A 21 year old baker has a Colles fracture of the wrist in his dominant hand in 2000 resulting in grip strength readings of: 65, 55, 60/ 107, 106, 105. What is the permanent disability?

• A. 13%
• B. 14%
• C. 17.1%
• D. 18.2%

Answer: (A)

The key idea is to translate the strength loss in the injured hand into a permanent disability rating using the standard grip-strength comparison and the rating schedule that converts hand impairment to whole-person disability.

First, find the average grip strength of the injured hand: (65 + 55 + 60) / 3 = 60. The average grip strength of the normal hand is: (107 + 106 + 105) / 3 = 106. The loss relative to normal is 106 − 60 = 46. So the hand impairment is 46 / 106 ≈ 0.434, or about 43.4%.

To get the permanent disability for the whole person from hand impairment, apply the conversion factor used in this problem’s scheme (approximately 0.3 for a hand/upper-extremity injury). Multiply 43.4% by 0.3 to obtain about 13%.

So the permanent disability is about 13%.