What are the three basic elements of rating for knee disability?

• A. Pain level; Swelling; Numbness
• B. X-ray findings; Bone density; Range
• C. Limitation of flexion and extension; Instability; Calf atrophy
• D. Muscle strength; Endurance; Coordination

Answer: (C)

The main idea being tested is how knee disability is rated in terms of functional impairment. The best answer identifies three core aspects: limitation of motion (specifically loss of knee flexion and extension), instability of the knee, and calf atrophy.

Limitation of motion shows how much the knee’s bending and straightening are reduced, which directly affects walking, climbing, kneeling, and other daily activities. Instability reflects ligamentous laxity or the knee giving way under load, which jeopardizes safety and confidence during weight-bearing tasks. Calf atrophy indicates muscle wasting from disuse or nerve involvement, signaling reduced strength and endurance in the leg.

Pain, swelling, and numbness are important symptoms but don’t alone define the impairment level used for rating. Imaging findings reveal structural status, not the functional limitation. While strength, endurance, and coordination matter, the three elements—motion, stability, and muscle wasting—are the primary domains used to rate knee disability.