial nerve palsy. Orthopedics, 1996. 19(6): p. 537-40.