Anterior Cervical Discectomy and Fusion (ACDF)

An ACDF is a common operation performed on the cervical spine through an anterior (front) approach. One or more cervical discs are removed to decompress the spinal cord and/or nerve root(s). The disc is replaced with a cage which is made of a very strong material (often composite carbon fibre / PEAK polymer). This cage has a cavity within it which is packed with a bone substitute which allows the bone above and below to grow through the cage thus joining the two vertebrae together, that is, a fusion.

Anatomy of the Cervical Spine

The cervical spine consists mainly of the vertebrae or bone of the spine with a disc in between each bone. There are seven cervical vertebrae (referred to as C1-7). The main part of the vertebra is called the body and is located at the front. The disc is located between the vertebral bodies. Each disc is referred to by the bones between which it sits. For example the C5/6 disc is located between the C5 and C6 vertebral bodies.

Behind the vertebral bodies there is a ring of bone that contains the spinal cord. The back of this ring is made of the lamina and spinous processes to which several muscles are attached. The spinal cord is surrounded by spinal fluid and is enclosed in a sac called the dura. At each level a nerve root emerges from the spinal cord exits the spine through a hole between each bone called the intervertebral foramen. That nerve root will supply feeling (sensation) to a particular area of the arm and will also supply particular muscles that perform different movements.

The disc is made of two main elements. The first is the annulus fibrosis. This is a strong outer layer made of criss-crossing fibres. The inside of the disc, or nucleus pulposis, is the soft gel-like centre which normally provides the cushioning function of the disc. When a disc becomes unhealthy the nucleus can become shrunken and loses its normal water content. As a result the annulus tends to bulge and in some cases can rupture leading to protrusion of the unhealthy nucleus into the spinal canal.

Indications for Surgery

The common indications for an ACDF are:

Spinal cord compression

Symptomatic: Myelopathy is spinal cord disease, often due to spinal cord compression which results in neurological changes such as clumsiness of the hands, weakness of the upper limbs and spasticity of the lower limbs. Patients often report difficulty using cutlery and doing up buttons. Eventually their walking becomes unsteady and they may fall or stager. There are differing degrees of severity and this will influence the expectations and potential outcomes from surgery.

Asymptomatic: Although the spinal cord may be compressed some patients will have no symptoms or they may have only neck pain. Surgery in this instance is controversial. Some surgeons always recommend surgery. However, the risks of surgery need to be balanced against the risks of future problems. The problems that may develop in the future include the development of myelopathy. This may happen gradually but can also happen suddenly, sometimes after very minor trauma and be very severe. This is referred to as a central cord syndrome. After balancing their options some patients will elect to proceed with surgery while others favour a conservative approach.

Nerve Root Compression

Radiculopathy is a clinical condition usually due to compression of a nerve root. The nerve root is the start of a nerve as it exits from the spinal cord and spinal canal. It usually will join with other nerve roots outside of the spinal canal to form various peripheral nerves. Nerve roots normally supply sensation to a particular area of the body as well as supply various muscles to make them move. Radiculopathy is most commonly painful and the area in which the patient experiences pain will often indicate the particular nerve involved. In addition there is often numbness and paraesthesia. Paraesthesia is commonly referred to as pins and needles. Again these may indicate the nerve root that is affected. Finally there may be weakness of a particular muscle or of a particular movement.

Nerve root compression causing radiculopathy is most commonly due to a disc protrusion or bony spurs (osteophytes). There are many other reasons for radiculopathy such as a synovial cyst for example.

Not all nerve root compression, which is often evident on CT or MRI scans, is symptomatic. We commonly see patients with nerve root compression on imaging but who have no symptoms. This does not require surgery as we are interested only in making the patients better and not their x-rays.

Before Surgery

Prior to surgery, patients may be asked to attend a preadmission clinic. This will involve routine blood tests and for some patients an ECG and chest X-ray. Patients that have significant co-morbidities or illness may require extra assessment. Patients at Westmead Private Hospital will have a pre-operative Doppler of the lower limbs which will be repeated after surgery. This is to assess patients for the presence of deep vein thrombosis (DVT).

Patients who are on aspirin or clopidogrel should cease those medications 7 days before surgery. For patients who are on warfarin, management will depend on the original reason for their warfarin. Some patients will require early admission and be started on heparin, for example, patients with mechanical heart valves. Others will just need to stop taking warfarin 2 days before surgery. The INR will be checked before surgery.

