Keywords : Vertebral Augmentation Procedures
Interspinous Process Decompression
Facet Distraction (DTRAX)
Scoliosis "Growing Rods"
Vertebral Augmentation Procedures
The vertebral body is a very strong structure designed by nature to carry great loads over our lifetime. However ageing and other diseases can cause osteoporosis that significantly weakens its architecture. Osteoporosis of old age can cause vertebral compression fracture with very little or no trauma at all. Tumors of the spine that has responded to chemotherapy and radiotherapy are also rendered very weak because of bone destruction caused by the tumor inside the vertebra. The vertebra becomes weak and collapses.
Vertebral augmentation procedure is a process of filling up the vertebral body with material to strengthen its stock and allow it to continue its weight bearing function. Big open surgeries are avoided in osteoporotic vertebral compression fractures and those with resolved tumors because patients are generally poor candidates for surgery. Kyphoplasty and Vertebroplasty are noble minimally invasive procedures that help restore the collapsed height of vertebra and augment it with polymethylmetacrylate (bone cement).
As we age, our bone density decreases causing varying degrees of osteoporosis. Advanced osteoporosis can lead to vertebral compression fracture even with just very minor injuries, bending or lifting. The vertebra collapses causing sever debilitating back pain. The collapse changes the biomechanics of the spine and leads to a cascade of domino effect leading to multiple levels of compression fractures.
When the vertebra is invaded by tumor it destroys its structure. Even when it has been successfully treated by chemotherapy or radiotherapy, the bone losses its capacity to heal and begins to slowly collapse. When the vertebra has contained active tumors or when it has been weakened by tumor, vertebral augmentation should be considered.
When vertebral compression sets in, it usually creates a domino effect of causing multiple vertebral compression fractures. Patients should be closely monitored to prevent this very disabling condition. Kyphoplasty is a very good option for such conditions.
Kyphoplasty is a very technical procedure that entails precision with flouroscopy. Every step is carefully being monitored. It is however a very minimally invasive procedure that we do as an out-patient surgery.
Kyphoplasty begins with only a puncture wound at the back with the patient asleep under anesthesia on their belly. Small trochar needles are used to enter the skin then the spine to deliver a fine drill that will create a small channel into the spine to access the collapsed segment of the spine. There is very little or no bleeding at all.
After a channel has been created within the collapsed vertebra, a deflated balloon is inserted and slowly inflated by a hand held hydraulic system. The balloon slowly expands and pushes the collapsed bone into correction. Once the correction has been achieved, the balloon is deflated and pulled out leaving two empty spaces on both sides of the vertebra.
A small cannula is then inserted into the cavity created by the balloon. This cannula or small tube is used to deliver polymethylmetacrylate (bone cement) into the cavity. The cavity is filled to capacity by slowly injecting the material while the surgeons are guided by flouroscopy. The bone cement is allowed to settle and hardened for a few minutes before patient is taken out of anesthesia. The procedure is sometimes done with the patient awake.
The precursor of kyphoplasty is vertebroplasty. Vertebroplasty is simply injecting a less viscous cement into the spine at high pressures. Kyphoplasty is safer because bone cement is injected as low pressures simply to fill up the cavity created by the balloon. Surgeons have better control of the flow of the cement unlike in vertebroplasty where surgeons have very poor control of the cement flow sometimes causing problematic leakages in areas where the cement in unwanted.
Interspinous Process Decompression (IPD Surgery)
One of the more common causes of severe back pain and leg pain (sciaitica) is central canal and foraminal stenosis. These conditions happen in a wide range of ages (young and old), severity of pathology ( mild, moderate, severe compressions), and patients' threshold of pain tolerance.
Most of these cases will easily respond to conservative management. But when conservative management fails some noble procedure works very well. Interspinous process decompression (IPD surgery) is a simple procedure that entails putting a wedge between the spinous processes of the level involved (red arrow shown below). It pushes the two collapsed vertebrae apart and indirectly decompresses both the central canal and the foramina. It is a minimally invasive procedure that works very well for very symptomatic sciatica in mild to moderate foraminal stenosis. It has poor results for advanced and severe foraminal stenosis.
IPD surgery works by these mechanisms- 1. it creates an indirect decompression of the collapsed foramina. The compressed nerves need only a small amount of extra space to be decompressed, 2. it stretches the buckled ligaments within the canal, 3. it unloads the facet joint that is now carrying more load since the disc has loss height, and 4. it unloads the posterior part of the prolapsed disc preventing irritation of many related structures.
IPD surgery uses sequential dilating probes that are inserted 6cm away from the midline to create a channel where the IPD device is inserted between the spinous processes of the level involved to distract it apart. Unlike most surgeries where you need to remove some muscles, ligaments or bones, IPD surgery does not violate any of the normal anatomy and merely inserts a small device to act as a wedge between a collapsed level. The final device is inserted in a minimally invasive fashion. The device has collapsed flanges (wings) that open up once deployed- anchoring it securely to the soft tssues found between two spinous processes.
