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

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

Answer: (A)

Permanent disability ratings for grip strength are determined by translating the measured loss of grip into a rate of impairment for the hand, then converting that into a whole-person (body) disability using a standard factor.

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

To convert hand impairment to a whole-person permanent disability, multiply by 0.30 (a standard 30% conversion factor for hand impairments). So 0.434 × 0.30 ≈ 0.130, i.e., about 13%.

Therefore, the permanent disability is about 13%.