Dual Versus Single Attending Surgeon Performance of Spinal Deformity Surgery? A Meta-Analysis.

BACKGROUND: The inclusion of 2 surgeons in spinal deformity surgery is considered beneficial by some. In fact, select studies indicate advantages such as reduced operation time and blood loss. Another observed decreased patient morbidity with a dual-surgeon approach, attributed to shorter operative times and reduced intraoperative blood losses. Therefore, this meta-analysis will assess the benefits of a having 2 surgeons compared to 1 surgeon during spine surgeries. METHODS: PubMed, Cochrane, and Google Scholar (page 1-20) were searched till January 2024. The clinical outcomes evaluated were the incidence of adverse events, the rate of transfusion, reoperation, and surgery-related parameters such as operative room time, length of stay (LOS), and estimated blood loss. RESULTS: Thirteen studies were included. A greater rate of complications was seen in patients operated upon by 1 surgeon (odds ratio = 0.50; 95% confidence intervals [CI]: 0.25-0.99, P = 0.05). Furthermore, operative room time (mean differences = -82.73; 95% CI: -111.42 to -54.03, P < 0.001) and LOS (mean differences = -0.91; 95% CI: -1.12 to -0.71, P < 0.001) were reduced in the dual surgeon scenario. No statistically significant difference was shown in the remaining analyzed outcomes. CONCLUSIONS: The presence of 2 surgeons in the odds ratiowas shown to reduce complications, operative room time, and LOS. More cost-effectiveness studies are needed in order to substantiate the financial advantages associated with the dual-surgeon approach.

Hybrid vs all pedicle screws constructs in adolescent idiopathic scoliosis: a metaanalysis of clinical and radiological outcomes.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) affects around 1 to 3% of young individuals, leading to spinal deformities typically exceeding a Cobb angle of 10 degrees without congenital or neuromuscular causes. Advances in treatment now include various surgical techniques such as posterior fusion utilizing all-pedicle screw constructs or hybrid constructs. METHODS: PubMed, Cochrane, and Google Scholar (pages 1-20) were searched up until February 2024. Comparative studies in which the cohort was separated into two groups (HC and PSC) were included. Data consisting of, surgery-related outcomes, sagittal radiographic outcomes, coronal radiographic outcomes, and patient-reported outcomes, was extracted and compared. RESULTS: Twenty-eight studies including 3435 patients were included. Higher rates of complications (Odds-Ratio = 1.99, p < 0.00001) and reoperations (Odds-Ratio = 2.82, p < 0.00001) were seen in the hybrid group. Better radiographic coronal correction was seen in the PSC group in both the major curve (Mean Difference = 5.97, p < 0.00001) and the secondary curve (Mean Difference = - 10.73, p < 0.0001). However, restoration of sagittal alignment was better in the HC group when assessing thoracic kyphosis (Mean Difference = 2.97, p = 0.02) and lumbar lordosis (Mean Difference = 3.17, p = 0.005). CONCLUSION: While all-pedicle screw constructs demonstrated greater stability in AIS compared to hybrid constructs, resulting in reduced rates of reoperations and complications, as well as improved correction of major and secondary curves, they were unable to fully restore optimal sagittal alignment.

Implant density in adolescent idiopathic scoliosis: a meta-analysis of clinical and radiological outcomes.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) affects 1-3% of adolescents, and treatment approaches, including the density of constructs in surgical fusion, vary among orthopedic surgeons. Studies have sought to establish whether high-density or low-density constructs offer superior clinical and radiological outcomes, yet conclusive results are lacking. This meta-analysis aims to provide a definitive answer to the controversial and ambiguous question surrounding the efficacy of different pedicle screw densities in treating AIS. METHODS: PubMed, Cochrane, and Google Scholar (page 1-20) were searched till December 2023. The studied outcomes were Major Cobb angle, major curve correction, lumbar curve, kyphosis (T5-T12), lumbar lordosis, coronal balance, LIV Tilt angle, TAV translation, LAV translation, apical trunk rotation, trunk shift, SRS-22, operative time, blood loss, complications and cost. RESULTS: Twenty-four studies (total of 1985 patients, 1045 in LD group and 940 in HD group) were included in this meta-analysis. A statistically significant better improvement in ATR (p = 0.02) and LIV tilt angle (p = 0.02) was seen in the high-density group. On the other hand, longer operative time (p = 0.002), blood loss (p = 0.0004) and costs (p = 0.02) were seen in the high-density group. No difference was seen in the remaining radiographic and clinical outcomes between both surgeries. CONCLUSION: Both low-density (LD) and high-density (HD) screw constructs show comparable and satisfactory radiographic and QOL for AIS patients. Furthermore, HD constructs had increased costs, operative time, and blood loss associated. However, a definitive conclusion cannot be made and more studies taking into account multiple additional variables are necessary to do so.

