Aims. Historically, patients undergoing surgery for adolescent idiopathic scoliosis (AIS) have been nursed postoperatively in a critical care (CC) setting because of the challenges posed by prone positioning, extensive exposures, prolonged operating times, significant blood loss, major intraoperative fluid shifts, cardiopulmonary complications, and difficulty in postoperative pain management. The primary aim of this paper was to determine whether a scoring system, which uses Cobb angle, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and number of levels to be fused, is a valid method of predicting the need for postoperative critical care in AIS patients who are to undergo scoliosis correction with posterior spinal fusion (PSF). Methods. We retrospectively reviewed all AIS patients who had undergone PSF between January 2018 and January 2020 in a specialist tertiary spinal referral centre. All patients were assessed preoperatively in an anaesthetic clinic. Postoperative care was defined as ward-based (WB) or critical care (CC), based on the preoperative FEV1, FVC, major curve Cobb angle, and the planned number of instrumented levels. Results. Overall, 105 patients were enrolled. Their mean age was 15.5 years (11 to 25) with a mean weight of 55 kg (35 to 103). The mean Cobb angle was 68° (38° to 122°). Of these, 38 patients were preoperatively scored to receive postoperative CC. However, only 19% of the cohort (20/105) actually needed CC-level support. Based on these figures, and an average paediatric intensive care unit stay of one day before stepdown to ward-based care, the potential cost-saving on the first postoperative night for this cohort was over £20,000. There was no statistically significant difference between the Total Pathway Score (TPS), the numerical representation of the four factors being assessed, and the actual level of care received (p = 0.052) or the American Society of Anesthesiologists grade (p = 0.187). Binary logistic regression analysis of the TPS variables showed that the preoperative Cobb angle was the only variable which significantly predicted the need for critical care. Conclusion. Most patients undergoing posterior fusion surgery for AIS do not need critical care. Of the readily available preoperative measures, the Cobb angle is the only predictor of the need for higher levels of care, and has a threshold value of 74.5°. Cite this article: Bone Joint J 2024;106-B(7):713–719

The scoliosis observed in chickens after pinealectomy resembles that seen in humans with an adolescent idiopathic scoliosis, suggesting that melatonin deficiency may be responsible. However, to date there have been no studies of pineal gland glucose metabolism in patients with adolescent idiopathic scoliosis that might support this hypothesis. We examined the excretion of urinary 6-sulfatoxyl-melatonin as well as the glucose metabolism of the pineal gland in 14 patients with an adolescent idiopathic scoliosis and compared them with those of 13 gender-matched healthy controls using F-18 fluorodeoxyglucose brain positron emission tomography. There was no significant difference in the level of urinary 6-sulfatoxyl-melatonin or pineal gland metabolism between the study and the control group. We conclude that permanent melatonin deficiency is not a causative factor in the aetiology of adolescent idiopathic scoliosis

Aims. To systematically evaluate whether bracing can effectively achieve curve regression in patients with adolescent idiopathic scoliosis (AIS), and to identify any predictors of curve regression after bracing. Methods. Two independent reviewers performed a comprehensive literature search in PubMed, Ovid, Web of Science, Scopus, and Cochrane Library to obtain all published information about the effectiveness of bracing in achieving curve regression in AIS patients. Search terms included “brace treatment” or “bracing,” “idiopathic scoliosis,” and “curve regression” or “curve reduction.” Inclusion criteria were studies recruiting patients with AIS undergoing brace treatment and one of the study outcomes must be curve regression or reduction, defined as > 5° reduction in coronal Cobb angle of a major curve upon bracing completion. Exclusion criteria were studies including non-AIS patients, studies not reporting p-value or confidence interval, animal studies, case reports, case series, and systematic reviews. The GRADE approach to assessing quality of evidence was used to evaluate each publication. Results. After abstract and full-text screening, 205 out of 216 articles were excluded. The 11 included studies all reported occurrence of curve regression among AIS patients who were braced. Regression rate ranged from 16.7% to 100%. We found evidence that bracing is effective in achieving curve regression among compliant AIS patients eligible for bracing, i.e. curves of 25° to 40°. A similar effect was also found in patients with major curve sizes ranging from 40° to 60° when combined with scoliosis-specific exercises. There was also evidence showing that a low apical vertebral body height ratio, in-brace correction, smaller pre-brace Cobb angle, and daily pattern of brace-wear compliance predict curve regression after bracing. Conclusion. Bracing provides a corrective effect on scoliotic curves of AIS patients to achieve curve regression, given there is high compliance rate and the incorporation of exercises. Cite this article: Bone Joint J 2024;106-B(3):286–292

