What percentage of compressive load is borne by facet joints?

The correct percentage of compressive load borne by facet joints is indeed around 30%. Facet joints, also known as zygapophyseal joints, play a crucial role in load-bearing and stability of the spine during various movements. They are responsible for resisting shear and torsional forces while also contributing to load sharing, particularly in the lumbar region.

Research shows that under typical physiological conditions, the facet joints can take on approximately 30% of the axial compressive load when the spine is in a neutral position or during certain activities. This function is vital for maintaining the overall integrity and functionality of the spine, particularly under weight-bearing situations.

This percentage highlights the significant contribution of facet joints in distributing forces experienced by the spine, especially in conjunction with intervertebral discs, which bear the majority of compressive loads in these scenarios. Understanding the role of facet joints aids in grasping how spinal mechanics work as a whole, which is essential for assessing conditions such as lower back pain and understanding treatment approaches.