Digital vs Conventional OSCE in Orthopedic Surgery: A Feasibility Cross-Sectional Study.

OBJECTIVE: Remote OSCEs (Objective Structured Clinical Examination) are an alternative evaluation method during pandemic periods but they have never been evaluated in orthopedic surgery. We aimed to evaluate whether remote OSCEs would be feasible, and efficient for assessment of undergraduate medical students. METHODS: A cross-sectional study was performed. Thirty-four students were randomly assigned into 2 equal groups, either the conventional OSCE group or the digital OSCE group. Three types of skills were assessed: technical procedure, clinical examination, and radiographic analysis. Students were graded and they filled in a satisfaction questionnaire for both types of OSCEs. RESULTS: The mean score, out of 20, was 14.3 ± 2.5 (range 9.3-19) for the digital sessions, versus 14.4 ± 2.3 (range 10-18.6) for conventional sessions (p = 0.81). Bland Altman Plot showed that 88% of students scored within agreement. The average global feedback was different for item repeatability, relevance, and OSCEs preference (p < 0.0001, p = 0.0001, and p < 0.0001 respectively). However, they did not report differences for the item concerning the organization (p = 0.2). CONCLUSION: The results of this comparative study between digital and conventional OSCEs showed comparable distance learning scores between the 2 groups, whatever the skill assessed. However, the student's evaluation showed some reticence to conduct again OSCEs remotely.

Induced-membrane technique for lower limb reconstruction after malignant bone tumour resection in paediatric patients: Complication and re-operation rates.

BACKGROUND: The objective of this study was to assess the complication and re-operation rates, evaluate the risk of non-union, and describe the functional outcomes at last follow-up in children and adolescents after lower-limb malignant tumour resection and reconstruction using the induced-membrane technique. HYPOTHESIS: Weight-bearing resumption 6 weeks after the second stage of the induced-membrane procedure promotes bone healing. MATERIAL AND METHODS: The study included 13 patients (9 with osteosarcoma, 3 with Ewing's sarcomas, and 1 with alveolar sarcoma) managed between 2000 and 2020 by oncological femoral or tibial resection followed, at a distance from adjuvant chemotherapy, by reconstruction using the induced-membrane technique. Non-union was the primary outcome measure and the MusculoSkeletal Tumor Society (MSTS) lower-limb functional score was the secondary outcome measure. Mean follow-up was 6.1 years (range, 2.0-12.7). At last follow-up, mean age was 18.1 years (range, 11.0-26.0) and the mean MSTS score was 66.6% (37.0-93.0%). RESULTS: After the second reconstruction stage, 8 complications developed in 6 patients (46%). Either a complication or limb-length inequality required 12 re-operations in 8 patients (61.5%). Non-union occurred after reconstruction in 5 (38.5%) patients. Early resumption of 50% weight-bearing 6 weeks after reconstruction was associated with bone healing (p=0.02). CONCLUSION: The non-union rate was 38.5%. Partial, 50% weight-bearing with two elbow crutches and an orthosis, if allowed by construct stability, may promote bone healing. LEVEL OF EVIDENCE: IV.

Defining threshold for sagittal correction in lumbar fractures.

