Hertel's 2002 narrative review synthesizes the functional anatomy of the three-joint ankle complex and builds a mechanistic framework for why lateral sprains recur. It defines and distinguishes mechanical instability from functional instability as the two overlapping drivers of chronic ankle instability (CAI). The review draws on cadaveric, biomechanical, and clinical literature to explain each specific insufficiency contributing to both entities.
A patient walks into your clinic 3 months after an ankle sprain: pain-free, dorsiflexion looks symmetric, but keeps re-spraining. This paper explains why. Postural-control deficits normalize on their own within months whether or not the patient rehabilitates — but patients who skip rehab are still more than twice as likely to re-sprain. Normal clinical exam does not mean the ankle is ready.
When you assess CAI, check both pillars. For mechanical contributors: anterior drawer and talar tilt for laxity, posterior talar glide mobility (restricted even when ROM looks normal at 12 weeks), and sinus tarsi tenderness suggesting subtalar synovitis. For functional contributors: single-leg balance, Star Excursion Balance Test performance, and peroneal strength.
Never assess only one plane. The talocrural joint moves triplanarly, and ATFL rupture causes rotational (internal rotation) instability that anterior drawer and talar tilt alone will miss. Comprehensive evaluation requires thinking in three planes.
Hertel's 2002 narrative review synthesizes the functional anatomy of the three-joint ankle complex and builds a mechanistic framework for why lateral sprains recur. It defines and distinguishes mechanical instability from functional instability as the two overlapping drivers of chronic ankle instability (CAI). The review draws on cadaveric, biomechanical, and clinical literature to explain each specific insufficiency contributing to both entities.
A patient walks into your clinic 3 months after an ankle sprain: pain-free, dorsiflexion looks symmetric, but keeps re-spraining. This paper explains why. Postural-control deficits normalize on their own within months whether or not the patient rehabilitates — but patients who skip rehab are still more than twice as likely to re-sprain. Normal clinical exam does not mean the ankle is ready.
When you assess CAI, check both pillars. For mechanical contributors: anterior drawer and talar tilt for laxity, posterior talar glide mobility (restricted even when ROM looks normal at 12 weeks), and sinus tarsi tenderness suggesting subtalar synovitis. For functional contributors: single-leg balance, Star Excursion Balance Test performance, and peroneal strength.
Never assess only one plane. The talocrural joint moves triplanarly, and ATFL rupture causes rotational (internal rotation) instability that anterior drawer and talar tilt alone will miss. Comprehensive evaluation requires thinking in three planes.