Early dynamic changes within the spine following posterior fusion using hybrid instrumentation in adolescents with idiopathic scoliosis: a gait analysis study.

INTRODUCTION: In adolescent idiopathic scoliosis (AIS) patients, mechanical consequences of posterior spinal fusion within the spine remain unclear. Through dynamic assessment, gait analysis could help elucidating this particular point. The aim of this study was to describe early changes within the spine following fusion with hybrid instrumentation in adolescents with idiopathic scoliosis, using gait analysis MATERIALS AND METHODS: We conducted a single-centre prospective study including AIS patients scheduled for posterior spinal fusion (PSF) using hybrid instrumentation with sublaminar bands. Patients underwent radiographic and gait analyses preoperatively and during early postoperative period. Among gait parameters, motion of cervicothoracic, thoracolumbar and lumbosacral junctions was measured in the three planes. RESULTS: We included 55 patients (mean age 15 years, 84% girls). Fusion was performed on 12 levels and mean follow-up was 8 months. There was a moderately strong correlation between thoracolumbar sagittal motion and lumbosacral junction pre- and postoperatively (R = - 0.6413 and R = - 0.7040, respectively, all p < 0.001), meaning that the more thoracolumbar junction was in extension, the more lumbosacral extension movements decreased. There was a trend to significance between postoperative SVA change and thoracolumbar sagittal motion change (R = - 0.2550, p = 0.059). DISCUSSION: This is the first series reporting dynamic changes within the spine following PSF using hybrid instrumentation in AIS patients. PSF led to symmetrization of gait pattern. In the sagittal plane, we found that thoracolumbar extension within the fused area led to decreased extension at cervicothoracic and lumbosacral junctions. Even though consequences of such phenomenon are unclear, attention must be paid not to give a too posterior alignment when performing PSF for AIS patients.

Curve location influences spinal balance in coronal and sagittal planes but not transversal trunk motion in adolescents with idiopathic scoliosis: a prospective observational study.

PURPOSE: In adolescent idiopathic scoliosis (AIS), spinal deformity can be seen in the thoracic or in the lumbar area. Although differences according to curve location are well described on standard radiographs, dynamic consequences of such difference remain unclear. Our objective was to explore the differences in dynamic spinal balance according to curve location in AIS patients using gait analysis METHODS: We prospectively included 22 females with AIS planned for surgical correction (16.3 years old, 81% Risser ≥ 4). Patients were divided into two matched cohorts, according to major curve location [right thoracic (Lenke 1) or left lumbar (Lenke 5)]. Gait analysis was performed the day before surgery. Global balance was analyzed as the primary outcome. Local curves parameters (dynamic Cobb angles) were defined as the secondary outcome. RESULTS: In coronal plane, Lenke 5 patients had a left trunk shift, whereas trunk was shifted to the right in Lenke 1 patients (- 20.7 vs 6.3, p = 0.001). In the sagittal plane, the main difference between the two groups was T12 position that remained over the pelvis during gait in Lenke 5 patients, whereas it was anterior to the pelvis in Lenke 1 patients. In the transversal plane, Lenke 5 and Lenke 1 patients presented the same gait abnormalities, with a global trunk rotation to the left (- 4.8 vs - 7.6, p = 0,165). CONCLUSION: This is the first study to provide the results of a direct comparison between Lenke 1 and Lenke 5 patients during gait. Curve location influenced coronal and sagittal balance, but abnormalities of transversal trunk motion were the same, wherever the curve was located. These slides can be retrieved under Electronic Supplementary Material.

Does static trunk motion analysis reflect its true position during daily activities in adolescent with idiopathic scoliosis?

INTRODUCTION: Adolescent idiopathic scoliosis is common condition in pediatric orthopedics that is generally analyzed with standard radiographs. However, the conditions under which the radiographs are made are completely different than the position that patients use during day-to-day activities. We hypothesized that the trunk's static position differs from its dynamic one. The aim of this study was to determine differences between the trunk's static and dynamic positions using motion analysis in adolescents with idiopathic scoliosis. PATIENTS AND METHODS: This prospective, single-center study enrolled adolescents with idiopathic scoliosis who were scheduled to undergo surgical correction. The day before the surgery, radiographs were made and motion analysis was performed (static and dynamic acquisitions). Various parameters were measured on the radiographs and motion analysis, including the coronal vertical axis (CVA), sagittal vertical axis (SVA) and coronal shoulder tilt. RESULTS: The study enrolled 62 patients with a mean age of 15.5 years. There was a significant correlation between the radiographic measurements and the static motion analysis results for most parameters. Conversely, dynamic measurements of CVA, SVA and coronal shoulder tilt were not correlated to their static measurements (R=0.229; 0.198 and -0.109 respectively, all p>0.05). The static coronal shoulder tilt was opposite to the one found during walking (-0.9° vs. 0.5°, p=0.031). DISCUSSION: Our study is the first to compare the trunk's static position with its dynamic position during walking in a cohort of adolescents with idiopathic scoliosis. Motion analysis provides new information about the trunk's dynamic positions. Based on our findings, radiographic analysis only partially captures the spinal alignment and cannot be used to draw reliable conclusions about the trunk's dynamic balance.