PURPOSE: Surgical indications for thoraco-lumbar fractures are driven both by neurological status, fractures instability and kyphotic deformity. Regarding kyphotic deformity, an angulation superior to 20° is considered by many surgeons as a surgical indication to reduce the disability induced by post-traumatic kyphosis. However, there is a lack of data reporting the ideal or theoretical lordosis that one must have in a particular lumbar segment on CT-scan. The main goal of this study was to determine the mean value for segmental lumbar lordosis according to pelvic incidence (PI) on a cohort of normal subjects. METHODS: The consecutive CT-scan of 171 normal adult subjects were retrospectively analyzed. The PI and the segmental lordosis (L4S1, L3L5, L2L4, L3L1, L2T12 and T11-L1) were measured on all CT-scan. The mean values were calculated for the global cohort and a sub-group analysis according to IP ranges (< 45°, 45 < IP < 60° and > 60°) was performed. RESULTS: The mean angular values for the whole cohort were IP: 54, 9°; L4S1: - 38, 1°; L3L5: - 30, 6°; L2L4: - 14, 1°; L1L3: - 4, 9°; T12L2: + 1, 9° and T11L1: + 5, 4°. The segmental values vary significatively with PI ranges, as for L3L5: - 26, 8° (PI < 45°); - 30° (45 < PI < 60°) and - 35, 1° (PI > 60°). CONCLUSION: These results provide a referential of theoretical values of segmental lordosis according to PI. This abacus may help spinal surgeon in their decision-making process regarding lumbar fractures, to determine the amount of sagittal correction needed, according to the PI range, to be adapted to the sagittal morphology of the patient. LEVEL OF EVIDENCE: III.

Does Spinal Surgery in Elderly Patients (Over 80 Years-Old) Lead to More Early Post-Operative Complications Than Lower Limb Prosthetic Surgery?

Purpose: Patients and surgeons may be reluctant on spinal surgery over 80 years old, fearing medical complications despite the possible improvement on quality of life. However, fewer reservations for lower limb prosthetic surgery (LLPS) seem to be arisen in this population. Is spinal surgery after 80 years-old responsible of more complications than lower limb surgery? Methods: The consecutive files of 164 patients over 80 years that had spinal surgery or LLPS were analyzed. The data collected pre-operatively were demographic, clinical and post-operatively the number and types of medical complications and length of stay. Results: The mean number of medical complications was 1.11 ± 0.6 [0-6] for spinal surgery and 1.09 ± 1.0 [0-3] for LLPS, (p = 0,87). The length of stay in orthopedic unit was comparable between the two groups: 10.7 ± 4.9 days [2-36] for SS and 10.7 ± 3.0 days [5-11] for LLPS (p = 0,96). Conclusion: The global rate of peri-operative complications and the length of hospital stay were similar between spinal surgery and lower limb prosthetic surgery. These results may be explained by the rising cooperation between geriatric specialist and surgeons and the development of mini-invasive surgical technics, diminishing the early post-operative complication rates.

Validation of the Total Disability Index (TDI) in French Version.

INTRODUCTION: The Total Disability Index (TDI) questionnaire has been developed to provide a more complete assessment of low back and neck pain, as they frequently co-occur. This study aimed at validating the TDI questionnaire in French, to determine if it could be used in France. HYPOTHESIS: The TDI French version is valid, reproducible and comparable to the English version. METHODS: This multicentric study prospectively included French-speaking volunteers, both patients admitted for spine surgery in two specialized spine centers and healthy individuals. Healthy subjects were recruited among students of an engineering school and medical staff. A booklet was given to the participants containing a Lumbar and Cervical Visual Analog Scale (respectively LVAS and CVAS), and the French versions of Oswestry Disability Index (ODI), Neck Disability Index (NDI) and TDI questionnaires. Statistical analysis included Cronbach's α calculation for internal consistency assessment, correlation analysis with ODI and NDI items for convergent validity, principal component analyses and factor analysis. Discriminant validity was assessed by comparing healthy subjects and patients using Student's t tests, and floor and ceiling effects search. RESULTS: 71 participants were included, with 34 (48%) healthy volunteers and 37 (52%) patients. Mean age was 45.2±19.6 years and 57% of the cohort were males. Internal consistency was good: Cronbach's α was calculated at 0.96 (95%CI: [0.95-0.98]). For each TDI item, a high correlation was found with ODI corresponding items, between 0.81 and 0.97 (p<0.001), and good correlation with NDI items, ranging from 0.65 to 0.96 (p<0.001). TDI correlated also with LVAS and CVAS (respectively 0.70 and 0.65, p<0.001). Principal component analyses indicated good correlation between the TDI items and between each item and TDI total score. Factor analysis indicated two main factors explaining 77% of TDI variance, constituted by all TDI items. Regarding discriminative validity, healthy subjects and patients presented significantly different TDI scores (p-values ≤0.01 for each item). Barplot representations of each TDI item revealed no major floor nor ceiling effects. CONCLUSION: This study confirms the reliability, feasibility and validity of the Total Disability Index questionnaire in its French version. Its validation allows its use in France. LEVEL OF EVIDENCE: II.

