The Rezaian Spinal Fixator

Dr. Rezaian invented the spinal fixator. The first paper about this invention was reported in the journal, “Orthopaedic Review”, in 1983 (click on the image to the left to see a full size image). The editorial chief, Alexander Garcia MD, commented on the fixator as a new way of treatment. (Click on the image of the editorial below and to the left to read it)

The Rezaian Spinal Fixator (RSF) is a simple turnbuckle appliance with a fixation mechanism on two extremities (see image on the right).

It simply replaces the compressed, burst, or damaged body of the vertebra. It corrects kyphotic deformity, completely relieves neural pressure anteriorly, and stabilizes the spine for early rehabilitation. Hospitalization period is 7 to 14 days. No external support is required.

In 1986, Ferguson et al. gave an algorithm for the treatment of unstable thoracolumbar fractures. After extensive biomechanical testing of existent instrumentation's for spinal fixation, they concluded that no one instrumentation was perfectly suited to handle all thoracolumbar fracture patterns. After improving their sublaminar segmental L and C fixation technique, complications still were reported at 27.8%. The experiences of others are the same.

Return to top

The spinal fixator described in this study represents a new approach for the management of fractures of the thoracolumbar spine.

In serious fractures of the thoracolumbar vertebrae with neurological deficit, the middle column commonly fails and the adjacent discs rupture; one or both protrude into the spinal canal. Furthermore, considering that 100% of the weight of the upper trunk is loaded over the bodies of the vertebrae, the basic stability of the spine as the weight-bearing axis is totally disturbed. Attempting decompression of the anterior part of the compressed cord from the posterior approach is difficult. Stabilization of the flexion moment by the posterior metallic splintage is mechanically unsound and consequently fails.

The Rezaian spinal fixator (RSF) has been invented to replace only the broken failed body of the vertebrae. It fully allows anterior decompression of the cord for a better neurological recovery, restores the failed body of the vertebrae, and corrects the kyphotic deformity for normal weight-bearing. It produces a secure stable spine for early rehabilitation. The need to include two or three vertebrae above and below the fracture site in mass fusion and the need for external support (e.g., cast, brace, jacket) are completely eliminated.

How it Works

The RSF is a form of a turnbuckle with a flat plate on each end, with four sharp spikes on each flat plate. Following the decompression of the cord, this appliance is imbedded between the two adjacent intact vertebral endplates. At the same time, the height of the collapsed vertebral body is restored by turning the turnbuckle mechanism; concomitantly, the kyphotic deformity is corrected. Based on a distraction compression mechanism, the fixator securely fixes and stabilizes the broken and unstable spine. It occupies approximately one-third of the body of the vertebra; two-thirds of the space is filled with bone graft when it is used for long-lasting fusion.

Experimental works on cadaver spines have proven that the procedure is biomechanically safe and sound. It allows decompression of the neural tissue, and does not demand inclusion of two or three vertebrae above and below the lesion. A section of rib and all broken pieces of the damaged vertebra will effectively bridge the vertebrae above and below the fixator and provide long-lasting fusion. Furthermore, the bone graft encircles the fixator and creates a safe barrier between it and vital structures (e.g. aorta and spinal cord).

Return to top

The RSF is indicated for the management of fractures of the thoracolumbar spine in any of the following conditions:

Replacing a diseased or injured vertebral body.
Restoring the height of a collapsed vertebral body.
Decompressing anteriorly the spinal cord and neural tissues.
Relieving back pain following spinal instability.
Generally, there is a combination of the above. The contraindications for RSF are:

No neurological deficit present.
Less than 15% compression of the vertebra.
The prerequisites for using an RSF are:

A good spot X-ray of the damaged segment of the vertebra must be available.
CT and MRI scans.
A myelogram (still the final and best method of determining the extent of compression of the spinal cord and neural tissues).
At least 4 units of blood must be available for this operation. (Recently autotransfusion in conjunction with the cell saver was used without the need for hemotransfusion.)

Results

The preliminary reports of the first 24 cases were presented at the annual meeting of the Scoliosis Research Society in 1981. Since then, 41 more procedures have been performed, for a total of 65 cases (29 women and 36 men). Their ages ranged from 17 to 72 years; 11 were complete and 54 were incomplete paraplegic cases. The etiology was primary (single myeloma) in one case, secondary metastasis in three cases, sequestrum of osteomyelitis with severe neurological involvement in four cases, and spondylolisthesis grade V with incomplete paraplegia and compressed osteoporotic fracture of T12 and L1 in three cases. The other 54 cases were traumatic with quadriplegia in one case and incomplete or complete paraplegia in 53 cases. Details of the levels of lesions are recorded in Table 1. Minimal follow-up time was 3 years, and maximum follow-up time was 8 years (average time, 4 years and 4 months).

No patient was operated on immediately after sustaining injury. The minimal interval of time between the accident and the operation was 16 days, and the maximum was 18 months. Minimal hospitalization time was 5 days, maximum 27. Repeat surgery was necessary in two cases due to malposition of the fixator. The detail of 43 fracture of thoraes lumbar is recorded in another paper under review.

No patient worsened neurologically; in contrast, all incomplete paraplegic cases were able to be ambulated. Out of 53 incomplete paraplegic cases, 41 patients returned to normal or near normal activities, five had to use a cane for ambulation, and seven had to have a short splint for drop foot or unstable ankles. One case of quadriplegia improved from grade A to grade C.

Return to top

No patient needed any external support (e.g., back brace, cast, etc.). It is important to note that the spines operated upon were always stable and pain-free under normal loading. No deformities of the spine were noticed in this group or in follow-up and routine X-ray examinations. Three cases are described in detail as examples. No instrument failure was noticed.

