Rib-vertebral Angle Research Articles

Combining Bilateral Magnetically Controlled Implants Inserted Parallel to the Spine With Rib to Pelvis Fixation: Surgical Technique and Early Results.

Spine-based fixation of magnetically controlled lengthening devices has been successfully performed for children with early-onset scoliosis. However, spinal manipulation may lead to ossifications, stiffness, and autofusion as previously described. To avoid these problems, a surgical technique combining bilateral externally controlled magnetic device implantation with a rib cradle and pelvic hook fixation was introduced by us in 2011. By using a bilateral single-rib or double-rib cradle fixation and a pelvic hook, the magnetic device is percutaneously inserted. The spine corrects indirectly without further manipulation. In small rib diameter or severe osteoporosis, double-rib cradles are used. Our introduced technique enables modification of the rib vertebral angle, which may be beneficial in children with spinal muscular atrophy and rib-cage deformity. This nonrandomized prospective study describes 18 children with neuromuscular scoliosis treated first by this method. All patients followed the same protocol, with expansion procedures being performed 5 months after surgery and every 3 months thereafter. Clinical, radiologic, and complication data were analyzed, showing a significant reduction in scoliosis and pelvic obliquity and an increase in spinal length, which could be maintained over a follow-up period of 1.2 years. The overall complication rate was lower than previously described, with 8%, 2 of them requiring surgery.

What Is the Actual 3D Representation of the Rib Vertebra Angle Difference (Mehta Angle)?

Cross-sectional study. To establish the relevance of the conventional two-dimensional (2D) rib vertebra angle difference (RVAD) and the relationship with the complex three-dimensional (3D) apical morphology in scoliosis. The RVAD, also known as Mehta angle, describes apical rib asymmetry on conventional radiographs and was introduced as a prognostic factor for curve severity in early onset scoliosis, and later applied to other types of scoliosis as well. An existing idiopathic scoliosis database of high-resolution computed tomography scans used in previous work, acquired for spinal navigation, was used. Eighty-eight patients (Cobb angle 46°-109°) were included. Cobb angle and 2D RVAD, as described by Mehta, were measured on the conventional radiographs and coronal digitally reconstructed radiographs (DRR) of the prone computed tomography scans. A previously validated, semiautomatic image processing technique was used to acquire complete 3D spinal reconstructions for the measurement of the 3D RVAD in a reconstructed true coronal plane, axial rotation, and sagittal morphology. The 2D RVAD on the x-ray was on average 25.3° ± 11.0° and 25.6° ± 12.8° on the DRR (P = 0.990), but in the true 3D coronal view of the apex, hardly any asymmetry remained (3D RVAD: 3.1° ± 12.5°; 2D RVAD on x-ray and DRR vs. 3D RVAD: P < 0.001). 2D apical rib asymmetry in the anatomical coronal plane did not correlate with the same RVAD measurements in the 3D reconstructed coronal plane of the rotated apex (r = 0.155; P = 0.149). A larger 2D RVAD was found to correlate linearly with increased axial rotation (r = 0.542; P < 0.001) and apical lordosis (r = 0.522; P < 0.001). The 2D RVAD represents a projection-based composite radiographic index reflecting the severity of the complex 3D apical morphology including axial rotation and apical lordosis. It indicates a difference in severity of the apical deformation. 4.

Radiographic and Respiratory Effects of Growing Rods in Children With Spinal Muscular Atrophy.

Respiratory weakness and spinal deformity are common in patients with spinal muscular atrophy (SMA). Posterior (distraction type) growing rods have recently gained favor as a treatment option in this population, due to their ability to prevent spinal deformity progression and their potential to allow lung volumes to increase over time. The objective of this study was to determine the impact of posterior growing rods on the spinal alignment and respiratory function in children with SMA with intermediate term follow-up. A single center, retrospective review was performed on SMA patients treated with growing rods, inserted between 2004 and 2010, with a minimum of 2-year follow-up. SMA type, changes in the route of bi-level positive airway pressure respiratory support and the amount of time receiving respiratory support are reported. Pulmonary function tests (PFTs) and radiographs were reviewed and data evaluated preinsertion, postinsertion, and at latest follow-up. Sixteen children with SMA (5 type I, 11 type II) met inclusion criteria. The average age of insertion was 5.8 (±1.5) years, the median number of lengthenings was 4 (range, 3 to 5), and the median time between insertion and last clinical review was 4.7 (range, 2.7 to 9.5) years. Radiographic review demonstrated significant (P<0.05) improvements in the following: Spinal curve magnitude, pelvic obliquity, space available for the lung, rib vertebral angle difference, and thoracic kyphosis following growing rod implantation. Thoracic and lumbar height and chest width and depth increased significantly (P<0.05) over the lengthening process. None of the patients initially required more than noninvasive positive pressure ventilation support. Fifteen of the 16 experienced no changes in their noninvasive positive pressure ventilation support needs throughout the study duration, requiring support only at night and naps. Serial PFTs were available for 6 children with SMA type II. PFTs demonstrated significant improvements in absolute forced vital capacity (FVC), minimal changes in the maximal inspiratory and expiratory pressures, and a gradual worsening of percent predicted FVC. Clinical respiratory support requirements appear to stabilize following the insertion and lengthening of posterior based growing rods in the SMA population. Similar to previous studies, increased spinal height and thoracic cavity size were noted throughout the process. Despite an increasing absolute FVC, the percent predicted FVC diminished over time. Level IV-therapeutic.

