STUDY DESIGN: Longitudinal cross-sectional study. BACKGROUND: In the early stages after total knee arthroplasty (TKA), quadriceps strength of the operated limb decreases and is substantially less than that of the nonoperated limb. This asymmetry in strength is related to asymmetrical movement patterns that increase reliance on the nonoperated limb. Over time, quadriceps strength in the operated limb increases but remains less than that in age-matched controls without knee pathology, whereas the quadriceps strength in the nonoperated limb gradually decreases. The purpose of this study was to investigate the changes in quadriceps strength and function of both limbs up to 3 years after TKA and to evaluate change in interlimb kinematic and kinetic parameters over time compared to that in age-matched individuals without knee pathology. METHODS: Fourteen individuals after TKA and 14 healthy individuals matched for age, weight, height, and sex participated in the study. Outcome measures included kinematics, kinetics, quadriceps strength, and functional performance. RESULTS: In participants who underwent TKA, quadriceps strength was significantly different between limbs at 3 months and 1 year after TKA, but not at 3 years after TKA. In this group, there was also a significant improvement in self-reported function between 3 months and 1 year after TKA, but a significant decrease between years 1 and 3 for the physical component summary score of the Medical Outcomes Study 36-Item Short-Form Health Survey. In the TKA group, there were few interlimb differences in joint kinematics and kinetics 3 years after TKA, which may be attributed to a combination of worsening in the nonoperated limb, as well as improvement in the operated limb. Differences between participants without knee pathology and those 3 years after TKA still existed for kinematic, kinetic, and spatiotemporal variables. CONCLUSION: As interlimb differences in quadriceps strength decrease after TKA, there are concomitant symmetrical improvements in temporospatial and kinetic gait parameters. The symmetry 3 years after TKA in quadriceps strength is primarily the result of progressive weakness in the nonoperated limb.
J Orthop Sports Phys Ther 2012;42(12):1039-1049, Epub 22 October 2012. doi:10.2519/jospt.2012.3763
KEY WORDS: biomechanics, joint replacement, walking
The purpose of this study was to investigate the changes in quadriceps strength and function of both limbs up to 3 years after total knee arthroplasty (TKA) and to evaluate change in interlimb kinematic and kinetic parameters over time compared to that in age-matched individuals without knee pathology.