A SIMPLE TECHNIQUE FOR THE ANTERIOR CERVICAL INTERBODY
FUSION FOLLOWING ANTERIOR DISECTOMY:
S.M. Rezaian, M.D., Ph.D., S. Nazo, M.D., S. El Farra, M.D.
California Orthopaedic Medical Clinic, Beverly Hills, CA 90211, and Empire Medical Clinic Abstract.
The Cruickshank procedure has been developed for anterior spinal fusion, according to which, the stability of the spine has been produced by using methyl methacrylate. At 6-9 months after surgery, fusion was noticed universally. Between January 1985 and January 1993, 81 patients underwent this procedure; 71 were followed from 1 to 6 years. All patients except one have proven satisfactory results. Fusion was achieved in all. Complications included temporary hoarseness in two patients only.
Key Words: Cruickshank procedure – Methyl methacrylate – Anterior cervical discectomy.
Anterior spinal fusion after anterior cervical discectomy using bone graft required neck immobilization postoperatively and was accompanied by serious complications. Donor site of the graft also carries morbidities.
The complications following classic anterior cervical discectomy and bone graft (horseshoe graft and coin graft) include: dislodging of the graft, absorption of the graft, and pseudoarthrosis. Donor site complications include hematoma, infection, lateral femoral cutaneous nerve injury, and muscle herniation. In addition, postoperative immobilization of the neck is a great inconvenience for the patient.
To overcome all of these difficulties and reduce morbidity, the late James Cruickshank, a neurosurgeon from Oregon, in 1984 presented a technique according to which, after anterior standard cervical discectomy, he accomplished the usual fusion by using methacrylate with excellent results. In 1985, I became aware of the technique and learned the details of the procedure from this brilliant neurosurgeon. With slight modification, I have used his technique with great success. Because Cruickshank died (1988) unfortunately soon after his preliminary report, his technique is worthy of being presented here so it can be explored by others.
Material and Method
From January 1985 until January 1993, 81 patients, aged 22-84, were operated on. Because of a short follow-up period 10 of these patients have been excluded from this review. Of the 71 remaining patients, there were 32 females and 39 males. Their ages ranged from 22 to 84. Of 81, 65 patients were between 30 and 60 years of age. Minimum follow-up was for 2 years and 2 months, and maximum follow-up was for 6 years.
All patients were suffering from severe neck and arm(s) pain, and radiculopathy, for between a minimum of 3 months and a maximum of 7 years, and had not responded to the usual cervical immobilization and other modes of conservative management. All patients had sensory deficits, motor weakness, or both in one or both upper extremities. Three patients over 70 years of age were suffering from cervical myelopathy.
Fusion was carried out at one level, namely C5-C6, in 44 patients and C6-C7 in seven patients, C3-C4 in two cases, two levels in 14 patients, and three levels in four patients. All patients except for two were in the hospital for 1-2 days. One patient was in the hospital 4 days; the other was in hospital for 5 days. No postoperative neck immobilization was required for any of these patients. All patients except two under 65 years of age returned to work in 1-2 weeks, all of them returned to their previous jobs, and no postoperative neck immobilization was required.
All patients had subjective signs and symptoms of cervical herniation of a disc. The diagnoses normally were reconfirmed by either myelogram and CAT scan or MRI and electromyogram.
All patients were informed that there is an alternative procedure, in which a bone graft from either the pelvis of the patient or a bone bank could be used for the procedure. All patients were given information about the procedure and all signed informed consents. Two patients had previous surgery with bone graft; the second operation was required in a second adjacent disc. These patients were particularly pleased with this new technique.
The surgery was carried out under general anesthesia. A Hartel traction was applied on the neck while the neck was hyperextended. We put a plastic bag of normal saline beneath the neck and between the shoulders. Standard anterior approach was made through a transverse incision on the right side of the neck: The subcutaneous tissue was infiltrated with 1% xylocaine with epinephrine. The skin and platysma were cut transversely. The automatic retractor was applied, and the deep fascia was opened obliquely at the anterior edge of the sternocleidomastoid muscle. Then, a gap between the carotid sheath and trachea and esophagus was opened laterally and medially, respectively, by blind dissection using two U.S. Army retractors.
The anterior aspect of the cervical spine was exposed, and the longissimus colli were identified. The level of the intended operation was checked by putting a mark on the involved disc; this was reconfirmed with X-ray. Then the standard anterior discectomy was carried out through a fenestration of the disc approximately 10 x 12 mm.
An attempt was made to evacuate all degenerative parts of the discs. Normally, the posterior longitudinal ligament is exposed, but was not opened intentionally. After completing the discectomy, traction was applied on the neck. Using an angled curette and pituitary rongeur the lateral recess was evacuated.
