Fractures of the Lateral Process of the Talus: A Diagnostic Challenge

1. Fractures of the Lateral Process of the Talus: A Diagnostic Challenge A Tutorial for Optimizing Detection Julia Crim, MD Bradley Hale, MD University of Utah

2. Lateral Process Talus Fractures • Fractures can be subtle and difficult to see on plain radiographs. • Fractures and their sequelae can lead to long-term debility. • Fractures are more common than previously thought. • A systematic approach to evaluation improves identification.

3. Objectives of this presentation. 1. Review pertinent anatomy. 2. Review common mechanisms and patient presentation. 3. Review imaging techniques including radiographs, CT and MRI. 4. Increase awareness of subtle signs associated with these fractures.

4. Lateral Process of Talus The superior margin of the lateral process is part of the lateral gutter of the ankle joint. Posterior subtalar joint The inferior margin of the lateral process forms the anterior portion of the posterior subtalar joint. Calcaneus Lateral process As part of both the tibiotalar and posterior subtalar joints, the lateral process is important in many complex motions including inversion, eversion, dorsiflexion, plantarflexion and gliding.

5. Radiograph of Lateral Process of the Talus Talus Calcaneus

6. Lateral Process from Above

7. Lateral Process on Coronal CT Lateral gutter Posterior subtalar joint

8. Radiograph of the Lateral Process Tibia Fibula Talus Lateral process AP mortise

9. Mechanism of Injury • Fracture occurs from inversion and dorsiflexion of foot . • Patients often present with ankle sprain. • Lateral process transmits compression force from tibia to calcaneus.

10. Common Causes of Fracture • Snowboarding • Fall from a height • Soccer • Occasionally MVA

11. Fracture Incidence • Uncommon? • Lateral process fractures first reported 1942. • Mukherjee (1974) reported that lateral process fractures accounted for less than 1% of 1500 ankle injuries reviewed. • Or undetected? • Hawkins (1965): 26% of talus fractures • 40-50% of lateral process fractures not detected at time of injury (Hawkins, Mukherjee, Mills and Horne)

12. Lateral Process Fracture • Divided into three types • May be displaced or non-displaced Type 2 – Fracture through the base of the process Type 3 – Comminuted Type 1 - Chip fracture off tip of process

13. Fracture Treatment • Cast • Screw fixation • Excision of comminuted fragments

14. Prognosis of Fracture • Good with early ORIF • Poor with casting or delayed ORIF

15. Prospective study of fx treatment • 23 intra-articular fractures with mean follow up of 24 months. • Functional outcome rating 0-100 • 4 underwent early ORIF; 3 rated 100, 1 rated 93 • 19 patients were casted • 4 rated 100 • 15 rated 65-95 • 11 complained of stiffness and/or pain with exercise • 4 unable to do activities of daily living Paul CC, Janes PC. Snowboarder’s talus fx; Skiing trauma and safety: intl symposium 1996

16. Potential Complications • Nonunion • Osteoarthritis of subtalar joint • Some may need subtalar arthrodesis

17. Recommended Imaging: Lateral Process Fx • AP, Mortise, Lateral • The fracture may be visible on only one view • Radiographs underestimate extent of fracture • Broden’s with plantarflexion • Internal rotation & neutral flexion • Lateral tomography (obsolete) • CT, including reconstructions • MRI

18. Radiographic findings • Visible fracture line or cortical step-off. • Non-visualization or decreased density of the tip of the lateral process. • Displacement or rotation. • Lateral soft tissue swelling, typically lower than seen in ankle sprain without fracture.

19. Pitfalls in Detection • Fracture may be visible on only one view. • Radiographs may underestimate fracture. • If suspicious, go to CT or MRI.

20. Radiographic finding 1:Cortical step-off 22 year old female soccer player reports twisting ankle during the game Normal lateral process

21. Radiographic finding 1:Cortical step-off 22 year old female soccer player reports twisting ankle during the game An oblique fracture with cortical step-off is seen through the anterior margin (blue arrow) of the lateral process. A subtle lucency is visible at the inferior margin (green arrow). Normal

22. Radiographic finding 2:Non-visualization of the tip of the process. A young snowboarder. Normal lateral process The tip of the lateral process is indistinct and poorly visualized

23. Radiographic finding 3:Displacement Another snowboarder (snowboarding can be dangerous!) Displaced fragment seen on both the AP (inferior displacement) and lateral projection (anterior displacement).

24. Radiographic finding 4:Soft tissue swelling Fracture STS Fracture STS Radiographs from two separate patients with lateral process fractures. Note that soft tissue swelling is present laterally, but is more inferior than is typically seen in an ankle sprain or distal fibular fracture.

25. Pitfall in detection: Fracture visible on only 1 view Fell off ladder. This fracture (which was initially missed) is seen only on the anterior projection where cortical irregularity is identified.

26. Pitfall in detection:Radiographs may underestimate extent of fracture. CT is recommended for any fracture larger than a flake. Radiographs show fracture which appears to be through the tip of the process. However, CT (including reconstructions) shows the fracture to be much larger, extending into the base of the process. The posterior subtalar joint is extensively disrupted.

27. Improving detection:If suspicious, MRI may be helpful. Sag STIR Initial radiographs interpreted as normal. Patient continued to have pain. MRI clearly shows fracture through the base of the process.

28. How accurate are radiographs in diagnosis of lateral process fractures?

29. Utah Series • 14 intra-articular lateral process fractures over 8 month interval • Patient age range 18-35 • 2 fractures initially missed by the resident physician, but detected on radiographs by the attending; 12 detected acutely on radiographs by the resident. • 7 had other associated fractures • 8 had CT, 1 had MRI

30. Views on which fractures were visible • Lateral only: 3 (including 1 missed fx) • Readily visible on lateral but difficult on AP: 2 • Lateral and AP: 5 • Lateral and mortise: 1 • AP only: 1 (missed) • Seen on all views: 2

31. Utah Series: Associated Fractures • 5 talus • 1 body • 2 neck • 1 head of talus* • 1 posterior process talus • 1 EDB origin avulsion • 1 nondisplaced central calcaneus* • 1 pilon *(seen on CT only)

32. Final Review • In reviewing this presentation we hope you were able to : • Become more familiar with the anatomy of the talus • Become more aware of the significance of lateral process fractures • Review important signs of this fracture • Better understand pitfalls and how to minimize them

33. References • Hawkins LG. (1965) Fractures of the lateral process of the talus. J Bone Joint Surg. 47A:275. • Heckman JC, McLean MR. (1985) Fractures of the lateral process of the talus. Clin Orthop 199:108-113. • Higgins TF, Baumgaertner, MR. (1999) Diagnosis and treatment of fractures of the talus: A comprehensive review of the literature. Foot Ankle Int. 20(9):595-604. • Mills HJ, Horne G. (1987) Fractures of the lateral process of the talus. Aust N.Z. J. Surg. 57:643-646. • Mukherjee SK, Pringle RM, Baxter AD. (1974) Fractures of the lateral process of the talus. J. Bone Joint Surg. 56B:263 • Paul CC, Janes PC. Snowboarder’s talus fx; Skiing trauma and safety: intl symposium 1996.

34. Thank You!