Initial Cast Correction as a Predictor of Treatment Outcome Success for Infantile Idiopathic Scoliosis.

Cast treatment for infantile idiopathic scoliosis patients ultimately corrects deformity in varying amounts. As the reasons for these differential outcomes are not fully elucidated, the aim of this study was to identify clinical and radiographic variables correlated with better cast correction. Patients in the Children's Spine Study Group and Growing Spine Study Group registries who underwent cast treatment for idiopathic scoliosis between 2005 and 2013 with 1-year minimum follow-up were included. Data including major curve and rib-vertebra angle difference before cast, initial in-cast application, after cast treatment, and at most recent follow-up were collected. Univariable and multivariable regression analyses were used to identify factors associated with lower major curves at most recent follow-up. A total of 68 patients were identified and followed for a mean of 2.5 (range, 1.1 to 5.4) years after cast treatment. Cast treatment lasted an average of 16.7 months, with a median of 6 cast applications (range, 2 to 19). Twenty-five subjects (37%) had a most recent major curve <15 degrees (success), whereas 43 had a curve that was >15 degrees (unresolved). Multivariable linear regression determined that younger age (P=0.02), smaller precast major curve (P<0.001), and greater percent major curve correction in initial cast (P=0.006) were associated with smaller major curve at most recent follow-up. Multivariable logistic regression determined that success patients were younger than unresolved patients (average age, 1.4 vs. 2.1 y; P=0.003), and had smaller in-cast major curves after initial cast application (average, 18 vs. 27 degrees; P=0.002). Infantile idiopathic scoliosis patients casted at an earlier age, with smaller major curves, and greater percent major curve correction in initial cast have the best prognosis. Patients' percent major curve correction, which may represent curve flexibility and/or cast quality, is a predictor of treatment success when age and precast major curve are also taken into account. Level III-retrospective study.

Serial Mehta Cast Utilization in Infantile Idiopathic Scoliosis: Evaluation of Radiographic Predictors

Mehta cast utilization has gained a considerable momentum as a nonoperative treatment modality for the initial management of infantile idiopathic scoliosis (IIS). Despite its acceptance, there is paucity of data that characterize the radiographic parameters associated with Mehta casting and the factors correlated with a sustained curve correction. A retrospective review of IIS patients who underwent Mehta casting was performed with a mean 2-year follow-up. X-rays were evaluated at each visit for the Cobb angle, focal deformity, rib-vertebral angle difference, and height of concavity and convexity of the apical 3 vertebrae. Concave-to-convex height ratios were calculated and tracked for each patient. Radiographic parameters were compared from precasting to after final casting, and from final casting to most recent follow-up. A total of 45 patients were identified, of whom 18 (40%) were male and 27 (60%) were female, with a mean age of 18.8±9.5 months at first casting and a mean follow-up of 37.7±19.7 months. Following final casting, the mean Cobb angle (25.6 vs. 52.7 degrees), focal deformity (17.4 vs. 30.5 degrees), rib-vertebral angle difference (18 vs. 32.3 degrees), and the concave-to-convex height ratios improved relative to precast parameters, respectively (P<0.001). At final follow-up, mean Cobb angle (16.2 vs. 25.6 degrees) and concave-to-convex height ratios progressively improved when compared with final cast measurements, respectively (P<0.001). Five (11%) patients did not demonstrate sustained curve correction at final follow-up, whereas 4 (9%) required growing-rod placement. Lastly, the regression analysis demonstrated improvements in the focal deformity (17.4 vs. 30.5) and the concave-to-convex height ratios of the +1 and -1 apical vertebrae from the precast to last cast periods (P<0.001). These findings were correlated with sustained Cobb angle correction from cast removal to the most recent follow-up. Radiographic parameters associated with control of progressive deformity for IIS include improvements in focal deformity and concave-to-convex height ratios for +1 and -1 apical vertebrae after final casting. Mehta casting is an effective treatment for symptomatic IIS and continues to provide IIS patients with significant curve correction. Level IV.

