In general, the amount of quadriceps atrophy that is present in one’s thigh is indicative of the amount of weakness present. In our experience, about 2 cm of quadriceps atrophy can be equivalent to about 70% of the strength of the contralateral side. Thus, it is important to evaluate the amount of quadriceps atrophy in patients to help determine the degree of weakness they may have and if they are making progress with a postoperative/postinjury rehabilitation program.
Measurement of thigh circumference is usually performed 15 cm proximal to the superior pole of the patella. The thigh circumference is measured in cm with a measurement tape and compared to the normal contralateral knee to determine the amount of quadriceps atrophy present.