What is a cervical lateral mass screw fixation?

The aim of a cervical lateral mass screw fixation is to stabilise the spine when it has been de-stabilised by another surgical procedure, or by trauma.

A lateral mass screw fusion is usually done as part of a nerve or spinal cord decompression procedure or a traumatic fracture stabilisation procedure, to maintain stability in the neck and prevent the risk of a deformity developing later. During the procedure, instrumentation is inserted to correct alignment and aid the fusion. Bone graft is placed between the vertebrae to aid the bony union and create a solid fused spine.

Reasons to consider a lateral mass fusion include: the presence of diseased bone or damaged joints in the neck that are causing neck pain or placing pressure on the spinal cord or the nerve roots leaving the spinal cord, resulting in pain, weakness or numbness in the arms or legs. Other common indications are degenerative diseases such as rheumatoid arthritis, traumatic fracture, tumour and congenital malformations. In instances of cancer and fractures there is often no alternative to having a fusion, whereas with degenerative joint disease, surgery is always optional.

Non-surgical alternatives

• Acupuncture
• Hot and cold pads
• Hydrotherapy
• Pain relieving medications
• Physical therapy
• Modifying activity levels to include:
  • Aerobic exercise, walking, cycling and swimming
  • Strength and flexibility training
• Weight loss

Surgical alternatives

• Steroid and local anaesthetic injections
• Other procedures such as anterior fusions and disc replacement surgery

No smoking

Smoking damages every part of the body and decreases the chance of a successful procedure. If you smoke, you should stop now.

Before the procedure

• Your doctor will complete a medical exam to ensure that you are in good general health before continuing with the operation.
• You will be advised when to stop any medications that will increase your risk of bleeding, including aspirin, anti-inflammatories, vitamin E, and some herbal remedies such as chamomile, gingko and fish oil, among others.
• You may be admitted the day of, or the day before, your procedure.
• Don’t eat or drink anything 6 hours before the procedure.
• Wear comfortable, loose-fitting clothing and leave all jewellery at home.
• An intravenous line will be inserted into a vein in your arm for ease of fluid administration.
• You may be given a sedative to make you drowsy before being given your anaesthetic.
• You will be given a general anaesthetic to put you to sleep.
• Let your doctor know if you develop a cold, fever or flu-like symptoms before your operation.

The procedure

The patient lies supine and his neck is cleaned. An incision is made and the overlying muscles are moved to the side. Using X-ray imaging, the surgeon confirms the correct level to fuse.  The screws are positioned using X-rays to aid in safe placement. The donor bone is inserted. The muscles are replaced and the wound is sutured closed.

Post-procedure

• The operation typically takes 2 to 3 hours.
• You may need to spend up to 5 nights in hospital.
• Your bowels may not open for a few days after the procedure, so pain medication, muscle relaxers and laxatives can be used as directed.
• You will experience some neck pain for 3 to four weeks.
• You may need to wear a soft cervical collar for 6 to 12 weeks.
• Numbness is slow to alleviate and some may persist permanently.
• Weakness may last for 6 to 12 weeks.
• Although feelings of pins and needles decrease immediately post-op, there may be fleeting recurring symptoms during the first few weeks of recovery.
• Only walking is permitted for the first 6 weeks.
• Avoid bending, twisting, lifting or making any other sudden movements.
• Don’t lift anything heavier than a bottle of milk for 2 weeks.
• Most people can resume normal daily activities after 3 weeks.
• Hardware usually doesn’t cause any problems and is permanently left in place.
• There is often some residual neck pain after the fusion from the pre-existing degenerative disease elsewhere in the neck.

Wound care

• The wound must be checked twice a day. If you notice any redness, swelling, green or yellow discharge, or opening of the wound, contact your GP immediately and call your surgeon.
• If you have small bandages on your incision, it’s important to keep these dry. Once they start peeling off, you may remove them (typically after 1 week). All external sutures will be removed in 1 to 2 weeks.
• Keep the wound dry. While you may shower, avoid bathing, swimming or using creams for a week.
• The incision site may be gently cleaned using soap and water. Rub gently and avoid using perfumed soaps.
• An appointment with your surgeon will be booked 6 weeks after the procedure and fusion will be confirmed using radiological imaging.