Serial Casting for Infantile Idiopathic Scoliosis: Radiographic Outcomes and Factors Associated With Response to Treatment.

Serial casting for early-onset scoliosis has been shown to improve curve deformity. Our goal was to define clinical and radiographic features that determine response to treatment. We retrospectively reviewed patients with idiopathic infantile scoliosis with a minimum of 2-year follow-up. Inclusion criteria were: progressive idiopathic infantile scoliosis and initial casting before 6 years of age. Two groups were analyzed and compared: group 1 (≥10-degree improvement in Cobb angle from baseline) and group 2 (no improvement). Twenty-one patients with an average Cobb angle of 48 degrees (range, 24 to 72 degrees) underwent initial casting at an average age of 2.1 years (range, 0.7 to 5.4 y). Average follow-up was 3.5 years (range, 2 to 6.9 y). Sex, age at initial casting, magnitude of spinal deformity, and curve flexibility (defined as change in Cobb angle from pretreatment to first in-cast radiograph) were not significantly different between groups (P>0.05). Group 1 had a significantly higher body mass index (BMI) than group 2 at the onset of treatment (17.6 vs. 14.8, P<0.05). Univariate analysis of demographic, radiographic, and treatment factors revealed that only BMI was predictive of Cobb improvement (P=0.04; odds ratio=2.38). Group 1 (n=15) had a significantly lower Cobb angle (21 vs. 56 degrees) and rib vertebral angle difference (13 vs. 25 degrees) compared with group 2 at latest follow-up (P<0.05). A significantly larger proportion of children who were casted at less than 1.8 years of age had a Cobb angle <20 degrees at latest follow-up (P=0.03). Group 2 maintained stable clinical and radiograph parameters from pretreatment to most recent follow-up. To maintain a homogeneous cohort, we excluded patients with syndromes and developmental delays. We believe that analyzing a homogeneous group provides more meaningful results than if we studied a heterogeneous sample. BMI was significantly associated with outcome such that for each unit increase in BMI, there is a 2.38× increase in the chance of improvement. Curve flexibility was similar between groups, which suggest that the amount of correction obtained at initial casting does not confirm treatment success. Key aspects of treatment that may determine success include age of less than 1.8 years at initiation of casting and derotation of the spine to correct rib vertebral angle difference of <20 degrees. Level IV-Therapeutic.

Intraobserver and Interobserver Measurement Variability of the Rib-Vertebral Angle Difference.

The rib-vertebral angle (RVAD) differentiates between progressive and resolving infantile idiopathic scoliosis (IIS) curves. Those with a RVAD<20 degrees often resolve without treatment, whereas those >20 degrees often progress and require treatment. The mathematical magnitude of RVAD measurement variability has not been described, and was thus the purpose of this study. It is important to know the reliability of RVAD measurements so as to understand changes that can be attributed to observer error alone. The purpose of the study was to mathematically determine the intraobserver and interobserver measurement variability of the RVAD difference in IIS. A convenience sample of 50 patients with IIS was selected. The RVAD was measured twice by 7 different observers separated by a minimum of 3 weeks. The 7 different readers chosen to measure the RVAD were 2 orthopaedic residents, 1 pediatric radiologist, and 4 attending pediatric orthopaedic surgeons. The same goniometer was used for all measurements. Intraobserver and interobserver measurement variability was determined using 3 well known used statistical methods. The 3 different methods used to determine intraobserver and interobserver variability using 95% prediction/confidence limits gave very similar results. Intraobserver variability was ∼24 degrees and the interobserver variability was ∼23 degrees. The utility of the RVAD in medical decision-making and counseling of patients with IIS should be approached with caution when used in isolation due to the large measurement variability. Level 3.

Rib-vertebral angle measurements predict brace treatment outcome in Risser grade 0 and premenarchal girls with adolescent idiopathic scoliosis.

To investigate the predictive role of rib-vertebral angle (RVA) measurements in early adolescent idiopathic scoliosis (AIS) girls with right thoracic curve during brace treatment. Early AIS (premenarchal and Risser 0) girls who had undergone brace treatment and had been followed regularly were recruited to this study. According to the bracing outcome, they were divided into Group A (non-progressed) and Group B (curve worsened over six degrees or indicated for surgery). Totally 48 girls were included. There were 30 and 18 patients in Groups A and B, respectively. Ratio of curve progression was significantly higher in patients with initial RVA difference (RVAD) ≥20° versus <20°, or convex RVA (CRVA) ≤68° versus >68°. From brace initiation to the latest follow-up, CRVA was found to be significantly higher in Group A versus Group B (P<0.05), while RVAD was higher in Group B versus Group A (P<0.05). Serial measurements revealed an increasing trend for RVAD (from 19±10° to 29±8°) yet a decreasing trend for CRVA (from 68±6° to 60±7°) in Group B, but both RVAD and CRVA were found to remain stable in Group A during the follow-up period. Association analyses showed that both RVAD ≥20° and CRVA ≤68° at brace initiation and at each follow-up were significantly associated with curve progression. The initial RVAD ≥20° and CRVA ≤68° serve as valid factors in predicting the risk of curve progression during bracing in early AIS. Constant watch on RVAD and CRVA can help to more accurately predict the effectiveness of bracing in these patients.