Other medications should be continued including those usually taken on the morning of surgery. These medications should be taken with a sip of water even though the patients may be nil by mouth otherwise

All patients undergoing a general anaesthetic will need to fast. That is, they should have nothing to eat or drink for around 8 hours prior to surgery. Failure to comply with this may necessitate cancellation of the procedure as it may expose the patient to significant risk. As most patients are admitted on the day of the surgery, the hospital will contact them to inform them of the time for admission, likely time of surgery and the required fasting times on the day before the surgery.

Smoking

It is well documented that the largest risk for failure of the bones to unite or fuse is smoking. Therefore patients must cease smoking prior to the surgery and must not restart smoking after the surgery. Failure to comply with this advice places the patient at risk of failure of fusion with pain and other problems as a consequence. Patients should seek help from their general practitioner in order to stop smoking prior to spinal fusion surgery.

Hospital

Most patients are admitted to hospital on the day of the surgery. Patients need to ensure that their latest X-rays, CT scans and MRI scans are with them when they come to hospital. These scans are the surgeon’s road map and without them the operation cannot proceed. If you do not have your pictures with you when you are admitted the operation may need to be cancelled. Except in rare circumstances, patients are responsible for these films, and are normally given back to them at the time of consultation. Patients at Westmead Public Hospital who have images taken at that hospital will usually have their films at the hospital.

Operation

The operation is performed under a general anaesthetic. An incision is marked in the anterior aspect of the neck at the appropriate level of the spine. The incision is usually made in a natural skin crease which provides a better cosmetic result. After preparing and draping the wound, the incision is made and a natural plane is dissected to expose the anterior aspect of the spine including the disc. An x-ray is performed to check that the correct disc is exposed. A small muscle on each side is dissected off the spine. Retractors are then placed in the wound to keep important structures away from the area.

The disc is then removed using a variety of instruments and is normally performed using the microscope. By completing the disc removed the membrane protecting the spinal cord and nerve roots (dura) is exposed and any disc material is removed from within the spinal canal. This decompresses the spinal cord and/or nerve roots. In some cases where there are bony spurs (osteophytes) then these will also be removed.

The bottom of the vertebral body above and the top of the vertebral body below are prepared and an appropriate size cage that is packed with a bone substitute is inserted. Bone is not normally taken from the hip as has been performed in the past. Once the cage is in position a plate is placed across the front of the vertebrae and secured using 4 screws. The wound is irrigated and checked for bleeding. A drain is always left behind as a precaution. The wound is then sutured with self-dissolving sutures and a dressing applied. The operation normally takes 1-2 hours depending on the patient and the pathology.

The patient is then woken from the anaesthetic and checked for neurological function. The patient is then observed overnight in the high dependency / intensive care before being transferred to the ward. The drain is usually removed on the day after surgery.

Expectations of surgery

The expectations for surgery will depend on the indication for surgery. However, almost all patients will have some common experiences. Patients are normally able to communicate and talk with their family within an hour or so of their surgery. The throat is often sore and some patients may experience discomfort on swallowing. This generally resolves within a few days but occasionally will take longer. Patients are normally able to eat and drink. The physiotherapists will help with exercises to assist in preventing neck stiffness. Patients are usually mobilised the day after surgery and would spend about 4 days in hospital. Some patients will leave hospital within 2 days while others will stay for up to one week depending on their speed of recovery.

Fusion of one level of the cervical spine may result in some limitation of movement. Most commonly only one level of the spine is fused. The reduction in functional movement of the cervical spine is normally small and only noticeable at extremes of motion such as when trying to turn around to look over the shoulder when driving. When two or more levels are fused the limitation of movement increases and people who undergo fusions at multiple levels will notice more stiffness. However they are still able to turn their head and bend their neck to a significant degree in most cases.

Myelopathy: Patients with a myelopathy have variable rates of recovery. The main reason for surgery in these patients is stop further deterioration. However around 50% will experience some improvement while 40% will remain unchanged and 10% will continue to deteriorate. Patients that have milder symptoms to begin with normally have a better rate of recovery than those with very severe symptoms. The reason for this is that once the spinal cord is damaged it has limited capacity for recovery.