On-going care

Despite having surgery, your neck will never return to full strength. You will always have a weak spot and you will need to commit to life long care to prevent further injury. Maintain correct posture, eliminate excess body fat, follow a daily exercise programme and avoid unnecessary stresses to your back.

The right to refuse

You have the right to informed refusal, which means you can delay or reject the recommended treatment of your condition. Be mindful, however, that this may lead to the worsening of your back pain and ask your doctor to detail what may happen should you choose not to undertake the recommended surgical treatment.

Potential complications

Allergic reaction to medication

This can cause a rash, swelling of the hands, joints, eyelids and throat, difficulty breathing, low blood pressure and death. An allergic reaction is easily controlled with the correct equipment and medication.

Adjacent Segment Syndrome

When a part of the spine has been fused – limiting movement in that area – stress can be transferred to the adjacent segments. This can increase wear and tear in these adjacent intervertebral discs, facet joints, pars articularis and ligamentum flava, and can lead to increased mobility and pain. Known as adjacent segment syndrome, or transitional syndrome, it is more likely when multiple segments are fused, abnormal alignment, facet joint injury during surgery, increased age and pre-existing degenerative changes. Up to 20% of fusion patients might need another operation to treat the symptoms related to the adjacent segment degeneration. A degree of pre-existing degenerative disease might be present in the adjacent segments and it is sometimes difficult to determine if abnormalities in the adjacent segments are due to adjacent segment disease or progression of pre-existing disease or a combination of both.

Anaesthesia

There are a number of different types of anaesthesia:

Local: the medication is injected into the skin around the site of the surgery to numb only surrounding tissues.

Regional: where the body part is anaesthetised by numbing major nerves or part of the spinal cord.

Conscious sedation: where a full anaesthetic is not given, rather, medications are used to create a near-sleep relaxed state.

General: where you are rendered unconscious and temporarily paralysed. In this instance, medication is given to you through an IV line, and machines breathe for you and monitor you together with the anaesthesiologist. Most spinal operations require general anaesthesia, so that you can’t move during the operation.

There are many possible complications associated with a general anaesthetic. 1 to 10% of these include:

Post-operative nausea and vomiting: this may last a few hours to several days. It can be the result of the operation, anaesthetic and pain killers.

Aches: as a result of lying immobile on a firm operation table for a long period of time.

Blurred vision/dizziness: due to low blood pressure from fluid loss or medication. Can be treated with fluid replacement and medications.

Bruising/pain: around injection and intravenous cannula sites. This usually settles by itself and the cannula can be moved if necessary.

Headaches: due to the anaesthetic, dehydration or anxiety. These may last a few hours but can be treated with medication.

Itchiness: can be an allergic reaction to drugs, sterilising fluid or sutures, or as a side effect of strong pain-relieving medication (opiates).

Memory loss/confusion: this is more common in older people who have had a general anaesthetic. There are many causes and may last a few days or even weeks.

Pain from drug injection: some drugs cause pain when they are injected.

Shivering: can be caused by medication, stress or low body temperature during the surgery. Shivering can be treated with a hot air blanket or medication.

Sore throat: from the breathing tube. This may last a few hours to a few days. Can be treated with pain-relieving lozenges.

Uncommon complications (0.1%) include:

Anaesthetic awareness: if you are ill, your anaesthesiologist may use more muscle relaxants and less general anaesthetic to reduce your risk. However, this may lead to you being aware of your body and your surroundings during the operation. Anaesthesiologists use monitors to observe your body’s reactions and adjust the medication doses. If you think you’ve been aware during the operation, it’s important to tell your anaesthesiologist afterwards.

Bladder problems: depending on the operation and the medications, men may find it difficult to urinate, while women tend to leak after the operation. If necessary, a urinary catheter is used to drain the bladder until control returns.

Chest infection: this may lead to breathing problems, but can be treated with antibiotics. This is more likely to occur in people who smoke.

Lip, teeth, tongue injury or jaw dislocation: this can be caused by difficulty placing the breathing tube, or by clenching your teeth as you recover from the anaesthetic.

Muscle pain: can be caused by a muscle-relaxing drug that is used to prevent vomiting during emergency surgery.

Slow breathing: can be due to some painkillers or muscle relaxants. Can be treated with medications.

Worsening of existing medical condition: your Anaesthesiologist will monitor your body closely and act to eliminate or reduce any medical complications.