Aims. To determine the value of scoliosis surgery, it is necessary to evaluate outcomes in domains that matter to patients. Since randomized trials on adolescent idiopathic scoliosis (AIS) are scarce, prospective cohort studies with comparable outcome measures are important. To enhance comparison, a core set of patient-related outcome measures is available. The aim of this study was to evaluate the outcomes of AIS fusion surgery at two-year follow-up using the core outcomes set. Methods. AIS patients were systematically enrolled in an institutional registry. In all, 144 AIS patients aged ≤ 25 years undergoing primary surgery (median age 15 years (interquartile range 14 to 17) were included. Patient-reported (condition-specific and health-related quality of life (QoL); functional status; back and leg pain intensity) and clinician-reported outcomes (complications, revision surgery) were recorded. Changes in patient-reported outcome measures (PROMs) were analyzed using Friedman’s analysis of variance. Clinical relevancy was determined using minimally important changes (Scoliosis Research Society (SRS)-22r), cut-off values for relevant effect on functioning (pain scores) and a patient-acceptable symptom state (PASS; Oswestry Disability Index). Results. At baseline, 65 out of 144 patients (45%) reported numerical rating scale (NRS) back pain scores > 5. All PROMs significantly improved at two-year follow-up. Mean improvements in SRS-22r function (+ 1.2 (SD 0.6)), pain (+ 0.6 (SD 0.8)), and self-image (+ 1.1 (SD 0.7)) domain scores, and the SRS-22r total score (+ 0.5 (SD 0.5)), were clinically relevant. At two-year follow-up, 14 out of 144 patients (10%) reported NRS back pain > 5. Surgical site infections did not occur. Only one patient (0.7%) underwent revision surgery. Conclusion. Relevant improvement in functioning, condition-specific and health-related QoL, self-image, and a relevant decrease in pain is shown at two-year follow-up after fusion surgery for AIS, with few adverse events. Contrary to the general perception that AIS is a largely asymptomatic condition, nearly half of patients report significant preoperative back pain, which reduced to 10% at two-year follow-up. Cite this article: Bone Joint J 2022;104-B(2):265–273

We studied 70 consecutive patients with adolescent idiopathic scoliosis who underwent corrective surgery. They were divided into two groups. In the study group of 38 patients one or more modern blood-conservation measures was used peri-operatively. The 32 patients in the control group did not have these measures. Both groups were similar in regard to age, body-weight, the number of levels fused and the type of surgery. Only two patients in the study group were transfused with homologous blood and these transfusions were ‘off-protocol’. Wastage of autologous pre-donated units was minimal (6 of 83 units). By contrast, all patients in the control group were transfused with homologous blood. In the study group there was a significant decrease (p = 0.005) in the estimated blood loss when all the blood-conservation methods were used. The use of blood-conservation measures, the lowering of the haemoglobin trigger for transfusion and the education of the entire team involved in the care of the patient can prevent the need for homologous blood transfusion in patients undergoing surgery for adolescent idiopathic scoliosis