Serial Derotational Casting in Idiopathic and Non-Idiopathic Progressive Early-Onset Scoliosis

IntroductionSerial derotational casting has been used as a definitive treatment or as delaying strategy in progressive idiopathic (IS) and non-idiopathic (NIS) early-onset scoliosis (EOS). MethodsRetrospective chart and radiographic review of patients who underwent serial casting for progressive EOS between 2005 and 2012 at a single institution. ResultsA total of 74 consecutive patients entered serial cast treatment. Twenty-eight were currently being casted, 30 completed cast treatment and were converted to thoracolumbosacral orthosis (TLSO), 9 were treated surgically, 6 were lost to follow-up, and 1 had no further treatment. The researchers diagnosed IS in 41 patients; 33 had NIS. At presentation the IS group had an average Cobb angle (CA) of 49° and a rib vertebral angle difference (RVAD) of 37°. The NIS group had a CA of 51° (p = .69) and RVAD of 37° (p = .94). In patients currently being casted, 19 IS patients had a decreased CA, from 47° to 27°. The 9 NIS patients had a decreased CA, from 62° to 57° (p = .0002). Cobb angle improvement was significantly better in IS (p = .0005). In the TLSO group the 17 IS patients had a decreased average CA, from 46° to 18°, after serial casting and the 13 NIS patients decreased CA from 42° to 32°. Patients with IS had better improvement in CA than the NIS group (p < .001). At last follow-up, this was reduced to 11° in the IS group and maintained at 32° in the NIS. In the IS group, 5 of 41 patients were converted to growth constructs, and 4 of 26 in the NIS group. Casting initiated before age 2 years yielded better curve correction for IS (p < .01) compared with NIS. ConclusionsProgressive idiopathic scoliosis patients had better curve correction with casting than NIS patients. Casting in IS patients before age 24 months yielded better curve correction. Patients who required surgery had a higher age and Cobb angle at presentation than those who transitioned to a TLSO. The surgical group was observed for a similar duration of time and there was no significant statistical difference. Although RVAD is a predictor of progression in infantile IS, it did not show a predictive value in the response to casting of either the IS or NIS groups.

Predictors of spine deformity progression in adolescent idiopathic scoliosis: A systematic review with meta-analysis.

To evaluate published data on the predictors of progressive adolescent idiopathic scoliosis (AIS) in order to evaluate their efficacy and level of evidence. (1) study design: randomized controlled clinical trials, prospective cohort studies and case series, retrospective comparative and none comparative studies; (2) participants: adolescents with AIS aged from 10 to 20 years; and (3) treatment: observation, bracing, and other. Ovid MEDLINE, Embase, the Cochrane Library, PubMed and patent data bases. All years through August 2014 were included. Data were collected that showed an association between the studied characteristics and the progression of AIS or the severity of the spine deformity. Odds ratio (OR), sensitivity, specificity, positive and negative predictive values were also collected. A meta-analysis was performed to evaluate the pooled OR and predictive values, if more than 1 study presented a result. The GRADE approach was applied to evaluate the level of evidence. The review included 25 studies. All studies showed statistically significant or borderline association between severity or progression of AIS with the following characteristics: (1) An increase of the Cobb angle or axial rotation during brace treatment; (2) decrease of the rib-vertebral angle at the apical level of the convex side during brace treatment; (3) initial Cobb angle severity (> 25(o)); (4) osteopenia; (5) patient age < 13 years at diagnosis; (6) premenarche status; (7) skeletal immaturity; (8) thoracic deformity; (9) brain stem vestibular dysfunction; and (10) multiple indices combining radiographic, demographic, and physiologic characteristics. Single nucleotide polymorphisms of the following genes: (1) calmodulin 1; (2) estrogen receptor 1; (3) tryptophan hydroxylase 1; (3) insulin-like growth factor 1; (5) neurotrophin 3; (6) interleukin-17 receptor C; (7) melatonin receptor 1B, and (8) ScoliScore test. Other predictors included: (1) impairment of melatonin signaling in osteoblasts and peripheral blood mononuclear cells (PBMC); (2) G-protein signaling dysfunction in PBMC; and (3) the level of platelet calmodulin. However, predictive values of all these findings were limited, and the levels of evidence were low. The pooled result of brace treatment outcomes demonstrated that around 27% of patents with AIS experienced exacerbation of the spine deformity during or after brace treatment, and 15% required surgical correction. However, the level of evidence is also low due to the limitations of the included studies. This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.

