Instrumented spine surgery
Instrumented spine surgery is surgery performed to treat spinal problems with the use of spinal implants (excluding pain modulation devices).
Instrumented spine surgery can be divided into 2 major categories: Fusion and non-fusion procedures.
Spinal traumatic injuries and degenerative diseases are the most common conditions which might require addition of implants during surgery but a variety of congenital and acquired conditions affecting the spine may also require instrumentation as part of their treatment.
A spine motion segments is defined as two bony levels with an intermediate disc which allows healthy motion to occur. The spinal discs are named after the bones that sit above and below the respective disc. For instance, L4 L5 disc is attached between L4 and L5 vertebral bodies.
Examples of instrumented spine procedures
There are many ways to achieve instrumentation of the spine. For simplicity, we will divide these into anterior and posterior procedures depending on the nature of the approach to the spine and the type of instrumentation achieved; i.e. posterior screws and rod fixation or inter body cage insertion or a combination of both.
Posterior spinal instrumentation procedure
Following standard preparation for major spinal procedures including general anesthesia, the patient is carefully positioned face down on the operating table to expose their back.
Posterior spinal instrumentation can be done on any segment of the spine from occiput to sacral segments (= head to tail). Fluoroscopy or image guidance is often used throughout to ensure accuracy of implantation.
Under sterile conditions, an incision is made on the level of disease to expose its posterior elements. For example, if the surgery is for fusion of lumbar level 4 to Lumbar level 5, all the bony posterior aspects of this motion segment are exposed.
Then screws are inserted in level 4 and level 5 on both sides. A fusion cage between the two vertebral bodies to be fused may be inserted in the same posterior approach or in a different approach discussed in the next section. This cage usually is filled with graft material to promote fusion (bone healing) between both levels. Image guidance is helpful to ensure optimal implant placement.
A rod in fixed into the screws on either side, to link the motion or motion segments, and give it more strength while fusion is taking place.
Modern spine surgery may also incorporate minimally invasive techniques to minimize skin incisions and underlying tissue damage while achieving the same surgical goals
Anterior or lateral spinal instrumentation procedure
Anterior spinal instrumentation is usually performed on cervical and lumbar segments, rarely on thoracic level.
At the lumbar segment, anterior approaches to the spine for fusion are becoming increasingly popular as they help restore the correct shape to the spine.
The aim of this surgery is to achieve fusion of the motion segment from an anterior, oblique or even lateral approach by inserting a fusion cage between the vertebral bodies in a minimally invasive fashion.
More often anterior surgery is combined with a posterior approach to achieve optimal fusion. This can be achieved in a single procedure or in a staged fashion.
Possible complications of spinal instrumented procedures
The complication profile of instrumented spine surgery is similar to non-instrumented surgery in many regards (please refer to previous chapter). However, some possible complications are specific to instrumentation of the spine and/or inherent to the approach used to achieve it.
Some specific common complications related to anterior approaches to the spine include:
- Neck swelling with breathing difficulty caused by bleeding or blood clot formation in the neck – rare
- Hoarseness of voice – common
- Sore throat – common
- Damage to dura resulting in spinal fluid leakage – rare
- Paralysis is extremely rare but may be caused by a spinal cord injury
- Spinal nerve injury. Injury to these nerves is the most common reason for anterior cervical surgery and new nerve injuries can also occur
- Swallowing difficulties – common
- All of the serious risks listed above are quite rare and, in the majority of cases, transient.
- Injury to blood vessels causing significant bleeding
- Abdominal wall defects causing hernia
- Retrograde ejaculation in males
- Deep vein thrombosis (clot formation in deep veins)
- Abdominal pain and abdominal obstructions
- Lower limb weakness or numbness
- Abnormal warmth and swelling of leg caused by injury or bruising to the nerves controlling the size of the vessels in the leg
All the risks listed above are quite rare and, in the majority of cases, transient.
- Various hardware failures requiring revision surgery; examples include screw misplacement, screw loosening, breaking or pull out, cage migration, rod breaking, etc.
- Risk of neural injury during insertion of the implants; especially the screws.
- Risk of more surgeries down the line due to degeneration of the levels adjacent to the fused level(s).
- Failure of bone healing i.e., fusion to occur, may result in persistent or recurrent worsening of pain, or problems with instrumentation.
- Other unforeseen risks.
Recommendations for recovery at home
Recovery usually takes 4 to 6 weeks after uncomplicated spinal fusion. It may take longer in older patients and in case of severe pre-existing disability, or in cases where many spinal levels have been operated on.
- Avoid lifting heavy objects (more than 2kg).
- Bending and twisting movements should be minimized.
- Get advice from your physiotherapist on how to lift in case you have to.
- Driving is also usually not allowed for several weeks during recovery.
- Swimming and baths not allowed when the wound is not yet healed yet.
- Stay active: It is recommended to take regular walks and do daily light exercises to relieve back pain and hasten recovery. Sitting for long periods put the operated site at increased pressure.
- Take adequate rest: a good sleep helps the body to recovery faster. Patients may find their back is sore upon waking up, this usually settles after a short walk or a shower.
Return to work usually depends on how quickly the patient recovers, the level of symptoms and type of occupation.
Our surgical team will offer any more specific advice when need be.