Traction Loading Human Coracohumeral Ligaments With 20 and 40 Newton Forces and Sustained Creep Deformation: A Preliminary Cadaveric Investigation

Abstract

Objectives

The purpose of this study was to determine if different force magnitudes, loading cycle repetitions, and loading speeds alter creep deformation (CD) during cyclical traction loading of human cadaveric coracohumeral ligaments (CHL).

Methods

Fifteen unembalmed human cadaveric CHL specimens were assigned to 3 groups based on maximal force and loading speed: (1) 40Nslow: 40N; 0.83 mm/s; (2) 20Nslow: 20N; 0.83 mm/s; (3) 20Nfast: 20N; 2.5 mm/s. All specimens underwent 360 cycles of traction loading in a material testing system. The material testing system collected CD during loading at 60-cycle intervals. Micrometer measurements determined CD 60 minutes after loading. Friedman’s ANOVA was used to compare within-group CD changes, and Kruskal-Wallis ANOVA was used to compare between-group CD differences.

Results

All groups demonstrated increased CD during 360 cycles (P < .003) without differences between groups at any 60-cycle interval (P > .05). Sixty minutes after loading, CD was 7% (±5) in the 20Nslow, 15% (±12) in the 40Nslow, and 13% (±7) in the 20Nfast groups without between-group differences (P = .353).

Conclusion

Cyclical traction loading cadaveric CHL specimens with 20N and 40N forces increased CD without a difference between groups. Creep deformation was partially retained 60 minutes after loading. No CD differences were found using 20N loads at 2 different loading speeds.