Contact areas and pressure distribution on the proximal articular surface of the proximal phalanx under sagittal plane loading.
Authors: Brama P A, Karssenberg D, Barneveld A, van Weeren P R
Journal: Equine veterinary journal
Summary
# Editorial Summary Brama and colleagues examined how load is distributed across the proximal articular surface of the first phalanx during various weightbearing conditions, using cadaveric equine forelimbs subjected to forces ranging from 1800 N (standing) to 12,000 N (jumping). Using methylene blue staining and pressure-sensitive films, they found that contact area expanded substantially with increasing load—from 63% of the articular surface at rest to 95% during simulated jumping—with progressive involvement of the dorsal articular margin. Critically, peak pressures concentrated at the dorsal margin during athletic loading (trot, gallop and jumping), whereas standing and walking horses showed minimal loading in this region, suggesting an intermittent but severely concentrated stress pattern at this site. These findings provide biomechanical explanation for the common clinical presentation of osteochondral lesions at the dorsal aspect of the first phalanx, indicating that performance demands rather than static posture drive pathology in this location. Understanding this load distribution has direct relevance for farriers optimising shoeing to manage breakover mechanics, veterinarians counselling on lesion prognosis, and coaches managing workload intensity in young or predisposed athletes.
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Practical Takeaways
- •Osteochondral lesions at the dorsal aspect of the proximal phalanx are biomechanically predictable outcomes of athletic work—consider this when evaluating young performance horses for soundness issues
- •Loading patterns differ substantially between gaits; walking and trotting spare the dorsal margin that bears extreme loads during galloping and jumping, suggesting progressive conditioning may be protective
- •Farriers and veterinarians should recognize that proximal phalanx joint damage is not just a training error but an inherent consequence of high-intensity loading—management must account for this inherent biomechanical vulnerability
Key Findings
- •Contact area on proximal phalanx articular surface increased from 63% at 1800 N (stance) to 95% at 12,000 N (jumping), with strong positive correlation (r=0.86)
- •Peak pressures concentrated at dorsal articular margin during athletic loading (5400-12,000 N), sites not loaded during standing or walking
- •Pressure patterns consistent across loads but progressively shifted dorsally with increasing load, expanding from central areas to articular edges
- •Combination of intermittent high loads during athletic performance and concentration at dorsal margin explains frequency of osteochondral lesions at this site