High Risk Multi-level Cervical Fusion
Adjunct Use of a Bone Growth Stimulator
A pleasant 65-year-old female had an anterior cervical discectomy and fusion (ACDF) performed at the C6-C7 level 6 years prior to presentation. She is 5'-3" tall and weighs 194 pounds. Her past medical history is notable for hypertension, asthma and hypercholesterolemia. She is a smoker; half a pack of cigarettes per day for the past 26 years. The patient is gainfully employed as a laborer on an assembly line.
Since the ACDF, she has experienced chronic neck pain. New symptoms have developed during the past 4 months. Using the visual analog scale (1 to 10, with 10 being the worse pain imaginable) she grades her pain as 10/10 in severity. Pain radiates down her left shoulder and into the biceps muscle. Other symptoms include:
- Hands: Bilateral loss of coordination, numbness, weakness. Reports she drops objects.
- Gait: Unstable with an unsteady feeling when upright on her feet.
The patient has full and symmetric strength in her upper extremities with the exception of her left bicep and extensor carpi radialis; both are 4/5. Sensation is grossly intact to light touch and pinprick bilaterally. Her reflexes are brisk; 3/4 bilaterally for biceps and brachioradialis. She has a prominent Hoffman's sign bilaterally and 2 beats of ankle clonus on the left. When ambulating, the patient has a waddling gait. A Spurling maneuver to the left reproduces her shoulder and biceps pain.
Non-steroidal anti-inflammatory drugs (NSAIDs)
Magnetic resonance imaging (Fig. 1A) demonstrates multi-level cervical spondylosis. At the C5-C6 level in Figure 1B, a posterior osteophyte effaces the spinal cord, and uncovertebral arthropathy results in severe left C5-C6 neuroforaminal stenosis.
Figure 2 is a sagittal CT demonstrating a pseudoarthrosis at C6-C7.
Dynamic cervical radiographs with flexion (Fig. 3A) and extension (Fig. 3B) demonstrate 3mm of mobile subluxation at C3-C4 and C4-C5.
In this case, the patient presents with symptoms and signs of both myelopathy and cervical radiculopathy. The weakness, numbness, and loss of coordination in her hands, along with gait instability, are all symptoms worrisome for myelopathy. Although the degree of central canal stenosis is not severe on the sagittal MRI (Fig. 1A), the bilateral Hoffman's sign and ankle clonus strongly suggests the patient is myelopathic. The distribution of pain and weakness in the left arm were both consistent with a left C6 radiculopathy, which corresponded well with the C5-C6 neuroforaminal stenosis noted on the MRI scan (Fig. 1B).
Suggest TreatmentIndicate how you would treat this patient by completing the following brief survey. Your response will be added to our survey results below.
Note to Physicians: Recombinant human Bone Growth Protein-2 is considered off-label use in cervical spine fusion surgery. Please see the package insert for a complete list of indications, warnings, precautions and other important medical information.
Note to Patients: Spine surgery is not for all patients. Please consult your doctor for information about treatment indications, warnings, precautions, and other important medical information.
Since the patient is apparently myelopathic with radicular weakness, surgery is strongly indicated. Clearly, the C5-C6 level must be addressed to decompress the central canal and left neuroforamen. However, due to the pseudoarthrosis at C6-C7 and the mobile subluxation at C3-C4 and C4-C5, it is decided that all 4 levels from C3-C4 to C6-C7 be included in the construct to avoid ending a construct adjacent to a level of instability. Unfortunately, the patient has multiple risk factors for developing a pseudoarthrosis in the setting of a four-level cervical fusion surgery. Smoking, obesity, and advanced age are all potential risk factors for developing a pseudoarthrosis in the patient.1 Most concerning, though, is the presence of a pseudoarthrosis from a previous single-level ACDF, which is a surgery with an arthrodesis rate of over 95%.2 Knowing that constructs involving more levels tend to have a higher pseudoarthrosis rate,2,3 a four-level fusion surgery in this patient offers a very high chance of developing a pseudoarthrosis.
A multi-modality approach was applied to this patient to minimize the risk of a pseudoarthrosis developing.