Efficiency of a novel vertebral body augmentation system (Tektona™) in non-osteoporotic spinal fractures.

BACKGROUND: The restauration of the local kyphosis is crucial to thoracolumbar fractures outcomes. Recently, the Tektona™ (Spine Art) system, constituted by a flexible lamella for corporeal reduction has emerged as a promising solution for osteoporotic fractures. However, no study has yet focused on its results on traumatic fractures. METHODS: A retrospective longitudinal study on prospectively collected data was conducted on 53 patients that had a kyphoplasty by Tektona™, associated or not to percutaneous fixation. The data collected were clinical, surgical and scannographic (measurement of AVH, MVH and PVH (anterior/medium/posterior vertebral height), and RTA (regional traumatic angle) in°), preoperatively, post-operatively and at last follow-up. RESULTS: Fractures were mainly located at the upper lumbar spine and were AOSpine A3 type for 74%. The mean RTA was 12° in pre-operative, 4° in post-operative (p = 2e- 9), and 8° at the last follow-up (p = 0,01). The mean correction of RTA for the fixation group was - 10 ± 6° versus - 7 ± 4° for the kyphobroplasty alone group (p = 0,006). The mean correction for fractures located at T10-T12 was - 9 ± 3°, - 9 ± 5° for L1, - 8 ± 3° for L2 and - 5 ± 3° for L3-L5 (p = 0,045). CONCLUSIONS: The Tektona® system appears to be efficient for acute thoraco-lumbar fractures, comparable to other available systems, allowing a real intracorporeal reduction work. Its relevance, especially in the long term needs further investigation. The association of a percutaneous fixation allow to obtain a better correction of the RTA but did not seem to prevent the loss of correction at follow-up.

Induced-Membrane Reconstruction After Calcaneum's Ewing Sarcoma in Children: A Report of 3 Cases.

Calcaneus's Ewing sarcoma is a rare location with a poor prognosis and remains challenging for tumor surgery. We present 3 cases of calcaneus resection for Ewing sarcoma in children and its reconstruction managed by induced-membrane technique. To our knowledge, this technique has never been published for hindfoot's tumor management. Three children (aged from 9 to 14 years) had partial or total resection of calcaneus initially replaced by a cement spacer. The second step consisted of removing the cement and filling the membrane cavity with autograft taken from the ipsilateral iliac crest, potentially combined with bone substitute. In the meantime, children received chemotherapy and possibly radiotherapy according to the Euro E.W.I.N.G. 99 protocol. It was possible to optimize bone formation as we carried out the bone grafting procedure sometime after the treatments. In one case, the evolution was marked by local septic complication, 9 months after resection, and by tumor recurrence in presacral soft tissues treated with radiotherapy and chemotherapy. Partial weightbearing was allowed after 6 weeks of cast, under the protection of a splint. Graft consolidation was achieved at a median of 3.2 months (3-3.5) for all. After a median follow-up of 9 years (5-13), all preserved their limb and were considered in remission. The 3 children reached adulthood, with a median age of 21 years (19-24.8). At last follow-up, median Musculoskeletal Tumor Score was 73% (63-87), and median American Orthopaedic Foot and Ankle Society hind foot score was 78 (72-87).

Estimating pulmonary function after surgery for adolescent idiopathic scoliosis using biplanar radiographs of the chest with 3D reconstruction.