Table 1. Level of Spinal Replacement

Case 1

A 27-year old female was involved in a serious motor vehicle accident. Four months later she was referred to the author. She was complaining of excruciating pain in her lower back, radiating to both her lower extremities. She was unable to walk but was able to stand with a walker. She was treated in a plastic jacket. Muscles lower limbs were Grade 2-4 with paresthesia from the groin down and she was diagnosed paraplegia (Frankel D). Her weight was 230 pounds. She underwent the operation outlined in this paper. Five days post-operatively she was able to walk with the aid of a walker. 3 ½ weeks later she walked out of the hospital without a cane or a walker. Four years later she was fully active, working as a security guard. A subsequent back injury, caused by struggling with two men, showed no change in RSF position; however, the CT scan showed the fixator embedded in bone. Her symptoms were relieved by conservative measures and she returned to her job in a few weeks.

Case 2

A 53-year old man had low back pain for 4 years. By biopsy it had been known that his back pain was due to a hupernephroma of the right kidney, involving the body of L4. In the 6 months prior to surgery his pain had been severe and during the last 6 weeks he had lost his ambulation ability (paraplegia grade C Frankel). A myelogram demonstrated complete blockage with destruction of the body of L4, and surgery was performed. The complete body of L4 was removed and a spinal fixator with some rib grafts was used to bridge the gap. Two days following surgery, the patient’s pain had disappeared, and he was able to walk without external support. His recovery was so remarkable that the urologist was able to remove the involved right kidney. The patient left the hospital 10 days later. He was seen in the office 3 months post surgery, when a bone scan showed no evidence of increased uptake in the skeletal system.

Eight months pager this patient returned with complaints of severe left sciatic pain. Tomograms and a CT scan showed a small tumor on the lateral side of the spinal canal at the level of L4-L5. Flexion an extension X-ray views confirmed that the spinal fixator was imbedded between L3 and L5 in the bone graft; there was no motion. The tumor was again excised through a posterolateral approach; the spine was fixed. The pathology confirmed it was metastasis of the previous hypernephroma. The patient, 3 years after the diagnosis of hypernethroma, and 14 months after excisional secondary metastasis from his IV lumbar vertebral body and fixation with the RSF, was doing well. He died, 2 years after the surgery, of lung metastasis and generalized debilitation.

Return to top

Case 3

A 54-year old woman had constant severe low back pain for 4 months. During the 6 weeks prior to surgery the patient was not able to walk due to the weakness of her lower extremities. Clinically, she was suffering from incomplete paraplegia below T10; a CT scan showed complete destruction of the bodies of T9 and T10; a myelogram showed incomplete blockage at the level of T10 – T11. Under high dosages of penicillin G (4 million units IV, P.B. q 6 h), she underwent surgery; the bodies of T9 and T10 were replaced by the RSF. All of her pain was relieved one day after the operation and wound healing was uneventful. Her neurological recovery was satisfactory and she left the hospital on her feet 10 days later; she was completely well 2 years later. X-rays of the spine showed the RSF was intact 3 years later.

This technique is not recommended for routine treatment of osteomyelitis of the spine, although it may be used in selected cases.

Complications

No deaths occurred and no patient worsened neurologically as a result of surgery. However, repeat surgery was needed in two cases because postoperative X-ray films showed unsatisfactory positioning of the spinal fixator. After a second intervention, such results were satisfactory. Superficial infection occurred in two cases; no deep infections and no thromboembolisms were noticed; no metal failure or dislodgement of the fixator was noticed. Pseudarthrosis occurred in one case.

Discussion

Considering the pathophysiologic feature of spinal injury, the neural tissues are commonly destroyed because of avascular necrosis caused by contusion or compression. This is due to bony or disc fragments rather than actual physical laceration. This causes spinal compartment syndrome, similar to limb compartment syndrome, which deserves special consideration.

Considering this hypothesis, the conservative management of spinal fractures is far from ideal in terms of scientific acceptance. Nevertheless, fractures of the spine have been treated conservatively for more than half a century because there has not been a safe spinal surgery technique for providing secure stability under weight loading. For this reason, surgery continues to be controversial. What type of surgery is best? Laminectomy has adverse effects. Posterior instrumentation (Harrington distraction) cuts down the hospitalization period, although long-term neurological recovery and spinal instability under loading condition are not superior to conservative treatment.

Luque segmental rod and wiring posterior plate and pedical screw fixation are technically difficult, involving 2 to 3 vertebrae above and below the lesion and therefore exposing the intact part of the cord and neural tissue (above the lesion) to further damage. Hence, this technique has been associated with complication rates as high as 37%. The above techniques do not offer a chance for real anterior decompression and do not restore the height of the compressed vertebral body for long-term safe weight bearing. External fixation of spine and side fixation of spine have been tried but in both techniques post operative external are recommended. A detailed review of the literature and comparison with the present techniques of anterior decompression of the cord and spinal stabilization, demonstrates the spinal fixator offers advantages worth consideration.

Return to top

Conclusion

When a vertebral body has collapsed because of a burst fracture or other pathology the ventor of gravity shifts forward and the axis of the vertebral column fails. The spinal canal compromises the compression over neural tissues, and neurological deficit ensues. In such a situation, based on biophysiological principles, decompression of the cord anteriorly is preferred to any posterior procedure. Based on biomechanical hypotheses, elimination of the pathologically offensive element and restoration of the height of the vertebral body is safer than any internal posterior splintage with 2 or 3 vertebrae above and below the lesion. Our experience to date indicates that RSF fulfills these aims.