Aims. The aim of this study was to assess the ability of morphological spinal parameters to predict the outcome of bracing in patients with adolescent idiopathic scoliosis (AIS) and to establish a novel supine correction index (SCI) for guiding bracing treatment. Methods. Patients with AIS to be treated by bracing were prospectively recruited between December 2016 and 2018, and were followed until brace removal. In all, 207 patients with a mean age at recruitment of 12.8 years (SD 1.2) were enrolled. Cobb angles, supine flexibility, and the rate of in-brace correction were measured and used to predict curve progression at the end of follow-up. The SCI was defined as the ratio between correction rate and flexibility. Receiver operating characteristic (ROC) curve analysis was carried out to assess the optimal thresholds for flexibility, correction rate, and SCI in predicting a higher risk of progression, defined by a change in Cobb angle of ≥ 5° or the need for surgery. Results. The baseline Cobb angles were similar (p = 0.374) in patients whose curves progressed (32.7° (SD 10.7)) and in those whose curves remained stable (31.4° (SD 6.1)). High supine flexibility (odds ratio (OR) 0.947 (95% CI 0.910 to 0.984); p = 0.006) and correction rate (OR 0.926 (95% CI 0.890 to 0.964); p < 0.001) predicted a lower incidence of progression after adjusting for Cobb angle, Risser sign, curve type, menarche status, distal radius and ulna grading, and brace compliance. ROC curve analysis identified a cut-off of 18.1% for flexibility (sensitivity 0.682, specificity 0.704) and a cut-off of 28.8% for correction rate (sensitivity 0.773, specificity 0.691) in predicting a lower risk of curve progression. A SCI of greater than 1.21 predicted a lower risk of progression (OR 0.4 (95% CI 0.251 to 0.955); sensitivity 0.583, specificity 0.591; p = 0.036). Conclusion. A higher supine flexibility (18.1%) and correction rate (28.8%), and a SCI of greater than 1.21 predicted a lower risk of progression. These novel parameters can be used as a guide to optimize the outcome of bracing. Cite this article: Bone Joint J 2022;104-B(4):495–503

Aims. To compare the rates of sagittal and coronal correction for all-pedicle screw instrumentation and hybrid instrumentation using sublaminar bands in the treatment of thoracic adolescent idiopathic scoliosis (AIS). Methods. We retrospectively reviewed the medical records of 124 patients who had undergone surgery in two centres for the correction of Lenke 1 or 2 AIS. Radiological evaluation was carried out preoperatively, in the early postoperative phase, and at two-year follow-up. Parameters measured included coronal Cobb angles and thoracic kyphosis. Postoperative alignment was compared after matching the cohorts by preoperative coronal Cobb angle, thoracic kyphosis, lumbar lordosis, and pelvic incidence. Results. A total of 179 patients were available for analysis. After matching, 124 patients remained (62 in each cohort). Restoration of thoracic kyphosis was significantly better in the sublaminar band group than in the pedicle screw group (from 23.7° to 27.5° to 34.0° versus 23.9° to 18.7° to 21.5°; all p < 0.001). When the preoperative thoracic kyphosis was less than 20°, sublaminar bands achieved a normal postoperative thoracic kyphosis, whereas pedicle screws did not. In the coronal plane, pedicle screws resulted in a significantly better correction than sublaminar bands at final follow-up (73.0% versus 59.7%; p < 0.001). Conclusion. This is the first study to compare sublaminar bands and pedicle screws for the correction of a thoracic AIS. We have shown that pedicle screws give a good coronal correction which is maintained at two-year follow-up. Conversely, sublaminar bands restore the thoracic kyphosis better while pedicle screws are associated with a flattening of the thoracic spine. In patients with preoperative hypokyphosis, sublaminar bands should be used to restore a proper sagittal profile. Cite this article: Bone Joint J 2020;102-B(3):376–382

Aims. The purpose of this study was to evaluate the incidence and analyze the trends of surgeon-reported complications following surgery for adolescent idiopathic scoliosis (AIS) over a 13-year period from the Scoliosis Research Society (SRS) Morbidity and Mortality database. Methods. All patients with AIS between ten and 18 years of age, entered into the SRS Morbidity and Mortality database between 2004 and 2016, were analyzed. All perioperative complications were evaluated for correlations with associated factors. Complication trends were analyzed by comparing the cohorts between 2004 to 2007 and 2013 to 2016. Results. Between 2004 and 2016, a total of 84,320 patients were entered into the database. There were 1,268 patients associated with complications, giving an overall complication rate of 1.5%. Death occurred in 12 patients (0.014%). The three most commonly reported complications were surgical site infection (SSI) (441 patients; 0.52%), new neurological deficit (293; 0.35%), and implant-related complications (172; 0.20%). There was a statistically significant but weak correlation between the occurrence of a SSI and the magnitude of the primary curve (r = 0.227; p < 0.001), and blood loss in surgery (r = 0.111; p = 0.038), while the occurrence of a new neurological deficit was correlated statistically significantly but weakly with age at surgery (r = 0.147; p = 0.004) and magnitude of the primary curve (r = 0.258; p < 0.001). The overall complication rate decreased from 4.95% during 2004 to 2007 to 0.98% during 2013 to 2016 (p = 0.023). Conclusion. An overall complication rate of 1.5% was found in our series after surgery for AIS, with a reduction of complication rates found in the second period of the analysis. Cite this article: Bone Joint J 2020;102-B(4):519–523

