Which of the following is not normally considered in knee disability rating?

• A. Calf circumference
• B. Limitation of flexion
• C. Instability
• D. Thigh atrophy

Answer: (A)

In rating knee disability, the assessment focuses on factors that directly reflect how the knee functions: how well it bends (range of motion), whether it remains stable under stress, and how surrounding muscles contribute to knee control. Calf circumference doesn’t reveal these knee-specific functions, so it isn’t normally used in determining the knee impairment.

Limitation of flexion is a direct measure of how far the knee can bend, which clearly affects daily activities and gait, making it a core factor in the rating. Instability indicates ligamentous laxity that compromises knee support, another essential determinant of how the knee performs. Thigh atrophy signals loss of muscle mass around the knee, particularly the quadriceps, which can worsen knee function and strength, so its presence is relevant to the impairment assessment.

Calf circumference, by contrast, reflects distal leg muscle size rather than the knee joint’s mechanics or the muscles most involved in knee function, which is why it’s not normally part of the knee disability rating.