Unilateral Versus Bilateral Cages in Lumbar Interbody Fusions: A Meta-Analysis of Clinical and Radiographic Outcomes.

BACKGROUND: Bilateral cages are often used for interbody fusion. However, this procedure may not be possible in some cases making unilateral cages a reasonable alternative. The literature remains divided on the clinical and radiological distinctions when comparing unilateral to bilateral cages in lumbar interbody fusion. Thus, this meta-analysis will analyze the clinical and radiographic outcomes between these 2 groups. METHODS: PubMed, Cochrane, and Google Scholar (page 1-20) were searched till January 2024. The clinical outcomes evaluated were the incidence of adverse events, surgery-related parameters, and patient reported outcomes. RESULTS: Lower rates of pseudoarthrosis, subsidence, were reported in the bilateral cages group (P = 0.01, P = 0.001, respectively) whereas shorter operative time (OR time), and lower estimated blood loss were seen in unilateral cage group (P < 0.001, and P = 0.003). There was no statistically significant difference in the remaining analyzed outcomes. CONCLUSIONS: Unilateral cages were shown to be superior due to their reduced OR time and estimated blood loss. As for the higher rate of pseudoarthrosis, this outcome may not be related to the cage numbers and it did not affect clinical outcomes. Nevertheless, one must consider other factors such as radiographic sagittal parameters before making a surgical decision.

Intensive Care Unit Admission After Spine Surgery: A Narrative Review.

INTRODUCTION: Intensive care unit (ICU) admissions constitute a substantial financial challenge for health care systems and patients and are linked to various potentially life-altering complications. A wide range of patient-related, surgical, and medical factors are associated with an increased risk of ICU admission following spine surgery. DISCUSSION: The most notable examples include lung, heart, and kidney disease, as well as estimated blood loss and length of surgery. Various scores that include the most significant patient- and procedure-related factors have been described to assess the risk associated with surgery for individual patients. To date, the fusion risk score and the American Society of Anesthesiologists score have been the most useful in predicting postoperative complications and admission to the ICU. However, other risk factors have also been implicated in ICU admission and length of stay. The current scores must further adapt by using the available evidence to fulfill their intended purpose. Moreover, a handful of measures have shown efficacy in decreasing ICU admission and length of stay, with their benefits still to be demonstrated by future research. CONCLUSION: This review underscores the risk factors predictive of ICU admission following spine surgery and will help surgeons and clinicians in patient stratification. However, future studies are needed to validate the role of protective measures in preventing ICU admissions and the significance of certain risk factors.

Will ChatGPT be Able to Replace a Spine Surgeon in the Clinical Setting?

OBJECTIVE: This study evaluates ChatGPT's performance in diagnosing and managing spinal pathologies. METHODS: Patients underwent evaluation by two spine surgeons (and the case was discussed and a consensus was reached) and ChatGPT. Patient data, including demographics, symptoms, and available imaging reports, were collected using a standardized form. This information was then processed by ChatGPT for diagnosis and management recommendations. The study assessed ChatGPT's diagnostic and management accuracy through descriptive statistics, comparing its performance to that of experienced spine specialists. RESULTS: A total of 97 patients with various spinal pathologies participated in the study, with a gender distribution of 40 males and 57 females. ChatGPT achieved a 70% diagnostic accuracy rate and provided suitable management recommendations for 95% of patients. However, it struggled with certain pathologies, misdiagnosing 100% of vertebral trauma and facet joint syndrome, 40% of spondylolisthesis, stenosis, and scoliosis, and 22% of disc-related pathologies. Furthermore, ChatGPT's management recommendations were poor in 53% of cases, often failing to suggest the most appropriate treatment options and occasionally providing incomplete advice. CONCLUSIONS: While helpful in the medical field, ChatGPT falls short in providing reliable management recommendations, with a 30% misdiagnosis rate and 53% mismanagement rate in our study. Its limitations, including reliance on outdated data and the inability to interactively gather patient information, must be acknowledged. Surgeons should use ChatGPT cautiously as a supplementary tool rather than a substitute for their clinical expertise, as the complexities of healthcare demand human judgment and interaction.