Aims. The aim of this retrospective study was to compare the correction achieved using a convex pedicle screw technique and a low implant density achieved using periapical concave-sided screws and a high implant density. We hypothesized that there would be no difference in outcome between the two techniques. Methods. We retrospectively analyzed a series of 51 patients with a thoracic adolescent idiopathic scoliosis. There were 26 patients in the convex pedicle screw group who had screws implanted periapically (Group 2) and a control group of 25 patients with bilateral pedicle screws (Group 1). The patients’ charts were reviewed and pre- and postoperative radiographs evaluated. Postoperative patient-reported outcome measures (PROMs) were recorded. Results. The number of implants (14.5 vs 17.1) and the implant density (1.5 vs 1.9) were significantly lower in Group 2 (p < 0.001). Operating time was 27 minutes shorter in Group 2 than in Group 1, with a mean of 217 minutes (SD 50.5; 120 to 346). The duration of surgery per instrumented vertebra was reduced by 19% in Group 2 (p = 0.011). No statistical difference was found in the postoperative Cobb angle, vertebral rotation, the relative correction achieved, or postoperative PROMs. Conclusion. Despite a lower implant density and achieving correction through a convex rod, surgical correction of the Cobb angle and vertebral body rotation was similar in both groups. Periapical pedicle screws and primary correction on the concave side do not seem to be mandatory in order to achieve good surgical results in idiopathic thoracic scoliosis. The operating time was shorter in the group with lower implant density. In conclusion, the technique provided good results and has the potential to reduce complications and costs. Cite this article: Bone Joint J 2021;103-B(3):536–541

Aims. The aim of this study was to evaluate whether, after correction of an adolescent idiopathic scoliosis (AIS), leaving out the subfascial drain gives results that are no worse than using a drain in terms of total blood loss, drop in haemoglobin level, and opioid consumption. Methods. Adolescents (aged between 10 and 21 years) with an idiopathic scoliosis (major curve ≥ 45°) were eligible for inclusion in this randomized controlled noninferiority trial (n = 125). A total of 90 adolescents who had undergone segmental pedicle screw instrumentation were randomized into no-drain or drain groups at the time of wound closure using the sealed envelope technique (1:1). The primary outcome was a drop in the haemoglobin level during first three postoperative days. Secondary outcomes were 48-hour postoperative oxycodone consumption and surgical complications. Results. All 90 patients were included in the primary outcome analysis (no drain = 43; drain = 47). The mean total postoperative blood loss (intraoperative and drain output) was significantly higher in the group with a subfascial drain than in the no-drain group (1,008 ml (SD 520) vs 631 ml (SD 518); p < 0.001). The drop in haemoglobin level did not differ between the study groups over the postoperative timepoints (p = 0.290). The 48-hour opioid consumption was significantly higher in the no-drain group (2.0 mg/kg (SD 0.9) vs 1.4 (SD 0.6); p = 0.005). Two patients in the no-drain and one patient in the drain group developed a surgical site infection. Conclusion. Leaving the subfascial drain out after pedicle screw instrumentation for AIS is not associated with higher postoperative haemoglobin levels. Patients treated without a subfascial drain needed 30% more opioids during the first 48 hours than those who had a drain. Cite this article: Bone Joint J 2022;104-B(9):1067–1072