Radiculopathy: Pain is the most common symptom of radiculopathy and, in most cases, is the first symptom to improve; often immediately after the surgery. Pins and needles may take longer but tend to improve quickly. Numbness takes the longest period to recover, perhaps even over 12 months and some patients may not experience full recovery of numbness. Weakness has variable recovery depending on severity and duration before surgery. Some patients will experience recovery immediately while others may have persistent weakness despite the surgery. Normally physiotherapy is required to treat weakness. Overall about 80% of patients will experience significant improvement in pre-operative symptoms while a further 20% will not improve as much as is hoped and 1-2% percentage will be worse off in relation pain or some other problem. No guarantees can be given in relation to the surgery.

Risks of the surgery

All surgery caries risk. There are risks common to all surgeries such as infection, bleeding, deep vein thrombosis (DVT), pulmonary embolism and those associated with a general anaesthetic.

Risks specific to this operation are those related to the approach, surgery around the spinal cord and fusion.

The main approach related risks are a small risk to the recurrent laryngeal nerve and oesophageal perforation. The recurrent laryngeal nerve is a nerve supplying the muscles for the vocal cord. Injury results in a very hoarse voice that may be permanent. Oesophageal perforation is rare and means a hole is inadvertently made in the muscular pipe that carries food to the stomach. This can result in a severe life threatening infection.

Surgery around the spinal cord and nerve roots carries a small risk of neurological injury that may be temporary or permanent. This could range from at the worst quadriplegia (inability to move the arms and legs), paraplegia or weakness/ numbness involving part of an arm or leg.

In relation to the fusion itself, there is a risk of the bones not healing together as one, i.e., non-union / failure of fusion. This may result in neck pain and revision surgery. There is a risk of adjacent segment disease. As the spine is fused at the level(s) of the pathology, more stress is placed across the levels above and below the level of the fusion. This may accelerate changes at those levels and cause similar problems, sometimes requiring surgery.

This is not an exhaustive list of potential complications but this information provides an overview of the more common complications that patients may be exposed to.

Hospital stay

The hospital stay is normally around 4 days in total but varies depending on the patient and their underlying condition. The day after the surgery the wound drain is removed and plain x-rays of the neck are obtained. During the hospital stay the patient receives daily physiotherapy. Patients will receive prophylactic subcutaneous heparin injections and are required to wear stockings to prevent DVTs. At Westmead Private Hospital DVT scans are routinely performed before and after surgery.

After surgery there is normally some discomfort and analgesia is provided. However the amount of analgesia is required is usually small. Constipation is a common complaint after surgery and is usually due to analgesics. Patients should inform staff if this becomes an issue.

The wound is normally cleaned and the dressing changed each day. After discharge no dressing is required. You may shower and then pat the wound dry with a clean towel afterwards. While the wound may get wet, do not soak it in the bath or in a pool for at least 2 weeks after the surgery. Do not rub the wound. If there are any concerns such as excessive redness, pain or ooze then you should have your GP review the wound as the first step.

At home

After discharge, it is advisable to rest for 2 weeks which should consist of normal daily activities. One should not sit in the one position for too long such as at a computer for more than 20 minutes at a time. Once you feel more confident then activities such as driving can resume. Normally one can drive after 2-4 weeks from the date of surgery. A return to work depends on the work environment. Those with sedentary jobs can usually begin to go back to work after 2 weeks. Those with more manual jobs should wait at least 4-6 weeks but it should be discussed with A/Prof Owler.

Post-operative follow-up

You should make an appointment to see A/Prof Owler 6 weeks from the date of surgery or thereabouts. At that visit any concerns can be discussed and the wound will be checked. A follow-up x ray is normally performed at 3 months after the surgery which should be delivered to A/Prof Owler’s office for review.

Restrictions after surgery

There are few long term restrictions after this surgery. Patients who undergo an ACDF are usually advised to avoid body contact sports such as rugby league and union as well as to avoid any activities where there may be undue strain on the neck.

For the first 2 weeks patients should not lift any significant weights. This can gradually be increased by 5 Kg every 2 weeks. By the post-operative visit at the 6 week point after surgery, patients should have been lifting <10Kg. After this the limit can be increased. There is a general lifting limit of 20Kg for most people but this may need to be varied depending on the patient’s occupation.

Important Information

This information was provided to assist you. While it has been prepared to provide accurate information the practice and techniques of surgery will differ between surgeons. Likewise the information is a generalisation in relation to the surgery and will vary between patients depending on the individual and their pathology. This information cannot cover all aspects of the surgery especially in relation to surgical risks and should not be considered an exhaustive explanation. Please contact A/Prof Owler’s office if there are any further concerns or questions.