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Updated: Jul 17, 2026
A Mouse Model of Ankle-Subtalar Complex Joint Instability
Published on: October 28, 2022
In vitro evaluation of the effect lateral process talar excision on ankle and subtalar joint stability
Phillip Langer1, Florian Nickisch, David Spenciner
1Rhode Island Hospital, Department of Orthopedics, Providence, RI 02903, USA.
Background:
Recent literature reflects a substantial increase in interest surrounding lateral talar process fractures. Previous anatomic investigations discovered that excision of a 1 cm3 fracture fragment from the lateral talar process involves approximately 100% of the lateral talocalcaneal ligament origin and 10% to 15% of both the posterior and anterior talofibular ligament insertions. The objective of this study was to determine the effect that excision of this 1 cm3 fragment has on ankle and subtalar joint stability.
Methods:
Ten fresh-frozen cadaver lower limbs were thawed before testing and placed in a clinical stress apparatus (Model SE 20, Telos, Marburg, Germany). Radiographs were taken before and after application of a 150 N of force. Three views (lateral, anteroposterior, 30-degree Bróden) were used to asses anterior tibiotalar translation (AT), talar tilt (TT), medial talocalcaneal motion (TCM), and talocalcaneal tilt (TCT) before and after excision of the 1 cm3 fragment the lateral talar process.
Results:
The mean increases in AT, TT, TCM and TCT after excision of the 1 cm3 fragment were: AT=1.0 mm+/-0.94 mm (p=0.0085); TT=0.4+/-0.52 degrees (p=0.0368); TCM=1.0 mm+/-1.25 mm (p=0.0319); TCT=1.2+/-1.32 degrees (p=0.0181).
Conclusions:
Since it has been generally accepted that a 3 mm increase in AT, 3-degree increase in TT, 5-mm increase in TCM, more than 5-degree increase in TCT define instability of the ankle and subtalar joints, respectively. These results suggest that excision of a 1 cm3 fragment causes neither ankle nor subtalar instability as defined by radiographic stress examination.
