Minimally Invasive Spine Surgery: Percutaneous Pedicle Screw Fixation
by: Sharad Rajpal, MD
Of the spectrum of metallic instrumentation techniques developed in spine surgery, pedicle screw fixation has gained the most popularity. As the technique and technologies for placement of percutaneous pedicle screws have progressed, so have the indications for their placement. Most surgeons will use percutaneous pedicle screw fixation as an adjunct to an anterior or posterior minimally invasive procedure.
However, one indication used in our practice is for patients who suffer from spinal fractures that, unfortunately, either cannot tolerate external bracing or do not want to lose the extra motion segments in their spine by undergoing a permanent spinal fusion procedure. The placement of percutaneous pedicle screws effectively acts like an “internal bracing” system which, after the fracture heals, can be removed without any long-term consequences.
A 21 year old woman presents to the emergency room following a motor vehicle accident. She has severe back pain but is neurologically intact on examination. A work-up reveals an L1 stable burst fracture (Figure 1). The patient is placed in a rigid brace but cannot tolerate wearing the brace because it exacerbates her fibromyalgia thus resulting in intolerable amounts of back pain. Given her young age, the option to “internally” brace the patient with internal fixation is chosen with the plan for scheduled hardware removal once the fracture has healed. The idea of fusing a minimum of two to three levels of her spine is a less ideal choice. Surgery is completed the following day with minimal blood loss and she is discharged home one day later without a brace (Figure 2). Approximately 12 months after placement of the internal hardware, it is removed as scheduled (Figure 3 left). The patient remains with motion above and below the fracture level with no consequences to the procedure except for the small stab incisions on her skin (Figure 3 right).
Figure 2. Upright standing AP/lateral x-rays show hardware fixation of the L1 fracture with percutaneous pedicle screws placed in T12, L1 and L2.
Figure 3. Upright standing lateral x-ray demonstrates the L1 fracture with improved alignment following the removal of the hardware (left) and stab incisions (right) from the placement of the screws compared to a dime (<18 mm in diameter).