Effect of patellectomy on the function of the quadriceps and hamstrings.

The Cybex-II isokinetic dynamometer was used to measure quadriceps and hamstrings function after unilateral patellectomy in twelve patients. The interval between surgery and testing averaged twenty-six months (range, fourteen to forty-two months). Data on isokinetic and isometric performance were compared with those of the untreated limb and with those of subjects who had not been operated on but who had been matched by age, sex, and weight. On the side that had been operated on, the peak torque of the quadriceps was significantly decreased whereas the peak torque of the hamstrings was preserved. Deficits in time factors related to the development of tension and high-speed performance were documented, revealing abnormalities in both muscle groups. Although patellectomy was successful in achieving relief of pain in these patients, the results of the study confirmed that the function of the knee muscles was compromised postoperatively. The objective findings documented alterations in muscle function that correlated well with the functional limitations described by the patients.