Introduction: The fractional curve of adult spinal deformity (ASD) can be difficult to treat. We sought to evaluate the outcomes of patients whose fractional curves were treated with either cMIS or open techniques without interbody (IB).
Methods: Retrospective review of 2 multicenter ASD databases (Open- prospective; MIS- retrospective), with the following inclusion criteria: age>18 years with fractional curves >10, = 3 levels of instrumentation, and one of the following: coronal Cobb angle (CCA)>20, PI-LL>10, PT>20, SVA >5cm. Fractional curve was measured from S1 and the last vertebrae of the lower Cobb. Only fractional curves of 10 degrees or greater were evaluated. In the OPEN cohort, only patients without IB were included.
Results: 888 patients met inclusion criteria for the database, of which 508 had complete 2- year data. 118 patients had their fractional curves treated, and after propensity matching for levels treated, 40 patients were eligible with either cMIS (20) or with open (20) surgery. Preop fractional curve was 18 in both groups and corrected to 6.9 in cMIS and 8.5 in open (p>0.05). cMIS patients had a smaller postop coronal Cobb (12.5 vs 24.3;p=0.02) and lower EBL (809cc vs 2299cc;p=0.002). Open patients had a higher SVA change (-1.96 vs +1.32 cm; p=0.036), more pelvic fixation (55% vs 15%;p=0.008), Both groups had similar pre and postop VAS leg pain with no difference between groups at 2 years (change VAS Leg -4.4 vs -2.2;p=0.06). There was no significant difference in change of Cobb angle, ODI, PI-LL, LL, or VAS Back.
Conclusions: Treating fractional curves with cMIS surgery improved leg pain and comparable correction to the open group, and when matched for levels treated, the outcomes remained similar.
Patient Care: Determining an effective and safe approach to treat the fractional curve will improve patient outcomes.
Learning Objectives: The fractional curve can be a major source of morbidity. Treatment can be difficult because of up-down stenosis. Adult spinal deformity can be treated with open or circumferencial MIS techniques. Treatment with cMIS techniques was shown to be as efficacious as open surgery when evaluating VAS leg scores. Moreover, correction of the fractional coronal Cobb angles were similar using cMIS techniques compared to open surgery.