What happens when both passive and active restraints in a joint fail to function correctly?
Answer
The joint fails to provide adequate resistance or corrective force to return to center
In a healthy joint, active and passive restraints work in a complementary system. Passive restraints like ligaments provide structural limits, while active restraints like muscles provide the dynamic force needed to adjust and stabilize the joint. When both systems fail, the joint lacks the necessary 'restoring force.' This force is critical for bringing the joint back to its center or neutral position after it has been disturbed. Without this corrective ability, the joint cannot manage the loads placed upon it, leading to the clinical manifestation of instability, where the structure is essentially left unsupported and prone to abnormal motion.
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