The biomechanical performance of the night-time Providence brace: experimental and finite element investigations

Effect of Postoperative Neck-Shaft and Anteversion Angles on Biomechanical Outcomes in Proximal Femoral Osteotomy: An In Silico Study

Effective surgical planning is crucial for maximizing patient outcomes following complex orthopedic procedures such as proximal femoral osteotomy. In silico simulations can be used to assess how surgical variations in proximal femur geometry, such as femur neck-shaft and anteversion angles, affect postoperative system mechanics. This study investigated the sensitivity of femur mechanics to postoperative neck-shaft angles, anteversion angles, and osteotomy contact areas using patient-specific finite element analysis informed by neuromusculoskeletal models. A sequential neuromusculoskeletal modeling and finite element analysis pipeline was used to simulate postoperative mechanics in three pediatric patients with varying demographic and anatomic features. Nine surgical configurations derived from permutations of the clinical envelope of neck-shaft angles and anteversion angles were simulated for the stance phase of gait. The outcome mechanics assessed were peak von Mises stresses on the bone-implant contact surfaces as well as interfragmentary movement and strain on the osteotomy location. Peak von Mises stress and interfragmentary movement and strain were on average 38% more sensitive to surgical variation in neck-shaft angle compared to anteversion angle. A significant negative correlation was detected between contact area and interfragmentary movement (r = -0.90, p < 0.0001) and strain (r = -0.45, p = 0.017). Overall findings suggest neck-shaft angle significantly influences postoperative femur mechanics and highlight the importance of maximizing contact area to limit interfragmentary motion and foster an optimal mechanical environment for bone healing and callus formation following proximal femoral osteotomy. Between-patient variation in sensitivity to proximal femoral geometry reinforced the importance of patient-specific surgical planning.

Enhancing Orthotic Treatment for Scoliosis: Development of Body Pressure Mapping Knitwear with Integrated FBG Sensors

Bracing is a widely used conservative treatment for adolescent idiopathic scoliosis (AIS) patients, yet there is no consensus on the optimal amount of force applied. Although a number of different sensors have been developed to continuously monitor the applied pressure and force, they have several limitations, including inadequate overall force distribution and displacement. They also cause discomfort with limited wearability. In this study, body pressure mapping knitwear (BPMK) integrated with fourteen silicone-embedded fiber Bragg grating (FBG) sensors is developed to monitor immediate and overall changes in force during the bracing treatment. A wear trial of the BPMK is conducted by using a validated soft AIS mannequin, and prediction equations have been formulated for the FBG sensors at individual locations. The findings indicate that the measured forces are in good agreement with those obtained from clinical studies, with peak forces around the padding regions reaching approximately 2N. This was further validated by using finite element (FE) models. When comparing X-ray images, the estimated differences in Cobb angles were found to be 0.6° for the thoracic region and 2.1° for the lumbar region. This model is expected to provide valuable insights into optimal force application, thus minimizing the risk of injury and enhancing bracing compliance and efficacy. Ultimately, this innovative approach provides clinicians with data-driven insights for safer and more effective bracing applications, thus improving the quality of life of AIS patients.

Optimized braces for the treatment of adolescent idiopathic scoliosis: A study protocol of a prospective randomised controlled trial

INTRODUCTION

Adolescent Idiopathic Scoliosis (AIS) is a 3D deformity of the spine that affects 3% of the adolescent population. Conservative treatments like bracing aim to halt the progression of the curve to the surgical threshold. Computer-aided design and manufacturing (CAD/CAM) methods for brace design and manufacturing are becoming increasingly used. Linked to CAD/CAM and 3D radiographic reconstruction techniques, we developed a finite element model (FEM) enabling to simulate the brace effectiveness before its fabrication, as well as a semi-automatic design processes. The objective of this randomized controlled trial is to compare and validate such FEM semi-automatic algorithm used to design nighttime Providence-type braces.

METHODS AND ANALYSIS

Fifty-eight patients with AIS aged between 10 to 16-years and skeletally immature will be recruited. At the delivery stage, all patients will receive both a Providence-type brace optimized by the semi-automatic algorithm leveraging a patient-specific FEM (Test) and a conventional Providence-type brace (Control), both designed using CAD/CAM methods. Biplanar radiographs will be taken for each patient with both braces in a randomized crossover approach to evaluate immediate correction. Patients will then be randomized to keep either the Test or Control brace as prescribed with a renewal if necessary, and will be followed over two years. The primary outcome will be the change in Cobb angle of the main curve after two years. Secondary outcomes will be brace failure rate, quality of life (QoL) and immediate in-brace correction. This is a single-centre study, double-blinded (participant and outcome assessor) randomized controlled trial (RCT).

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT05001568.