PEDICLE SUBTRACTION OSTEOTOMY

In order to straighten the spine, in some cases, it is necessary to surgically remove a portion of the vertebra body and other posterior parts as well.

Scoliosis Quiz

3 percent of individuals with progressive curvature may eventually experience severe problems that can include scoliosis and back pain, spinal problems, and nerve compression causing numbness, weakness, and leg pain.

Pedicle Subtraction Osteotomy

Pedicle Subtraction Osteotomy (PSO) is a surgical procedure that removes a wedge-shaped portion of the vertebra to repair kyphotic abnormalities. It appears as a more drastic treatment and entails the removal of a wedge-shaped portion of the vertebral body. In addition, it also removes all of the posterior parts (spinous process, lamina, facet joints, and pedicles). This procedure gets used to repair spinal deformities and, particularly, sagittal malalignment with severe kyphosis. The surgeon performs this difficult procedure using a posterior route. Then the surgeon will dislocate the spine in the procedure and add posterior segmental stability and instrumentation.

Who should get a Pedicle Subtraction Osteotomy?

Patients with severe kyphotic deformities have received PSO treatment and tolerated them well. The procedure works well for patients with kyphosis that need a significant correction. Especially, if the deformity appears in the lumbar spine or if a previous fusion limits the use of less drastic osteotomy methods. The treated level might receive a significant adjustment of 30–40 degrees thanks to PSO. To correct spinal abnormalities, surgeons utilize a procedure called a pedicle subtraction osteotomy (PSO).

Osteotomy literally translates to “to remove bone,” as the term says. In this procedure, one or more bone structures will get removed (or added to) by your doctor during a PSO. PSOs are level 2 deformity repair procedures in the context of spinal osteotomies. A posterior column osteotomy treats less problematic cases. A vertebral column resection treats more severe cases.

Although the Thought of Removing Bone Seems Severe, Here’s Why it Works:

Your back isn’t perfectly straight. Instead, your upper back bends slightly forward, and your lower back has a small sway (called lordosis) (known as kyphosis). These curves are a perfect mirror image of each other. However, they work as a unit to maintain the alignment of your head and pelvis. The flat back condition might result from losing our natural curve. Kyphosis, or a permanent slump, can develop if we gain too much curvature. Despite being diametrically opposed, these issues are referred to as sagittal imbalance. Simply put, this describes how we lean either forward (chin on chest syndrome) or backward. The PSO corrects this by making a hinge on the spine’s rear side… and then shutting it. Closing the gap results in the lumbar spine’s lower back gaining lordosis and the thoracic spine’s upper back losing kyphosis.

The Procedure for Pedicle Subtraction Osteotomy?

Ankylosing spondylitis sufferers were the target audience for the first description of PSO. The benefit includes the treatment of kyphosis without extending the anterior column (and potentially stretching and injuring vascular structures). Additionally, it eliminates the morbidity linked to the anterior approach. The spine is addressed from the back, and pedicle instrumentation is applied across the areas required for deformity stabilization and repair. Remove the spinous process, lamina, and facet joints to expose the designated vertebrae. The indicated vertebra gets exposed and the spinous process, lamina, and facet joints are removed.

The upper and lower levels of lamina 1 are also removed to prevent twisting of the neural structures after modification. Next, resect the pedicle at the affected level to the base of the posterior vertebra, preserving the existing nerve root. The surgeon places a temporary rod for stabilization before excising the anterior column. Subperiosteal dissection of the vertebral body is performed and a retractor is placed. The amount of bone required for the planned correction gets removed with the appropriate instrument.

The surgeon uses a temporary rod to stabilize the spine during deformity correction, and the surgeon examines the dura mater to ensure that neurological compression does not exist. Neuromonitoring continues to ensure that no new neurological changes have occurred.  The surgeon completes the procedure by inserting final instrumentation and completing the bone graft fusion. 

When does Pedicle Subtraction Osteotomy Occur?

