Influence of head and neck position on radiographic measurement of intervertebral distances between thoracic dorsal spinous processes in clinically sound horses
Authors: Berner D., Winter K., Brehm W., Gerlach K.
Journal: Equine Veterinary Journal
Summary
# Editorial Summary Dorsal spinous process (DSP) impingement in the thoracic spine is commonly diagnosed using radiographic measurement of intervertebral distances, yet this study reveals a critical confounding variable: head and neck positioning significantly alters these measurements in clinically sound horses. Berner and colleagues obtained lateral radiographs from 23 horses in three distinct head and neck positions, systematically measuring the distances between adjacent thoracic DSPs (T8–T15) using a standardised perpendicular measurement technique relative to a tangent line along the processes. Low head and neck positions increased intervertebral distances across the mid-to-caudal thoracic region, whilst elevated positions compressed these spaces—a pattern particularly pronounced between T8 and T15—with intermediate positions showing progressive narrowing from cranial to caudal vertebrae. These findings have significant implications for diagnostic practice: radiographic assessment of DSP impingement must account for head and neck position during image acquisition, as failure to standardise positioning could result in either false-positive diagnoses of impingement in high-headed horses or missed pathology in those positioned lower, potentially affecting treatment decisions and case management. The authors also identified the T12 DSP as a reliable anatomical landmark for consistent radiographic identification, which may improve reproducibility of measurements across different practitioners and clinical settings.
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Practical Takeaways
- •Standardise head and neck position during radiographic examination for dorsal spinous process spacing — positioning dramatically affects measurements and diagnostic interpretation
- •High head and neck positions artificially narrow intervertebral spaces on radiographs; use consistent positioning to avoid false-positive diagnoses of impingement
- •Use the 12th thoracic dorsal spinous process as a reliable reference landmark when evaluating thoracic spine radiographs
Key Findings
- •Low head and neck position increased intervertebral distances between dorsal spinous processes at T8-T15 compared to high position (P<0.05)
- •High head and neck position decreased intervertebral distances, potentially mimicking or exacerbating impingement on radiographs
- •The 12th thoracic dorsal spinous process serves as a reliable anatomical landmark due to significant morphological differences from adjacent processes
- •Intervertebral distances decreased cranially to caudally in intermediate head and neck positions (P<0.01)