Resident Physician University of Pittsburgh Medical Center Pittsburgh, Pennsylvania, United States
Introduction: Multi-rod constructs (MRCs [≥3 rods]) can provide significant benefits for operated adult spinal deformity (ASD) patients. Few reports have focused on assessing MRS usage patterns/trends and the various factors which may influence surgical decision-making (i.e., selection of rod configurations). As such, our study objective was to analyze a large North American ASD cohort and to report potential trends in MRC usage during the previous decade (2008-2020).
Methods: A prospective multicenter consecutive series of ASD patients was reviewed. Inclusion criteria was the following: diagnosis of ASD (scoliosis ≥20°, sagittal vertical axis ≥5cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°), ≥5 level posterior instrumented fusion, and minimum 2-year follow-up. MRCs were subdivided as follows: 4-rod constructs (4-MRC; bilateral supplemental rods), 3-rod constructs (3-MRC; unilateral supplemental rod), 3-rod constructs with kickstand (KICKSTAND; supplemental rod with distal pelvic fixation ipsilateral to coronal shift). To assess potential trends in MRC usage, index operations were categorized by date (2008-2014 vs. 2015-2017 vs. 2018-2020) and by use of 3-column osteotomy (3CO).
Results: From 2008-2020, 1195 index operative patients met inclusion criteria. Of these, 285 (23.8%) index operations used MRCs. Overall, MRC utilization increased significantly from 2008-2014 to 2015-2017 to 2018-2020 (p < 0.001): 11.9% (69/579) vs. 34.2% (161/471) vs. 37.9% (55/145), respectively. This trend remained significant (p < 0.001) for index operations with 3CO (n=245): 29.1% (41/141) vs. 79.1% (68/86) vs. 77.8% (14/18) and without 3CO (n=950): 6.4% (28/438) vs. 24.4% (94/385) vs. 32.3% (41/127). For 3CO MRC: use of 4-MRC, 3-MRC, and KICKSTAND was not significantly different across these time intervals (p>0.05); 4-MRC comprised the majority (~70%) of 3CO MRCs. For non-3CO MRC: use of 3-MRC decreased (p=0.001) and KICKSTAND increased (p=0.008) significantly across time intervals; use of 4-MRC increased but the trend was not significant (p=0.276).
Conclusion : The use of multi-rod constructs in ASD surgery increased significantly from 2008-2020. This trend may be related to increased use of 4-rod constructs for 3-column osteotomy operations (circa 2015) and, more recently, kickstand rods for coronal correction or a supplemental third rod.
