Effect Of Limb Rotation on Measurements Of Equine Metacarpophalangeal Radiographs

Abstract

Objective: Metacarpophalangeal joint (MCPJ) radiographic parameters were developed to evaluate MCPJ conformation of equine  forelimbs but the effect of joint rotation during radiography on these parameters has not been reported. The current study examined the  effect of the rotation around the vertical axis of MCPJ on 27 MCPJ parameters (12 angles and 15 ratios) and identified the acceptable range of rotation at which minimal changes have occurred in these parameters.

Design: MCPJs of seven right equine forelimbs were loaded in a load cell to obtain the normal MCPJ angle. They were frozen at −20C° and  then scanned using a CT-scan machine. The collected slices were reconstructed to obtain a 3D module of MCPJs, and the dorsopalmar  view at zero angle (ZDP) were identified. The view was then rotated around the vertical axis of MCPJ. Snapshots were taken for MCPJ at  −10°, −5°, Zero, +5° and +10° angles. All the parameters were measured on the total 35 radiographs and statistically analysed. Differences  were estimated per 5° of MCPJ rotation for all the parameters.

Animals: MCPJs of seven right forelimbs from seven different horses with  no MCPJ abnormalities.

Results: Generally, the ratio parameters were less affected than the angular parameters during MCPJ rotation.  

Conclusion and clinical relevance: Rotational angles of vertical ±10° from ZDP were considered as an acceptable range for reliable  radiographic measurements of MCPJ parameters.