Instrumentation Techniques to Prevent Proximal Junctional Kyphosis and Proximal Junctional Failure in Adult Spinal Deformity Correction: A Systematic Review of Clinical Studies.

Abstract

Systematic review. To summarize the results of clinical studies investigating spinal instrumentation techniques aiming to reduce the postoperative incidence of proximal junctional kyphosis (PJK) and/or failure (PJF) in adult spinal deformity (ASD) patients. EMBASE and Medline® were searched for articles dating from January 2000 onward. Data was extracted by 2 independent authors and methodological quality was assessed using ROBINS-I. 18 retrospective- and prospective cohort studies with a severe or critical risk of bias were included. Different techniques were applied at the upper instrumented vertebra (UIV): tethers in various configurations, 2-level prophylactic vertebroplasty (2-PVP), transverse process hooks (TPH), flexible rods (FR), sublaminar tapes (ST) and multilevel stabilization screws (MLSS). Compared to a pedicle screw (PS) group, significant differences in PJK incidence were found using tethers in various configurations (18% versus 45%, <i>P</i> = 0.001, 15% versus 38%, <i>P</i> = 0.045), 2-PVP (24% vs 36%, <i>P</i> = 0.020), TPH (0% vs. 30%, <i>P</i> = 0.023) and FR (15% versus 38%, <i>P</i> = 0.045). Differences in revision rates for PJK were found in studies concerning tethers (4% versus 18%, <i>P</i> = 0.002), 2-PVP (0% vs 13%, <i>P</i> = 0.031) and TPH (0% vs 7%, <i>P</i> = n.a.). Although the studies are of low quality, the most frequently studied techniques, namely 2-PVP as anterior reinforcement and (tensioned) tethers or TPH as posterior semi-rigid fixation, show promising results. To provide a reliable comparison, more controlled studies need to be performed, including the use of clinical outcome measures and a uniform definition of PJF.