Biomechanics of Prophylactic Tethering for Proximal Junctional Kyphosis: Comparison of Posterior Tether Looping Techniques

Instrumentation techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction—a systematic review of biomechanical studies

“…Suture loops and tethers have been shown to significantly reduce the flexion and/or extension ROM. However, these effects appear only to be biomechanically relevant if sufficient pretension is applied while the effect-size was also shown to depend on the amount of pretension [27,29,30,32]. Overall, reduced flexion-extension ROMs were accompanied with decreased IDPs, indicating reduced transfer of stresses to the vertebral bodies, and therefore the possible reduction of both PJK and PJF incidence.…”

“…1, B). Alternatively, three studies investigated the use of tethers in human cadaveric pure bending tests [27,29,32]. Tethers were connected from either the spinous process or from the lamina at the UIV+1 (and/or UIV+2) to a crosslink at UIV-1, usually pretensioned by caudal displacement of the crosslink (Fig.…”

“…1, C). This was achieved using Mersilene tape [29,32] or commercially available sublaminar wires [27].…”

“…Mar et al (2019a) investigated the effect of different pretension levels (0, 22, 44, 66, 88N) of suture loops on single human functional spinal units (T11−T12) and measured a reduced flexion ROM as well as decreased IDPs with increasing suture loop pretension [30]. In another study by the same authors, these suture loops were pretensioned to 22N [29]. Significant decrease in flexion ROM (p=.007) was found at the index segment and IDP levels were found at the index (p=.007) and index+1 (p=.002) segment.…”

“…Mar et al also compared suture loops to three different tethering configurations tethering from UIV+1 and UIV+2 spinous processes to the crosslink at the UIV [29]. These tethers were likewise pretensioned to 22N.…”