Adaptations in equine axial movement and muscle activity occur during induced fore- and hindlimb lameness: A kinematic and electromyographic evaluation during in-hand trot.
Authors: Spoormakers Tijn J P, St George Lindsay, Smit Ineke H, Hobbs Sarah Jane, Brommer Harold, Clayton Hilary M, Roy Serge H, Richards James, Serra Bragança Filipe Manuel
Journal: Equine veterinary journal
Summary
# Editorial Summary Understanding how the back adapts during lameness is crucial for practitioners assessing horses and planning rehabilitation, yet the relationship between thoracolumbar motion and underlying muscle activity remains unclear. Spoormakers and colleagues used three-dimensional motion capture combined with surface electromyography to record eight clinically sound horses trotting at baseline and during experimentally induced forelimb and hindlimb lameness (2–3/5 severity), examining kinematic changes in the thoracolumbar spine and pelvis alongside longissimus dorsi muscle activity at two spinal levels. Both lameness types significantly increased maximal thoracolumbar flexion and pelvic pitch range of motion, yet hindlimb lameness additionally produced marked lateral bending shifts towards the sound side and reciprocal changes in muscle activation timing and intensity—patterns notably absent during forelimb lameness. These findings reveal that forelimb and hindlimb lameness provoke distinctly different compensatory strategies: forelimb lameness primarily affects cranio-caudal (flexion–extension) movement, whilst hindlimb lameness engages lateral bending and axial rotation alongside changes in longissimus recruitment. For farriers, physiotherapists and veterinarians, these insights suggest that diagnostic assessment and rehabilitation protocols may need to account for region-specific spinal adaptations; however, validation in naturally lame clinical cases will be essential before translating these controlled laboratory findings into evidence-based practice guidelines.
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Practical Takeaways
- •Horses with hindlimb lameness show distinctly different spinal compensation patterns (lateral bending + axial rotation) compared to forelimb lameness (primarily flexion-extension), which may inform diagnosis and rehabilitation strategies.
- •Induced lameness causes measurable changes in thoracolumbar mobility and muscle timing detectable by motion capture and electromyography, validating these technologies for clinical gait assessment in equine practice.
- •The differential compensatory mechanisms between forelimb and hindlimb lameness suggest targeted treatments should account for these distinct patterns rather than applying uniform approaches.
Key Findings
- •Maximal thoracolumbar flexion and pelvis pitch range of motion increased significantly during both induced forelimb and hindlimb lameness.
- •During hindlimb lameness, peak lateral bending increased toward the nonlame side and decreased toward the lame side, with bilateral longissimus muscle activity increase at T14 and L1.
- •Forelimb lameness adaptations occurred primarily in cranio-caudal (flexion-extension) direction, while hindlimb lameness involved lateral bending and axial rotation components.
- •Longissimus muscle activation was delayed on the nonlame side and precipitated on the lame side during hindlimb lameness but not during forelimb lameness.