Physical Significance of the Rib Vertebra Angle Difference and Its 3-Dimensional Counterpart in Early-Onset Scoliosis

Study DesignAnalysis of the rib vertebra angle difference (RVAD) on coronal plane radiographs and the 3-dimensional (3D) RVAD and Local RVAD in the vertebral reference frame from 3D reconstructions of the spine and rib cage of early-onset scoliosis patients (cross-sectional study). ObjectivesTo determine the relationship of RVAD with the geometry of the chest wall. Summary of Background DataAlthough scoliosis is a complex 3D deformity, RVAD is measured on coronal plane radiographs. No clear physical significance has been established for this measurement from a 3D perspective. MethodsWe measured RVAD on posteroanterior radiographs of 42 infantile scoliotic patients (Cobb > 20°) from T4 to T10 using Mehta's method. We computed RVAD 3D using the same landmarks from the 3D reconstruction generated from the calibrated biplanar radiographs. Local RVAD was measured in the local vertebral frontal plane, based on the axial rotation of each vertebra. We divided cases into Phase I and II, based on the rib head overlap with the apical vertebral body on coronal plane radiographs. ResultsApical Local RVAD correlated with Metha's RVAD (Phase I: r = 0.690; Phase II: r = 0.666), and RVAD 3D (Phase I: r = 0.908; Phase II: r = 0.862). Maximal values of RVAD and RVAD 3D were above the apex. Rib vertebra angle difference and Local RVAD were significantly different at the level of maximal RVAD (p < .001) but not at the apex (p = .800). The difference between Local RVAD and maximal RVAD correlated with vertebral axial rotation (Phase I: r = 0.691; Phase II: r = 0.659). ConclusionsRib vertebra angle difference not only indicates asymmetry of the ribs in relation to the spine, it is a compound of physical factors including vertebral axial rotation. The root of its prognostic value remains unclear. Rib vertebra angle difference 3D can serve as an alternative to determine true asymmetry in the costovertebral geometry.

Early-onset Scoliosis

In few areas does orthopedic care have a more profound impact than on early-onset scoliosis, a condition that can diminish a child’s life expectancy and quality of life if not treated promptly and appropriately. ClassifiCation In the United States, scoliosis diagnosed before the age of 4 years is categorized as infantile scoliosis. Idiopathic scoliosis diagnosed between ages 4 and 10 years is classified as juvenile idiopathic scoliosis. In the United Kingdom, scoliosis diagnosed before the age of 5 years is termed earlyonset scoliosis. Although such semantics may be important for research purposes, the clinician must simply bear in mind the gravity of treating scoliosis with an onset at a young age. Because scoliosis progression is related to growth and peak growth velocity, scoliosis in infants and preschool-aged children has the potential for rapid and severe progression. Early-onset scoliosis may be further subdivided based on a variety of parameters. As in other forms of scoliosis, the etiology is an important factor in determining treatment and prognosis. Mehta 1 reported less success in the treatment of infantile scoliosis in patients with underlying syndromes and neuromuscular conditions. Infantile scoliosis is also classified as resolving or progressive, and this distinction is critical. Curves in approximately 80% of infants with scoliosis will resolve without intervention. 2 This resolution usually begins as the children develop trunk musculature around the time they begin cruising. Mehta 2 reported radiographic findings that are associated with progressive infantile scoliosis. These parameters include documented progression of the Cobb angle on successive radiographs, a difference in the rib–vertebral angle at the apex of the deformity of more than 20°, rib phase 2, and a double

The Rib Vertebra Angle Difference and its Measurement in 3D for the evaluation of early onset scoliosis.

The Rib Vertebra Angle Difference (RVAD) as defined by Mehta (1972) is used to predict the progression of early onset scoliosis. No clear physical significance has been established for this measurement. The purpose of this study was to evaluate the RVAD along the thoracic spine and the equivalent measurement on 3D reconstructions of the spine and rib cage of early onset scoliosis patients in order to determine their relationship with the geometry of the chest wall and evolution along the spine. The RVAD was measured on PA radiographs of 42 infantile scoliotic patients (Cobb &gt;20°) from T4 to T10 according to the method described by Mehta. The RVAD 3D was computed using the same landmarks from the 3D reconstruction generated from the calibrated biplanar radiographs. Cases were divided into Phase I and Phase II using Mehta's classification based on the rib head overlap with the apical vertebral body on coronal plane radiographs. A linear relationship exists between the Metha (2D) and 3D RVAD for both Phase I (r = 0.87) and Phase II (r = 0.78) patients. For more severe deformities (RVAD 3D ≥ 35°), a relationship was found between RVAD 3D and the axial rotation of the thoracic vertebrae (r = 0.51) in Phase II patients. However, no significant relationship exists between axial rotation and RVAD 3D for Phase I patients as well as Mehta's RVAD. Maximal RVAD measurements were located 2 &amp;frac12; levels above the apical vertebra. Results indicated that RVAD 3D provides additional information to Mehta's RVAD on the torsional nature of the deformity. Considering the importance of clinical indices to assess the progression of early onset scoliosis, this study raises some questions on looking solely at the RVAD measured on radiographs at the apical vertebra of Phase I patients and suggests considering also levels above the apex of the scoliotic curve and 3D measurements. Further investigation is required to fully understand the 3D nature of the spine and rib cage deformities.

