sprain: Wrenching or twisting of a joint with partial rupture of its attaching ligaments.
strain: Overstretching a muscle.
Invariably, both conditions are trauma-induced. Of the two, and the terms are often (incorrectly) used interchangeably, the sprain is the more serious. There are three classifications of a sprain:
• Grade 1: Mild/minimal sprain with no ligamentous tear. There may be pain, swelling and tenderness.
• Grade 2: Moderate sprain with an incomplete or partial rupture of ligaments or tendons. There is marked pain, swelling, bruising, decreased range of movement and minor instability of the joint.
• Grade 3: Joint injury with complete tearing of the associated ligament. Presents as severe pain, swelling, hemorrhage, significant joint instability and no range of movement.