AIMS: This study addressed two questions: first, does surgical correction of an idiopathic scoliosis increase the volume of the rib cage, and second, is it possible to evaluate the change in lung function after corrective surgery for adolescent idiopathic scoliosis (AIS) using biplanar radiographs of the ribcage with 3D reconstruction? METHODS: A total of 45 patients with a thoracic AIS which needed surgical correction and fusion were included in a prospective study. All patients underwent pulmonary function testing (PFT) and low-dose biplanar radiographs both preoperatively and one year after surgery. The following measurements were recorded: forced vital capacity (FVC), slow vital capacity (SVC), and total lung capacity (TLC). Rib cage volume (RCV), maximum rib hump, main thoracic curve Cobb angle (MCCA), medial-lateral and anteroposterior diameter, and T4-T12 kyphosis were calculated from 3D reconstructions of the biplanar radiographs. RESULTS: All spinal and thoracic measurements improved significantly after surgery (p < 0.001). RCV increased from 4.9 l (SD 1) preoperatively to 5.3 l (SD 0.9) (p < 0.001) while TLC increased from 4.1 l (SD 0.9) preoperatively to 4.3 l (SD 0.8) (p < 0.001). RCV was correlated with all functional indexes before and after correction of the deformity. Improvement in RCV was weakly correlated with correction of the mean thoracic Cobb angle (p = 0.006). The difference in TLC was significantly correlated with changes in RCV (p = 0.041). It was possible to predict postoperative TLC from the postoperative RCV. CONCLUSION: 3D rib cage assessment from biplanar radiographs could be a minimally invasive method of estimating pulmonary function before and after spinal fusion in patients with an AIS. The 3D RCV reflects virtual chest capacity and hence pulmonary function in this group of patients. Cite this article: Bone Joint J 2022;104-B(1):112-119.

Balance, barycentremetry and external shape analysis in idiopathic scoliosis: What can the physician expect from it?

OBJECTIVE: Our objective was to establish a corridor of normality for the external shape 3D parameters and then to assess these variables in adolescent idiopathic scoliosis (AIS). METHODS: Adolescent with mild and severe AIS were included prospectively, as well as a control group of asymptomatic subjects. A quasi-automatic 3D reconstruction of the spine and manual 3D reconstruction of the external envelope was performed from biplanar radiography. The center of mass position, the axial intersegmental moment resulting at the apex and junctional vertebrae, and the coronal trunk balance were automatically computed. A normality corridor of asymptomatic subjects was calculated as the range [5th-95th percentiles] for external shape parameters at each vertebral level. RESULTS: Forty-one asymptomatic subjects (19 females; 22 males; 21 yo, SD=4) and sixty AIS (56 females; 4 males; 13 years old, SD=1.9; 30 mild and 30 severe; 34 thoracic curves and 26 thoraco-lumbar or lumbar curves) were included. All parameters based on the external shape showed differences between AIS and controls, as well as between mild and severe scoliosis. For instance, the intersegmental moment applied to the upper junctional vertebra was above the 95th percentile of controls in 70% of AIS patient. The percentage of severe patients showing parameters higher than the normality corridor was significantly higher than mild patients (p<0.0001). CONCLUSIONS: The analysis of center of mass, vertebral intersegmental moment and coronal trunk balance parameters appear to be relevant in characterizing the 3D deformity of adolescent idiopathic scoliosis. The upper junctional intersegmental moment seems to be able to distinguish the different stages of curvature severity.

Feasibility of Rib Kinematics and Intercostal-Space Biomechanical Characterization by Ultrasound in Adolescent Idiopathic Scoliosis.

