In vivo attachment site to attachment site length and strain of the ACL and its bundles during the full gait cycle measured by MRI and high-speed biplanar radiography: Response

• Published in: Journal of biomechanics 2020-08, Vol.109, p.109918-109918, Article 109918
• Main Authors: Englander, Zoë A., Spritzer, Charles E., DeFrate, Louis E.
• Format: Article
• Language: English
• Subjects: Age; Anterior Cruciate Ligament; Computer simulation; Failure; Gait; Hypotheses; Knee; Ligaments; Magnetic Resonance Imaging; Radiography; Strain gauges; Studies; Surgical implants; Walking
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2020.109918

To reiterate the objective of our study, we were most interested in the timing and knee position leading to increased ACL strain during walking. [...]our definition of ACL reference length (its length in a relatively extended position during MRI) will not change the conclusions of our study, that the ACL and its bundles are longest with the knee in extension. (19%) (Levine et al., 2013) in a cadaver model under simulated loading conditions. [...]it is unclear why the authors have concluded that the peak ACL strain value reported in our paper is close to failure when it is similarly close to strain values measured in subjects performing exercises intra-operatively with strain gauges implanted. [...]to reiterate the objectives of our study, while different definitions of reference length influence the magnitude of strain reported in any study, we were interested in identifying the timing of ACL loading during walking as well as the influence of knee flexion on ACL strain.