Neurosurgery notes/Procedures/TL spine procedures/Growth rod

Growth rod

View Details
logo
Parent item
TL spine procedures
notion image

Modern Luque Trolley technique (MLT)

General Approach and Concept

  • The MLT retains the initial concept of self-guided growth (passive growth elongation) without fusion in the trolley segment.
  • It utilizes a minimal-invasive technique.
  • The system employs a four-rod construct.
  • The goal is to provide self-guided spinal growth, maintain curve correction, reduce implant failure, and avoid repeating surgeries.
  • It uses newly designed gliding implants, consisting of fixed distal and proximal anchors and the apical trolley gliding vehicles.
  • Contraindications
    • The MLT should not be performed if suitable apical pedicles are absent or if apical capture cannot be achieved, as this is a contraindication to the system.

Fixed Proximal and Distal Fixation

  • The MLT requires rigid proximal and distal fixation.
  • Fixed spinal anchors, ideally pedicle screws, are placed at the proximal and distal ends of the construct.
  • A subperiosteal dissection is performed only at these proximal and distal ends to place the fixed spinal anchors.
  • These fixed segments (two or three) must fuse.
  • Pedicle screws are used for fixation instead of the sublaminar wires used in the original Luque trolley, helping to reduce implant failure.

Apical Gliding Mechanism

  • The core of the system involves newly developed apical pedicle screw-based spinal anchors. These are referred to as apical gliding anchors or apical trolley gliding vehicles.
  • These gliding anchors allow for maximal apical translation.
  • The system uses two pairs of overlapping spinal rods. These rods are non-locking and self-growing.
  • The 5–6 mm titanium rods extend from the proximal to distal fixed anchors, overlapping specifically at the intercalary (apical) segments.
  • The gliding anchors maintain correction by keeping the rods parallel and engaged.
  • As the spine grows, the fixed proximal rods shift away from the distal ones, permitting passive growth elongation.

Surgical Exposure for Gliding Anchors

  • The procedure begins with a midline skin incision over the targeted spinous process.
  • For the intercalary gliding anchors (at the apex), a trans-muscular dissection is utilized to minimize spontaneous fusion.
  • This approach involves detaching the muscular fascia lateral to the spinous process, preserving the Multifidus and Spinalis over the lamina while mobilizing the Longissimus and Iliocostalis laterally, similar to the Wiltse approach.
  • The muscular layer is later closed over the gliding implants and rods.
  • Gliding pedicle anchors are inserted via this trans-muscular plane with minimal exposure of the transverse process to identify the starting point, ensuring the adjacent facet joint remains intact.

Curve Correction

  • Reduction maneuvers, including apical translation and rod derotation, are performed to achieve deformity correction.
  • The number and location of gliding anchors are optimized for apical control and minimized to avoid spontaneous fusion.