In vitro assessment of movements of the sacroiliac joint in the horse.

The research explores the horse’s sacroiliac joint (SIJ), focusing on its movements, relation to disease, and effects of surgical intervention on its stabilization. Although the SIJ plays a significant role in a horse’s performance, understanding its biomechanics has been challenging due to its low-motion nature.

Objective and Methodology

The researchers aimed to determine the movement capabilities of the sacroiliac joint (SIJ) in horses, specifically in the sagittal plane. They also wanted to examine the effects of two types of anatomical dissection, sacrosciatic and sacrotuberal desmotomy, on the joint’s stability. They performed these tests using six in vitro anatomical specimens.

For this study, they carried out cycles of bending and straightening (flexion-extension) of the lumbosacral joint (LSJ) both before and after the surgical process, desmotomy. To measure the angles involved, they used kinematic triads, which were securely attached to the sacrum, the spinous process of the L5 vertebra, and the iliac wing.

Results

The results indicated that the lumbosacral joint (LSJ) experienced consistent bending and straightening movements. However, the only detected movement in the sacroiliac joint (SIJ) was a slight rocking motion, or nutation, during the bending (flexion) of the LSJ.

Surgical intervention (desmotomy) resulted in an increased nutation. It’s noteworthy that these movements were small and only associated with the bending of the LSJ. The surrounding ligaments had a heavy impact on the joint’s stability.

Conclusions

The limited motion of the sacroiliac joint (SIJ) makes its in vivo biomechanical study difficult. The study concluded that even small movements in the SIJ are integral to the function of the joint, particularly during the bending of the LSJ. As a result, the ligaments surrounding the joint are crucial for its stabilization.

Given these findings, the researchers suggest that additional in vitro studies are necessary to categorize individual ligaments’ roles. This further research would help to better comprehend the clinical implications of the joint tears frequently identified during the post-mortem examination.