The aim of this work was to determine the feasibility of combined ultrasonography and elastography measurement to characterize the mechanical properties of the intercostal space during breathing. Eighteen asymptomatic participants (ages 13 ± 2 y) and six participants with adolescent idiopathic scoliosis (AIS) were included (Cobb angle 60° ± 12°). Ultrasonographic and elastographic clips were acquired of T8-T9 ribs and the intercostal space. The two adjacent ribs were tracked to infer the breathing cycle. Shear-wave speed (SWS) was measured in the intercostal space at different stages of the breathing cycle. SWS was symmetric in the control group, during both expiration and inspiration. In AIS, the SWS during inspiration was higher in the convex side than in the concave one (p = 0.02). Furthermore, SWS was higher during inspiration than expiration in the control group and in the AIS convex side, but not in the AIS concave side (p > 0.05). This new method combining echography and shear-wave elastography allowed measurement of the mechanical characteristics of the intercostal space at different phases of the breathing cycle and highlighted differences between the AIS and control groups. This approach opens the way to further analyses of the biomechanical characteristics of breathing in severe AIS.

The orthopedic characterization of cfap298tm304 mutants validate zebrafish to faithfully model human AIS.

Cerebrospinal fluid (CSF) circulation relies on the beating of motile cilia projecting in the lumen of the brain and spinal cord cavities Mutations in genes involved in cilia motility disturb cerebrospinal fluid circulation and result in scoliosis-like deformities of the spine in juvenile zebrafish. However, these defects in spine alignment have not been validated with clinical criteria used to diagnose adolescent idiopathic scoliosis (AIS). The aim of this study was to describe, using orthopaedic criteria the spinal deformities of a zebrafish mutant model of AIS targeting a gene involved in cilia polarity and motility, cfap298tm304. The zebrafish mutant line cfap298tm304, exhibiting alteration of CSF flow due to defective cilia motility, was raised to the juvenile stage. The analysis of mutant animals was based on micro-computed tomography (micro-CT), which was conducted in a QUANTUM FX CALIPER, with a 59 µm-30 mm protocol. 63% of the cfap298tm304 zebrafish analyzed presented a three-dimensional deformity of the spine, that was evolutive during the juvenile phase, more frequent in females, with a right convexity, a rotational component and involving at least one dislocation. We confirm here that cfap298tm304 scoliotic individuals display a typical AIS phenotype, with orthopedic criteria mirroring patient's diagnosis.

A Novel Classification of 3D Rib Cage Deformity in Subjects With Adolescent Idiopathic Scoliosis.

STUDY DESIGN: This was a multicentric cross-sectional descriptive study. OBJECTIVE: To analyze patterns of 3D rib cage deformity in subjects with adolescent idiopathic scoliosis (AIS) and their relationship with the spinal deformity. SUMMARY OF BACKGROUND DATA: Subjects with AIS present with rib cage deformity that can affect respiratory functions. The 3D rib cage deformities in AIS and their relationship to the spinal deformity are still unelucidated. METHODS: A total of 200 AIS and 71 controls underwent low-dose biplanar x-rays and had their spine and rib cage reconstructed in 3-dimensional (D). Classic spinopelvic parameters were calculated in 3D and: rib cage gibbosity, thickness, width, volume and volumetric spinal penetration index (VSPI). Subjects with AIS were classified as: group I with mild rib cage deformity (n=88), group II with severe rib cage deformity (n=112) subgrouped into IIa (high gibbosity, n=48), IIb (high VSPI, n=48), and IIc (both high gibbosity and VSPI, n=16). RESULTS: Groups IIa and IIb had a higher Cobb angle (33 vs. 54 degrees and 46 degrees, respectively) and torsion index (11 vs. 14 degrees and 13 degrees, respectively) than group I. Group IIb showed more severe hypokyphosis (IIb=21 degrees; IIa=33 degrees; I=36 degrees; control=42 degrees) with a reduced rib cage volume (IIb=4731 cm3; IIa=4985 cm3; I=5257 cm3; control=5254 cm3) and thickness (IIb=135 mm; IIa=148 mm; I=144 mm; control=144 mm). Group IIa showed an increasingly large local gibbosity descending from proximal to distal levels and did not follow the axial rotation of the spine. Group IIc showed characteristics of both groups IIa and IIb. CONCLUSIONS: This new classification of 3D rib cage deformity in AIS shows that the management of cases with high VSPI (groups IIb and IIc) should focus on restoring as much kyphosis as possible to avoid respiratory repercussions. Treatment indications in groups I and IIa would follow the consensual basic principles reported in the literature regarding bracing and surgery.