Approaches in Anterior Column Support in Adult Spinal Deformity Surgery: A Meta-Analysis of Clinical and Radiologic Outcomes.

OBJECTIVE: This meta-analysis was conducted to compare anterior lumbar interbody fusion (ALIF) with transforaminal lumbar interbody fusion (TLIF) in terms of postoperative complications, improvement in radiographic parameters, and patient-reported outcomes. METHODS: PubMed, Cochrane, and Google Scholar (pages 1-20) databases were searched up to June 2023. The studied outcomes were the rate of rod failures, rod failures requiring revision surgery, all complications, all revision surgeries, the change in pelvic tilt, sacral slope, Cobb angle, lumbar lordosis (LL), sagittal vertical axis, the postoperative pelvic incidence-LL, and LL, and the improvement in back pain and Oswestry Disability Index (ODI). RESULTS: Six studies were included in this meta-analysis. ALIF showed higher postoperative lordosis (P = 0.003) and better improvement in ODI (P = 0.0001). No difference was seen in the remaining outcomes between ALIF and TLIF. CONCLUSIONS: Although ALIF had better improvement in ODI, the mean difference was 6.5 points, which is below the minimal clinically important difference, stripping this result of any clinical value. Furthermore, even though ALIF had better postoperative lordosis, the change in LL postoperatively was not different between ALIF and TLIF. With no difference in complications, sagittal and coronal alignment, and patient-reported outcomes, TLIF was shown in this study to be favored instead of ALIF in adult spinal deformity surgery to avoid all the double approach-related comorbidity.

Exceptional Spinal Mobility Caused by Charcot Disease: Case Description with Several Years of Follow-Up.

A spinal cord injury is now the most common cause of Charcot Spinal Arthropathy (CSA). Paraplegia, loss of pain sensation, laminectomies, and spinal fusions involving more than 5 levels are all risk factors for developing this condition. Low back pain and spinal abnormalities are common symptoms. Circumferential arthrodesis is the chosen treatment. Implant failure and new-onset CSA, which necessitates re-instrumentation, are some of the risks associated with this treatment. This is the case of a patient with a post-traumatic spinal cord injury presenting with spinal Charcot disease with a very long follow-up. We report a unique complication with the replacement of the discal space and portions of the vertebral bodies by fibrotic tissue with an extraordinary spinal movement in the coronal and sagittal planes. Recurrent Charcot disease at the same level or at a caudal level is a devastating complication in spinal surgery. Since this disease naturally exposes the patient to iterative surgeries, it would be wise to limit the extent of the arthrodesis to an optimal number of levels sufficient to ensure perfect stability of the construct and not to be very extensive from the first surge. The risk would increase the fused levels which limit the availability of mobile buffer levels and increase the stress on the remaining levels. Regular follow-ups to the patient should be done to detect recurrence at the same site or distal to the instrumentation.

Transforaminal lumbar interbody fusion using banana-shaped and straight cages: meta-analysis of clinical and radiological outcomes.

