A Closer Look At Lateral Talar Process Fractures With Snowboarding Injuries
As the winter season continues, physicians need to become more aware of snowboarding injuries. The number of ankle injuries continues to rise and, in particular, lateral talar process (LTP) fractures seem to be occurring more frequently within the snowboarding population.
Kirkpatrick, et al., conducted a prospective study of 3,213 snowboarding injuries that occurred at 12 Colorado ski resorts between 1988 and 1995.1 These injuries consisted of 15.3 percent injuries to the ankle and 1.8 percent injuries to the foot. In regard to the ankle injuries, 44 percent of injuries were related to fractures and 52 percent were sprains.
Specifically, there were 216 ankle fractures. Seventy-eight of these ankle fractures were talar fractures and 74 of these were LTP fractures. These LTP fractures accounted for 34 percent of ankle fractures and 15 percent of all ankle injuries. According to other research, there is a 15-fold increase in the risk of LTP injuries with snowboarding in comparison to the general population. 2
Traditionally, patients with ankle injuries related to snowboarding presented to the hospital with lateral ankle pain, swelling and instability. Most new patients during the sport’s conception underwent workups for lateral ankle sprains. It soon became apparent that under-treating snowboarding injuries could result in long-term sequelae such as malunion, nonunion, subtalar and/or ankle arthritis.
However, time has provided a greater understanding of the anatomy and the biomechanics involved with snowboarding. Currently, lateral ankle sprain treatment includes radiographic analysis for fracture and joint disruption. However, due to the nature and location of this particular injury, it is still difficult to differentiate between a lateral ankle sprain and a fracture of the lateral talar process.
Understanding The Relationship Between The LTP And The STJ
Little is known about the functional significance of the lateral talar process, let alone what stabilizes it during activity. 3 We do know that the lateral talar process is a wedge-shaped prominence of the lateral aspect of the talar body that extends from its articulation with the medial aspect of the fibular articular surface distal to the posteroinferior surface of the talus. 4 Therefore, “a fracture of the lateral process of the talus involves both the talofibular articulation of the ankle joint and the posterior talocalcaneal articulation of the subtalar joint.”4
Cadaveric studies have clarified how much these joints are affected by LTP injuries. In a 2007 study, researchers discussed the stability of the lateral side of the ankle by describing three ligamentous attachments to the LTP that create a “circumferential skirt” of tissue. These attachments include the lateral talocalcaneal, anterior talofibular and posterior talofibular ligaments.3 Historically, surgeons did not excise large fragments but utilized open reduction internal fixation (ORIF) due to the fear of creating instability to the subtalar joint (STJ).5,6
DiGiovanni, et al., discovered with cadaveric anatomical dissection that this fear was unfounded.3 Their thesis, arbitrarily derived from Heckman in 1996 and DiGiovanni in 2003, was that excision of a LTP fracture fragment of 1 cm3 would only affect three lateral stabilizing ligaments that stabilize the ankle joint and not the STJ. 7,8
The lateral talocalcaneal is the only ligament that crosses the STJ while the other two are specific to the ankle joint. The lateral root of the extensor retinaculum, cervical and interosseous ligaments still remain unaffected by LTP fractures because they do not insert into the LTP, and therefore continue to provide stability to the STJ.
In relation to this study, further research examined the effect of excision of a 1 cm3 fragment from the LTP to the ankle and subtalar joints9 The results indicated that there was no instability at the ankle or at the subtalar joint upon removal of the fragment after comparing non-stressed and stressed measurements.