The xrays above show a picture of a spine before and after surgery. The yellow arrow shows a collapsed or stenotic foramina between L4-L5. We can see the IPD device on the right side. One can easily see that the foramina has significantly opened after the IPD device was applied between L4-L5. The picture below shows the very small scar left behind by the procedure. We almost always perform this procedure on an out-patient basis with most patients going home with very little or no discomfort.
Cervical Facet Fusion "DTRAX" Surgery
Medicine is fastly evolving to provide solutions to man's ailments. During the last decade or so new techiques in spine surgery have evolved to provide minimally invasive spine surgery for certain spine conditions. All the procedures below are current "new technology" or "avant-garde procedures" in the field of spine surgery. All of them are available in our country- pioneered by our faculty in the country to treat Filipino patients.
Early onset scoliosis is a pressing orthopedic problem. It is usually a progressive lateral deformity of the spine diagnosed before the age of 10. It should be distinguished if it is:
- Infantile scoliosis
- Juvenile scoliosis
- Congenital scoliosis
- Neuromuscular scoliosis
- Ayndromic scoliosis
Patients with early onset scoliosis should have a thorough work-up consisting of properly taken X-rays and oftentimes CTScans and MRIs to fully assess extent of the deformity and other related organ system problems. Patients should be assessed and treated by other specialists if other organ systems are affected.
Patients should be advised close out-patient follow up to monitor if scoliosis is progressing at an alarming rate. Bracing is the standard treatment to control or prevent progression of deformity. In a considerable number of patients, bracing can significantly complicate the situation especially in patients with whom "thoracic insufficiency syndrome" can develop.
Scoliosis "Growing Rod" Surgery
“Thoracic Insufficiency Syndrome” is a newly characterized disorder. It is defined as the inability of the chest wall to support normal respiration and lung growth. The chest wall that includes the spine, the ribs, and the sternum are the engines of respiration. If scoliosis progresses it will affect chest wall volume, symmetry and function. Bracing will not work well for these patients, so surgery should be instituted early to prevent the lungs from stunted growth and development. But the usual fusion surgery of the spine will greatly affect the growth of the patient.
A new technology, called “Growing Rods” is used to splint the spine in a corrected alignment to prevent the progression of the deformity and allow growth of the spine and the chest wall. “Growing Rod” scoliosis surgery is a semi-minimally invasive spine surgery where special rods are anchored and inserted into the pediatric spine as shown in this video.
After surgery, a magnetic current lengthens the rod on a periodic schedule to provide more correction as the patient grows in order to prevent progression of deformity and to allow chest wall development. This is done on an out-patient basis with no need to admit the patient causing no physical and psychological stress to the growing child.
Cervical radiculopathy is a condition when a patient experiences a nagging pain and weakness over the neck, shoulder and arm. This is usually associated with a cervical disc herniation (soft disc), or a narrowing of the window in the spine- called the "foramen", where the nerve root of the cervical spine exits as it goes to the arms. Patients usually improve with conservative management but a certain number will need surgery if their condition has been refractory to conservative treatment.
Pain is usually felt over the neck, shoulder, arm, forearm and fingers with or without associated weakness of elbow flexion and extension and power grip
Usual pathology is a disc herniation or a bone spur also called an "osteophyte" that compresses directly on the nerve root or when it causes narrowing of the cervical foramina where the nerve root exits as it goes to our upper extremity
Cervical Disc Herniation compressing on the nerve
Osteophyte or bone spur narrowing the foramen
The DTRAX implant is a small titanium wedge-plate with a screw that inserts between it. The screw opens the titanium plates in order to expand the wedge. It is designed to be applied between the facets of the cervical spine over the area where the pathology is found in order to distract the foramen to enlarge its volume. Bone graft is injected between the facet to fuse that specific level alone.
The procedure is done in a minimally invasive fashion where the instruments used to deploy the implant are inserted percutaneously through small 1.5cm incision at the back of the patient. The whole procedure is done under flouroscopy guidance. One can see the image of the cervical spine with the instrument positioned in the cervical facet.
This post-operative x-rays show a narrowed foramen because of bone spurs. After the DTRAX procedure, you will observe that the volume of the affected foramen became bigger thus allowing more space for the nerve root.
This post-operative x-rays show significant improvement in the volume of the foramen after the DTRAX surgery from an almost occluded condition before the procedure.
The DTRAX surgery is called a percutaneous posterior cervical facet distraction and fusion procedure. It is a minimally invasive surgery that leaves 2 small scars at the base of the neck. The procedure can be performed as an ambulatory out-patient surgery.
Cross Section of a Normal Chest
Cross Section with Scoliosis
A progressively worsening scoliosis produces lateral bending and rotation of the spine which inadvertently deforms the chest wall of a patient because the ribs are supple and pliant. The pressure points of a brace can put undue stress on the ribs and prevent it from developing. There is a need to place the control of correction directly on the spine itself.
On a monthly basis, patients with growing rods visit their doctor. Patients lie on their belly and a magnet actuator is held over the growing rods in order to lengthen it slowly over a period of one to two years. The whole process is done in a matter of 2-3 minutes without pain or discomfort for the patient.