Very rare complications (0.0005 to 0.01% of general anaesthetics) include:

Death: is very rare and usually occurs when 4 or more complication occur simultaneously. Death from anaesthesia occurs in 1 of every 200 000 cases,

Equipment failure: vital equipment can fail, but this is very rare, and monitors give immediate warnings.

Eye damage: eyelids are taped shut to protect them during surgery. Rarely, sterilizing fluid may leak under the eyelids, or you may rub your eyes while waking from the anaesthetic. Any discomfort is usually temporary.

Nerve damage – stretch, compression, incision or puncture: recovery usually occurs within 3 months of the procedure.

Serious allergic reaction to medication: This is noticed and treated quickly, but can very rarely cause death, even in healthy people.

Artery injury – Vertebral

The vertebral artery passes close to the vertebral bodies in the neck. Injury during surgery is very rare, but laceration can cause bleeding. In the unlikely event that the bleeding can’t be controlled, injury may lead to a stroke and cause permanent disability such as blindness or paralysis, or death.

Cerebrospinal Fistula

This is when the dura (which contains the spinal cord and the cerebrospinal fluid) is torn and cerebrospinal fluid leaks out of the sac. Symptoms include a headache when standing, back or limb pain, nausea, vomiting, dizziness, ringing in the ears or sensitivity to bright light, including a risk of infection and meningitis. The dural tear may reseal spontaneously or it may need best rest, drainage or surgery to repair.

Death

No operation is risk-free. Complications resulting from a procedure can range from minor troubles to major disability. Even when a surgery has gone well, serious problems can still arise and result in pneumonia, heart attack, stroke or even death. The entire medical team is highly trained and committed to eliminating all risk pre-, during and post-surgery as much as is humanly possible.

Deep Vein Thrombosis

Any surgery can put you at an increased risk of deep vein thrombosis (a blood clot that forms inside the large deep veins of the legs). The reason for this is twofold: The blood’s clotting mechanism is activated by surgery, injury to blood vessels, immobility and anaesthetic effects during and after the surgery make it easier for clots to develop.

The danger of a DVT is that it can block the blood flow from the legs back to the heart, causing swelling of the legs with resultant pain. If the clot doesn’t dissolve properly, the swelling and discomfort can become permanent. Alternatively, the clot in the leg can detach and travel up the veins to the lungs, where it blocks the smaller lung blood vessels and stops the blood flow. This is called a pulmonary embolus, or PE. If the PE is large enough, or there are many of them, it can cause death.

Patients who are at additional risk of DVT are: over the age of 50, have varicose veins, have had a previous heart attack, cancer, atrial fibrillation, an ischemic stroke, diabetes, previous DVT, heart failure, combined oral contraceptive pill use, smoking, obesity, leg weakness and inherited clotting abnormalities.

Durotomy

The dura is a thin layer of tissue that forms a sac containing the brain, spinal cord and nerve roots. This sac is filled with cerebrospinal fluid and can be torn during spinal surgery. It’s a complication that is more difficult to avoid during repeat surgery in the same location, or when operating on severe spinal narrowing or a large disc herniation. A dural tear – and the subsequent leakage of cerebrospinal fluid – can cause a headache when standing, back or limb pain, nausea, vomiting, dizziness, ringing in the ears or eye pain from bright light. A continual leak can lead to a cerebrospinal fluid cyst under the skin or leakage of fluid from the wound. Dural tears can reseal spontaneously, or it may need bed rest, a blood patch procedure, draining or an additional operation to repair.

Epidural Hematoma

Should bleeding occur into the epidural space around the spinal cord, it can form a blood clot known as an epidural hematoma. If the hematoma is large, it can compress the spinal cord and nerve roots leading to pain, weakness, numbness and bowel and bladder problems. A surgical procedure may be needed to stem the bleeding and remove the hematoma.

Eye Injury

During general anaesthesia the patient’s eyes are taped shut to protect them from the risk of drying or scratching. Should they become dry or scratched however, they typically heal within a day or two. Blindness is a rare complication that can be caused by too much pressure on the eyeball or decreased blood flow through the eye (ischemic optic neuropathy (ION)). Blindness due to ION is a 0,1% risk and is associated with emboli, prolonged spine surgery in patients older than 70, a face-down operating position, diabetes, intraoperative blood loss/hypotension and ankylosing spondylitis (poor position owing to a deformity of the neck).

