Introduction. Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional deformity of the spine with unclear etiology. Due to the asymmetry of lateral curves, there are differences in the muscle activation between the convex and concave sides. This study utilized a comprehensive thoracic spine and ribcage musculoskeletal model to improve the biomechanical understanding of the development of AIS deformity and approach an explanation of the condition. Methods. In this study, we implemented a motion capture model using a generic rigid-body thoracic spine and ribcage model, which is kinematically determinate and controlled by spine posture obtained, for instance, from radiographs. This model is publicly accessible via a GitHub repository. We simulated gait and standing models of two AIS (averaging 15 years old, both with left lumbar curve and right thoracic curve averaging 25 degrees) and one control subject. The marker set included extra markers on the sternum and the thoracic and lumbar spine. The study was approved by the regional Research Ethics Committee (Journal number: H17034237). Results. We investigated the difference between the muscle activation on the right and left sides including erector spinae (ES), psoas major (PS), and multifidus (MF). Results of the AIS simulations indicated that, on average throughout the gait cycle, the right ES, left PS and left MF had 46%, 44%, and 23% higher activities compared to the other side, respectively. In standing, the ratios were 28%, 40%, and 19%, respectively. However, for the control subject, the differences were under 7%, except ES throughout the gait, which was 17%. Conclusion. The musculoskeletal model revealed distinct differences in force patterns of the right and left sides of the spine, indicating an instability phenomenon, where larger curves lead to higher muscle activations for stabilization. Acknowledgement. The project is funded by the European Union's Horizon 2020 program through Marie Skłodowska-Curie grant No. [764644]

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.

Background

Surgical treatment of AIS includes several purposes such as arrest deformity progression through a solid fusion, obtain a permanent correction of the deformity and others.

Aims

Scoliosis is a lateral curvature of the spine with associated rotation, often causing distress due to appearance. For some curves, there is good evidence to support the use of a spinal brace, worn for 20 to 24 hours a day to minimize the curve, making it as straight as possible during growth, preventing progression. Compliance can be poor due to appearance and comfort. A night-time brace, worn for eight to 12 hours, can achieve higher levels of curve correction while patients are supine, and could be preferable for patients, but evidence of efficacy is limited. This is the protocol for a randomized controlled trial of ‘full-time bracing’ versus ‘night-time bracing’ in adolescent idiopathic scoliosis (AIS).

7% of adolescent idiopathic scoliosis (AIS) patients also present with a pars defect. To date, there are no available data on the results of fusion ending proximal to a spondylolysis in the setting of AIS. The aim of this study was to analyze the outcomes of posterior spinal fusion (PSF) in this patient cohort, to investigate if maintaining the lytic segment unfused represents a safe option.

Retrospective review of all patients who received PSF for AIS, presented with a spondylolysis or spondylolisthesis and had a min. 2-years follow-up. Demographic data, instrumented levels and preoperative radiographic data were collected. Mechanical complications, coronal or sagittal parameters, amount of slippage and pain levels were evaluated.

Data from 22 patients were available (age 14.4 ± 2.5 years), 18 Lenke 1–2 and four Lenke 3–6. Five patients (24%) had an isthmic spondylolisthesis, all Meyerding I. The mean preoperative Cobb angle of the instrumented curves was 58 ± 13°. For 18 patients the lowest instrumented vertebra (LIV) was the last touched vertebra (LTV); for two LIV was distal to the LTV; for two, LIV was one level proximal to the LTV. The number of segments between the LIV and the lytic vertebra ranged from 1 to 6. At the last follow-up, no complications were observed. The residual curve below the instrumentation measured 8.5 ± 6.4°, the lordosis below the instrumented levels was 51.4 ± 13°. The magnitude of the isthmic spondylolisthesis remained constant for all included patients. Three patients reported minimal occasional low back pain.

The LTV can be safely used as LIV when performing PSF for the management of AIS in patients with L5 spondylolysis

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine characterized by a Cobb angle of at least 10 degrees. The goal of surgery is to not only prevent progression but restore sagittal and coronal balance, protecting cardiopulmonary function and improving cosmesis.

We reviewed the impact of deformity correction surgery in terms of radiology and patient reported outcome(PROMs).

