Demystifying the Functional Subtalar Joint Through a Better Understanding of its Functional Demands
Speaker 1: Jennifer McKeon
Speaker 2: Patrick McKeon
Background & Relevance: Over the past 50 years, the epidemiological trends associated with chronic ankle instability (CAI) have not changed. Emerging evidence over the past 20 years implicates subtle subtalar instability as a key contributing factor to the recalcitrant nature of CAI. However, a major barrier to linking the contributions of subtalar instability to CAI is an appreciation for its complex anatomy and biomechanics. Traditionally, the anatomical description of subtalar joint has been limited to the talus and calcaneus. Consequently, evaluation of the subtalar joint’s structural integrity has been limited to either the talar tilt or the medial subtalar glide test. This represents a major gap in the evidence and subsequently a major gap in our clinical understanding of subtalar instability in CAI. The functional subtalar joint is far more complex, consisting of functional interrelationships among the talocalcaneal, talonavicular, and calcaneocuboid articulations. The primary goal of this workshop is to provide participants with a clinical framework for understanding the functional subtalar joint in order to help them develop an enhanced ability to uncover dysfunction that may contribute to CAI.
In the first section of this workshop, we will provide participants with a framework for evaluating walking and running gait using the foot and ankle rockers. These rockers help to contextualize the functional demands of absorption, propulsion, and stability across the lower extremity as they relate to pronation and supination of the functional subtalar joint. Specifically, the foot and ankle rocker system provides a logical framework for linking key events of the ankle to pronation and supination events of the functional subtalar joint. Through this experience, participants will learn simple rules of thought to streamline gait evaluation as it relates to foot and ankle pathology.
In the second section of the workshop, we will guide participants through the anatomy and biomechanics of the functional subtalar joint. By linking the anatomy and complex mechanics of the functional subtalar joint to the foot and ankle rockers, we will help participants better understand how this joint complex becomes dysfunctional. Participants will be able to gain a better appreciation for the foot’s transition between a supple platform and rigid lever through the lens of the medial and lateral columns of the foot that the functional subtalar joint controls. Using the emerging evidence from subtalar instability, we will then provide the anatomical and mechanical factors that can help guide clinicians to develop a more robust evaluation of functional subtalar joint integrity. These factors include key palpation points related to functional subtalar joint ligamentous support and a clinical stress test that stresses these ligaments more appropriately.
A better understanding of the anatomy and complex mechanics of the functional subtalar joint can lead clinicians to a better ability to observe and describe functional subtalar instability. From better observation and description, more appropriate intervention strategies can be developed to enhance outcomes in those with CAI.
Learning Objective 1: Participants will be able to explain the foot and ankle rockers during gait as they relate to the functional demands of absorption, propulsion, and stability.
Learning Objective 2: Participants will be able to interpret the anatomy and complex mechanics of the functional subtalar joint through the functional demands of absorption, propulsion, and stability.
Learning Objective 3: Participants will be able to relate the anatomy and complex mechanics of the functional subtalar joint to key evaluation factors in order to develop a more robust ability to recognize dysfunction.