A Closer Look At Lateral Talar Process Fractures With Snowboarding Injuries
- Volume 22 - Issue 2 - February 2009
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What The Studies Reveal About Inversion And Eversion With LTP Fractures
In 2003, Funk, et al., introduced a new theory for the development of LTP fractures with snowboarding. 2 Researchers obtained 10 cadaveric legs to determine whether there was a difference in the number of LTP fractures with inversion or eversion coupled with dorsiflexion and axial loading. The result indicated the need for a rotational component to induce the fracture.
The rationale began with the work of Wagner, et al., and Wang, et al. 14,15 These pressure-sensitive studies have contradicted that inversion is necessary to induce a fracture of the lateral process of the talus. In fact, these studies have demonstrated that stress distributed across the STJ upon inversion actually deviates medially, whereas the stress disperses and concentrates laterally in eversion.
The position in which one rides a snowboard also favors eversion. Kirkpatrick, et al., noted that the most common mode of injury was from falling (74.7 percent). The next most common injuries were due to twisting (11.6 percent) and collision with a tree (8.2 percent).1
When falling induces injury, it reportedly occurs parallel to the long axis of the snowboard. Most snowboarding injuries happen to the leading foot (the foot that points downhill) at the time of the injury. 1,10,16 This illustrates the importance of foot position to the mechanism of injury because the position of the foot is in a natural state of dorsiflexion, particularly when riding toe side (facing the mountain).
In the aforementioned study by Funk and colleagues, they dorsiflexed the specimens at the ankle 30 degrees to the horizontal and subjected them to various amounts of inversion rotation or eversion rotation (48 to 62 degrees excursion).2 All inverted positions (four total specimens) with dorsiflexion failed to produce a fracture of the LTP. The remaining six were subjected to eversion and all produced fractures to the LTP. All specimens, both inverted and everted, were exposed to a constant axial loading force of 2.5 kN.
A Pertinent Primer On Injury Classification
Hawkins described the fracture of the lateral talar process in 1965. At this time, there was lack of consensus in descriptive terminology and minimal data from small population samples. The largest accumulation of data was from a study in 1943 by Marotolli, who added four patients of his own with LTP fractures to six already collected with no follow-ups to treatment.17 Hawkins developed a classification system based on 13 patients with LTP fractures for identification and treatment. 11 He described the following three types of LTP fractures.
Type I. This is a simple fracture of the lateral process of the talus that extends from the talofibular articular surface down to the posterior talocalcaneal articular surface of the subtalar joint.
Type II. This is a comminuted fracture that involved both the fibular and posterior calcaneal articular surfaces of the talus and the entire lateral process.
Type III. This is a chip fracture of the anterior and inferior portion of the posterior articular process of the talus. Be aware that one can only view type III fractures on a lateral radiograph or CT scan within the region of the sinus tarsi.
Bladin and McCrory, as well as others, are reorganizing Hawkins’s original classification in an attempt to better guide treatment regimens.11,18,19 According to their categorization, type I is a chip fracture, type II is a single large fragment and type III is a comminuted fracture.
After determining the fracture type, identify whether the fracture is displaced or non-displaced. As for primary therapy, non-displacement injuries receive conservative treatment whereas displacement injuries receive ORIF or surgical debridement. If necessary, one can perform secondary therapy (debridement) upon non-displaced primary therapy failures (debridement).