The senior authors prospectively maintained database from 2003 –2022 was retrospectively analysed in terms of pre- and post-operative patient reported outcome measures (SRS 22) as well as radiological parameters.

44 patients with AIS were identified with pre and post op PROMS. The average age at surgery was 15yrs with 84% female. 38% had a Lenke 1 curve and 3 patients had Lenke 6 curves. 73% had posterior surgery.

There was a total improvement in SRS 22 scores by 7.8%. Patients reported significant satisfaction with treatment 4.8/5 and improvement in self-image with a change of 0.4 (p<0.001). However, no difference in function, pain and mental health were recorded.

Overall, proximal thoracic (PT) curves improved from 24 degrees to 11 degrees (p<0.001), Main thoracic (MT) curve 55 degrees to 19 degrees and Thoracolumbar/Lumbar curves (TL/L) 45 degreesto 11 degrees. Pre-operative flexibility and post-operative correction were 0.40 and 0.41 respectively for PT curve. MT was 0.32 and 0.67. That for TL/L was 0.57 and 0.71 respectively.

Surgery yields significant main curve correction correlating with high patient reported satisfaction rate. Although total SRS 22 score yielded 7.8% improvement, sub-analysis of self-image showed the most significant improvement.

Adolescent idiopathic scoliosis is a three-dimensional deformity of the spine, affecting 1–3% of the population.

Most cases are treated conservatively. Curves exceeding 45° in the thoracic spine and 40° in the lumbar spine may require correction and fusion surgery, to limit the progression of the curve and prevent restrictive pulmonary insufficiency (curves above 70°). When fusion is required, it may be performed either by posterior or anterior approaches. Posterior is useful for thoracic (Lenke I) curves, notably to correct the thoracic hypokyphosis frequently observed in AIS. Anterior approaches by thoraco-lombotomies allow an effective correction of thoraco-lumbar and lumbar curves (Lenke V and VI), with fewer levels fused than with posterior approaches. However, the approach requires diaphragm splitting and one may be concerned about the long-term pulmonary consequences. The literature provides conflicting insight regarding the consequences of the approach in anterior scoliosis correction, the interpretation of the results being difficult knowing that the correction of the scoliosis itself may improve pulmonary function.

This is a retrospective observational study done at a Tertiary Institution. The HRQOL scores have been collected as a prospective cohort. Clinical and radiographic data was collected from patients charts and analysed by two senior surgeons

A cohort of 64 patients were operated in the given time period. 50 patients met the inclusion criteria. No major complications were reported. The Union rate was 100% and no post operative complications were noted. Pre and post SRS scores improved in all patients.

The Anterior approach for Lenke V AIS gives great surgical exposure and allows for excellent correction of Cobb angle with minimal risk to the patient.

The current study aims to compare the clinico radiological outcomes between Non-Fusion Anterior Scoliosis (NFASC) Correction and Posterior Spinal Fusion (PSF) for Lenke 5 curves at 2 years follow up.

Methods:38 consecutive Lenke 5 AIS patients treated by a single surgeon with NFASC (group A) or PSF (group B) were matched by age, Cobb's angle, and skeletal maturity. Intraoperative blood loss, operative time, LOS, coronal Cobbs, and SRS22 scores at 2 years were compared. Flexibility was assessed by modified Schober's test. Continuous variables were compared using student t-tests and categorical variables were compared using chi-square.

The cohort included 19 patients each in group A and B . Group A had M:F distribution of 1:18 while group B had 2:17. The mean age in group A and group B were 14.8±2.9 and 15.3±3.1 years respectively. The mean follow-up of patients in groups A and B were 24.5±1.8 months and 27.4±2.1 months respectively. Mean pre-op thoracolumbar/lumbar (TL/L) cobbs for group A and group B were 55°±7° and 57.5°±8° respectively. At two years follow up, the cobbs for group A and B were 18.2°±3.6° and 17.6°±3.5° respectively (p=0.09). The average operating time for groups A and B were 169±14.2 mins and 219±20.5 mins respectively (p<0.05). The average blood loss of groups A and B were 105.3±15.4 and 325.3±120.4 respectively (p<0.05). The average number of instrumented vertebra between groups A and B were 6.2 and 8.5 respectively (p<0.05). The average LOS for NFASC and PSF was 3.3±0.9 days and 4.3±1.1 days respectively (p<0.05). No statistically significant difference in SRS 22 score was noted between the two groups. No complications were recorded.

