Which sprain grade is a complete rupture with marked instability and functional loss?

Which sprain grade is a complete rupture with marked instability and functional loss?

• A. Grade I: microscopic fiber disruption, minimal swelling, no or slight instability
• B. Grade II: partial tear with swelling and moderate instability
• C. Grade III: complete rupture with marked instability and functional loss
• D. Grade IV: avulsion fracture

Answer: (C)

When a ligament is fully torn, the joint loses its main stabilizing restraint, so instability is pronounced and function is significantly impaired. Sprain grades reflect how much of the ligament is damaged: a complete rupture means the ligament has no intact fibers left to support the joint, which explains the marked instability and functional loss described. Weaker grades involve less damage—microscopic fiber disruption with minimal swelling and little instability, or a partial tear with swelling and moderate instability. An avulsion fracture is a bone fragment pulled off by the ligament, not a pure ligament tear, so it’s a different pattern of injury. So the scenario matches the complete rupture grade.

When a ligament is fully torn, the joint loses its main stabilizing restraint, so instability is pronounced and function is significantly impaired. Sprain grades reflect how much of the ligament is damaged: a complete rupture means the ligament has no intact fibers left to support the joint, which explains the marked instability and functional loss described. Weaker grades involve less damage—microscopic fiber disruption with minimal swelling and little instability, or a partial tear with swelling and moderate instability. An avulsion fracture is a bone fragment pulled off by the ligament, not a pure ligament tear, so it’s a different pattern of injury. So the scenario matches the complete rupture grade.