Finite Element Comparison of the Spring Distraction System and the Traditional Growing Rod for the Treatment of Early Onset Scoliosis

Lemans, Justin V C; Kodigudla, Manoj; Kelkar, Amey; Jayaswal, Daksh; Castelein, René M.; Kruyt, Moyo C.; Goel, Vijay K.; Agarwal, Aakash

doi:10.1097/brs.0000000000004297

Cited by 2 publications

(4 citation statements)

References 38 publications

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“…Rod fracture is a common complication with high incidence rates, especially in growing rod implants used for EOS patients [ 4 – 9 ]. A recent proof-of-concept study developed a patient-specific FEA framework to identify and validate the high-stress regions of traditional growing rods against their fracture location obtained from clinical registry data [ 22 , 23 ].…”

Section: Discussionmentioning

confidence: 99%

“…Three patient-specific FEA models of the thoracolumbar spine (T1-S1) were developed to match the pre-operative (pre-op) scoliosis curve to corresponding patient registry (Growing Spine Study Group, San Diego, CA) and biplanar radiographs, as described previously [ 22 ]. In brief, a healthy pediatric spine FEA model was modified using a custom MATLAB script (MATLAB Inc., Natick, MA) to induce patient-specific biplanar deformity [ 8 , 9 , 22 ]. Input data for necessary parameters like Cobb angle, thoracic kyphosis, lumbar lordosis, and the spinal height (T1-S1) were measured using Surgimap software (Surgimap, Nemaris Inc., New York, NY) from the patient radiographs (Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…This was followed by application of bilateral longitudinal distraction, application of weight-specific follower load, and application of a 1 Nm flexion moment at the T1 vertebra to simulate worst-case bending motion [ 22 , 23 , 28 ]. The interactions between different interfaces of the FEA model are as listed in similar studies published previously [ 8 , 9 , 22 ]. The inferior endplate (base) of the S1 vertebra was fixed in all directions during all steps.…”

Section: Methodsmentioning

confidence: 99%

“…Barring the latter, a common complication across these techniques is rod fractures. Multiple studies have reported a high incidence (> 25%) of rod fractures endemic to the most used traditional and magnetic growing rod techniques [ 4 – 9 ]. Given the high usage and significant failure incidence of these rods in EOS, research focused on prospective identification of potential failure-prone regions in rods might facilitate improved implant design as well as surgical planning.…”

Section: Introductionmentioning

confidence: 99%

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Validation of a patient-specific finite element analysis framework for identification of growing rod-failure regions in early onset scoliosis patients

Jayaswal,

Kodigudla,

Kelkar

et al. 2024

Spine Deform

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Purpose Growing rods are the gold-standard for treatment of early onset scoliosis (EOS). However, these implanted rods experience frequent fractures, requiring additional surgery. A recent study by the U.S. Food and Drug Administration (FDA) identified four common rod fracture locations. Leveraging this data, Agarwal et al. were able to correlate these fractures to high-stress regions using a novel finite element analysis (FEA) framework for one patient. The current study aims to further validate this framework through FEA modeling extended to multiple patients. Methods Three patient-specific FEA models were developed to match the pre-operative patient data taken from both registry and biplanar radiographs. The surgical procedure was then simulated to match the post-operative deformity. Body weight and flexion bending (1 Nm) loads were then applied and the output stress data on the rods were analyzed. Results Radiographic data showed fracture locations at the mid-construct, adjacent to the distal and tandem connector across the patients. Stress analysis from the FEA showed these failure locations matched local high-stress regions for all fractures observed. These results qualitatively validate the efficacy of the FEA framework by showing a decent correlation between localized high-stress regions and the actual fracture sites in the patients. Conclusions This patient-specific, in-silico framework has huge potential to be used as a surgical tool to predict sites prone to fracture in growing rod implants. This prospective information would therefore be vital for surgical planning, besides helping optimize implant design for reducing rod failures.

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