Influence of Chronic Lameness on Thoracolumbar Musculus Multifidus Structure in the Horse.
Authors: Sullivan Hayley M, Acutt Elizabeth V, Barrett Myra F, Salman Mo D, Ellis Katherine L, King Melissa R
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Chronic limb lameness compromises the kinetic chain, yet its effects on spinal stabiliser muscles remain poorly characterised in equine medicine. Sullivan and colleagues used ultrasonography to measure thoracolumbar multifidus cross-sectional area (CSA) across thirty-six horses stratified into sound, forelimb-lame, and hindlimb-lame groups, scanning at multiple vertebral levels to assess lateralised muscular changes. Horses with forelimb lameness demonstrated significantly reduced multifidus CSA across all measured levels compared to sound controls (P = 0.002), whilst the hindlimb-lame group showed intermediate atrophy patterns; the T18 vertebral level consistently exhibited the largest CSA regardless of lameness status. These findings demonstrate that chronic peripheral lameness drives measurable axial skeletal adaptation through muscular atrophy of the primary spinal stabiliser, suggesting that effective lameness management must address secondary back dysfunction to restore normal force distribution through the kinetic chain and prevent compensatory musculoskeletal deterioration.
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Practical Takeaways
- •Forelimb lameness causes measurable atrophy of back muscles even when lameness appears to be resolved clinically—consider back assessment as part of lameness workup
- •The thoracolumbar region (especially T18) requires specific attention during rehabilitation, as m. multifidus dysfunction compromises spinal stabilization and may perpetuate or cause secondary lameness
- •Horses recovering from chronic forelimb lameness may benefit from targeted back rehabilitation protocols to restore m. multifidus function and prevent kinetic chain compensation
Key Findings
- •M. multifidus cross-sectional area at T18 was significantly larger than all other measured spinal levels regardless of lameness status (P ≤ 0.05)
- •CSA at all spinal levels was significantly smaller in forelimb lame horses compared to sound horses, regardless of side (P = 0.002)
- •Chronic forelimb lameness results in measurable axial skeletal adaptation with decreased m. multifidus CSA
- •This is the first study demonstrating that naturally occurring chronic lameness impacts the axial skeleton structure