Using a sharp ring curette, a biconcavity cavity was created between the end plate of the above and below vertebrae, approximately 12 mm radiation. On many occasions, there was some bleeding from the curetted bone which was controlled by using Gel foam.
Next, the anterior aspect of the posterior longitudinal ligament was covered with a piece of Gel foam 3 x 5-6 mm. While traction between 15 and 20 pounds was applied on the neck, the space was opened 1-2 mm, creating a larger cavity, which was filled with low-viscosity methyl methacrylate. (The methyl methacrylate was prepared by the nurse and poured in 5-cc syringes with a no.14 IV catheter.) We cut the catheter short, about 6 cm, and poured the bone cement inside the disc space while traction was applied on the neck by the anesthesiologist. With this amount of traction it is customary to open a 1 – 2 mm inter vertebral space. Then 1.5 to 2 cc of methyl methacrylate was poured in the space. Traction was held constant until the bone cement was hardened. The methyl methacrylate glue loses some heat when it changes from the soft stage to the hard stage. With the small amount that we were using, this heat loss was not important. Second, its volume increases as it hardens. Then the traction was released, and the stability of the neck was tested. (Depending on the circumstances, an X-ray is occasionally taken in the operating room.) We closed the surgical wound in standard fashion and left a 0.25 inch Pen rose drain inside of the wound.
The drain was removed postoperative day 1, and the patient was ambulated and send home without any external neck immobilization, at 1 day after surgery.
All of these patients were operated upon by the senior author. The clinical results were assessed by sending a questionnaire to the patients, and clinically they have been assessed by the second authors independently.
All patients except two had complete or nearly complete relief of the pain after the surgery. All patients except two were in the hospital for 1 night. All patients except three between 22 and 65 returned to work 1-2 weeks after surgery. Two of those patients had multiple injuries including multiple back surgery and went to total disability. Pain persisted in one young girl who sought a second opinion. That physician sharply disagreed with this technique and revised the surgery at 3 months after the initial procedure. He attempted to fuse with autologous bone graft from her pelvis, and the donor site became infected. As a result, the patient was hospitalized for 27 days and, unfortunately, is still in pain.
The results for the rest of the patients have been very satisfactory. Postoperative and subsequent X-rays have shown body fusion in all of these patients. In two patients, a fibrous union was recognized, but clinically they were symptom free.
There was one patient in this series who had a C4-C5 fusion, using autogenous iliac graft. At 2 years after surgery the patient was still unable to work and complained of pain in the neck that radiated to the left arm. At the time of surgery, the surgeon informed the patient that there was another disc, which he did not regard at the time as being bad enough to require surgery. At 2 years later, C5-C6 showed degenerative herniation with impingement of the nerve at this level. The patient was told about the Cruickshank technique and underwent the surgery. His symptoms were relieved immediately and at 5 days post surgery, he returned to work as an electrician. A second patient with similar experiences confirmed the advantage of this new technique. Of all these patients, five cases are described as examples below.
Case Number 1
A 68-year old man, well-developed and well-nourished for his age, was suffering from low neck pain and right arm and forearm pain for 6 years and 2 months. Because the pain was so severe, he was unable to lie down and had to sleep on a couch for the last three months of that period. All other treatment, including multi-epidural block, did not relieve his symptoms. Two days after surgery with the Cruickshank procedure he was absolutely symptom free. He returned to work in a matter of days and at 6 years later, he is symptom free.
Case Number 2
A 35-year old woman with a 2-year history of neck pain radiating to both arms was unable to go to work and underwent the surgery. Two weeks after surgery, she was able to return to work and has worked symptom-free for 10-12 hours per day ever since.
Case Number 3
A 64-year old woman with difficulty in walking and numbness all over her body was diagnosed with myelopathy of the cervical spine and had surgery at two levels: C5-C6 and C6-C7. Two days after surgery, she was able to walk without a cane and at 2.5 years later, she is symptom-free.
Case Number 4
A 52-year old woman was out of work for 18 months because of neck pain radiating to both arms. The pain caused her to drop objects from her right hand. She underwent this surgery, and at 1 day post op, all of her symptoms disappeared completely. At 1 month later, she started her job an is symptom-free six years later.
The Smith and Robinson technique and Cloward procedure are actually over 40 years old. Their relevant complications (sometimes frightening) are well documented in the literature, and mortality may be associated with neural or esophageal injury.
Unfortunately, plunging an instrument into the spinal cord and slippage of a graft have been accompanied by serious spinal cord injury. The incidence of myelopathy has been reported in between 0.35% - 1.8% of cases. Esophageal perforation and injury has been reported in the literature.