Our study shows no significant difference in PSF and NFASC in terms of Cobbs correction and SRS scores, but the NFASC group had significantly reduced blood loss, operative time, and fewer instrumented levels. NFASC is an effective alternative technique to fusion to correct and stabilize Lenke 5 AIS curves with preservation of spinal motion.

The current study aims to find the role of Enhance Recovery Pathway (ERP) as a multidisciplinary approach aimed to expedite rapid recovery, reduce LOS, and minimize morbidity associated with Non Fusion Anterior Scoliosis Correction (NFASC) surgery.

A retrospective analysis of 35 AIS patients who underwent NFASC with Lenke 1 and Lenke 5 curves with a minimum of 1 year of follow-up was done. Patient demographics, surgical details, postoperative analgesia, mobilization, length of stay (LOS), patient satisfaction survey score with respect to information and care, and 90 days complications were collected.

The cohort included 34 females and 1 male with a mean age of 15.2 years at the time of surgery. There were 16 Lenke 1 and 19 Lenke 5 in the study. Mean preoperative major thoracic and thoracolumbar/lumbar Cobb's angle were 52˚±7.6˚ and 51˚±4.5˚ respectively. Average blood loss and surgical time were 102 ±6.4 ml and 168 ± 10.2 mins respectively. Average time to commencing solid food was 6.5±1.5 hrs. Average time to mobilization following surgery was 15.5± 4.3 hrs. The average duration to the stopping of the epidural was 42.5±3.5 hrs. The average dose of opioid consumption intraoperatively was 600.5±100.5 mcg of fentanyl i.v. and 12.5±4.5 mg morphine i.v. Postoperatively opioids were administered via an epidural catheter at a dose of 2 mg of morphine every 24 hours up to 2 days and an infusion of 2mcg/hr of fentanyl along with 0.12-0.15% ropivacaine. The average duration to transition to oral analgesia was 55.5±8.5 hrs .20 patients had urinary catheter and the average time to removal of the catheter was 17.5±1.4 hrs. 25 patients had a chest tube and the average time to remove of chest tube was 25.5±3.2 hrs. The average length of hospital stay was 3.1±0.5 days. No patient had postoperative ileus or requirement of blood transfusion or any other complications. No correlation was found between LOS and initial cobb angle.

The application of ERP in AIS patients undergoing NFASC results in reduced LOS and indirectly the cost, reduced post-operative opioid use, and overall improve patient satisfaction score.

The purpose of this study is to evaluate risk factors for distal construct failure (DCF) in posterior spinal instrumented fusion (PSIF) in adolescent idiopathic scoliosis (AIS). We observed an increased rate of DCF when the pedicle screw in the lowest instrumented vertebra (LIV) was not parallel to the superior endplate of the LIV, however this has not been well studied in the literature. We hypothesise a more inferiorly angled LIV screw predisposes to failure and aim to find the critical angle that predisposes to failure.

A retrospective cohort study was performed on all patients who underwent PSIF for AIS at the Starship Hospital spine unit from 2010 to 2020. On a lateral radiograph, the angle between the superior endplate of the LIV was measured against its pedicle screw trajectory. Data on demographics, Cobb angle, Lenke classification, instrumentation density, rod protrusion from the most inferior screw, implants and reasons for revision were collected.

Of 256 patients, 10.9% (28) required at least one revision. The rate of DCF was 4.6% of all cases (12 of 260) and 25.7% of revisions were due to DCF. The mean trajectory angle of DCF patients compared to all others was 13.3° (95%CI 9.2° to 17.4°) vs 7.6° (7° to 8.2°), p=0.0002. The critical angle established is 11°, p=0.0076. Lenke 5 and C curves, lower preoperative Cobb angle, titanium only rod constructs and one surgeon had higher failure rates than their counterparts. 9.6% of rods protruding less than 3mm from its distal screw disengaged.

We conclude excessive inferior trajectory of the LIV screw increases the rate of DCF and a screw trajectory greater than 11° predisposes to failure. This is one factor that can be controlled by the surgeon intraoperatively and by avoiding malposition of the LIV screw, a quarter of revisions can potentially be eliminated.

