Effect of standing tarsal angle on joint kinematics and kinetics.
Authors: Gnagey L, Clayton H M, Lanovaz J L
Journal: Equine veterinary journal
Summary
# Editorial Summary: Standing Tarsal Angle and Its Functional Consequences Tarsal joint pathology remains a significant cause of hind limb lameness in horses, yet surprisingly little objective data exists on how conformation influences the mechanical demands placed on this joint during movement. Gnagey and colleagues used three-dimensional motion capture and force plate analysis to quantify tarsal kinematics and kinetics across 16 horses stratified by standing tarsal angle—classified as small (<155.5°), intermediate (155.5–165.5°) or large (>165.5°)—measuring net joint moments and powers throughout the stance phase using inverse dynamics. Horses with large standing angles demonstrated substantially less tarsal flexion and energy absorption during impact, generated lower vertical impulses, and exhibited reduced net extensor moments compared with those having small or intermediate angles. This conformation-driven reduction in shock attenuation during the loading phase may predispose horses with straighter hocks to tarsal degenerative joint disease, whilst the diminished extensor moment could compromise propulsive capacity; however, the lower net joint moments theoretically reduce stress on plantar ligaments and associated soft tissue structures. For practitioners, these findings suggest that standing tarsal conformation warrants consideration during both lameness investigation and performance assessment, as it directly influences how forces are distributed through the joint—with straighter angles favouring certain injury patterns whilst potentially mitigating others.
Read the full abstract on PubMed
Practical Takeaways
- •Evaluate standing tarsal angle as part of pre-purchase or lameness examinations, as conformation directly influences shock absorption and joint loading patterns during movement
- •Horses with naturally large tarsal angles may be at higher risk for tarsal joint disease but lower risk for plantar ligament injury—tailor conditioning and therapeutic protocols accordingly
- •Consider tarsal angle when assessing suitability for discipline; horses with large angles may have reduced propulsive capacity and greater concussive forces through the joint
Key Findings
- •Horses with large standing tarsal angles (>165.5°) showed significantly less tarsal flexion and energy absorption during impact phase compared to those with small (<155.5°) or intermediate angles
- •Large tarsal angles resulted in reduced vertical impulse and lower net extensor moments during stance, potentially limiting propulsive ability
- •Less concussion absorption in large-angled tarsi may increase degenerative joint disease risk, while reduced joint moments may paradoxically protect against plantar ligament desmitis
- •Tarsal angle stratification remained consistent throughout the stance phase, indicating standing conformation reliably predicts dynamic joint behaviour