| Background:The etiology of Adolescent Idiopathic Scoliosis(AIS)is still unclear,and a three-dimensional spinal deformity characterizes it.Bracing is the most effective intervention in the conservative management of AIS,and the appropriate corrective force is critical to the treatment outcome.If too much stress is applied,side effects such as pressure sores can occur,affecting patient compliance and orthotic results.In recent years,pressure sores caused by bracing have become a significant concern.Although there have been clinical reports of pressure sores during brace treatment,the mechanisms of their occurrence and the corresponding influencing factors still need to be fully clarified.Objective:The main aim of our study was to investigate the incidence of pressure ulcers and related factors among patients with Rigo A-type AIS who wore the Cheneau-type brace.Furthermore,we developed a finite element model to simulate the three-point mechanical system of the brace applied to the patient’s trunk.The primary objective of this model was to calculate and analyze post-correction outcomes while identifying the most effective stress level or adjustment for ensuring the curative effect and reducing the risk of pressure ulcers.Methods:Using a prospective design for the first part,the study population was 79 patients with AIS who met the inclusion criteria and attended the Guangdong Sports Rehabilitation and Orthotic Devices Engineering Technology Development Centre between October 2020 and November 2022.All patients were treated with the Cheneau-type brace and observed for skin pressure ulcers.The Researchers immediately stopped patients who developed grade II pressure sores from wearing the brace and provided them with dressing changes and skin care.They followed up on patients who did not have or only had grade I pressure sores for six months before discontinuing observation.Collecting general information and full-length spine radiographs from all patients with AIS and calculating their body mass index(BMI),the rate of correction of the Cobb angle in the chest immediately after wearing the brace,and the rate of rebound of the Cobb angle in the chest within 24 hours of removal of the brace after the occurrence of a pressure sore or within 24 hours of removal of the brace after observation had ceased if no pressure sore occurred.Using Cox regression analysis to analyze the risk factors for grade II pressure ulcers was performed.Using finite element analysis methods is the second part.Performing a CT examination on the patient with Rigo A type AIS was followed by constructing a torso model using medical modeling software(Mimics 21.0,Geomagic Studio 2017,Solid Works 2018,Ansys 17.0)and loading gravity to verify the validity of the model.Simulating the corrective forces of the brace on the torso involved applying thrusts.Simulating the mean corrective force obtained from clinical monitoring was done separately for group A.The skin tolerance pressure threshold reported in the literature for group B coupled to the torso model of AIS patients.The thrust loads in groups A and B,which were different,were consistent in terms of region,area,and direction.In particular,the left axillary thrust area was 38.5 cm~2,and the direction was along the lateral abdomen to the medial dorsum;the left lumbar thrust area was 116 cm~2,and the direction was along the lateral dorsum to the medial abdomen;and the right thoracic thrust area was 143.9 cm~2,and the direction was along the lateral dorsum to the medial thorax.On this basis,the load cases were set in order of site for groups A and B,respectively:0.1Mpa,0.08Mpa,and 0.15Mpa for group A;0.035Mpa,0.035Mpa,and0.035Mpa for group B.Finally,the 3D imaging parameters of the spine and analyzing the forces applied to the skin.Results:Part I prospective results:Following 79 patients with Rigo A wearing the Cheneau-type brace,was carried out.The mean primary thoracic Cobb angle correction rate in these patients immediately after wearing the brace was 48.38±9.11%.During the six-month observation period,the incidence of grade I skin pressure ulcers was 36.70%,and grade II skin pressure ulcers were 16.45%,giving a total of 53.16%.Further,Cox regression analysis revealed that BMI and main thoracic Cobb angle rebound rate were the main risk factors;a 1 unit increase in BMI was associated with a 65%reduction in the risk of grade II pressure ulcers,during a 1 unit increase in the main thoracic Cobb angle rebound rate was associated with a 15%increase in the risk of grade II pressure ulcersThe second part of the finite element simulation analysis revealed that there were differences in the correction results between two sets of loading conditions,A and B.These sets of loading conditions involved the use of the Cheneau-type brace and the AIS torso model under gravity loading conditions.The results show that the corrective pressure improves the imaging parameters in both coronal and sagittal planes under both loading conditions.Under Group B loading conditions,the sagittal parameters(TK,LL)were within the physiological equilibrium,the disc gap changes and disc stress distribution in the parietal spine were more favorable than in Group A,and skin compression and displacement were less than in Group A.Suggesting that Group B is consistent with the expected outcome of clinical correction.Conclusions:The main thoracic Cobb angle rebound rate was a risk factor for developing pressure sores with the AIS brace treatment,while BMI was a protective factor.Further,using finite element modelling,founding that the Cheneau-type brace under Group B loading conditions could balance the 3D imaging parameters of the spine while improving the intervertebral space height and disc stress distribution in the parietal spine,keeping the pressure on the soft tissues of the skin within tolerable limits and reducing the likelihood of skin pressure sores and creating favourable conditions for the spine. |
PDF Full Text Request