Active Insufficiency occurs when a muscle cannot contract fully across both joints it crosses.

• A. Active Insufficiency
• B. Passive Insufficiency
• C. Functional Excursion
• D. PROM

Answer: (A)

Active insufficiency happens when a muscle that crosses two joints is already shortened across both joints, so it can’t generate full contraction to move the distal segment. When a multi‑joint muscle is shortened at both ends, the overlap of its contractile filaments isn’t enough to produce strong force, limiting its ability to shorten further and produce the desired movement at the far joint. A common example is the gastrocnemius crossing the knee and ankle: with the knee flexed, the gastrocnemius is shortened across the knee and can’t plantarflex the ankle as effectively, illustrating the muscle’s limited contraction across both joints. In contrast, passive insufficiency concerns a muscle being stretched to its maximal length across the joints, and PROM refers to moving a joint without the muscle actively contracting.