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Paper #26: Maximal Force Generated by Magnetically Controlled Growing Rods Decreases with Rod Lengthening

Selina Poon, Hillard T Spencer, Ronen Sever

    Spine Deformity
    |January 31, 2020
    PubMed

    Insights

    Magnetically controlled growing rods (MCGR) may lose lengthening strength over time, potentially reducing spine growth with each adjustment. This study quanties the force decrease during MCGR lengthening.

    Area of Science:

    • Orthopedic surgery
    • Biomedical engineering
    • Spinal deformity correction

    Background:

    • Magnetically controlled growing rods (MCGR) offer an alternative to traditional growing rods, reducing the need for repeated surgical interventions in pediatric spinal deformities.
    • The lengthening mechanism's strength is crucial for effective spine elongation, but its behavior over increasing rod lengths is not fully understood.

    Purpose of the Study:

    • To evaluate the maximal force generated by magnetically controlled growing rods (MCGR) at various stages of lengthening.
    • To determine the relationship between MCGR length and the force produced by its lengthening mechanism.

    Main Methods:

    • Maximal generated force of MCGR was measured.
    • Measurements were taken at three distinct lengthened positions.
    • Force data was analyzed in relation to the additional length achieved.

    Main Results:

    • An average decrease in maximal force of 0.089 pounds per millimeter of additional length was observed.
    • The force generated by the MCGR diminishes as the rod is lengthened.

    Conclusions:

    • The decrease in lengthening force may lead to reduced spine length gained with each subsequent MCGR adjustment.
    • Further investigation is warranted to optimize MCGR lengthening protocols for maximum efficacy in pediatric patients.

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