Reliability of Radiographic Measures for Infantile Idiopathic Scoliosis

Radiographic measures such as the rib vertebral angle difference (RVAD), Cobb angle, and space available for the lung (SAL) help to guide treatment and measure treatment effects in patients with infantile idiopathic scoliosis. This study aimed to evaluate the intraobserver and interobserver reliability of these radiographic measures. Forty-five spine radiographs of skeletally immature patients (age, two months to four years) with infantile idiopathic scoliosis were measured with use of Surgimap software. Three pediatric orthopaedic surgeons and a pediatric orthopaedic fellow identified the major curve apex, rib-vertebra phase, Cobb angle, and end vertebrae and calculated the RVAD and SAL values at two separate time points. Interobserver and intraobserver reliability of the RVAD, Cobb angle, and SAL values were assessed with use of intraclass correlation coefficients (ICCs). Fleiss kappa coefficients were calculated for categorical variables. The RVAD (ICC = 0.86 to 0.92) and Cobb angle (ICC = 0.99) measurements had high reliability. The SAL value had substantial interobserver reliability (ICC = 0.66) and moderate intraobserver reliability (ICC = 0.73). Despite the high agreement for the Cobb angle, the choice of the major curve vertebrae (kappa = 0.19 to 0.39) and apical vertebra varied (kappa = 0.57 to 0.62). Observers were more likely to choose the same apical vertebra in large curves (r = 0.483, p = 0.001). The agreement for the apical rib-vertebra phase was substantial (kappa = 0.67). Paired RVAD measurements fell within ≤ 10° of each other in 82% of cases, but the remaining 18% of the RVAD measurements showed >10° of variation. Measurements used to guide treatment of infantile idiopathic scoliosis curves were reliable despite standard radiographic measurement error and the difficulty in obtaining quality images in young patients. Clinicians are dependent on seemingly objective radiographic data. The reliability of the Cobb angle and RVAD measurements in infantile scoliosis was high but not devoid of variability that could skew the ability to accurately and reliably suggest the best course of treatment. The SAL value was a less reliable measure. Treatment recommendations for infantile idiopathic scoliosis should rely on the synthesis of objective and clinically subjective data, as variations in radiographic measurements can lead to inconsistencies in management and to inconsistent treatment outcomes.

Study of the rib cage deformity in children with 10°-20° of Cobb angle Late Onset Idiopathic Scoliosis, using Rib-Vertebra Angles Aetiologic implications

The aim of the study is to compare the rib-vertebra angles (RVAs) between children with 10 degrees - 20 degrees of Cobb angle late onset idiopathic scoliosis (LOIS) and non-scoliotic children. The RVAs of 47 children, with mean age 12.4 years, who presented LOIS with a Cobb angle 10 degrees - 20 degrees, were studied. The children were classified into three groups according to the site of the scoliotic curve: 17 children had thoracic (T), 14 children had thoracolumbar (TL) and 16 children had lumbar (L) curves. The RVAs of the scoliotic children were compared to the RVAs of 60 non-scoliotic children of a similar age group, who were studied in the past. The comparison of the right and left RVAs within each group showed that the children who had: T curves differ at the level T4, T5, T6, T7 and T8, TL curves differ at the level T3, and L curves differ at the level T7 and T12. The comparison of the ipsilateral RVA's between the scoliotic groups showed that between: T and TL curves there are no differences at any thoracic level, between T and L curves the RVAs differ at the T7 level on the right side, whereas there are no differences between the RVAs on the left side, between TL and L curves the RVAs differ at the level T5, T6, and T7 on the right and at the level T5 on the left side. Comparing the RVAs between the scoliotic and nonscoliotic children, it was apparent that the scoliotic children rib cage had lower RVAs (p<0.01) at almost all thoracic levels. It has been reported that RVAs is an expression of the resultant muscle forces, which act on each rib. It was also suggested that RVA asymmetries by weakening the spinal rotation-defending system are aetiological for idiopathic scoliosis, (Burwell et al 1992). This study shows that scoliotic children with small curves have underdeveloped thoracic cage compared to nonscoliotic counterparts. The differences are more apparent in the scoliotic children with thoracic curves. It is suggested that the differences of the RVAs between right and left side in this group are an expression of asymmetric muscle forces acting on the thoracic cage. It is concluded that asymmetric muscle forces participate in the pathogenesis of idiopathic scoliosis on the thoracic cage, which deforms early.

