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.