Fluoroscopy

Fluoroscopy is similar to an “X-ray movie”. A continuous X-ray beam is passed through the body part being examined, affording the surgeon instant imagery of the inside of a patient during a procedure enabling him or her to accurately position any devices. The disadvantage of fluoroscopy is that X-rays can potentially cause cancer, reproductive abnormalities, cataracts and radiation dermatitis. That said, the exposure during surgical procedures is usually not significant and doctors make use of protective lead shields and minimize the intensity and duration of exposure.

Hematoma

During any surgery, some blood vessels will be cut. And although the surgeon stops all significant bleeding before closing the wound, there are instances in which bleeding restarts and forms a collection of blood in the tissues. Known as a hematoma, this can cause pain, put pressure on the adjacent tissues or become infected. A drainage tube may need to be inserted or a surgical operation performed.

Haemorrhage

Surgeons may need to cut some blood vessels in order to access the spinal operation site. The surgeon will plan the surgical route to avoid large blood vessels and will make sure that all bleeding has stopped before finishing the operation. Occasionally, one of these vessels can re-bleed after the procedure and if the rate, or the location of the bleed is problematic, a further procedure may be needed to stem the bleeding and drain the accumulated blood clot.

Implant Failure

Spinal fusion operations use screws, plates, rods and spacers to hold the vertebrae in correct alignment while the bone fuses together over the first few months. Once the bone fuses these implants are no longer necessary but are often left in place. Sometimes, before the bone has fused, an implant may break or shift from its correct position, causing pain, injury to adjacent tissues, mal-alignment (of bones) or non-fusion of bones (non-union, pseudoarthrosis). Another operation may be needed to remove or replace the implant.

Implant Misplacement

Spinal fusion operations use screws, plates, rods and spacers to hold the vertebrae in correct alignment while the bone fuses together over the first few months. Rarely, because of anatomical variations, equipment limitations or system failures, the implants are not optimally placed and a follow-up procedure is needed.

Infection

Infections occur in less than 1% of spinal operations and are more likely in patients that smoke, have diabetes, are overweight, or had a hematoma. Symptoms of an infected wound include: increased pain, swelling, tenderness, redness, oozing (clear or yellow fluid), slowness to heal, or if the patient experiences fever or chills.

Infections can be superficial (involving the skin), which usually respond to oral antibiotics and washing of the site. Sometimes the wound needs cleaning and re-suturing. Deep infections (involving the vertebrae or spinal cord) are more serious and may need intravenous antibiotics and an operation to drain the infection. On rare occasions, infected bone graft or hardware may need to be removed.

Malignant Hyperthermia

This rare life-threatening condition is passed down through families and can be triggered by some drugs that are used for general anaesthesia. In susceptible people, the drugs can cause an uncontrolled increase in skeletal muscle calcium levels and muscle contraction, leading to decreased blood oxygen and increased blood carbon dioxide and body temperature. This can lead to circulatory collapse and death if not quickly treated. Symptoms usually develop within an hour of drug administration. As yet, there is no simple test to diagnose susceptibility but it is usually found during drug administration or suspected if a family member develops the symptoms. While treatment is effective, it is critical that patients, who have a family history of malignant hyperthermia, discuss this with their doctor so that the use of the potential trigger drugs can be avoided.

Neck Pain

Neck pain (similar or different to the original neck pain) after the procedure is to be expected. It is usually temporary. However, in some patients, the original neck pain can persist or it can be worse.

Nerve Injury – Cervical

Because the vertebrae surround the spinal nerve roots and spinal nerves, surgery on the vertebra can injure the nerve roots. These nerves can be bruised, stretched, torn or cut while accessing or repairing the damaged vertebra. If a nerve is injured, it can cause pain as well as temporary or permanent, partial or complete, loss of sensation or movement in the patient’s arm. Locating, protecting and mobilising the spinal nerves are the most difficult and time-consuming part of most spine surgeries and surgeons exercise the utmost of care while doing so.

Nerve Injury – C5

Even after a technically successful cervical surgery, injury to the C5 nerve root can occasionally happen, with symptoms sometimes occurring up to one month after the surgery. The C5 nerve root is shorter than the other nerve roots, and given its location, it is often stretched during surgery. The C5 is the only nerve supply to the muscles that elevate the shoulder, so any injury leads to an obvious weakness of this muscle. Partial recovery occurs over weeks to months, but it can take years.