Biomechanical Evaluation of Intercostal Muscles in Healthy Children and Adolescent Idiopathic Scoliosis: A Preliminary Study.

Spine deformity during adolescent idiopathic scoliosis can induce a rib-cage deformity. This bone deformity can have direct consequences on the chest-wall muscles, including intercostal muscles, leading to respiratory impairments in individuals with severe cases. The aim of this study was to determine whether shear-wave elastography can be used to measure intercostal-muscle shear-wave speed (SWS) in healthy children and those with adolescent idiopathic scoliosis (AIS). Nineteen healthy participants and 16 with AIS took part. SWS measurements were taken by three operators, twice each. Average SWS was 2.3 ± 0.4 m/s, and inter-operator reproducibility was 0.2 m/s. SWS was significantly higher during apnea than in normal breathing (p < 0.01) in both groups. No significant difference was observed between groups in apnea or in normal breathing. Characterization of the intercostal muscles by ultrasound elastography is therefore feasible and reliable for children and adolescents with and without scoliosis.

Towards a predictive simulation of brace action in adolescent idiopathic scoliosis.

Bracing is the most common treatment to stop the progression of adolescent idiopathic scoliosis. Finite element modeling could help improve brace design, but model validation is still a challenge. In this work, the clinical relevance of a predictive and subject-specific model for bracing was evaluated in forty-six AIS patients. The model reproduces brace action and the patient's spinopelvic adjustments to keep balance. The model simulated 70% or more patients with geometrical parameters within a preselected tolerance level. Although the model simulation of the sagittal plane could be improved, the approach is promising for a realistic and predictive simulation of brace action.

Spine slenderness and wedging in adolescent idiopathic scoliosis and in asymptomatic population: an observational retrospective study.

PURPOSE: The origin of the deformity due to adolescent idiopathic scoliosis (AIS) is not known, but mechanical instability of the spine could be involved in its progression. Spine slenderness (the ratio of vertebral height to transversal size) could facilitate this instability, thus playing a role in scoliosis progression. The purpose of this work was to investigate slenderness and wedging of vertebrae and intervertebral discs in AIS patients, relative to their curve topology and to the morphology of control subjects. METHODS: A total of 321 AIS patients (272 girls, 14 ± 2 years old, median Risser sign 3, Cobb angle 35° ± 18°) and 83 controls were retrospectively included (56 girls, median Risser 2, 14 ± 3 years). Standing biplanar radiography and 3D reconstruction of the spine were performed. Geometrical features were computed: spinal length, vertebral and disc sizes, slenderness ratio, frontal and sagittal wedging angles. Measurement reproducibility was evaluated. RESULTS: AIS girls before 11 years of age had slightly longer spines than controls (p = 0.04, Mann-Whitney test). AIS vertebrae were significantly more slender than controls at almost all levels, almost independently of topology. Frontal wedging of apical vertebrae was higher in AIS, as expected, but also lower junctional discs showed higher wedging than controls. CONCLUSION: AIS patients showed more slender spines than the asymptomatic population. Analysis of wedging suggests that lower junctional discs and apex vertebra could be locations of mechanical instability. Numerical simulation and longitudinal clinical follow-up of patients could clarify the impact of wedging, slenderness and growth on the biomechanics of scoliosis progression. These slides can be retrieved under Electronic Supplementary Material.

Early Ultrasound Follow-Up of Extension-Type Supracondylar Fractures Treated by the Collar-and-Cuff (Blount) Technique.

