Somatic Dysfunction Following Ankle Inversion Injury
The most likely resulting somatic dysfunction from an inversion ankle injury is an anterior fibular head (Option A).
Biomechanical Mechanism
During an ankle inversion injury, the foot undergoes supination and adduction in a plantar-flexed position 1. This mechanism creates specific forces through the lateral ankle structures that propagate proximally:
- The fibula is pulled anteriorly and inferiorly as the lateral ligaments (particularly the anterior talofibular ligament) are stressed during the inversion mechanism 2
- Internal tibial rotation occurs as a compensatory response to the inversion stress, but the fibular head moves anteriorly relative to the tibia 1
- The anterior displacement of the fibular head is the characteristic somatic dysfunction pattern seen with lateral ankle sprains 2
Clinical Context
Inversion injuries represent 25% of all musculoskeletal injuries and 50% of sports-related injuries 1, 2, 3. The anterior talofibular ligament is the most commonly injured structure in these injuries 2, and the forces transmitted through this ligament during injury create the anterior fibular head dysfunction pattern.
Why Not the Other Options
- External tibial rotation (Option B): This would be associated with eversion injuries or syndesmotic injuries, not inversion injuries 1
- Internal tibial rotation (Option C): While the tibia may rotate internally as a compensatory mechanism, this is not the primary somatic dysfunction; the fibular head displacement is the key finding 1
- Posterior fibular head (Option D): This pattern would be inconsistent with the anterior and inferior pull created by lateral ligament stress during inversion 2
Common Pitfall
Do not confuse lateral ankle sprains (inversion injuries affecting the anterior talofibular ligament) with high ankle sprains (syndesmotic injuries from dorsiflexion-eversion-external rotation mechanisms), which would produce different somatic dysfunction patterns 2.