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

Aims. The aim of the present study was to answer the question whether curve morphology and location have an influence on rigid conservative treatment in patients with adolescent idiopathic scoliosis (AIS). Methods. We retrospectively analyzed AIS in 127 patients with single and double curves who had been treated with a Chêneau brace and physiotherapeutic specific exercises (B-PSE). The inclusion criteria were the presence of structural major curves ≥ 20° and < 50° (Risser stage 0 to 2) at the time when B-PSE was initiated. The patients were divided into two groups according to the outcome of treatment: failure (curve progression to ≥ 45° or surgery) and success (curve progression < 45° and no surgery). The main curve type (MCT), curve magnitude, and length (overall, above and below the apex), apical rotation, initial curve correction, flexibility, and derotation by the brace were compared between the two groups. Results. In univariate analysis treatment failure depended significantly on: 1) MCT (p = 0.008); 2) the apical rotation of the major curve before (p = 0.007) and during brace treatment (p < 0.001); 3) the initial and in-brace Cobb angles of the major (p = 0.001 and p < 0.001, respectively) and minor curves (p = 0.015 and p = 0.002); 4) major curve flexibility (p = 0.005) and the in-brace curve correction rates (major p = 0.008, minor p = 0.034); and 5) the length of the major curve (LoC) above (p < 0.001) and below (p = 0.002) the apex. Furthermore, MCT (p = 0.043, p = 0.129, and p = 0.017 in MCT comparisons), LoC (upper length p = 0.003, lower length p = 0.005), and in-brace Cobb angles (major p = 0.002, minor p = 0.027) were significant in binary logistic regression analysis. Conclusion. Curve size, location, and morphology were found to influence the outcome of rigid conservative treatment of AIS. These findings may improve future brace design and patient selection for conservative treatment. Cite this article: Bone Joint J 2021;103-B(2):373–381

Aims. The aim of this study was to determine the influence of pelvic parameters on the tendency of patients with adolescent idiopathic scoliosis (AIS) to develop flatback deformity (thoracic hypokyphosis and lumbar hypolordosis) and its effect on quality-of-life outcomes. Patients and Methods. This was a radiological study of 265 patients recruited for Boston bracing between December 2008 and December 2013. Posteroanterior and lateral radiographs were obtained before, immediately after, and two-years after completion of bracing. Measurements of coronal and sagittal Cobb angles, coronal balance, sagittal vertical axis, and pelvic parameters were made. The refined 22-item Scoliosis Research Society (SRS-22r) questionnaire was recorded. Association between independent factors and outcomes of postbracing ≥ 6° kyphotic changes in the thoracic spine and ≥ 6° lordotic changes in the lumbar spine were tested using likelihood ratio chi-squared test and univariable logistic regression. Multivariable logistic regression models were then generated for both outcomes with odds ratios (ORs), and with SRS-22r scores. Results. Reduced T5-12 kyphosis (mean -4.3° (. sd. 8.2); p < 0.001), maximum thoracic kyphosis (mean -4.3° (. sd. 9.3); p < 0.001), and lumbar lordosis (mean -5.6° (. sd. 12.0); p < 0.001) were observed after bracing treatment. Increasing prebrace maximum kyphosis (OR 1.133) and lumbar lordosis (OR 0.92) was associated with postbracing hypokyphotic change. Prebrace sagittal vertical axis (OR 0.975), prebrace sacral slope (OR 1.127), prebrace pelvic tilt (OR 0.940), and change in maximum thoracic kyphosis (OR 0.878) were predictors for lumbar hypolordotic changes. There were no relationships between coronal deformity, thoracic kyphosis, or lumbar lordosis with SRS-22r scores. Conclusion. Brace treatment leads to flatback deformity with thoracic hypokyphosis and lumbar hypolordosis. Changes in the thoracic spine are associated with similar changes in the lumbar spine. Increased sacral slope, reduced pelvic tilt, and pelvic incidence are associated with reduced lordosis in the lumbar spine after bracing. Nevertheless, these sagittal parameter changes do not appear to be associated with worse quality of life. Cite this article: Bone Joint J 2019;101-B:1370–1378