Correlations linking static quantitative gait analysis parameters to radiographic parameters in adolescent idiopathic scoliosis.

BACKGROUND: Radiography is the main tool used to assess spinal deformities in patients with adolescent idiopathic scoliosis (AIS) but requires repeated exposure to ionising radiation, potentially raising safety concerns. Consequently, new methods are needed. Among them, the acquisition of static parameters during quantitative gait analysis (QGA) has received attention in recent years. However, no data on correlations linking static QGA parameters to standard radiographic parameters are available. The objective of this study was to assess correlations between static QGA parameters and standard radiographic parameters in patients with AIS. HYPOTHESIS: Spinal deformities in patients with AIS can be evaluated based on static QGA parameters. PATIENTS AND METHODS: We studied patients scheduled for surgery to treat AIS. On the day before surgery, QGA was performed and antero-posterior and lateral radiographs obtained. QGA involved analysing the positions of 32 reflective markers, including 6 used to assess the spine. The coronal vertical axis (CVA), thoracic and lumbar Cobb angles, sagittal vertical axis (SVA), thoracic kyphosis, lumbar lordosis, and pelvic tilt were recorded and compared to the corresponding radiographic parameters. RESULTS: The study included 57 patients, including 48 (84%) females, with a mean age of 15.2 years. Among them, 45 had Lenke 1 and 12 Lenke 5 scoliosis. The mean main Cobb angle was 51.9°. In the coronal plane, significant correlations with the corresponding radiographic parameters were found for the CVA (R=0.524, p<0.01) and thoracic Cobb angle (R=0.599, p<0.01). All the sagittal parameters correlated significantly with the corresponding radiographic parameters: SVA, R=0.313; pelvic tilt, R=0.342; thoracic kyphosis, R=0.575; and lumbar lordosis, R=0.360 (p<0.05 for all four parameters). CONCLUSIONS: In this study, static QGA parameters accurately reflected the spinal deformities visualised radiographically. The lumbar deformity was more difficult to characterise, probably because it was mild in our population. Research efforts should focus on improving the performance of QGA, notably for detecting curve progression. Thus, QGA may allow a decrease in radiation exposure of patients with AIS. LEVEL OF EVIDENCE: III.

Knee function after limb salvage surgery for malignant bone tumor: comparison of megaprosthesis and distal femur allograft with epiphysis sparing.

PURPOSE: Limb salvage surgery is increasingly used for the treatment of distal femur bone sarcomas. Total knee replacement using megaprosthesis and epiphysis-sparing biologic reconstruction using an allograft are widely used in order to preserve joint motion. We aimed to compare the results of these procedures using gait analysis in patients undergoing limb salvage surgery. METHODS: Fifteen patients were included, nine undergoing allograft with epiphysis sparing (Allograft group) and six undergoing megaprosthesis (Megaprosthesis group). Every patient underwent a gait analysis using the Plug-in-Gait protocol. Spatiotemporal parameters, knee kinematics, and kinetics were compared between the two groups and a cohort of ten asymptomatic subjects. Knee function was assessed by the Gait Deviation Index (GDI) and the Gilette Gait Index (GGI). RESULTS: Both treatment groups showed decreased knee flexion during the loading response phase. Megaprosthesis patients showed a decreased knee flexion all along stance phase. There was no difference in gait pattern between the treatment groups. GDI was significantly lower in Megaprosthesis and Allograft patients when compared to controls (86.4 and 84.3 vs 94, all p < 0.05). This difference was not clinically relevant. CONCLUSION: Our study reveals that Megaprosthesis and Allograft patients did not show differences in gait patterns and global function. Even though Allograft and Megaprosthesis patients have significant changes in gait pattern, knee function is acceptable with effective gait mechanisms. Changes occur during stance phase and are due to the quadriceps weakness. The particular pattern of gait in Megaprosthesis patients could be a concern for prosthesis wear and should be investigated on this specific aspect. LEVEL OF EVIDENCE: 4.