Baseline gait muscle activation patterns differ for osteoarthritis patients who undergo total knee arthroplasty 5–8 years later from those who do not

OBJECTIVE: To determine if baseline quadriceps and hamstrings muscle activity patterns differed between those with medial-compartment knee osteoarthritis who advanced to total knee arthroplasty (TKA) and those who did not, and secondly to examine associations between features extracted from principal component analysis (PCA) and discrete measures. METHODS: Vastus lateralis and medialis, rectus femoris, and lateral and medial hamstrings surface electromyograms were collected from 54 individuals with knee osteoarthritis during walking. Amplitude and temporal characteristics from PCA, co-contraction indices (CCI) for lateral and medial muscle pairs, and root mean square (RMS) amplitudes for early, mid, late, and overall stance were calculated from electromyographic waveforms. At follow-up 5-8 years later, 26 participants reported undergoing TKA. Analysis of Variance models tested for differences in PC scores and discrete measures between TKA and no-TKA groups (alpha= 0.05). Pearson product moment correlation coefficients were calculated between PC scores and discrete variables. RESULTS: The TKA group had higher hamstrings activity magnitudes (PC1), prolonged activity in mid-stance (PC2) for all muscles, and greater lateral CCI. TKA had higher hamstrings RMS activity for all stance phases, and higher mid and late-stance quadriceps RMS activity. PC1 was highly correlated with RMS amplitude (highest overall and early stance). PC2 was correlated with mid and late-stance RMS. CCIs were correlated with PC1 and PC2, with greater variance explained for PC1. CONCLUSION: Those advancing to TKA had higher magnitudes and more prolonged agonist and antagonist activity, consistent with less joint unloading. These gait muscle activation patterns indicate a potential conservative intervention target.