Three-dimensional kinematics of the tarsal joint at the trot.

This research study demonstrates the three-dimensional movement of the tarsal joint in healthy Quarter Horses while trotting, finding evidence that some movements occur outside the tarsocrural joint, which could assist in understanding the cause and effects of lameness in the tarsal joint.

Research Methodology

• The study was conducted on four healthy Quarter Horses. The focus of the study was the tarsal joint, an area that is prone to injury in many sport horses.
• To measure the three-dimensional kinematics of the tarsal joint, targets were attached directly to the bones of the tarsal joint using steel pins. Two pins were inserted each into the lateral side of the right hindlimb, and marker triads were fixed to the end of each pin.
• The tests involved recording the three-dimensional movement of the tarsal joint bones while the horses were trotting. This provided real-time motion data of the tarsal joint during a common activity.

Research Findings

• The study found that the rotation and translation of the tarsal joint during trotting were mostly coupled with the flexion angle. This means that these movements generally occur simultaneously, indicating that they are interdependent.
• Evidence of non-coupled motion (independent movements) was found in the internal and external rotation of the tarsal joint during the stance phase of trotting and in translations during the swing phase. This suggests that not all movements in the tarsal joint are interdependent.
• Although most tarsal joint movement happens in the tarsocrural joint (the primary joint in the tarsus), other areas within the tarsal joint also showed some degree of motion, both in rotation and translation. Some of these motions are associated with the ‘snapping’ phenomenon in the tarsal joint, where the joint makes a snapping/clicking noise during movement.

Research Implications

• The information obtained from this study provides valuable reference data about the three-dimensional kinematics of the tarsal joint in horses. This can aid additional research studies into the causes and effects of tarsal joint lameness.
• Understanding the independent and interdependent motions of the tarsal joint under normal conditions could help identify abnormal movements that signal potential injury or disease. This knowledge would in turn support the design of preventative or rehabilitative measures for equine athletes.