38 - Can MCID Be Achieved in Elderly Patients Undergoing MIS Deformity Surg...

General Session: MIS-4

Presented by: P. Park - View Audio/Video Presentation (Members Only)


P. Park(1), D. Okonkwo(2), K-M. Fu(3), S. Nguyen(4), M. Wang(5), J. Uribe(6), N. Anand(7), G. Mundis(4,8), V. Deviren(9), R. Fessler(10), C. Shaffrey(11), D. Chou(9), P. Mummaneni(9), International Spine Study Group

(1) University of Michigan, Ann Arbor, MI, United States
(2) University of Pittsburgh Medical Center, Pittsburgh, PA, United States
(3) Weill Cornell, New York, NY, United States
(4) San Diego Center for Spinal Disorders, San Diego, CA, United States
(5) University of Miami, Miami, FL, United States
(6) University of South Florida, Tampa, FL, United States
(7) Cedars Sinai, Los Angeles, CA, United States
(8) Scripps Clinic, La Jolla, CA, United States
(9) University of California, San Francisco, San Francisco, CA, United States
(10) Rush University, Chicago, IL, United States
(11) University of Virginia, Charlottesville, VA, United States


Hypothesis: MCID can be achieved in elderly patients undergoing MI surgery for ASD. Design: Multicenter retrospective study.

Introduction: Minimally invasive surgery (MIS) has been used to treat adult spinal deformity (ASD) with the potential benefit of decreased approach related morbidity. The objective of this study was to determine whether a minimal clinically important difference (MCID) could be achieved in patients 65 years and older who underwent MIS for ASD.

Methods: A multicenter database of patients who underwent MIS for ASD was queried. Inclusion criteria for the database: diagnosis of ASD with at least one of the following: coronal Cobb (CC) ≥20°, SVA >5cm, PT>25°, or thoracic kyphosis >60°. Of 190 patients, 42 aged 65 years and older were identified. Outcome metrics assessed were ODI and VAS back and leg pain. MCID, per Copay, Glassman et al 2008, was defined as a positive change of 12.8 ODI, 1.2 VAS back pain, and 1.6 VAS leg pain. To evaluate relative change, the number of patients who improved 30% or more from baseline values was also assessed.

Results: Mean age was 70.3 years and 31 (73.8%) were female. Mean follow-up was 32.1 months. An average of five levels (0-14) were fused posteriorly in addition to a mean of 4 interbody fusions (range: 1-8 levels ). 5 patients underwent anterior interbody fusion without posterior instrumentation. There were no significant changes in any sagittal plane parameters (table 1). CC improved from 35° to 18° (p< 0.001). 14 (33.3%) patients had a complication with 6 (14.3%) requiring a reoperation. Patients showed significant improvement in ODI, VAS back and leg (p< 0.001). In this patient population, 64.3% achieved MCID for ODI, and 66.7% improved at least 30% from baseline. Similarly, for VAS back and leg, 82.9% and 72.2%, respectively, reached MCID and 80.5% and 75.0%, saw at least 30% improvement from baseline values.

Conclusions: The difference in patients reaching MCID for VAS back and leg vs ODI may suggest that MIS techniques effectively improve spine related symptoms but are left with functional limitations. A modest percentage of patients in this cohort were able to achieve MCID. However, this study did not address severe sagittal deformity, therefore results may not be applicable to that specific patient population.

Table 1: Radiographic and clinical outcomes in patients of 65 years and older who underwent MI deformity surgery.