Methodological considerations for the calculation of cumulative compression exposure of the lumbar spine: a sensitivity analysis on joint model and time standardization approaches.
Cumulative lumbar spine loading has attracted much attention as a factor associated with the development of low back pain. While evidence supports cumulative loading to be a plausible mechanism in explaining several workplace injuries, research establishing a threshold limit value (TLV) for cumulative spine loading has been challenging. The lack of a TLV or even a trend towards harmful cumulative load values may suggest that methodological considerations are greatly influencing the results. This paper examines the impact of different joint models (single muscle equivalent, an electromyography-based third order polynomial, a modified version of the polynomial and a hybrid approach) to determine cumulative spine compression, as well as the importance of time standardization in the calculation of a daily cumulative loading dose. Findings demonstrated that the polynomial predicted cumulative compression values were 43-53% higher than those with all other models tested and the single muscle equivalent predicted loads 18% higher than loads predicted using a modified polynomial. Profound differences between modelling approaches suggest that caution should be taken when selecting a muscle model to determine cumulative spine compressive loading. Time standardized cumulative compression values were found to be 28.3% greater than non-standardized estimates, illustrating the importance of selecting a standard time frame in the calculation of cumulative spine compression.
Fischer
S L
SL
Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
Albert
W J
WJ
McClellan
A J
AJ
Callaghan
J P
JP
D000328:Adult; D000465:Algorithms; D001696:Biomechanical Phenomena; D002170:Canada; D006804:Ergonomics / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D017116:Low Back Pain; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D013117:Spinal Cord Compression / Q000503:physiopathology*; D020711:Threshold Limit Values