Case SeriesEffect of Lowest Instrumented Vertebra on Trunk Mobility in Patients With Adolescent Idiopathic Scoliosis Undergoing a Posterior Spinal Fusion
Introduction
Posterior spinal fusion with instrumentation (PSFI) is the standard of care for correcting spine deformities in individuals with adolescent idiopathic scoliosis (AIS) and Cobb angles exceeding 50° [1], [2], [3]. Long-term results suggest that PSFI can effectively limit curve progression and ensure spine stability for individuals with AIS [4], [5], [6], [7].
Although PSFI effectively corrects spine deformity, postoperative limitations in intersegmental mobility among the fused vertebral levels ultimately result in reduction of overall trunk mobility (ie, forward flexion, backward extension, bilateral lateral bending, and bilateral axial rotation) [4], [5], [6], [7], [8], [9], [10]. Furthermore, some studies suggest that loss in trunk mobility may cause an increased compensatory mobility at unfused segments adjacent to the fusion, which may eventually lead to spinal degeneration of unfused segments and low back pain [4], [6], [8], [9], [10], [11], [12].
Currently, few studies have attempted to accurately measure reduction in trunk mobility after fusion. Recent studies have commonly employed either inclinometers or motion capture techniques to accurately quantify trunk mobility reduction after surgical fusion [8], [9], [10]. However, these studies are not without limitations, which range from being retrospective to using heterogeneous sampling of different fusion techniques (ie, anterior spinal fusion, posterior spinal fusion, or both), and to using unvalidated or nonstandardized models of kinematic computation for determining spine range of motion (ROM) [8], [9], [10], [13].
Despite the obvious reduction in trunk mobility after fusion, even fewer clinical studies conclusively address how surgical choice of the lowest instrumented vertebra (LIV) influences the amount of reduction. The direct impact of LIV level on postoperative trunk mobility in patients with AIS has not been conclusively demonstrated [8], [9], [10], [13], [14], [15], [16]. Today, many clinicians are still faced with difficult questions posed by families who inquire about changes to expect after fusion, particularly how reductions in trunk mobility vary with LIV over time. The purpose of this study was to quantitatively examine and compare trunk mobility in individuals with AIS undergoing posterior spinal fusion surgery at different LIVs preoperatively and at 1 and 2 years postoperatively. We hypothesized that PSFI terminating at a more distal LIV will result in greater reductions in sagittal, coronal, and transverse plane trunk kinematics during trunk bending tasks while standing. Specifically, we expected that fusion to the distal lumbar segments would result in greater reductions in kinematic peaks and overall trunk ROM than fusion terminating at proximal lumbar and thoracic segments.
Section snippets
Study design and participants
This was a prospective study performed on a sample of convenience between October 2007 and August 2012 at a single specialized pediatric orthopedic institution. A consecutive series of 120 patients had a posterior spinal fusion during that time, of which 47 patients (7 male and 40 female) agreed to participate in this institutional review board–approved study as the scoliosis group. Thirty-nine patients made the 1-year follow-up visit (mean, 1.15 years; range, 0.8–1.5 years) and 36 made the
Effect of surgery on trunk kinematics
There was a postoperative reduction in all trunk kinematic measures for trunk motion in all 3 planes (p < .0001). In the first postoperative evaluation visit, there was an average reduction of 16° (57%) in peak axial rotation to the left, 15° (61%) in average peak axial rotation to the right, and 31° (59%) in average axial rotation ROM. Postoperative mean reductions of 24° (56%), 17° (45%), and 41° (51%) were also observed in peak lateral bending to the left, to the right, and lateral bending
Discussion
The central finding of this study is that PSFI results in reduced trunk mobility in all motion planes (p < .0001). Distal LIV fusions limit postoperative peak forward flexion more than proximal fusions (p = .04) (Table 4). The limitation in peak forward flexion with distal LIV was considered clinically significant and trended toward statistical significance, although it did not achieve it at α = .01. Reductions in peak forward flexion after surgery were 28% at T12, 24% at L1, 36% at L2, 66% at
References (30)
- et al.
Centre of mass motion during gait in persons with myelomeningocele
Gait and Posture
(2003) - et al.
A gait analysis data collection and reduction technique
Human Movement Science
(1991) - et al.
The upper body segmental movements during walking by young females
Clin Biomech (Bristol, Avon)
(2003) - et al.
Human movement analysis using stereophotogrammetry—Part 3: soft tissue artifact assessment and compensation
Gait and Posture
(2005) - et al.
Use of the Milwaukee brace for progressive idiopathic scoliosis
J Bone Joint Surg Am
(1996) - et al.
Curve progression in idiopathic scoliosis
J Bone Joint Surg Am
(1983) Idiopathic scoliosis: natural history
Spine (Phila Pa 1976)
(1986)- et al.
Long-term follow-up of adolescent idiopathic scoliosis patients who had Harrington instrumentation and fusion to the lower lumbar vertebrae: is low back pain a problem?
