A non-optimized follower load path may cause considerable intervertebral rotations

Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis

“…4. The concept of FL was effectively applied to in vitro experiments and the path of FL was known to be an important factor to avoid the induced bending by non-optimized compressive FL [29]. According to Rohlmann et al [30], applying 500 N of FL acting in the center of each vertebral body and directed to the centers of the adjacent vertebral bodies delivered the most probable ISRs among six different loading modes for simulating standing.…”

Inter-laboratory variability in in vitro spinal segment flexibility testing

“…Since the introduction of the follower load by Patwardhan et al, numerous studies have investigated its value in the testing of in vitro spinal segments (Goel et al, 2006;Patwardhan et al, 1999;Rohlmann et al, 2001Rohlmann et al, , 2009Cripton et al, 2000;Wilke et al, 2003;Renner et al, 2007;Dreischarf et al, 2010). Proponents of the follower load argue that the system's application of pure compressive loads to the entire spinal segment more accurately simulates the physiologic effect of in vivo muscle forces (Goel et al, 2006;Patwardhan et al, 1999;Rohlmann et al, 2001).…”

“…Proponents of the follower load argue that the system's application of pure compressive loads to the entire spinal segment more accurately simulates the physiologic effect of in vivo muscle forces (Goel et al, 2006;Patwardhan et al, 1999;Rohlmann et al, 2001). However, recent biomechanical and finite element modeling studies have shown that the specific method of follower load application has a significant impact on biomechanical outcomes (Rohlmann et al, 2009;Cripton et al, 2000;Dreischarf et al, 2010). According to Dreischarf et al (2010), nonoptimized follower load paths and ill-defined starting conditions can make comparisons between laboratories more difficult and lead to questionable conclusions.…”

“…However, recent biomechanical and finite element modeling studies have shown that the specific method of follower load application has a significant impact on biomechanical outcomes (Rohlmann et al, 2009;Cripton et al, 2000;Dreischarf et al, 2010). According to Dreischarf et al (2010), nonoptimized follower load paths and ill-defined starting conditions can make comparisons between laboratories more difficult and lead to questionable conclusions. This study has several limitations.…”

Preclinical evaluation of posterior spine stabilization devices: can the current standards represent basic everyday life activities?

“…M Ext = 7.5 Nm). The FL load, describing the effect of muscular forces and body weight, was simulated using connector elements following spine curvature: their endpoints were adjusted to achieve negligible rotations upon application of connector force [24]. When possible, the internal loads predicted on the rod were Further details on the L2-L4 model can be found in [16] Eur Spine J compared with the measurements obtained in vivo on a group of instrumented patients who were asked to perform the same activities [19,20]: the bridge stabilization model and the anterior support model were thus compared, respectively with data measured on patients before and after anterior interbody fusion (''BAIF'' and ''AAIF'', respectively).…”