Dr. Corina Nüesch (Basel / CH), David Koch (Basel / CH), Franziska Schmitter (Basel / CH; Freiburg i. Br.), Marlene Mauch (Basel / CH), Prof. Karl Stoffel (Basel / CH), Dr. Petros Ismailidis (Basel / CH), Prof. Annegret Mündermann (Basel / CH)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Background
While muscle activation during walking has been shown to improve after both total knee arthroplasty (TKA)1 and total hip arthroplasty (THA)2, temporal muscle activation patterns have not been compared to healthy controls.
Aim
Investigating whether temporal muscle activation patterns and strength differ between patients after TKA or THA and healthy controls.
Method
We included 14 patients 1 year after TKA (age 72±11 years; body mass index 26.5±3.7 kg/m2), 15 patients 1 year after THA (anterior minimal invasive approach; 66±11 years; 27.3±2.6 kg/m2), and 17 healthy controls (64±8 years; 25.7±4.0 kg/m2). All participants underwent a gait analysis with simultaneous measurement of surface electromyography (EMG) of the vastus medialis, semitendinosus and gluteus medius. EMGs were normalized to maximal voluntary contractions during isokinetic knee flexion/extension (60°/s) or isometric hip abduction on a dynamometer. Differences between patients and controls in EMG envelope time series (% gait cycle (GC)) were analyzed using statistical parametric mapping with independent sample t tests (P<0.05).
Results
Patients after TKA had higher gluteus medius (4-11%GC, P=.042), semitendinosus (0-8%GC, P=.014; 97-100%GC, P=.044) and vastus medialis muscle activity (17-24%GC, P=.023; 27-32%GC, P=.029; Fig.1), and lower knee flexion and extension strength (P<.008; Fig.2) than controls. Muscle activation patterns and strength of patients after THA did not differ from healthy controls (Fig.1&2).
Conclusion
Muscle activation patterns of patients 1 year after THA have recovered to the level of healthy controls. Patients 1 year after TKA had higher muscle activity, especially in the loading response. Together with the lower knee muscle strength, this could be a compensatory mechanism to increase stability. Therefore, further strength training may be warranted especially in patients after TKA.
1Hubley-Kozey et al. Clin Biomech. 2010; 2Agostini et al. J Arthroplasty. 2014