Nerve Injury – Lateral Femoral Cutaneous

The lateral femoral cutaneous nerve supplies sensation to the front of the thigh. It usually passes under the inguinal ligament in front of the hip, however, in some people it passes over the anterior iliac crest, near the site of bone graft removal. This nerve can be injured during bone graft removal or by prolonged pressure while lying in surgery. Injury can cause pain, pins and needles or numbness on the front to the thigh called meralgia paresthetica. Pressure injuries usually resolve within 3 months, but if the nerve has been cut, the symptoms may be permanent.

Nerve Injury – Ulnar

During surgery the medical team carefully positions the patient’s body so that the injured region is easily accessible. This can result in the ulnar nerve (located in the arm) being compressed or stretched at the elbow. Symptoms of pain, numbness or weakness in the hand can appear up to 4 days after surgery and usually disappear over a few weeks.

Non-union

Failure of the two vertebrae to fuse into one solid bone is called non-union or pseudo arthritis This occurs in about 10% of spine fusion operations. Nicotine products, including chewing tobacco, and cigarette and cigar smoking, can slow bone healing and significantly increase the likelihood of non-union. Consuming high doses of non-steroidal anti-inflammatory drugs after the operation can also increase the risk of non-union. Other causes are excessive alcohol intake, the location and number of segments fused, osteoporosis and some medical diseases. Non-union can cause worsening pain and may cause the supporting hardware to break. Additional surgery may be required to add more bone graft, replace the hardware or add an electrical stimulator to encourage the fusion to heal.

Osteomyelitis

Osteomyelitis is a bacterial infection of bone or the bone marrow. It can occur as a result of surgery, especially after the replacement of foreign material in the bone, or as a result of an adjacent infection. Symptoms can take up to 4 weeks to appear after surgery – the most common of which is worsening pain after an initial period of relief. Risk factors include age, smoking, obesity, diabetes, malignancy, chemotherapy, immune suppression, malnutrition, indwelling venous catheters, concurrent infections and extended hospitalization. Osteomyelitis is difficult to treat and often requires weeks or months of intravenous antibiotics and a surgical procedure to clean the area.

Post-Laminectomy Instability and Kyphosis

When bone, ligaments or muscle is removed from the posterior spine during a laminectomy, it can lead to an anterior strength imbalance. This, in turn, can pull that part of the spine into a kyphotic (flexed) posture. This occurs more commonly in children, or when multiple levels are included, or at higher levels in the cervical spine. Over time, degeneration and the development of a kyphotic deformity can occur, causing pain, muscle fatigue and the compression of the spinal cord and nerve roots.

Pressure Sores

Prolonged surgery and bed rest can result in the formation of skin pressure sores over prominent bones. The nursing team carefully place, pad and manoeuvre the patient to prevent this from happening.

Quadriplegia

The spine surrounds and protects the spinal cord. This means that surgery to the cervical spine can damage the cervical spinal cord, resulting in loss of movement and sensation in the torso and limbs. Quadriplegia may be complete, with no movement or sensation below the level of the spinal cord injury, or incomplete with some movement or sensation. Quadriplegia may involve impairment of movement and sensation of the limbs and torso, urinary and faecal incontinence, impotence and digestion and breathing difficulties. Quadriplegics are also at an increased risk of pressure sores, osteoporosis, fractures, frozen joints, thrombosis, respiratory infections, pneumonia and cardiovascular disease.

Residual Pain

Surgery can’t restore the back to a pre-diseased state. This means that some remaining post-procedural pain is very common. Furthermore, a degree of discomfort from the operation site – and pain from adjacent areas already damaged by the disease or by their own degenerative problems – can be expected. Usually, any residual pain is mild, but it may be severe or even worse than the original problem.

Urinary Tract Infection

Given that patients undergo general anaesthetic during surgery and are confined to recuperative bed rest, they aren’t able to go to the toilet to urinate. As such, a urinary catheter is passed along the urethra to freely drain the bladder and avoid bladder discomfort. The presence of a urinary catheter does increase the risk of bacteria entering the bladder and causing a urinary tract infection. Treatment usually requires the catheter to be removed, followed by a course of antibiotics.