PURPOSE: Transforaminal lumbar interbody fusion (TLIF) surgery rate increased over the last decade. There is no consensus about the better shape of cage to use in TLIF. This meta-analysis was conducted to compare the shape focusing on bony union, lordosis restoration as well as perioperative complications. METHODS: PubMed, Cochrane, and Google Scholar (page 1-20) were searched till September 2022. The clinical outcomes consisted of the bony union, segmental and lumbar lordosis restoration, quality of life, and operation-related outcomes. RESULTS: Only 5 studies were included in this meta-analysis. Straight-shaped cages tended to have a lower subsidence rate compared to banana-shaped cages (p = 0.10), had a better restoration of segmental lordosis (p < 0.0001), better disc height restoration (p = 0.01), as well as a higher Oswestry Disability Index decrease (p = 0.0002). CONCLUSION: Straight-shaped cages had a better restoration of lumbar lordosis, disc height, and a lower subsidence rate when compared to banana-shaped cages. This may be explained by the absence of the optimal placement of the curved cages, which is at the most anterior part of the disc space. Better conducted randomized controlled trial could strengthen these findings.

What is the best referral strategy for axial spondyloarthritis? A prospective multicenter study in patients with suspicious chronic low back pain.

OBJECTIVE: To assess the value of referral strategies for axial spondyloarthritis (axSpA) in patients with suspicious chronic inflammatory low back pain (LBP), to estimate the value of inflammatory back pain (IBP) for referral, and to identify the predictive factors of the final diagnosis of axSpA in Middle Eastern Arab countries. METHODS: The study was multicentric, prospective, and conducted in LBP first-line clinics (rheumatology, internal, family medicine, orthopedic surgery, neurosurgery, and neurology). Consecutive adult patients aged under 45years were included in case of LBP suspicious of inflammatory nature according to the first-line physician. The rheumatologist's final diagnosis was the gold standard. The diagnostic properties of ten referral strategies (Brandt I, II, III, Hermann, RADAR, RADAR 2/3, MASTER, Braun, CAFASPA, and ASAS) and of IBP were calculated. A multivariable logistic regression identified the clinical predictive factors of axSpA. RESULTS: In 515 referred patients, axSpA was confirmed in 48%, refuted in 43%, and diagnosis remained inconclusive in 9%. The optimal referral strategy was the MASTER (PLR 3.3), which comprises IBP, good response to NSAIDs, positive HLA-B27, and SpA family history. Considering strategies without HLA-B27, the RADAR 2/3 had a PLR of 2.9 (IBP, good response to NSAIDs, any extra-musculoskeletal manifestation). The predictive factors for axSpA were MRI sacroiliitis, positive HLA-B27, high CRP, psoriasis, IBP, and longer symptom duration. Of all patients, 35% were self-referred, 16% were referred by primary care physicians, and 15% by neuro/orthopedic surgeons. CONCLUSION: Optimizing physicians' awareness of these clinical features may enhance referral in axSpA.

Vertebroplasty versus Kyphoplasty in the Treatment of Osteoporotic Vertebral Compression Fractures: A Meta-Analysis.

BACKGROUND: One of the most frequent consequences of osteoporosis is osteoporotic vertebral compression fractures, which makes it one of the most prevalent health care crises in the world. Two things are needed to manage them: 1) pain management, and 2) fracture stabilization. To take care of both, 2 methods are commonly used: 1) vertebroplasty and 2) kyphoplasty (KP) without a clear consensus on which is the better one. A meta-analysis was done comparing both techniques in the management of osteoporotic vertebral compression fractures. METHODS: PubMed, Cochrane, and Google Scholar (page 1-20) were searched updated to October 2022. Two reviewers determined the eligibility of the studies independently. Only 8 studies were included in the meta-analysis. The clinical outcomes consisted of the complications (cement leakage, adjacent level fractures), the visual analog scale scores, Oswestry disability index, kyphotic wedge angle, and vertebral body height restoration. RESULTS: KP was shown to be superior to vertebroplasty in terms of reducing cement leakage, and increasing postoperative vertebral body height. The comparison of the rest of the outcomes was statistically insignificant between both techniques. CONCLUSIONS: Although KP could significantly increase postoperative vertebral body height and decrease the risk of cement leakage, the fact that it is more costly and has a longer operative time raises the question about the cost effectiveness of the procedure.

Scheuermann's kyphosis: update on pathophysiology and surgical treatment.

