Mineralisation or Ossification of the Interosseous Ligament of the Centrodistal Joint of the Horse: Is There an Association with Osteoarthritis?
Authors: Skelly E., Dyson S.
Journal: Equine Veterinary Journal
Summary
# Editorial Summary: Mineralisation of the Centrodistal Interosseous Ligament and Hock Osteoarthritis Skelly and Dyson's systematic radiological analysis examined whether ossification of the interosseous ligament in the centrodistal joint correlates with osteoarthritis development—a clinically relevant question given the hock's complexity and importance in performance horses. Reviewing radiographs from 700 horses (1,170 tarsi) over seven years, the authors established baseline appearances of the normal interosseous space and applied a standardised grading system to characterise mineralisation patterns and associated bone changes. Complete ossification of the interosseous ligament occurred in only 2.8% of tarsi (33/190), but these cases demonstrated a striking association with osteoarthritis, present in 81.8% of completely ossified joints; in contrast, patchy ossification without complete loss of the radiolucent space showed far lower osteoarthritic prevalence (18.5%). Notably, only 51.5% of the severely ossified group exhibited clinical distal tarsal pain, suggesting radiological changes may precede or exist independently of lameness signs. For practitioners, these findings emphasise the importance of careful interosseous ligament assessment during routine hock radiography as an indicator of osteoarthritic change, though the absence of pain does not exclude significant pathology—highlighting the need to integrate radiological findings with clinical examination and diagnostic anaesthesia rather than relying on imaging alone.
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Practical Takeaways
- •Always examine the centrodistal interosseous ligament region when radiographing the hock—complete ossification in this location is highly predictive of distal hock arthritis and clinical pain
- •Partial mineralisation (patchy opacity) is less commonly associated with osteoarthritis and may represent an incidental finding; clinical correlation is essential before attributing lameness to these changes
- •Horses with complete interosseous ligament ossification warrant careful assessment for distal tarsal pain and early intervention, as the majority develop radiographic evidence of joint degeneration
Key Findings
- •Mineralisation or ossification of the centrodistal joint interosseous ligament occurred in 16.2% (190/1170) of tarsi examined over 7 years
- •Complete ossification of the interosseous ligament was associated with osteoarthritis of the centrodistal joint in 81.8% (27/33) of tarsi, with 51.5% showing distal tarsal pain
- •Patchy increased opacity within the interosseous space occurred in 157/190 tarsi with abnormalities, but only 18.5% (29/157) showed concurrent centrodistal osteoarthritis
- •Normal interosseous space appears as a uniform oval-shaped radiolucent area; assessment of this region should be routine during tarsal radiographic evaluation