Use of ultrasonic bone scalpel (UBS) is becoming popular in spinal surgery. This study presents the safety profile of UBS for posterior release in surgical correction of adolescent idiopathic scoliosis (AIS).

From 2016 to 2018, UBS (Misonix) was used by the senior author in a variety of spinal operations. Data for intraoperative complications when this devise was used for posterior correction of AIS were collected. Revision cases were excluded.

UBS was used for posterior release of AIS in 65 patients (58 female, seven male) with an average age of 15.6 years (range 11–23). Average length of posterior instrumentation was 12 levels (range 6–14). Instrumentation was exclusively from T2 to L4. To achieve adequate release for correction, UBS was used to perform a total of 644 modified in-situ chevron osteotomies (average ten, range six to 12) and 31 rib osteotomies. Overall, three complications (4.6 %) were directly related to the use of UBS: one haemopneumothorax, which was successfully treated with a chest drain; and two loss of motor-evoked potentials during monitoring, which led to the postponement of the final correction. These two patients did not have any neurological problems and their surgery was completed successfully within 1 week of the initial surgery. One late deep infection was reported. This was not thought to be directly related to the use of UBS.

Use of UBS in the posterior surgical treatment of AIS appears to be relatively safe with a low level of acceptable complications. However, appropriate training is required for the use of UBS.

To determine whether spinal facet osteoblasts at the curve apex display a different phenotype to osteoblasts from outside the curve in patients with adolescent idiopathic scoliosis (AIS). Intrinsic differences in the phenotype of spinal facet bone tissue and in spinal osteoblasts have been implicated in the pathogenesis of AIS. However, no study has compared the phenotype of facet osteoblasts at the curve apex with the facet osteoblasts from outside the curve in patients with AIS.

Facet bone tissue was collected from three sites, the concave and convex side at the curve apex and from outside the curve from three female patients with AIS (aged 13–16 years). Micro-CT analysis was used to determine the density and trabecular structure. Osteoblasts were then cultured from the sampled bone. Osteoblast phenotype was investigated by assessing cellular proliferation (MTS assay), cellular metabolism (alkaline phosphatase and Seahorse Analyser), bone nodule mineralisation (Alizarin red assay), and the mRNA expression of Wnt signalling genes (quantitative RT-PCR).

Convex bone showed greater bone mineral density and trabecular thickness than did concave bone. The convex side of the curve apex exhibited a significantly higher proliferative and metabolic phenotype and a greater capacity to form mineralised bone nodules than did concave osteoblasts. mRNA expression of SKP2 was significantly greater in both concave and convex osteoblasts than in non-curve osteoblasts. The expression of SFRP1 was significantly downregulated in convex osteoblasts compared with either concave or non-curve.

Intrinsic differences that affect osteoblast function are exhibited by spinal facet osteoblasts at the curve apex in patients with AIS.

The routine use of intraoperative vancomycin powder to prevent postoperative wound infections has not been borne out in the literature in the pediatric spine population. The goal of this study is to determine the impact of vancomycin powder on postoperative wound infection rates and determine its potential impact on microbiology.

A retrospective analysis of the Harms Study Group database of 1269 adolescent idiopathic scoliosis patients was performed. Patients that underwent a posterior fusion from 2004-2018 were analyzed. A comparative analysis of postoperative infection rates was done between patients that received vancomycin powder to those who did not. Statistical significance was determined using Chi-squared test. Additionally, the microbiology of infected patients was examined.

In total, 765 patients in the vancomycin group (VG) were compared to 504 patients in the non-vancomycin group (NVG). NVG had a significantly higher rate of deep wound infection (p<0.0001) and associated reoperation rate compared to VG (p<0.0001). Both groups were compared for age, gender, race, weight, surgical time, blood loss, number of levels instrumented, and preop curve magnitude. There were significant differences between the groups for race (p<0.0001); surgical time (p=0.0033), and blood loss (p=0.0021). In terms of microbiology, VG grew p.acnes (n=2), and serratia (n=1), whereas NVG grew p.acnes (n=1) and gram positive bacilli (n=1). The remaining cultures were negative.

The use of intraoperative vancomycin powder in adolescent idiopathic scoliosis appears to contribute significantly to deep wound infection prevention and reduction of associated reoperations. Based on this study's limited culture data, Vancomycin does not seem to alter the microbiology of deep wound infections.

