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Type IIB talar neck fractures associated with avascular necrosis
A lateral incision and placement of a lateral plate with medial screws can aid talar neck fracture treatment, stabilization.
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A new classification type for talar neck fractures may help orthopedic surgeons identify a patient who is at a high risk of avascular necrosis after surgical fixation of the fracture.
“With the new classification, we have a better way of explaining not only to ourselves, but to patients, what we can expect,” Roy W. Sanders, MD, told Orthopedics Today.
At Orthopedics Today Hawaii 2017, Sanders noted a paper by Heather A. Vallier, MD, and colleagues altered the way talar neck fractures are classified by adding a new subgroup: the type IIB fracture. In type II fractures the ankle remains located, but there were a variety of subtalar injuries. By documenting the long-term outcomes of these different type II injuries, the type IIB fracture “where the ankle is still located, but the subtalar joint is completely dislocated, emerged,” Sanders said.
“The important difference is that with type IIB fractures, there is a much higher avascular necrosis (AVN) rate,” Sanders said. “When you look at type I and type IIA fractures, there are low rates of avascular necrosis in them because you have not torn the subtalar joint apart. But, the type IIB and Hawkins type III fractures both have significant rates of avascular necrosis,” he said.
Another study by Vallier and colleagues from 2004 showed that although type I and IIA talar neck fractures had no AVN, type IIB fractures had a 25% rate of osteonecrosis and type III fractures had a 64% rate of osteonecrosis, Sanders noted.
“[Patients] have a better chance of having a normal talus if they have a type I, obviously, or a type IIA. But, the IIBs, with the subtalar dislocation, and the type IIIs are [at a] high rate of avascular necrosis, no matter what you do,” he said.
The type of incision made to treat talar neck fractures is equally important, according to Sanders.
Historically, a single medal incision was used, but during the last few years a lateral approach has been added to guarantee an anatomic reduction, especially in terms of rotation. Using a lateral approach from the anterior distal tibiofibular ligament to the fourth metatarsal should help reduce potential problems with these fractures, Sanders said.
“As early as 1992, Dr. Bruce Sangeorzan showed that even a small step-off in the talar neck reduction would translate into a larger malreduction at the subtalar joint,” he said.
Sanders also noted that when comminution is present, a lateral plate can be used in conjunction with medial screws to help with stabilization and reduce the risk of deformity.
“You should not try to put a plate medially because there is no place to put it and it will scrape the medial malleolus when the patient dorsiflexes,” Sanders told Orthopedics Today. “[Surgeons] need [to place] the screws in the standard location on the medial side and, if the neck is comminuted, then they need to put a plate on the lateral side to maintain the length of the entire medial column so the hindfoot does not go into varus.”
Patients with comminuted Hawkins type III fractures have a risk of AVN that approaches 100%, according to Sanders. In addition, a study showed about half the patients with type III talar neck fractures who underwent reconstructive surgery within 1 year of injury required another surgical procedure — typically a fusion — within 10 years of their initial treatment. – by Casey Tingle
- References:
- Sanders RW. Foot fractures: Pearls of treatment. Presented at: Orthopedics Today Hawaii 2017; Jan. 8-12, 2017; Lahaina, Hawaii.
- Sangeorzan BJ, et al. J Orthop Res. 1992;10:544-551.
- Vallier HA, et al. J Bone Joint Surg Am. 2004;86:1616-1624.
- Vallier HA, et al. J Bone Joint Surg Am. 2014;doi:10.2106/JBJS.L.01680.
- For more information:
- Roy W. Sanders, MD, can be reached at Florida Orthopaedic Institute, 13020 Telecom Parkway N., Temple Terrace, FL 33637; email: ots1@aol.com.
Disclosure: Sanders reports he receives royalties from Linvatec, Smith & Nephew, Stryker and Zimmer Biomet; receives intellectual property rights/is a patent holder with Foot Innovations, Linvatec, Quikfix, Smith & Nephew, Stryker and Zimmer Biomet; receives consulting fees from Acumed, Linvatec, NuVasive, Smith & Nephew, Stryker and Zimmer Biomet; is on the speaker’s bureau for Linvatec, Smith & Nephew, Stryker and Zimmer Biomet; receives fees for non-CE services directly from a commercial interest or its agent from Smith & Nephew and Zimmer Biomet; and performs contracted research for Smith & Nephew.
Perspective
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David J. Hak, MD, MBA, FACS
Dr. Sanders highlights the importance Valliers modification of the Hawkins classification in predicting the outcome of type II talar neck fractures. Type IIB talar neck fractures, in which the subtalar joint is dislocated, have a higher AVN risk (25% vs. 0%) than type IIA fractures in which the subtalar joint remains located.
Dr. Sanders also highlights the importance of using dual incisions to achieve anatomic reduction, especially to avoid unappreciated malrotation, which can occur when only a medial incision is used. Mini-fragment plates are being used increasingly for fracture fixation, including comminuted talar neck fractures. They should be placed on the lateral border of the talar neck, while a lag screw is placed in the medial aspect of the calcaneus.
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