BACKGROUND: Extension-type supracondylar fractures can be treated with external immobilization, with the elbow flexed 100°. However, this technique requires early evaluation by true lateral x-ray of the elbow to detect secondary fracture displacement. QUESTIONS/PURPOSE: The purpose of this work is to evaluate whether ultrasound imaging is suitable for demonstrating initial reduction of supracondylar fractures and early secondary displacement of the fracture. METHODS: Fourteen patients aged 3 to 7 years (mean, 4.8 years) were treated by closed reduction under general anesthesia and immobilization with a collar and cuff. All patients had early postoperative x-rays and ultrasonography on day 1, as well as day 8 x-rays and ultrasonography. Ultrasonograms were performed by an experienced senior radiologist. RESULTS: In all cases, a complete reduction was confirmed at initial follow-up on both sonogram and intraoperative fluoroscopy. In 13 of 14 cases, no secondary displacement of the fracture was noted at day 8 on either ultrasonography or x-ray images. In 1 case, a secondary displacement was noted at day 8 on ultrasonography and confirmed by the lateral x-ray. CONCLUSIONS: Our study found a complete agreement assessing the quality of intraoperative reduction of supracondylar fractures by radiographs and ultrasonography. These results confirm that ultrasound imaging is suitable for demonstrating secondary displacements of supracondylar fractures in children. We postulate that in Gartland types II and III fractures treated by Blount procedure, a negative ultrasound result at day 8 follow-up may reduce the need for further radiographs. However, in any doubtful situation, the need for conventional radiographs remains. LEVEL OF EVIDENCE: Diagnostic study, level II.

Shear wave elastography of lumbar annulus fibrosus in adolescent idiopathic scoliosis before and after surgical intervention.

OBJECTIVES: To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic (AIS) patients before and after surgery, and compare them with asymptomatic controls. METHODS: Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle ranging between 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed (SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurements took place before surgery, and 3 months (N = 13) or 1 year after (N = 12). RESULTS: No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher in preop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop (3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended to decrease with the Cobb angle (Spearman's rho = - 0.4, p = 0.05). CONCLUSION: Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomatic ones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing of mild scoliosis has an effect on disc properties. KEY POINTS: • Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis. • Disc elastography tends to normalize 1 year after surgery.

Rib Cage Measurement Reproducibility Using Biplanar Stereoradiographic 3D Reconstructions in Adolescent Idiopathic Scoliosis.

BACKGROUND: A reproducibility study of preoperative rib cage three-dimensional (3D) measurements was conducted for patients with Adolescent Idiopathic Scoliosis (AIS). No prior reliability study has been performed for preoperative 3D reconstructions of the rib cage by using stereoradiography in patients with preoperative AIS. Our objective was to assess the reliability of rib cage 3D reconstructions using biplanar stereoradiography in patients with AIS before surgery. METHODS: This series includes 21 patients with Lenke 1 or 2 scoliosis (74±20 degrees). All patients underwent low-dose standing biplanar radiographs. Two operators performed reconstructions twice each. Intraoperator repeatability, interoperator reproducibility, and intraclass coefficients (ICC) were calculated and compared between groups. RESULTS: The average rib cage volume was 4.71 L (SD±0.75 L). Two SD was 0.19 L with a coefficient of variation of 4.1%; ICC was 0.968. The thoracic index was 0.6 (SD±0.1). Two SD was 0.03 with a coefficient of variation of 4.7% and a ICC of 0.820. As for the Spinal Penetration Index (6.4%; SD±2.4), 2SD was 0.9% with a coefficient of variation of 14.3% and a ICC of 0.901. The 3D rib hump 2SD (average 27±8 degrees) was 1.4 degrees. The coefficient of variation and ICC were respectively 5.1% and 0.991. CONCLUSIONS: Three-dimensional reconstruction of the rib cage using biplanar stereoradiography is a reliable method to estimate preoperative thoracic parameters in patients with AIS. LEVEL OF EVIDENCE: Level IV-diagnostic study.