Scheuermann's Kyphosis (SK) is a rigid spinal kyphosis. Several theories have been proposed concerning its pathogenesis, but it is, to this day, still unknown. It has a prevalence of 0.4-8.3% in the population with a higher incidence in females. Clinical examination with x-rays is needed to differentiate and confirm this diagnosis. Non-surgical management is reserved for smaller deformities and in skeletally immature patients, whereas surgery is recommended for higher deformities. Combined anterior and posterior approach was considered the gold standard for the surgical treatment of this disease, but there is an increasing trend toward posterior-only approaches especially with use of segmental fixation. This study reviews the pathophysiology of SK while proposing a treatment algorithm for its management.

Global malalignment in adolescent idiopathic scoliosis: the axial deformity is the main driver.

PURPOSE: To evaluate the global alignment of non-operated subjects with adolescent idiopathic scoliosis. METHOD: A total of 254 subjects with AIS and 64 controls underwent low dose biplanar X-rays and had their spine, pelvis, and rib cage reconstructed in 3D. Global alignment was measured in the sagittal and frontal planes by calculating the OD-HA angle (between C2 dens to hip axis with the vertical). Subjects with AIS were classified as malaligned if the OD-HA was > 95th percentile relative to controls. RESULTS: The sagittal OD-HA in AIS remained within the normal ranges. In the frontal plane, 182 AIS were normally aligned (Group 1, OD-HA = 0.9°) but 72 were malaligned (Group 2, OD-HA = 2.9°). Group 2 had a more severe spinal deformity in the frontal and horizontal planes compared to Group 1 (Cobb: 42 ± 16° vs. 30 ± 18°; apical vertebral rotation AVR: 19 ± 10° vs. 12 ± 7°, all p < 0.05). Group 2 subjects were mainly classified as Lenke 5 or 6. 19/72 malaligned subjects had a mild deformity (Cobb < 30°) but a progressive scoliosis (severity index ≥ 0.6). The frontal OD-HA angle was found to be mainly determined (adjusted-R2 = 0.22) by the apical vertebral rotation and secondarily by the Lenke type. CONCLUSIONS: This study showed that frontal malalignment is more common in distal major structural scoliosis and its main driver is the apical vertebral rotation. This highlights the importance of monitoring the axial plane deformity in order to avoid worsening of the frontal global alignment.

Assessment of the axial plane deformity in subjects with adolescent idiopathic scoliosis and its relationship to the frontal and sagittal planes.

PURPOSE: Investigate the axial plane deformity in the scoliotic segment and its relationship to the deformity in the frontal and sagittal planes. METHODS: Two hundred subjects with AIS (Cobb ≥ 20°) underwent low dose biplanar X-rays with 3D reconstruction of the spine and pelvis. All structural curves were considered and were distributed as follows: 142 thoracic (T), 70 thoracolumbar (TL), and 47 lumbar curves (L). Common 3D spino-pelvic and scoliosis parameters were collected such as: frontal Cobb; torsion index (TI); hypokyphosis/lordosis index (HI). Parameters were compared between each type of curvature and correlations were investigated between the 3 planes. RESULTS: Frontal Cobb was higher in all T (45 ± 19°) and TL (41 ± 15°) curves compared to L curves (35 ± 14°, p = 0.004). TI was higher in T curves when compared to TL and L curves (TI: 15 ± 8°, 9 ± 6°, 7 ± 5°, p < 0.001). HI was similar between curve types. T curves showed significant correlations between the 3 planes: Cobb vs. TI (r = 0.76), Cobb vs. HI (r = - 0.54) and HI vs. TI (r = - 0.42). The axial plane deformity was related to the frontal deformity and the type of curvature (adjusted-R2 = 0.6). CONCLUSION: Beside showing the most severe deformity frontally and axially compared to TL and L curves, the T curves showed strong correlations between the 3 planes of the deformity. Moreover, this study showed that the axial plane deformity cannot be fully determined by the frontal and sagittal deformities, which highlights the importance of 3D assessment in the setting of AIS.

Gait kinematic alterations in subjects with adult spinal deformity and their radiological determinants.

