Is achieving optimal spinopelvic parameters necessary to obtain substantial clinical benefit? An analysis of patients who underwent circumferential minimally invasive surgery or hybrid surgery with open posterior instrumentation
It is now well accepted that spinopelvic parameters are correlated with clinical outcomes in adult spinal deformity (ASD). The purpose of this study was to determine whether obtaining optimal spinopelvic alignment was absolutely necessary to achieve a minimum clinically important difference (MCID) or substantial clinical benefit (SCB).
A multicenter retrospective review of patients who underwent less-invasive surgery for ASD was conducted. Inclusion criteria were age ≥ 18 years and one of the following: coronal Cobb angle > 20°, sagittal vertical axis (SVA) > 5 cm, pelvic tilt (PT) > 20°, or pelvic incidence to lumbar lordosis (PI-LL) mismatch > 10°. A total of 223 patients who were treated with circumferential minimally invasive surgery or hybrid surgery and had a minimum 2-year follow-up were identified. Based on optimal spinopelvic parameters (PI-LL mismatch ± 10° and SVA < 5 cm), patients were divided into aligned (AL) or malaligned (MAL) groups. The primary clinical outcome studied was the Oswestry Disability Index (ODI) score.
There were 74 patients in the AL group and 149 patients in the MAL group. Age and body mass index were similar between groups. Although the baseline SVA was similar, PI-LL mismatch (9.9° vs 17.7°, p = 0.002) and PT (19° vs 24.7°, p = 0.001) significantly differed between AL and MAL groups, respectively. As expected postoperatively, the AL and MAL groups differed significantly in PI-LL mismatch (−0.9° vs 13.1°, p < 0.001), PT (14° vs 25.5°, p = 0.001), and SVA (11.8 mm vs 48.3 mm, p < 0.001), respectively. Notably, there was no difference in the proportion of AL or MAL patients in whom an MCID (52.75% vs 61.1%, p > 0.05) or SCB (40.5% vs 46.3%, p > 0.05) was achieved for ODI score, respectively. Similarly, no differences in percentage of patients obtaining an MCID or SCB for visual analog scale back and leg pain score were observed. On multivariate analysis controlling for surgical and preoperative demographic differences, achieving optimal spinopelvic parameters was not associated with achieving an MCID (OR 0.645, 95% CI 0.31–1.33) or an SCB (OR 0.644, 95% CI 0.31–1.35) for ODI score.
Achieving optimal spinopelvic parameters was not a predictor for achieving an MCID or SCB. Since spinopelvic parameters are correlated with clinical outcomes, the authors’ findings suggest that the presently accepted optimal spinopelvic parameters may require modification. Other factors, such as improvement in neurological symptoms and/or segmental instability, also likely impacted the clinical outcomes.
ABBREVIATIONSAL = aligned; ASD = adult spinal deformity; cMIS = circumferential minimally invasive surgery; MAL = malaligned; MCID = minimum clinically important difference; ODI = Oswestry Disability Index; PI-LL = pelvic incidence to lumbar lordosis; PT = pelvic tilt; SCB = substantial clinical benefit; SVA = sagittal vertical axis; VAS = visual analog scale.
Correspondence Paul Park: University of Michigan, Ann Arbor, MI. email@example.com.
INCLUDE WHEN CITING Published online February 22, 2019; DOI: 10.3171/2018.11.SPINE181261.
Disclosures Dr. Park reports being a consultant for the following: Globus Medical, NuVasive, Allosource, and Medtronic; he receives royalties from Globus Medical; and he receives research support from Pfizer and Vertex. Dr. Fu reports being a consultant for the following: SI-Bone, DePuy, Globus, and 4web. Dr. Eastlack reports being a consultant for the following: Aesculap, K2M, NuVasive, Seaspine, SI-Bone, Spine Innovation, and Titan; he receives royalties from Globus Medical; he has direct stock ownership in the following: Carevature, DiFusion, NuVasive, Alphatec, Spine Innovation, Seaspine, and Invuity; he has received clinical or research support for the present study from NuVasive, Scripps Clinic Medical Group, and Seaspine; and he holds patents with Invuity, Globus Medical, and NuTech. Dr. Mundis reports being a consultant for the following: NuVasive, K2M, Viseon, Seaspine, and Allosource; he receives royalties from K2M and NuVasive; and he is a speaker for DePuy. Dr. Uribe reports being a consultant for NuVasive; and he receives royalties from NuVasive. Dr. Wang reports being a consultant for the following: DePuy-Synthes Spine, Stryker, K2M, and Spineology; he is a patent holder with DePuy-Synthes Spine; and he has direct stock ownership in the following: ISD, Spinicity, and MDP. Dr. Than reports being a consultant for Bioventus and Medtronic. Dr. Okonkwo reports being a consultant for NuVasive, Zimmer Biomet, and Stryker; he is a patent holder with Zimmer Biomet; and he receives royalties from Zimmer Biomet and NuVasive. Dr. Anand reports being a consultant for Medtronic and Spinal Balance; he has direct stock ownership in Atlas Spine, Globus Medical, GYS Tech, Medtronic, Paradigm Spine, and Theracell; he is a patent holder with Medtronic; and he receives royalties from Medtronic, Globus Medical, and Elsevier. Dr. Chou reports being a consultant for Globus and Medtronic; he receives royalties from Globus Medical. Dr. Oppenlander reports being a consultant for Globus Medical. Dr. Mummaneni reports being a consultant for Globus, DePuy Spine, and Stryker; he has direct stock ownership in Spinicity/ISD; he receives support for a non–study-related clinical or research effort that he oversees from NREF; he receives honoraria from AOSpine and Spineart; and he receives royalties from DePuy Spine, Thieme Publishers, Taylor and Francis, and Springer Publishers. Dr. Kanter receives royalties from NuVasive and Zimmer. Dr. Nunley is a consultant for K2M; he receives royalties from K2M and LDR; he has stock or stock options in Amedica, Paradigm Spine, and Spineology; and he receives research support from Mesoblast, Organogenesis, Pfizer, Seikagaku, Simplify, Spinal Kinetics, Spineology, Vertiflex, and Zimmer-Biomet. Dr. Fessler reports being a consultant for DePuy; receives royalties from DePuy; receives speaker fees from Benvenue; and has ownership in In Queue Innovations.
CopayAGGlassmanSDSubachBRBervenSSchulerTCCarreonLY: Minimum clinically important difference in lumbar spine surgery patients: a choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and pain scales. Spine J8:968–9742008
SchwabFPatelAUngarBFarcyJPLafageV: Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery. Spine (Phila Pa 1976)35:2224–22312010
YukawaYKatoFSudaKYamagataMUetaTYoshidaM: Normative data for parameters of sagittal spinal alignment in healthy subjects: an analysis of gender specific differences and changes with aging in 626 asymptomatic individuals. Eur Spine J27:426–4322018