Introduction: While the use of three column osteotomy (3CO) in complex spinal deformity is associated with improved outcomes and acceptable complication rates, we have yet to compare outcomes after 3CO based on varied degrees of preoperative malalignment and determine when 3CO is warranted.
Methods: Revision complex spinal deformity patients from a multicenter study group who were fused from at least L1 and proximal to S1 and below with available baseline and 1 year (1Y) follow-up were isolated. Patients were stratified by whether they had 3CO (3CO+) and those that did not (3CO-). 3CO- cohort was further assessed based on development of complications and regional failure. Analysis controlled for age, gender, BMI, CCI, frailty, baseline deformity (PT, PI-LL, TPA, C7-PL), and levels fused. Multivariable regression determined which sagittal parameters were predictive of good outcomes. Conditional inference tree (CIT) was used to determine thresholds.
Results: 132 CADS patients met inclusion, with no significant difference in age, gender, BMI, CCI, and frailty. Deformity at baseline was significantly worse in 3CO+. Despite fewer levels fused in 3CO+(10.7 vs 13.3, p<.05) cohort, there was higher EBL (2.2L vs 1.2L, p< 0.001), increased rates of massive blood loss(13% vs 1%, p=0.008), LOS(9.9 vs 6.6 days, p< 0.001), SICU admission (87±35% vs 60±49%, p=0.007), discharge to SNF or rehab. Differences amongst cohorts in 1Y radiographic alignment, with 3CO- cohort having worse PT (24.2° vs 19.6°, p=0.008) and TPA (21.5° vs 16.3°, p=0.01). Parameters predictive of mechanical complications were: increasing PT (OR: 1.325 [1.003-1.750], p=.048) and increasing TPA (OR: 1.064 [1.012-1.119], p=.016). Thresholds values for baseline deformity associated with favorable outcomes in 3CO+ were: PT < 15.3° (p=0.047), PI-LL < 47.5° (p=0.026), TPA < 33.2° (p=0.047).
Conclusion : The use of three-column osteotomy in revision complex spinal deformity surgery is associated with improved alignment by 1 year relative to those that did not. Threshold values for radiographic parameters were found to be PT < 15.3°, PI-LL < 47.5°, and TPA < 33.2° being associated with favorable outcomes when using a 3CO.
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