Clinical significance of osseous spurs on the dorsoproximal aspect of the third metatarsal bone.

This study investigated the clinical significance of osseous spurs (bony outgrowths) found on the third metatarsal bone of horses. The research found that these spurs were common but their relevance to health and lameness wasn’t clear. The study concluded that the presence of these spurs may be incidental unless they’re associated with other radiological abnormalities, suggesting the spurs occur more frequently in horses with osteoarthritis in their lower hock joints.

Background and Objective

• Osseous spurs are common on the dorsoproximal aspect of the third metatarsal bone (MtIII) in horses. Despite their frequent occurrence, the medical relevance of these spurs is not well understood.
• The purpose of the research was twofold. Firstly, to ascertain the point of attachment of the dorsal metatarsal ligament and the tendons of the tibialis cranialis and fibularis tertius. This knowledge would help to distinguish if periarticular osteophytes and entheseophytes could be differentiated radiologically. Secondly, to establish the regularity of osseous spurs’ occurrence on the dorsoproximal aspect of MtIII.
• The study hypothesised that the frequency of such osseous spurs would be higher in lame horses compared to clinically normal ones. It was also proposed that the rate would be higher in horses suffering from distal hock joint pain or proximal suspensory desmitis, as opposed to horses with other causes of hindlimb lameness.

Methodology

• The study was retrospective in nature, examining clinical data and tarsal radiographs of 455 horses. Horses were divided into groups based on their hindlimb lameness diagnosis.
• Radiographs were screened to identify the presence of an osseous spur on the dorsoproximal aspect of MtIII. Any abnormalities in the distal tarsal joints were also graded.
• The researchers used Chi-squared tests to analyse potential associations between the presence of spurs, lameness, diagnosis group, and the severity of distal tarsal joint abnormalities.

Results

• Osseous spurs were found in 25% of horses, with 13% of horses that had bilateral radiographs featuring bilateral spurs.
• No significant difference was found in the presence of spurs between lame and non-lame horses, or between horses with other causes of hindlimb lameness and horses with proximal suspensory desmitis and/or distal tarsal joint pain.
• However, the presence of an osseous spur was significantly associated with the grade of radiological abnormality in the distal tarsal joints.
• In many cases, it wasn’t possible to definitively distinguish between osteophytes and entheseophytes.

Conclusions

• The research suggested that the presence of an osseous spur on the dorsoproximal aspect of MtIII, in the absence of other radiological abnormalities, may be an incidental finding and not necessarily an indicator of a health issue.
• Moreover, the study found these osseous spurs may occur more frequently in cases where there are radiological abnormalities present in the distal tarsal joints. This could indicate distal tarsal joint osteoarthritis.
• The actual clinical significance of such spurs must be verified through intra-articular analgesia – a method of pain relief in which medication is injected directly into a joint.