Pedicle screw fixation is performed alone or in conjunction with spinal fusion to stabilize the spine. Pedicle screws provide stability by providing anchor points where metal rods are used to connect them. Pedicle screw fixation can be performed in a minimally invasive manner and is called percutaneous pedicle screw fixation.
What is percutaneous pedicle screw fixation?
Percutaneous pedicle fixation is a minimally invasive technique of inserting the pedicle screw. It does not require large traditional incisions as done in conventional open surgery, instead, screws and rods are inserted through multiple small incisions.
The muscle retraction in traditional open surgery is associated with significant morbidity leading to muscle denervation and atrophy, devascularization and increased bleeding, infections and postoperative pain in comparison with percutaneous pedicle screw fixation. Fusion and fixation are performed to relieve pain caused by painful abnormal motion in degenerative spinal conditions, to stabilize the spine in case of spinal fractures, to treat instability due to infection or tumour or to correct a spinal deformity.
Indication for percutaneous pedicle screw fixation
Degenerative spinal disorders
Failed back syndrome
In conjunction with interbody fusion for stabilisation
What are the symptoms?
Symptoms depend upon the underlying spinal condition and vary accordingly
Varying intensity of back pain
Standing or walking will usually make the pain worse
Difficulty or inability to walk affecting mobility
In more severe cases, the fracture may cause nerve symptoms including numbness, tingling, muscle spasms, weakness of lower limbs, bowel/bladder problems
How is it diagnosed?
X-ray of the spine is the first modality of imaging.
Computed tomography is required to assess the nature of fracture and MRI is performed to see the degree of neural injury and compression on nerves and spinal cord.
MRI is also helpful in evaluating soft tissue damage to the ligaments and discs.
Dual-energy x-ray absorptiometry (DEXA) - This test is the established standard for measuring bone mineral density and can determine if osteoporosis (brittle bones) exists.
What are the treatment options?
Pain management – Analgesic and NSAIDs.
Modified physical activity and rest.
Surgery is necessary when the spine appears unstable, needing stabilisation in the form of percutaneous screw fixation to support the spine until the fracture heals.
Percutaneous pedicle fixation is performed under general anaesthesia. First, tiny small incisions are made on the patient’s back under x-ray or navigation guidance. The pedicle is accessed through the pedicle cannula and guidewire is inserted through the cannula into the pedicle. The fascia and muscle must be dilated using dilators which allow for screw placement. The pedicle is prepared by placing the tap over the guidewire to accommodate the screw inside the vertebrae. The entire screw assembly is inserted over the guidewire and into the pedicle, after which guidewire is removed. All screws are inserted in this fashion, after inserting the required number of screws all screws are interconnected with a rod on either side. Rods are inserted into special slots at the screw heads and locked into place. The surgical instruments (screw extenders ) are then removed, and the incisions are closed with sutures.