BACKGROUND: Adults with spinal deformity (ASD) are known to have postural malalignment affecting their quality of life. Classical evaluation and follow-up are usually based on full-body static radiographs and health related quality of life questionnaires. Despite being an essential daily life activity, formal gait assessment lacks in clinical practice. RESEARCH QUESTION: What are the main alterations in gait kinematics of ASD and their radiological determinants? METHODS: 52 ASD and 63 control subjects underwent full-body 3D gait analysis with calculation of joint kinematics and full-body biplanar X-rays with calculation of 3D postural parameters. Kinematics and postural parameters were compared between groups. Determinants of gait alterations among postural radiographic parameters were explored. RESULTS: ASD had increased sagittal vertical axis (SVA:34 ±â€¯59 vs -5 ±â€¯20 mm), pelvic tilt (PT:19 ±â€¯13 vs 11 ±â€¯6°) and frontal Cobb (25 ±â€¯21 vs 4 ±â€¯6°) compared to controls (all p < 0.001). ASD displayed decrease walking speed (0.9 ±â€¯0.3 vs 1.2 ±â€¯0.2 m/s), step length (0.58 ±â€¯0.11 vs 0.64 ±â€¯0.07 m) and increased single support (0.45 ±â€¯0.05 vs 0.42 ±â€¯0.04 s). ASD walked with decreased hip extension in stance (-3 ±â€¯10 vs -7 ±â€¯8°), increased knee flexion at initial contact and in stance (10 ±â€¯11 vs 5 ±â€¯10° and 19 ±â€¯7 vs 16 ±â€¯8° respectively), and decreased knee flexion/extension ROM (55 ±â€¯9 vs 59 ±â€¯7°). ASD had increased trunk flexion (12 ±â€¯12 vs 6 ±â€¯11°) and reduced dynamic lumbar lordosis (-11 ±â€¯12 vs -15 ±â€¯7°, all p < 0.001). Sagittal knee ROM, walking speed and step length were negatively determined by SVA; lack of lumbar lordosis during gait was negatively determined by radiological lumbar lordosis. SIGNIFICANCE: Static compensations in ASD persist during gait, where they exhibit a flexed attitude at the trunk, hips and knees, reduced hip and knee mobility and loss of dynamic lordosis. ASD walked at a slower pace with increased single and double support times that might contribute to their gait stability. These dynamic discrepancies were strongly related to static sagittal malalignment.

Toward understanding the underlying mechanisms of pelvic tilt reserve in adult spinal deformity: the role of the 3D hip orientation.

PURPOSE: To explore 3D hip orientation in standing position in subjects with adult spinal deformity (ASD) presenting with different levels of compensatory mechanisms. METHODS: Subjects with ASD (n = 159) and controls (n = 68) underwent full-body biplanar X-rays with the calculation of 3D spinopelvic, postural and hip parameters. ASD subjects were grouped as ASD with knee flexion (ASD-KF) if they compensated by flexing their knees (knee flexion ≥ 5°), and ASD with knee extension (ASD-KE) otherwise (knee flexion < 5°). Spinopelvic, postural and hip parameters were compared between the three groups. Univariate and multivariate analyses were then computed between spinopelvic and hip parameters. RESULTS: ASD-KF had higher SVA (67 ± 66 mm vs. 2 ± 33 mm and 11 ± 21 mm), PT (27 ± 14° vs. 18 ± 9° and 11 ± 7°) and PI-LL mismatch (20 ± 26° vs - 1 ± 18° and - 13 ± 10°) when compared to ASD-KE and controls (all p < 0.05). ASD-KF also had a more tilted (34 ± 11° vs. 28 ± 9° and 26 ± 7°), anteverted (24 ± 6° vs. 20 ± 5° and 18 ± 4°) and abducted (59 ± 6° vs. 57 ± 4° and 56 ± 4°) acetabulum, with a higher posterior coverage (100 ± 6° vs. 97 ± 7° for ASD-KE) when compared to ASD-KE and controls (all p < 0.05). The main determinants of acetabular tilt, acetabular abduction and anterior acetabular coverage were PT, SVA and LL (adjusted R2 [0.12; 0.5]). CONCLUSIONS: ASD subjects compensating with knee flexion have altered hip orientation, characterized by increased posterior coverage (acetabular anteversion, tilt and posterior coverage) and decreased anterior coverage which can together lead to posterior femoro-acetabular impingement, thus limiting pelvic retroversion. This underlying mechanism could be potentially involved in the hip-spine syndrome.

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.