ACDF (Anterior Cervical Discectomy and Fusion)
What are the structures of the cervical spine?
What is an ACDF?
An ACDF (Anterior Cervical Discectomy and Fusion) 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 / PEEK polymer). This cage has a cavity within it which is packed with a bone substitute which allows the bone from the vertebrae above and below to grow through the cage thus joining the two vertebrae together, that is, a fusion.
Why is an ACDF performed?
The common indications for an ACDF are:
Spinal cord compression
Symptomatic spinal cord compression
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 spinal cord compression
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
This 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 an 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 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 muscle or of a 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 they have no symptoms. This does not require surgery as we are interested only in making the patients better, and not their x-rays.
Related conditions to ACDF
What is an ACDF procedure?
This common neurosurgical operation is performed under a general anaesthesia. Once the patient is positioned an incision is marked on 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 using magnified vision. By completing the disc removal 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) 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. Prof Owler does not usually harvest bone 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 sometimes 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 unit before being transferred to the ward. The drain is usually removed on the day after surgery.
What are the expectations after 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 2-4 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.
In most cases a cervical collar is not used after surgery.
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.
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 90% of patients will experience significant improvement in pre-operative symptoms, while a further 10% 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.
Will an ACDF limit the movement of my neck?
Fusion of one level of the cervical spine may result in some limitation of movement. When 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.
What are the risks of an ACDF?
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 the 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.
How long is the hospital stay and what happens during that time?
The hospital stay is normally around 2-4 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.
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.
What do I need to do at home after an ACDF?
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 physical jobs should wait at least 6 weeks but it should be discussed with Prof Owler.
When do I see Prof Owler in follow-up?
A post-operative appointment is normally arranged at 6 weeks post-surgery. The appointment is normally provided to the patient at the time of discharge from hospital.
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 Prof Owler’s office for review.
What restrictions do I have after an ACDF?
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.