What is the defining feature of Phase 4 of biomechanical changes?

In Phase 4 of biomechanical changes, the defining feature is the completion of fusion and ankylosis. This phase is characterized by significant alteration of the spinal structures where the bony changes compromise the normal mobility of the spine. Fusion refers to the joining together of vertebrae, which eliminates intervertebral motion, while ankylosis signifies the complete loss of mobility in the affected segments, leading to a rigid and less flexible spine. Understanding this phase is crucial because it indicates advanced degenerative changes and the possibility of chronic pain and disability, which are important considerations in chiropractic care and treatment planning. Recognizing these changes helps practitioners assess the severity of biomechanical issues and the appropriate responses or interventions necessary for patient care.