Analysis of Concave and Convex Rib-vertebral Angle, Angle Difference, and Angle Ratio in Patients With Lenke Type 1 Main Thoracic Adolescent Idiopathic Scoliosis Treated by Observation, Bracing or Posterior Fusion, and Instrumentation

Retrospective review. The aim of this study is to describe the radiologic changes in rib-vertebral angles (RVAs), rib-vertebral angle differences (RVADs), and rib-vertebral angle ratios (RVARas) in patients with Lenke type 1 main thoracic adolescent idiopathic scoliosis treated by observation, bracing, or posterior fusion and instrumentation, and to compare these with normal individuals. The RVA measurement has been shown to be a valid and reproducible method and its asymmetries are related to age, sex, and laterality patterns of the curvature. However, studies of RVA and RVAD in patients with adolescent idiopathic scoliosis are scarce and there are no data regarding the assessment of the ratio between concave and convex RVA. A retrospective chart and radiograph review was carried out for 66 consecutive adolescent female patients with Lenke type 1 main thoracic idiopathic scoliosis and 14 normal counterparts. Patients were divided into 5 groups: normal individuals (group 1); scoliotic patients with Cobb angle <30 degrees (group 2A); scoliotic patients with Cobb angle more than 30 degrees (group 2B), scoliotic patients treated by bracing (group 3), and scoliotic patients treated by posterior fusion and instrumentation (group 4). Overall values (mean ± SD) of the RVAs on the concave side were 90.5 ± 17 degrees in group 1, 90.3 ± 15.8 degrees in group 2A, 88.8 ± 15.4 degrees in group 2B, 87.5 ± 13.3 degrees in group 3, and 86.7 ± 17 degrees in group 4. On the convex side, values were 90.0 ± 17.3 degrees in group 1, 86.3 ± 13.7 degrees in group 2A, 80.7 ± 14.4 degrees in group 2B, 82.9 ± 13.2 degrees in group 3, and 81.7 ± 16.2 degrees in group 4. Overall values (mean ± SD) of the RVADs at all levels were 0.5 ± 0.7 degrees in group 1, 4 ± 4.8 degrees in group 2A, 8 ± 4 degrees in group 2B, 4.7 ± 5.6 degrees in group 3, and 5.1 ± 5.2 degrees in group 4. The RVARa values (mean ± SD) at all levels were 1.008 ± 0.012 degrees in group 1, 1.041 ± 0.061 degrees in group 2A, 1.102 ± 0.151 degrees in group 2B, 1.056 ± 0.078 degrees in group 3, and 1.061 ± 0.071 degrees in group 4. Convex RVA was smaller than concave RVA between T1 and T10 in all groups of patients. RVAD and RVARa values in the scoliotic segment were greater in patients with untreated scoliosis more than 40 degrees than in patients with an untreated deformity of <25 degrees or in patients, treated by bracing or surgery, with a residual curve of <25 degrees. These measurements are a useful tool in the armamentarium of the surgeon treating spinal deformities and could be used to better characterize the deformity and/or to evaluate effects of brace or surgical treatment.

Rib-Vertebral Angle Difference and Convex Rib-Vertebral Angle as Risk Factors in Predicting Curve Progression during Bracing in Young Children with Idiopathic Scoliosis

Rib-Vertebral Angle Difference and Convex Rib-Vertebral Angle as Risk Factors in Predicting Curve Progression during Bracing in Young Children with Idiopathic Scoliosis