To compare preoperative and postoperative Health Related Quality of Life (HRQoL) scores in operated Adolescent Idiopathic Scoliosis (AIS) patients with and without concomitant isthmic spondylolisthesis. A retrospective study of a prospective cohort of 464 individuals undergoing AIS surgery between 2008 and 2018 was performed. All patients undergoing surgery for AIS with a minimum 2-year follow-up were included. We excluded patients with prior or concomitant surgery for spondylolisthesis. HRQoL scores were measured using the SRS-22 questionnaire. Comparisons were performed between AIS patients with vs. without concomitant spondylolisthesis treated non-surgically. AIS surgery was performed for 36 patients (15.2 ±2.5 y.o) with concomitant isthmic spondylolisthesis, and 428 patients (15.5 ±2.4 y.o) without concomitant spondylolisthesis. The two groups were similar in terms of age, sex, preoperative and postoperative Cobb angles. Preoperative and postoperative HRQoL scores were similar between the two groups. HRQoL improved significantly for all domains in both groups, except for pain in patients with spondylolisthesis. There was no need for surgical treatment of the spondylolisthesis and no slip progression during the follow-up duration after AIS surgery. Patients undergoing surgical treatment of AIS with non-surgical management of a concomitant isthmic spondylolisthesis can expect improvement in HRQoL scores, similar to that observed in patients without concomitant spondylolisthesis

This study aimed to identify factors associated with increased rates of blood transfusion in patients with adolescent idiopathic scoliosis (AIS) treated with posterior spinal fusion (PSF).

A retrospective case-control study was performed for AIS patients treated at a large children's hospital between August 2018 and December 2020. All patients with a diagnosis of AIS were evaluated. Data on patient demographics, AIS, and transfusion parameters were collected. Univariate regression and multivariate logistic modeling were utilized to assess risk factors associated with requiring transfusion. Odds ratios (OR) and 95% confidence interval (CI) were calculated. Surgeries were done by three surgeons and thirty anesthesiologists. To quantify the influence of anesthesia practice preferences a categorical variable was defined as “higher-transfusion practice preference”, for the provider with the highest rate of transfusion.

A total of 157 AIS patients were included, of whom 56 were transfused RBC units (cases), and 101 did not receive any RBC transfusion (controls). On univariate analysis, the following variables were significantly correlated with receiving RBC transfusion: “higher-transfusion practice preference,” “administration of crystalloids,” “receiving fresh frozen plasma (FFP),” “receiving platelets,” “pre-operative hemoglobin,” “cell saver volume,” and “surgical time.” On multiple regression modeling, “pre-operative hemoglobin less than 120 g/L” (OR 14.05, 95% CI: 1.951 to 135.7) and “higher-transfusion practice preference” (OR 11.84, 95% CI: 2.505 to 63.65) were found to be meaningfully and significantly predictive of RBC transfusion.

In this cohort, we identified pre-operative hemoglobin of 120 g/L as a critical threshold for requiring transfusion. In addition, we identified significant contribution from anesthesia transfusion practice preferences. Our multivariate model indicated that these two factors are the major significant contributors to allogenic blood transfusion. Although further studies are required to better understand factors contributing to transfusion in AIS patients, we suggest standardized, peri-operative evidence-based strategies to potentially help reduce variations due to individual provider preferences.

Recently, there is ongoing evidence regarding rapid recovery after orthopaedic surgery, with advantages for the patient relative to post operative pain, complications and functional recovery. The aim of this study is to present our experience in rapid recovery for adolescent idiopathic scoliosis in the last 2 years.

Retrospective study of 36 patients with adolescent idiopathic scoliosis, (age range 11 to 18 years) treated with spinal thoraco-lumbar posterior fusion with rapid post-operative recovery, compared with a similar group, treated with traditional protocol.

We found a statistically significant difference in terms of length-of-stay, patient-controlled-analgesia and use of oppioid and post operative blood transfusions. There was no difference in post operative infection rate.

Our experience shows better functional recovery, satisfactory controlled analgesia and reduction in costs of hospitalization with the use of ERAS protocols.

