Sentence:  His arm had been giving him some trouble and Rector was not enough of a medical expert to determine whether it had healed improperly or whether Hino was simply rebelling against the tedious work in the print shop , using the stiffness in his <WSD>arm</WSD> as an excuse . 
Meaning of the word marked with <WSD> tags:  a human limb; technically the part of the superior limb between the shoulder and the elbow but commonly used to refer to the whole superior limb