Spine (Phila Pa 1976)
(2009) - et al.
Long-term follow-up of patients with idiopathic scoliosis not treated surgically
J Bone Joint Surg Am
(1969) - et al.
Long term follow-up of patients with idiopathic scoliosis treated surgically: a preliminary subjective study
Clin Orthop Relat Res
(1976)
Long-term follow-up of scoliosis fusion
J Bone Joint Surg Am
Prospective evaluation of trunk range of motion in adolescents with idiopathic scoliosis undergoing spinal fusion surgery
Spine (Phila Pa 1976)
Does the lower instrumented vertebra have an effect on lumbar mobility, subjective perception of trunk flexibility, and quality of life in patients with idiopathic scoliosis treated by spinal fusion?
J Spinal Disord Tech
The effect of scoliosis fusion on spinal motion: a comparison of fused and nonfused patients with idiopathic scoliosis
Spine (Phila Pa 1976)
Quality of life and back pain: outcome 16.7 years after Harrington instrumentation
Spine (Phila Pa 1976)
Cited by (21)
How do spine instrumentation parameters influence the 3D correction of thoracic adolescent idiopathic scoliosis? A patient-specific biomechanical study
2021, Clinical BiomechanicsCitation Excerpt :A punctual validation on each of 1080 simulated scenarios is absolutely impossible in reality for the same patient, however, it is possible to make an indirect comparison of model predictions with the available published evidence. Specific quantitative data in terms of the resulting 3D correction (outputs) and input-output correlations fall within the range of available clinical (Abul-Kasim et al., 2011; Allia et al., 2018; Cidambi et al., 2012; Clément et al., 2017; Lamerain et al., 2014; Ohashi et al., 2020; Prince et al., 2014; Sabah et al., 2018; Salmingo et al., 2014; Solla et al., 2020; Udoekwere et al., 2014) and biomechanical (La Barbera et al., 2021a; Le Navéaux et al., 2016; Martino et al., 2013; Wang et al., 2016) data. Overall, the study's findings indicate that the current approach captured the primary biomechanical effects of specific instrumentation parameters on 3D correction on a patient-specific basis.
In silico patient-specific optimization of correction strategies for thoracic adolescent idiopathic scoliosis
2021, Clinical BiomechanicsCitation Excerpt :Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional (3D) deformity of the spine (Shen et al., 2020; Lenke et al., 2008). Surgical fusion is the preferred surgical treatment for progressive curves >45°, aiming at reducing the magnitude of the deformity, restoring a well-balanced posture, and preventing curve progression, while minimizing the instrumented segments (Abelin-Genevois et al., 2018; Ohashi et al., 2020; Udoekwere et al., 2014; Ketenci et al., 2018; Fischer et al., 2018). These objectives rely on accurate selection of fusion levels and the application of adequate corrective forces through the instrumentation.
Effect of Surgical Fusion on Volitional Weight-Shifting in Individuals With Adolescent Idiopathic Scoliosis
2016, Spine DeformityCitation Excerpt :The L3+ Group also showed decrease in MXE-EPE, suggesting that they need less readjustment of their initial weight-shift than preoperatively. Although prior studies were inconsistent on the change in spinal motion at unfused levels at 2 years [26,32,39], this did not appear to affect individuals' volitional weight-shifting ability in the present study. Within the same cohort, the L3+ group had increased range of motion in a prior study that approached significance (p = .04) between the first and second year postoperation [26].
Effects of Spinal Fusion for Idiopathic Scoliosis on Lower Body Kinematics During Gait
2018, Spine DeformityCitation Excerpt :Several decreases in mobility were still observed at the two-year visit. Although the trunk lateral bending ROM during walking was decreased (average ROM 4.6°, 2.8°, and 2.0° for the control, L2+, and L3– groups, respectively), this is well below the total available lateral bending ROM, which was measured to range from 37° to 57° reported in our previous study that included the same patients [5]. Findings from the current study suggest that available ROM is not the cause of these gait deviations.
Author disclosures: UIU (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); JJK (grants from DePuy Synthesis, grants from Hainer Foundation, grants from the Helen Kay Charitable Trust); AG (grants from DePuy Synthesis, grants from Hainer Foundation, grants from the Helen Kay Charitable Trust); SH (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); ST (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); MR (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); PFS (consultant for DePuy Spine and Orthopediatrics; shareholder with Pioneer Surgical); KWH (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); PG (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); AKA (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis); GFH (grants from Helen Kay Charitable Trust, grants from Hainer Foundation, grants from DePuy Synthesis).
This study was supported by grants from DePuy Synthesis, the Hainer Foundation, and the Helen Kay Charitable Trust, US Department of Education NIDRR Grant H133P100008, and Grant UL1RR031973 from the Clinical and Translational Science Award (CTSA) program of the National Center for Research Resources (NCRR) and the National Center for Advancing Translational Sciences (NCATS).