Quantification of Equine Sacral and Iliac Motion During Application of Manual Forces and Comparison Between Motion Capture With Skin-Mounted and Bone-Fixated Sensors.
Authors: Goff Lesley M, McGowan Catherine M, Condie Peter, Jasiewicz Jan, van Weeren Rene
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Understanding how the sacroiliac joint actually moves in living horses is crucial for those diagnosing and treating pelvic dysfunction, yet previous motion studies relied on cadaveric specimens. Goff and colleagues directly measured in vivo sacral and iliac motion in six Thoroughbreds by simultaneously recording movement data from both skin-mounted sensors and bone-fixated sensors (attached via Steinmann pins) placed over the tuber sacrale and third sacral spinous process, whilst an investigator applied manual forces to induce cranial, caudal, and oblique rotations of the pelvis. Flexion-extension motions were the largest observed movements (mean 2.08° ± 0.35° with bone-fixated sensors), though axial rotation produced the most prominent readings when using skin-mounted sensors alone (1.70° ± 0.48°). Critically, the poor correlation between skin and bone-mounted markers—particularly for axial rotation—demonstrates that palpable skin movement significantly overestimates or misrepresents actual bony motion at the sacroiliac region. For practitioners relying on manual palpation to assess sacroiliac dysfunction, this finding underscores an important limitation: external tissue movement cannot reliably predict underlying skeletal kinematics, suggesting that clinical palpation assessment should be interpreted cautiously and integrated with additional diagnostic approaches rather than used as a standalone diagnostic tool.
Read the full abstract on PubMed
Practical Takeaways
- •Manual palpation-based diagnosis of sacroiliac motion in horses is limited by the inability to accurately detect bone movement through skin; clinical palpation may not reflect actual bony motion
- •When assessing sacroiliac dysfunction, be aware that small degrees of motion (1-2°) are being measured, requiring precise diagnostic techniques beyond manual palpation
- •Skin-mounted motion capture systems commonly used in equine research may underestimate or misrepresent actual skeletal motion, affecting interpretation of biomechanical studies
Key Findings
- •Flexion-extension motion was the largest mean motion measured during pelvic manipulation with bone-fixated sensors (2.08° ± 0.35°)
- •Axial rotation produced the largest values with skin-mounted sensors (1.70° ± 0.48°)
- •Poor correlation existed between skin-mounted and bone-fixated sensors across all orthogonal planes
- •Bony kinematics cannot be reliably predicted from skin-mounted sensors due to significant differences in measurement accuracy