1. Pre-operative smoking cessation and weight loss programs
2. An anterior and posterior surgery, including anterior cervical discectomies and placement of interbody grafts along with posterior stabilization with lateral mass (C3-C5) and pedicle (C7) screws. Bone morphogenic protein (BMP) was not used because it can significantly increase neck swelling and dysphagia in anterior cervical discectomy and fusion cases.4
3. Post-operative use of a Pulsed Electromagnetic Fusion (PEMF) stimulator for several months after surgery.
Using this combined strategy, the patient underwent the four-level fusion surgery and developed a solid arthrodesis at all four levels within a year (Fig. 4).
Surgeon's Rationale: PEMF
There is a substantial amount of literature to show the efficacy of PEMF (Pulsed Electromagnetic Field) bone growth stimulation. The studies show that patients, in particular those with high risk factors such as obesity, smoking, diabetes, and multi-level fusions are key candidates to use the device as an adjunct to fusion surgery.
The Cervical-Stim® (Orthofix® Spine Stimulation, Lewisville, TX) bone growth stimulator prescription was necessary in this case considering the patient's high chance of nonunion. Her risk factors going into the multi-level fusion: obesity, smoking, advanced age, and failed single-level fusion. With a combined strategy incorporating proper surgical technique, and bone growth stimulation, a solid arthrodesis formed at all 4 levels within one year.
Post-operatively, a left C5 palsy resolved within 6 months. On examination during follow-up one year after surgery, the patient has full strength with no Hoffman's sign bilaterally and her gait is normal. She has no arm pain, although she notes considerable neck stiffness.
A lateral radiograph one year after surgery demonstrates solid arthrodesis from C3 to C7 (Fig. 4).
1. Phillips et al. Anterior Cervical pseudoarthrosis. Natural history and treatment. Spine. 1997; 22(14) 1585-9.
2. Wang J, McDonough P, Endow K, et al. The effect of cervical plating on single-level anterior cervical discectomy and fusion. Journal of Spinal Disorders. 1999 Dec;12(6):467-71.
3. Wang J, McDonough P, Kanim L, et al. Increased fusion rates with cervical plating for three-level anterior cervical discectomy and fusion. Spine. 2001 Mar 15;26(6):643-6.
4. Buttermann G. Prospective nonrandomized comparison of an allograft with BMP versus iliac-crest autograft in anterior cervical discectomy and fusion. The Spine Journal. 2008 May;8(3):426-35.
Dr. McCall provides an interesting and difficult clinical case scenario, which unfortunately is not that uncommon. How do you treat a patient with a spinal pseudoarthrodesis, such that it does not happen again? This case is further complicated in that the patient now requires further surgical treatment for adjacent level disease. In this case, Dr. McCall and his team must be commended on their excellent treatment of this patient and the clinical outcome.
In his initial assessment Dr. McCall noted the cervical pseudoarthrosis and, more importantly, he recognized that the patient remained an exceptionally high risk for the development an additional pseudoarthrosis with further surgical intervention. This increased risk is based not only on the patient's history of not being able to obtain a solid arthrodesis in the setting of a single-level anterior cervical discectomy and fusion with allograft. She also has the further risks of continued tobacco usage and attempting to obtain an arthrodesis at the junctional region with a long lever-arm.
The patient presents for evaluation with a new onset of pain over the last four months, which she grades as 10/10 in severity. Since the pain is "new" one would infer that these symptoms are not related to her previous pseudoarthrosis. This pseudoarthrosis has been stable for what appears to be over five years and asymptomatic. This is an important point, since not all patients with a pseudoarthrosis require treatment and this is particularly true if the patient is asymptomatic.
The main clinical presenting symptom appears to be the acute to subacute C6 radiculopathy. The imaging studies (MRI) clearly illustrate severe foraminal stenosis at C5-C6 which is the most likely cause for her symptoms.
This patient had Hoffmann's signs which would not be expected in a 65-year-old female and, therefore, may be suggestive of myelopathy. Further, the new and progressive symptoms of loss of fine movements and gait difficulties would suggest a more recent progression of her myelopathy rather than residual from prior surgery and spinal compression.
