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: When treating a fractional curve, a minimally invasive approach can be applied and may be less disruptive for the patient.
Learning Objectives: By conclusion of this session, participants should be able to understand the importance of treating the fractional curve, and cMIS surgery has similar outcomes to OPEN treatment.