Patient-specific Distraction Regimen to Avoid Growth-rod Failure

Area of Science:

• Biomechanical Engineering
• Spinal Surgery
• Pediatric Orthopedics

Background:

• Juvenile idiopathic scoliosis (JIS) treatment often involves growth rods, which can fracture.
• Previous research suggests frequent, smaller distractions reduce rod failure risk.
• A clinical method to determine optimal distraction intervals based on individual patient factors is lacking.

Purpose of the Study:

• To establish the relationship between JIS curve flexibility and the required distraction frequency to prevent growth rod fracture.
• To develop a methodology for determining patient-specific distraction intervals.
• To enhance the safety and efficacy of growth rod treatment in JIS.

Main Methods:

• Finite element analysis of a scoliotic spine model.
• Parametric study varying disc material properties to alter spinal stiffness.
• Calculation of stresses on growth rods under different distraction frequencies and spinal stiffness.

Main Results:

• A relationship was established between curve flexibility (Cobb's angle correction under gravity) and required distraction interval for growth rods.
• Increased spinal stiffness correlated with increased stress on the rods and a higher required optimal distraction frequency.
• Optimal distraction interval is time-dependent, decreasing as the spine stiffens due to autofusion.

Conclusions:

• Finite element modeling can inform clinical practice for mitigating growth rod fracture.
• A relationship between optimal distraction interval and curve flexibility can be established.
• This approach allows for patient-specific treatment adjustments to improve outcomes in JIS.