There is a significant positive association between hours of brace wear and rate of success in the treatment of Adolescent Idiopathic Scoliosis (AIS). The abandon rate reported in the literature averages 18%. In a recent randomized trial conducted at our center; the abandon rate was 4%. We aim to document the abandon rate towards brace treatment during the COVID-19 pandemic and its impact on AIS progression. We reviewed a database of AIS patients recruited between March and September 2020. Inclusion criteria were patients with AIS under brace treatment according to SRS criteria. The patients were divided in 2 cohorts: those with a self-reported good adherence to treatment and those who voluntarily abandoned treatment during follow-up. Patients with irregular adherence were excluded. Data analysis included age, gender, Risser stage, type of brace, Cobb angles at first visit and last follow-up (mean 11 months) and % of progression. Unpaired student tests were used for comparison. 154 patients met inclusion criteria. 20 patients were excluded due to irregular adherence. 89 patients (age: 12.1 y.o. ±1.4) reported good adherence to treatment, while 45 patients (age: 12.6 y.o. ±1.5) abandoned treatment, an abandon rate of 29%. The cohort of compliant patients started treatment with a mean main thoracic (MT) curve of 26° and finished with 27°. The mean difference between measurements was +0.65°±7.5; mean progression rate was −4.6%. However, patients who abandoned treatment started with a mean MT curve of 28° and finished with 33°, with a mean increase of +5°±8 and a mean progression rate of −11%. The differences between the 2 cohorts were statistically significant (p=0.002). Five (5) patients from the abandon group were offered for surgery because of curve progression. The abandon rate of brace treatment in AIS significantly increased during the first wave of COVID-19 pandemic. Patients who voluntarily discontinued treatment had significant increases in curve progression and surgical indication rates

Background

Scoliosis is described as a lateral spinal curvature exceeding ten degrees on radiograph with vertebral rotation. Approximately 80% of scoliosis presentations are adolescent idiopathic scoliosis (AIS). Current management for AIS in the UK occurs in Surgeon or Paediatrician-led clinics and can be conservative or surgical. The musculoskeletal assessment and triage of AIS appears well-suited to an advanced physiotherapist practitioner (APP) skill set. The aim of this service evaluation was to scope, develop, implement and evaluate a four-month pilot of an APP-led AIS triage pathway.

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.

There is a need for non-radiographic, objective outcome measures for children with Adolescent Idiopathic Scoliosis (AIS). Standing balance and stability is altered in children with AIS. The Margin of Stability (MoS) has been used to compare gait stability in clinical populations. Our objective was to compare the MoS in anterior-posterior (MoS. AP. ) and mediolateral (MoS. ML. ) directions in girls with AIS to Controls. Girls with AIS and healthy girls walked at three speeds on an instrumented treadmill wearing retroreflective markers, surrounded by motion capture cameras. The MoS. AP/ML. was calculated at left and right heel strike. Data was processed in Visual 3D. A two-way ANOVA was used to compare MoS. AP/ML. between group, speed and the interaction between group and speed. Pearson's correlation coefficient was used to compare the MoS to Cobb angle. Statistical significance was accepted when p > 0.05. A priori power analysis suggested 12 participants per group. Three Cases and four Controls were recruited. Girls with AIS all had right-sided main thoracic curves (Lenke type 1a, 61.3° ± 10.0°). MoS. AP. was significantly bigger for Cases compared to Controls on the left (p=0.038) and right foot (p=0.041). There was no significant difference between Cases and Controls for MoS. ML. , but there was a visual trend for a smaller MoS. ML. in Cases. There was no significant difference for speed or the interaction between group and speed for MoS. AP. or MoS. ML. In Cases, MoS. AP. increased with increasing Cobb angle on the left (r. 2. =0.687, p=0.054) and right (r. 2. =0.634, p=0.067) and MoS. ML. decreased with increasing Cobb angle on the left (r. 2. =-0.912, p=0.002). Further subjects are being recruited. Girls with Lenke type 1a AIS are more stable in the AP direction and less stable in the ML direction than Controls during treadmill walking. AP stability increases and ML stability decreases with increasing Cobb angle. This research suggests that the MoS could be used as an outcome measure for children with AIS. Continued work is required to increase the power of this study. Further work could consider these changes during walking overground, measuring an MoS or MoS-like measure using a wearable device, and in different curve types