Aims. Closed suction subfascial drainage is widely used after instrumented posterior spinal fusion in patients with a spinal deformity. The aim of this study was to determine the effect of this wound drainage on the outcomes in patients with adolescent idiopathic scoliosis (AIS). This was a further analysis of a randomized, multicentre clinical trial reporting on patients after posterior spinal fusion using segmental pedicle screw instrumentation. In this study the incidence of deep surgical site infection (SSI) and chronic postoperative pain at two years’ follow-up are reported. Methods. We conducted a randomized, multicentre clinical trial on adolescents undergoing posterior spinal fusion for AIS using segmental pedicle screw instrumentation. A total of 90 consecutive patients were randomized into a ‘drain’ or ‘no drain’ group at the time of wound closure, using the sealed envelope technique (1:1). The primary outcomes in the initial study were the change in the level of haemoglobin in the blood postoperatively and total blood loss. A secondary outcome was the opioid consumption immediately after surgery. The aim of this further study was to report the rate of deep SSI and persistent postoperative pain, at two years' follow-up. Results. As previously reported, the mean 48-hour opioid consumption was significantly higher in the no drain group (2.0 mg/kg (SD 0.8) vs 1.4 mg/kg (SD 0.7); p = 0.005). There were no delayed deep SSIs. At two years’ follow-up, the mean Scoliosis Research Society 24-item questionnaire (SRS-24) total score did not differ between the groups (4.11 (SD 0.47) vs 4.16 (SD 0.33); p = 0.910). The mean SRS-24 pain score was 4.28 (SD 0.48) in the no drain group compared with 4.33 (SD 0.66) in the drain group (p = 0.245). Seven patients (19%) in the no drain group and six in the drain group (14%) reported moderate to severe pain (numerical rating scale ≥ 4) at two years’ follow-up (p = 0.484). The general self-image domain score was significantly higher in the no drain group compared with the drain group (4.02 (SD 0.74) vs 4.59 (SD 0.54); p < 0.001). Conclusion. The main finding in this study was that more severe pain immediately after surgery did not result in a higher incidence of chronic pain in the no drain group compared with the drain group. Back pain and health-related quality of life at two years’ follow-up did not differ between the groups. The patient-reported self-image domain was significantly better in the no drain group compared with the drain group. Cite this article: Bone Joint J 2024;106-B(10):1176–1181

Aims. The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results. Methods. Consecutive AIS patients treated with an MIS technique at two tertiary centres from June 2013 to March 2016 were retrospectively included. Preoperative patient deformity characteristics, perioperative parameters, power of deformity correction, and complications were studied. A total of 93 patients were included. The outcome of the first 25 patients and the latter 68 were compared as part of our safety analysis to examine the effect of the learning curve. Results. In the first 25 cases, with a mean follow-up of 5.6 years (standard deviation (SD) 0.4), the mean preoperative major Cobb angle was 57.6° (SD 9.8°) and significantly corrected to mean 15.4° (SD 5.6°, 73% curve correction). The mean preoperative T5-T12 was 26.2 (SD 12.8) and significantly increased to mean 32.9 (SD 8.3). Both frontal and sagittal plane correction was conserved two years after surgery. The rate of perioperative complications was 12% and three further complications occurred (three deep delayed infection). In the latter cases, 68 patients were included with a mean follow-up time of three years (SD 0.6). The mean preoperative major Cobb angle was 58.4° (SD 9.2°) and significantly corrected to mean 20.4° (SD 7.3°).The mean preoperative T5-T12 kyphosis was 26.6° (SD 12.8°) and was significantly increased to mean 31.4° (SD 8.3°). Both frontal and sagittal correction was conserved two years after surgery. The perioperative (30 day) complication rate was 1.4%. Two (2.9%) additional complications occurred in two patients. Conclusion. MIS for AIS is associated with a significant correction of spine deformity in the frontal and sagittal planes, together with low estimated blood loss and short length of stay. The perioperative complication rate seems to be lower compared with the standard open technique based on the literature data. The longer-term safety of MIS for AIS needs to be documented with a larger cohort and compared with the standard posterior approach. Cite this article: Bone Joint J 2020;102-B(4):506–512

