A comparison of loading characteristics during the timed up and go test pre-and post-total knee arthroplasty in patients with osteoarthritis

Abstract

The timed up and go (TUG) test is commonly used to measure functional ability in a variety of patient populations. However, improved assessment of function could be attained with the addition of kinetics during the TUG test. A longitudinal, repeated measures evaluation of 12 osteoarthritic patients, set to undergo TKA and 12 control subjects was conducted using the TUG test pre-TKA and six months post-TKA. Kinetic variables during stance and push-off, collected from two forces plates, and time to completion for the TUG test were examined. Separate one-way, repeated measures ANOVAs were completed to examine change over time in each dependent variable. Data from both subject samples were combined, revealing significant correlation between TUG time to completion and loading rate (p=0.000, r=-0.795), anteroposterior maximum ground reaction force (p=0.000, r=-0.753) and contact time (p=0.000, r=0.882) during both time periods. There were significant increases in loading rate (p=0.023) and significant decreases in TUG time to completion (p=0.016) and contact time (p=0.013) in TKA subjects at six months. Significant main effects were reported between TKA and control subjects for loading rate (p=0.003), TUG time to completion (p=0.017), and contact time (p=0.007). Post-hoc analysis revealed TKA patients have a decreased loading rate (p<0.001), increased TUG time to completion (p=0.007), and increased contact time (p=0.004) when compared to controls prior to surgery. Based on these results, a decrease in time to completion may not only be due to an increase in walking speed post-TKA, but also the ability to load the limb more quickly upon standing. Therefore, a decrease in time to completion of the TUG test could indicate a better ability to accept weight and a greater overall function within the involved limb.