Recurrent laryngeal nerve injury has been reported in between 1% and 11% of cases. However, complications associated with the bone graft and fusion are more common. Extrusion of graft usually occurs anteriorly away from the spinal cord, and it can be associated with dysphagia, tracheal obstruction, kyphotic deformity, and neurological symptoms. Anterior dislodging of the graft is reported in between 1% and 13% of cases.
Pseudoarthrosis anterior cervical fusion has been reported in between 12% and 26% of cases.
The failure of anterior cervical fusion has been reported in between 10% and 26% of cases.
When we compare the results of our series, however small, with the literature, the following results are evident: There was no slippage of the graft, no nonunion, and no neurological deficits after surgery. For this reason, we think this new surgery to be a very worthwhile approach.
Methyl methacrylate has been used in orthopaedic surgery and neurosurgery for over 30 years, with various satisfactory results. However, the use of methyl methacrylate in the wrong indication may be disastrous. Methyl methacrylate has been used and reported in the literature on patients who have developed massive sepsis as a result of such surgery. Bone cement does not attach to cortical bone, and wire fixation used in conjunction with methyl methacrylate soon loosens, and the reduction will be lost.
Methyl methacrylate also has been used for posterior stabilization of metastatic lesion of the body of vertebrae, and the result has been disastrous. For this reason, the use of methyl methacrylate for spine stabilization has been condemned. The use of a massive amount of bone cement in replacing the body of cervical vertebrae has been accompanied by significant displacement and disastrous results.
With our technique, one should realize that methyl methacrylate is used in a completely closed cavity, with maximum distraction. When the methyl methacrylate is hardened, we have proven that it will increase in volume and produce further distractive compression between two vertebrae. As a result, two vertebrae will be locked together and nature will produce bone around this constructed fixed material, in time. Methyl methacrylate does not stick to the vertebrae and bone will not attach to methyl methacrylate.
In terms of heat production by methyl methacrylate, we note to our orthopaedic colleagues that the amount we use is very small, about 2 ml. Furthermore, posterior longitudinal ligament and the dura and foraminae are covered by Gel foam. There is no chance that a little heat would harm neural tissues. Similarly, neurosurgeons have questioned us about fusion in the face of methyl methacrylate. In answer to this, we note that the distraction technique in orthopaedic surgery is well known, that is, distraction and fusion of the ankle joint: While ligaments of the ankle are intact, a large bone graft is pushed with force inside of the joint. This stabilizes the joint, and fusion takes place over time. Similarly,
when the majority of the annulus fibers are intact, traction will open the foraminae 1-2 mm. In this situation, the posterior longitudinal and foraminae are covered by Gel foam and the cavity between end plates of the above and below vertebrae is filled with methyl methacrylate. This will produce immobilization between the two vertebrae. In time, normally 4-6 months, bone healing will proceed around the methyl methacrylate across the adjacent vertebrae. Experimental work by the senior author has shown that immobilization of the knee of rabbits for 9 months leads to complete fusion of the knee. Similarly, immobilization of two vertebrae by using methyl methacrylate leads to fusion.
Additional advantages of methyl methacrylate is that, unlike bone graft, it will not shrink, and will not develop necrosis. As a result, the inter vertebral foramina will be opened, and will be kept open until the bone fusion is completed. However, we must emphasize that sepsis is a potential risk when using methyl methacrylate, but when using prophylactic antibiotic, we never encountered any infection in this series.
Other authors who use methyl methacrylate and have been encouraged by the results are Taheri, Genest, and Kurts. The senior author had the honor to be the Chairman of a Symposium on Cervical Spine Surgery sponsored by the International College of Surgeons held in Washington, D.C., in April 1987. During this symposium, Dr. James Cruickshank was alive and chaired a round table during that meeting. There was inquiry from the faculty, and altogether, it was reported that 861 surgeries using methyl methacrylate for cervical disc fusion had been used by seven surgeons.
Only one case of dislodging of methyl methacrylate was reported. A 60-year old woman was at her hairdresser 3 weeks after surgery. While her hair was being shampooed, her neck was hyperextended, and the methal methacrylate popped out. The patient was rushed to the hospital and the surgery was revised. Luckily, the result was equally good. For this reason, hyper-extension of the neck is not recommended until 3 months after surgery.
Other motions of the neck can start 1-2 days after surgery. With limited experience, we firmly believe that this procedure compares favorably with the previous technique and, therefore, it is worthy of consideration.
A new technique for the anterior cervical fusion following cervical discectomy is described (Cruickshank Procedure). The results of the first 61 cases, followed from 2 years and 2 months to 6 years are presented. A short review of the literature is carried out, and the results are compared, and contrasted.