Low bone mass and osteopenia have been described in the axial and peripheral skeleton of patients with adolescent idiopathic scoliosis (AIS). Recently, many studies have shown that gene polymorphism is related to osteoporosis. However, no studies have linked the association between IL6 gene polymorphism and bone mass in AIS. This study examined the association between bone mass and IL6 gene polymorphism in 198 girls with AIS. The polymorphisms of IL6-597 G→A, IL6-572 G→C and IL6-174 G→A and the bone mineral density in the lumbar spine and femoral neck were analysed and compared with their levels in healthy controls. The mean bone mineral density at both sites in patients with AIS was decreased compared with controls (p = 0.0022 and p = 0.0013, respectively). Comparison of genotype frequencies between AIS and healthy controls revealed a statistically significant difference in IL6-572 G→C polymorphism (p = 0.0305). There was a significant association between the IL6-572 G→C polymorphism and bone mineral density in the lumbar spine, with the CC genotype significantly higher with the GC (p = 0.0124) or GG (p = 0.0066) genotypes. These results suggest that the IL6-572 G→C polymorphism is associated with bone mineral density in the lumbar spine in Korean girls with AIS

Aims. The aim of this study was to investigate whether including the stages of ulnar physeal closure in Sanders stage 7 aids in a more accurate assessment for brace weaning in patients with adolescent idiopathic scoliosis (AIS). Methods. This was a retrospective analysis of patients who were weaned from their brace and reviewed between June 2016 and December 2018. Patients who weaned from their brace at Risser stage ≥ 4, had static standing height and arm span for at least six months, and were ≥ two years post-menarche were included. Skeletal maturity at weaning was assessed using Sanders staging with stage 7 subclassified into 7a, in which all phalangeal physes are fused and only the distal radial physis is open, with narrowing of the medial physeal plate of the distal ulna, and 7b, in which fusion of > 50% of the medial growth plate of distal ulna exists, as well as the distal radius and ulna (DRU) classification, an established skeletal maturity index which assesses skeletal maturation using finer stages of the distal radial and ulnar physes, from open to complete fusion. The grade of maturity at the time of weaning and any progression of the curve were analyzed using Fisher’s exact test, with Cramer’s V, and Goodman and Kruskal’s tau. Results. We studied a total of 179 patients with AIS, of whom 149 (83.2%) were female. Their mean age was 14.8 years (SD 1.1) and the mean Cobb angle was 34.6° (SD 7.7°) at the time of weaning. The mean follow-up was 3.4 years (SD 1.8). At six months after weaning, the rates of progression of the curve for patients weaning at Sanders stage 7a and 7b were 11.4% and 0%, respectively for those with curves of < 40°. Similarly, the rates of progression of the curve for those being weaned at ulnar grade 7 and 8 using the DRU classification were 13.5% and 0%, respectively. The use of Sanders stages 6, 7a, 7b, and 8 for the assessment of maturity at the time of weaning were strongly and significantly associated (Cramer’s V 0.326; p = 0.016) with whether the curve progressed at six months after weaning. Weaning at Sanders stage 7 with subclassification allowed 10.6% reduction of error in predicting the progression of the curve. Conclusion. The use of Sanders stages 7a and 7b allows the accurate assessment of skeletal maturity for guiding brace weaning in patients with AIS. Weaning at Sanders stage 7b, or at ulnar grade 8 with the DRU classification, is more appropriate as the curve did not progress in any patient with a curve of < 40° immediately post-weaning. Thus, reaching full fusion in both distal radial and ulnar physes (as at Sanders stage 8) is not necessary and this allows weaning from a brace to be initiated about nine months earlier. Cite this article: Bone Joint J 2021;103-B(1):141–147