The presence of a cervical myelopathy in the post-operative setting can be a diagnostic dilemma. Specifically in this case, the Hoffmann's signs and leg clonus may be residual long-tract signs from her prior compression and spinal cord injury which did not resolve after of the her surgical decompression. The persistence of residual long tract signs is quite common in post-operative myelopathic patients. However, in this particular patient, the author was able to localize the pathologic compression proximal to the prior surgical site. This was apparent due to her brisk reflexes in the biceps and brachioradialis muscles or at a proximal C6 level. Therefore, with a patient with prior spinal surgery one must correlate their symptoms and neurologic exam with the radiographs to determine if further spinal cord compression in the etiology of their progressive myelopathy.
Once surgical treatment was determined to be necessary, the next question arises as to surgical approaches. She appears to have greatest degree of cord compression at C5-C6 level which is the adjacent level to the prior C6-C7 pseudoarthrosis. Further assessment of the plain radiographs illustrates the patient to have a kyphotic cervical spine with the apex at C4-C5 and a degenerative subluxation at C3-C4 and C4-C5 levels.
Therefore, the goals and objectives of surgery should be to decompress the spinal cord and eliminate the painful radiculopathy. Dr. McCall, in reviewing the options for treatment, notes several options including proceeding with an anterior approach alone, anterior posterior or posterior surgery alone. In addition he includes the options of utilizing bone morphogenic protein (BMP) as an adjuvant.
In this patient, due to her ventral compression as well as kyphotic cervical spine, I would agree with an anterior approach. I would also agree with the avoidance of bone morphogenic protein in the anterior cervical setting due to the numerous reports of anterior cervical swelling and dysphagia. Further due to the increased risk of a pseudoarthrosis a multiple level decompression and fusion would be aided by a concurrent posterior fusion. I believe it is reasonable to proceed with decompression and fusion from C3-C7. An alternative would be to decompress and fuse only the C5-C and C6-C7 levels, and monitor the patient closely.
In this particular case, the author has identified several potential risk factors for pseudoarthrosis. As in all surgical cases, some factors may be minimized with patient education as well as using alternative surgical approaches and techniques. In this patient, pre-operative smoking cessation was imperative, as this is the single greatest risk factor for developing a pseudoarthrosis. Secondly, using an anterior and posterior approach provides excellent stabilization, as well as immobilization, and further utilizes the anterior compression to maximize the development of solid fusion. Lastly, the use of a pulsed electromagnetic fusion stimulator for several months after surgery further improves the patient's chance for a solid arthrodesis.
In this patient that already had a confirmed pseudoarthrosis in addition to several other risk factors, the use of the electromagnetic stimulator is an additional influence that helps assure an arthrodesis. Electrical stimulation in spinal fusions has been shown to enhance fusion in the lumbar spine surgeries.1 These devices generate an electromagnetic field1-4 which promotes cellular activity, but in order to be successful must be between worn two to four hours5,6 a day for an extended period of time, three to six months post-operatively. The Goodwin study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusion required patients to wear the device 24 hours each day and suggested that patient compliance can become as issue.1 Therefore, in the patient population with risk factors for pseudoarthrosis, the concurrent use of a pulsed electromagnetic field stimulator may provide for establishing of a solid union and improved patient outcomes.5,6
1. Goodwin CB, et al. Improved outcomes in the patient population utilizing simulators with posterolateral fusions. Spine, Vol. 24 (13) 1999, 1349-57.
2. Kane WJ. Direct current electrical bone growth stimulation for spinal fusion. Spine. 1988 Mar;13(3):363-5.
3. Gan JC, Glazer PA. Electrical stimulation therapies for spinal fusions: current concepts. European Spine Journal. 2006 15:1301-1311. Accessed October 14, 2010. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2438580/pdf/586_2006_Article_87.pdf
4. Linovitz RJ, Pathria M, Bernhardt M, et al. Combined Magnetic Fields Accelerate and Increase Spine Fusion. A double-blind, randomized, placebo-controlled study. Spine 2002 Jul 1;27(13):1383-9; discussion 1389.
5. Foley KT, Mroz TE, Arnold PM, et al. Randomized, prospective, and controlled clinical trial of pulsed electromagnetic field stimulation for cervical fusion. The Spine Journal 2008 May-Jun;8(3):436-42.
6. Simmons JW Jr, Mooney V. Thacker I. Pseudarthrosis after lumbar spine fusion: non-operative salvage with pulsed electromagnetic fields. American Journal of Orthopedics. 2004 Jan;33(1): 27-30.