Growing Rods for Scoliosis in Spinal Muscular Atrophy

Retrospective analysis of patients with spinal muscular atrophy (SMA) treated with growing rod (GR) instrumentation for scoliosis. To evaluate structural effectiveness, complications, and length of hospital stay associated with GRs for scoliosis in SMA and to compare values with those of infantile and juvenile idiopathic scoliosis (IIS/JIS). Most studies evaluate GR effectiveness in all patients. We specifically examined SMA and IIS/JIS. We searched a multicenter database and found 15 patients with SMA and scoliosis treated with GRs for 54 ± 33 months. Radiographic measurements, complications, and hospital stay durations were compared with those of 80 GR patients with IIS/JIS observed for 43 ± 31 months. Measures of rib collapse, including T6:T10 mean rib-vertebral angle and T6:T12 thoracic width, were compared. Student t test was used to compare SMA and IIS/JIS values (significance level, P = 0.05). Primary radiographic measurements in patients with SMA improved from preoperative to latest follow-up as follows: curve, 89° ± 19° to 55° ± 17°; pelvic obliquity, 31° ± 14° to 11° ± 10°; space-available-for-lung ratio, 0.86 ± 0.15 to 0.94 ± 0.21; and T1-S1 length grew 8.7 ± 3.2 cm. Rib collapse continued despite GR treatment in SMA but not in IIS/JIS. Hospital stays were longer for SMA than for IIS/JIS for lengthening procedures (P = 0.01) and trended to be longer for initial surgery (P = 0.08) and final fusion (P = 0.06). Patients with SMA and IIS/JIS experienced, respectively, 0.5 and 1.1 major complications per patient (P = 0.02). GRs improve trunk height and the space-available-for-lung ratio while controlling curve and pelvic obliquity in young patients with SMA with severe scoliosis, but they do not halt rib collapse. For patients with SMA, hospital stays were longer than those for patients with IIS/JIS, whereas the rate of major complications was lower.

The Effect of Differing Spinal Fusion Instrumentation on the Occurrence of Postoperative Crankshaft Phenomenon in Adolescent Idiopathic Scoliosis

Retrospective. To compare the occurrence of the crankshaft phenomenon in patients with adolescent idiopathic scoliosis (AIS) who underwent hybrid, consecutive pedicle screw or interval pedicle screw instrumentation for posterior spinal fusion. Scoliosis may progress after posterior spinal fusion in skeletally immature patients with AIS. The crankshaft phenomenon occurs when the anterior column continues to grow in the face of posterior fusion causing characteristic twisting of the fused segment. The optimal surgical method for preventing the occurrence of this complication has not been determined. Sixty seven patients with AIS who underwent posterior fusion over a 6-year period were divided into groups according to fixation method: hybrid instrumentation, interval pedicle screw placement, or consecutive pedicle screw placement. Preoperative, postoperative, and follow-up radiographic measures, including Cobb angle, apical vertebral rotation (AVR), apical vertebral transposition (AVT), rib vertebral angle difference (RVAD) and trunk shift (TS) were assessed. The occurrence of the crankshaft phenomenon was determined. The mean follow-up duration was 36 months. There were no between-the-group differences in demographics or preoperative or immediate postoperative measures. At the last follow-up, significant differences among the groups were apparent for Cobb angle, AVR, AVT, RVAD, and TS (all P<0.05). Cobb angle, AVR, AVT, RVAD, and TS significantly increased between the postsurgery and the last follow-up in the hybrid instrumentation group (all P<0.0167). Only TS increased significantly in the 2 other groups. There were 7 cases of crankshaft phenomenon occurrence in the hybrid instrumentation group (33%), but none in the other 2 groups. These findings suggest that in skeletally immature patients with AIS, hybrid instrumentation cannot effectively prevent occurrence of the crankshaft phenomenon, whereas interval and consecutive pedicle screw instrumentation may be more (and equally) efficacious in this regard.

Changes of concave and convex rib–vertebral angle, angle difference and angle ratio in patients with right thoracic adolescent idiopathic scoliosis

The aim of this study is to describe the radiological changes in rib-vertebral angles (RVAs), rib-vertebral angle differences (RVADs), and rib-vertebral angle ratios (RVARas) in patients with untreated right thoracic adolescent idiopathic scoliosis and to compare with the normal subjects. The concave and convex RVA from T1 to T12, the RVADs and the RVARas were measured on AP digital radiographs of 44 female patients with right convex idiopathic scoliosis and 14 normal females. Patients were divided into three groups: normal subjects (group 1), scoliotic patients with Cobb's angle equal or <30° (group 2) and scoliotic patients with Cobb's angle over 30° (group 3). Overall values (mean±SD) of the RVAs on the concave side were 90.5°±17° in group 1, 90.3°±15.8° in group 2 and 88.8°±15.4° in group 3. On the convex side, values were 90.0°±17.3° in group 1, 86.3°±13.7° in group 2 and 80.7°±14.4° in group 3. Overall values (mean±SD) of the RVADs at all levels were 0.5°±0.7° in group 1, 4.0°±4.8° in group 2 and 8.0°±4.0° in group 3. The RVARa values (mean±SD) at all levels was 1.008°±0.012° in group 1, 1.041°±0.061° in group 2 and 1.102°±0.151° in group 3. RVAD and RVARa values in the scoliotic segment were greater in patients with untreated scoliosis over 30° than in patients with an untreated deformity of <30° or normal subjects. A significant effect between groups was observed for the RVA, RVAD and RVARa variables. Measurement of RVA, RVAD and RVARa should not only be performed at and around the apex of a thoracic spinal deformity, but also extended to the whole thoracic spine.