Aims. The aim of this study was to report a retrospective, consecutive series of patients with adolescent idiopathic scoliosis (AIS) who were treated with posterior minimally invasive surgery (MIS) with a mean follow-up of two years (. sd. 1.4; 0.9 to 0 3.7). Our objectives were to measure the correction of the deformity and record the peri-operative morbidity. Special attention was paid to the operating time (ORT), estimated blood loss (EBL), length of stay (LOS) and further complications. Patients and Methods. We prospectively collected the data of 70 consecutive patients with AIS treated with MIS using three incisions and a muscle-splitting approach by a single surgeon between June 2013 and February 2016 and these were retrospectively reviewed. There were eight male and 62 female patients with a mean age of 15 years (. sd. 4.5 ) with a mean body mass index of 19.8 kg/m. 2. (. sd. 5.4). The curves were classified according to Lenke; 40 curves were type 1, 15 were type 2, three were type 3, two were type 4, eight were type 5 and two were type 6. Results. The mean primary Cobb angle was corrected from 58.9° (. sd. 12.6°) pre-operatively to 17.7° (. sd.  10.2°) post-operatively with a mean correction of 69% (. sd. 20%, p < 0.001). The mean kyphosis at T5 to T12 increased from 24.2° (. sd. 12.2°) pre-operatively to 30.1° (. sd. 9.6°, p < 0.001) post-operatively. Peri-operative (30 days) complications occurred in three patients(4.2%): one subcutaneous haematoma, one deep venous thrombosis and one pulmonary complication. Five additional complications occurred in five patients (7.1%): one superficial wound infection, one suture granuloma and three delayed deep surgical site infections. The mean ORT was 337.1 mins (. sd. 121.3); the mean EBL was 345.7 ml (. sd. 175.1) and the mean LOS was 4.6 days (. sd. 0.8). Conclusion. The use of MIS for patients with AIS results in a significant correction of spinal deformity in both the frontal and sagittal planes, with a low EBL and a short LOS. The rate of peri-operative complications compares well with that following a routine open technique. The longer term safety and benefit of MIS in these patients needs to be evaluated with further follow-up of a larger cohort of patients. Cite this article: Bone Joint J 2017;99-B:1651–7

Aims. The aim of this study was to investigate the impact of maturity status at the time of surgery on final spinal height in patients with an adolescent idiopathic scoliosis (AIS) using the spine-pelvic index (SPI). The SPI is a self-control ratio that is independent of age and maturity status. Patients and Methods. The study recruited 152 female patients with a Lenke 1 AIS. The additional inclusion criteria were a thoracic Cobb angle between 45° and 70°, Risser 0 to 1 or 3 to 4 at the time of surgery, and follow-up until 18 years of age or Risser stage 5. The patients were stratified into four groups: Risser 0 to 1 and selective fusion surgery (Group 1), Risser 0 to 1 and non-selective fusion (Group 2), Risser 3 to 4 and selective fusion surgery (Group 3), and Risser 3 to 4 and non-selective fusion (Group 4). The height of spine at follow-up (HOS. f. ) and height of pelvis at follow-up (HOP. f. ) were measured and the predicted HOS (pHOS) was calculated as 2.22 (SPI) × HOP. f. One-way analysis of variance (ANOVA) was performed for statistical analysis. Results. Of the 152 patients, there were 32 patients in Group 1, 27 patients in Group 2, 48 patients in Group 3, and 45 patients in Group 4. Significantly greater HOS. f. was observed in Group 3 compared with Group 1 (p = 0.03) and in Group 4 compared with Group 2 (p = 0.02), with similar HOP. f. (p = 0.75 and p = 0.83, respectively), suggesting that patients who undergo surgery at Risser grade of 0 to 1 have a shorter spinal height at follow-up than those who have surgery at Risser 4 to 5. HOS. f. was similar to pHOS in both Group 1 and Group 2 (p = 0.62 and p = 0.45, respectively), indicating that undergoing surgery at Risser 0 to 1 does not necessarily affect final spinal height. Conclusion. This study shows that fusion surgery at Risser 0 may result in growth restriction unlike fusion surgery at Risser 3 to 4. Despite such growth restriction, AIS patients could reach their predicted or ‘normal’ spinal height after surgery regardless of baseline maturity status due to the longer baseline spinal length in AIS patients and the remaining growth potential at the non-fusion levels. Cite this article: Bone Joint J 2018;100-B:1372–6

Aims

This study aimed to evaluate rasterstereography of the spine as a diagnostic test for adolescent idiopathic soliosis (AIS), and to compare its results with those obtained using a scoliometer.