A normal spine contains a few moderate curves that, when seen from the side, balance one another and place the body’s center of gravity over the pelvis. Sagittal balance describes this alignment. The causes of Sagittal imbalance can point to conditions that move the body’s center of gravity too far in front of the pelvis and include hyperkyphosis, ankylosing spondylitis, and flatback syndrome. Pedicle subtraction osteotomy addresses sagittal imbalance. Viewed from behind, a normal spine is straight. Scoliosis is a side-to-side curve that is apparent from behind. Occasionally, a pedicle subtraction osteotomy might treat a little degree of scoliosis. There are degrees of spinal curvature that provide doctors with the severity of the curve. For instance, scoliosis, a side-to-side curve, has a curve of at least 10 degrees. Average spine kyphosis ranges from 20 to 40 degrees; a kyphosis of 70 degrees or more may require surgery.

PSO provides approximately 30 degrees of compensation. It works well for acute kyphosis, some cases of the flat back syndrome, and some cases of ankylosing spondylitis. Most frequently, the lumbar region is affected (lower spine). Compared to other deformity correction surgeries, PSO removes a moderate amount of bone and allows for moderate realignment. It eliminates the pedicles that connect the back of the target vertebra to its front, the laminae, the facet joints at the back of the target vertebra, and the vertebrae above and below, as well as a section of the target vertebral body.

Pedicle Subtraction Procedure Performed?

A pedicle removal osteotomy occurs when the patient goes under general anesthesia. Spinal cord monitoring techniques such as SSEP (Somatosensory Evoked Potentials) and MEPs (Motor Evoked Potentials) measure nerve electrical activity and help ensure spinal safety during surgery. Once the patient becomes unconscious, they are carefully placed face down on a special folding operating table. Following a central back incision, the bones of the spinal column are visible. Following that, the surgeon inserts screws into the vertebrae above and below the targeted region.

Screws are placed in the pedicles, the thick columns of bone that join the back and front of the vertebra, giving them the name “pedicle screws.” The rods that will keep the spine in place while it heals will have attachment locations thanks to the pedicle screws above and below the target vertebra later in the procedure. Next, the surgeon removes a protrusion called an appendage from behind the target vertebra. The surgeon hollows out the space under the pedicle of the target vertebra and removes the pedicle. The surgeon then widens the space and creates a wedge-shaped cavity in the vertebrae.

Once completed, the wedge-shaped top and bottom are placed together. This closes the wedge and corrects the deformity by about 30 degrees. The surgeon gradually unfolds the specialized operating table from an inverted “V” shape to a flatter position until the bone surfaces touch and the wedge closes. To keep the spine in place while it heals, rods are inserted into the pedicle screws. The upper and lower wedge’s bone surfaces will fuse into one solid bone as they develop together, giving the vertebra long-lasting strength and stability.

How Should I Prepare for this Procedure?

It’s crucial to cease using tobacco products before any deformity repair operation. The effects of nicotine on bone fusion and surgical results are quite negative. Speak to your neurosurgeon if you use cigarettes or smoke now about stopping. Patients or parents of patients should make sure they are aware of the intended outcomes of your operation, the potential dangers, and what to anticipate from the healing process. Speak with the neurosurgeon treating you or your child if you have any questions at all concerning the treatment or the healing process. Write down any questions you or your child have as they come up to make it simpler, then bring the list with you to your visits.

Tell your doctor about any drugs or dietary supplements you or the patient take, especially those that might thin your blood, such as aspirin. Before your surgery, your doctor may advise you or the patient to cease taking certain drugs. Before the procedure, list all drugs you are taking to make it simpler. If you or the patient have a latex, food, or medicine allergy, please let your doctor know (some surgical gloves contain latex). Remove any nail paint or acrylic nails the day before surgery, skip makeup, and take off all jewelry. Bring any necessary materials, including a toothbrush, toothpaste, and dentures. Upon registration, an ID bracelet will be placed on your wrist and will contain your name, birthday, and the name of the surgeon.

Pedicle Subtraction Osteotomy’s Benefits and Drawbacks?

Although pedicle subtraction osteotomy is a difficult spinal reconstruction with high hazards, it offers good treatment for severe kyphosis. Infection, neurologic damage, dura rupture, instrumentation failure, non-union (pseudo-arthrosis), chronic pain, DVT, PE, chronic discomfort, and the necessity for revision surgery are a few of these. Each patient is different, and the only way to fully understand the risks and advantages of having surgery to address your issue is to have a thorough assessment with a spine surgeon who is very experienced and has completed a fellowship.  All of our doctors at the Southwest Scoliosis and Spine Institute have completed fellowships and are experts when it comes to spine health.

 

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