Deformation of the equine pelvis in response to in vitro 3D sacroiliac joint loading.

The research examines how the pelvis of a horse deforms in response to 3D load applied on the sacroiliac joint, suggesting that such deformation should be seen as a normal reaction to any movement of this joint.

Objective and Methodology

• The primary objective of this research studies the displacement of the equine (horse) pelvis when the sacroiliac joint is subjected to 3-dimensional loading. This process investigates the poorly understood relationship between pelvic mechanics and the sacroiliac joint, which, when injured, can lead to poor performance in horses.
• The methodology involves physically creating load on the sacroiliac joint on horse specimens using a material testing system (MTS) and utilizing nine reflective triads attached to the sacropelvic bone prominences for stereophotogrammetric analysis of displacement and joint kinematics.
• 3D loading is achieved by simulating nutation-counternutation and left and right lateral bending of the sacroiliac joints through actuation. Furthermore, torsion is applied on the sacrum to induce its axial rotation.
• The study measures the vectors of marker displacement in orthogonal planes of motion during the loading of sacropelvic specimens, comparing the magnitude and direction of triad displacements between the left-right markers and loading conditions.

Results

• The findings illustrate that nutation-counternutation of the sacroiliac joint leads to both vertical displacement of the ischial tuberosities and cranial-caudal displacement of the ilium wings.
• Lateral bending results in rotational displacement within the plane of all pelvic landmarks, while axial rotation of the sacrum causes elevation of the ilium wing on the same side and depression of the contralateral ilium wing.
• The study also notes significant differences between the paired left-right side during most of the sacroiliac joint loading conditions. It finds similar magnitudes of pelvic displacement during nutation-counternutation, left-right lateral bending, and right-left axial rotation.

Conclusions

• The conclusions drawn from the research indicate that the equine pelvis is not rigid and experiences asymmetric deformation during most sacroiliac joint movements.
• It suggests that this pelvic deformation should be considered a normal response to any sacroiliac joint movement, providing valuable insights into the mechanics and behavior of the horse pelvis under strain or load, which could be beneficial in veterinary diagnosis and treatment of issues related to gait and movement in horses.