Minimally invasive techniques are increasingly used in adult deformity surgery as surgeon familiarity improves and long-term data are published. Concerns raised in such cases include pseudarthrosis at levels where interbody grafts are not utilized. Few previous studies have specifically examined the thoracolumbar component of long surgical constructs, which is commonly instrumented without interbody or intertransverse fusion.
A retrospective analysis was performed on all patients who underwent hybrid minimally invasive deformity corrections in two academic spine centers over a 9-year period. Inclusion criteria were at least 2 rostral levels instrumented percutaneously, ranging from T8 to L1 as the upper end of the construct. Fusion assessment was made using CT when possible or radiography. Common radiographic parameters and clinical variables were assessed pre- and postoperatively.
A total of 36 patients fit the inclusion criteria. Baseline characteristics included a 1:1.8 male/female ratio, average age of 65.7 years, and BMI of 30.2 kg/m2. Follow-up imaging was obtained at a mean of 35.7 months. The average number of levels fused was 7.5, with an average of 3.4 instrumented percutaneously between T8 and L1, representing a total of 120 rostral levels instrumented percutaneously. Fusion assessment was performed using CT in 69 levels and radiography in 51 levels. Among the 120 rostral levels instrumented percutaneously, robust fusion was noted in 25 (20.8%), with 53 (44.2%) exhibiting some evidence of fusion. Pseudarthrosis was noted in 2 rostral segments (1.7%). There were no instances of proximal hardware revision. Eight patients exhibited radiographic proximal junctional kyphosis (PJK; 22.2%), none of whom underwent surgical intervention.
In the present series of adult patients with scoliosis undergoing thoracolumbar deformity correction, rostral segments instrumented percutaneously have a very low rate of pseudarthrosis, with radiographic evidence of bone fusion occurring in more than 60% of patients. The rate of PJK was acceptable and similar to other published series.
ABBREVIATIONSASA = American Society of Anesthesiologists; ASD = adult spinal deformity; LL = lumbar lordosis; MIS = minimally invasive surgery; PI = pelvic incidence; PJK = proximal junctional kyphosis; PT = pelvic tilt; rhBMP-2 = recombinant human bone morphogenetic protein-2; SVA = sagittal vertical axis; TK = thoracic kyphosis; UIV = upper instrumented vertebrae.
Correspondence S. Shelby Burks: Lois Pope LIFE Center, Miami, FL. firstname.lastname@example.org.INCLUDE WHEN CITING Published online August 16, 2019; DOI: 10.3171/2019.5.SPINE19192.Disclosures Dr. Wang reports being a patent holder for DePuy-Synthes Spine; having direct stock ownership in Medical Device Partners and Innovative Surgical Devices; serving as a consultant to DePuy-Synthes Spine, K2M, Spineology, and Stryker; receiving royalties from the Children’s Hospital of Los Angeles, DePuy-Synthes Spine, Springer Publishing, and Quality Medical Publishing; serving on the medical advisory board for Vallum; and receiving research grants from the US Department of Defense. Dr. Uribe serves as a consultant for, has direct stock ownership in, and receives royalties and research support from NuVasive, and also serves as a consultant to Misonix and SI-BONE.
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