Pseudarthrosis after four-level anterior cervical discectomy and fusion without posterior fixation.

OBJECTIVE: Fusion rates and long-term outcomes are well established for anterior cervical discectomy and fusion (ACDF) of 3 levels or fewer, but there is a paucity of similar data on 4-level fusions. The authors evaluated long-term fusion rates and clinical outcomes after 4-level ACDF without supplemental posterior instrumentation. METHODS: The authors retrospectively reviewed patients who underwent 4-level ACDF at a single institution with at least 1-year of radiological follow-up. Fusion was determined by measuring change in interspinous distance at each segment on dynamic radiographs or by the presence of bridging bone on CT scans at minimum 1-year follow-up. Clinical outcomes were assessed using Neck Disability Index and Short Form-36. RESULTS: A total of 63 patients (252 levels) met the inclusion criteria for the study, with a mean follow-up of 2.6 years. Complete radiographic fusion at all 4 levels was observed in 26 patients (41.3%). Of the 37 patients (58.7%) with radiographic pseudarthrosis, there was a mean of 1.35 nonfused levels. The fusion rate per level, however, was 80.2% (202/252 levels). The most common level demonstrating nonunion was the distal segment (C6-7), showing pseudarthrosis in 29 patients (46.8%), followed by the most proximal segment (C3-4) demonstrating nonunion in 9 patients (14.5%). The mean improvement in Neck Disability Index and Short Form-36 was 15.7 (p < 0.01) and 5.8 (p = 0.14), respectively, with improvement in both scores surpassing the minimum clinically important difference. One patient (1.6%) required revision surgery for symptomatic pseudarthrosis, and 5 patients (7.9%) underwent revision for symptomatic adjacent-segment disease. Patient-reported outcomes results are limited by the low rate of 1-year follow-up (50.8%), whereas reoperation data were available for all 63 patients. CONCLUSIONS: More than half of patients undergoing 4-level ACDF without posterior fixation demonstrated pseudarthrosis of at least 1 level-most commonly the distal C6-7 level. One patient required revision for symptomatic pseudarthrosis. Patient-reported outcomes showed significant improvements at 1-year follow-up, but clinical follow-up was limited. This is the largest series to date to evaluate fusion outcomes in 4-level ACDF.

Establishing a Reference Procedure Length for Anterior Cervical Fusions: The Role for Standards in Surgical Process Improvement.

Surgical process improvement strategies are increasingly being applied to specific procedures to improve value. A critical step in any process improvement strategy is the identification of performance benchmarks. Procedure length is a performance benchmark for anterior cervical discectomy and fusion (ACDF) procedures; therefore, we sought to establish reference procedure lengths for 1-level, 2-level, and 3-level ACDFs at both teaching and non-teaching institutions and to describe methods for using this information to advance surgical process improvement initiatives. We performed a retrospective analysis of consecutive ACDFs performed at a resident teaching institution (RT) and a non-teaching institution (NT) for all 1-level, 2-level, and 3-level ACDFs. Mean case lengths and patient outcomes were calculated for individual surgeons and institutions. After limiting cases to 1-level, 2-level, and 3-level ACDFs and applying all exclusion criteria, 991 cases at the RT institution and 131 cases at the NT institution (a total of 1122 cases) were available for analysis. The mean (SD) procedure length for 1-level, 2-level, and 3-level ACDFs at the RT versus NT institutions were 121.9 min (36.3 min) and 73.6 min (29.7 min) (p<0.001), 172.7 min (44.8 min) and 112.0 min (43.0 min) (p<0.001), and 218.3 min (54.9 min) and 167.6 min (54.2 min) (p<0.001), respectively. Thirty-day outcomes were the same between institutions, except that the RT institution had a shorter mean hospital length of stay for 2-level ACDFs (1.6 days versus 2.9 days, p=0.001). This study is the first to attempt to establish a standard reference procedure length for 1-level, 2-level, and 3-level ACDFs. These data can guide efforts in surgical process improvement.

Failures in Thoracic Spinal Fusions and Their Management.

Instrumented fixation and fusion of the thoracic spine present distinct challenges and complications including pseudarthrosis and junctional kyphosis. When complications arise, morbidity to the patient can be significant, involving neurologic injury, failure of instrumentation constructs, as well as iatrogenic spinal deformity. Causes of fusion failure are multifactorial, and incompletely understood. Most likely, a diverse set of biomechanical and biologic factors are at the heart of failures. Revision surgery for thoracic fusion failures is complex and often requires revision or extension of instrumentation, and frequently necessitates complex soft tissue manipulation to manage index level injury or to augment the changes of fusion.

Implementation of a Standardized Multimodal Postoperative Analgesia Protocol Improves Pain Control, Reduces Opioid Consumption, and Shortens Length of Hospital Stay After Posterior Lumbar Spinal Fusion.

BACKGROUND: Multimodal analgesia regimens have been suggested to improve pain control and reduce opioid consumption after surgery. OBJECTIVE: To institutionally implement an evidence-based quality improvement initiative to standardize and optimize pain treatment following neurosurgical procedures. Our goal was to objectively evaluate efficacy of this multimodal protocol. METHODS: A retrospective cohort analysis of pain-related outcomes after posterior lumbar fusion procedures was performed. We compared patients treated in the 6 mo preceding (PRE) and 6 mo following (POST) protocol execution. RESULTS: A total of 102 PRE and 118 POST patients were included. The cohorts were well-matched regarding sex, age, surgical duration, number of segments fused, preoperative opioid consumption, and baseline physical status (all P > .05). Average patient-reported numerical rating scale pain scores significantly improved in the first 24 hr postoperatively (5.6 vs 4.5, P < .001) and 24 to 72 hr postoperatively (4.7 vs 3.4, P < .001), PRE vs POST, respectively. Maximum pain scores and time to achieving appropriate pain control also significantly improved during these same intervals (all P < .05). A concomitant decrease in opioid consumption during the first 72 hr was seen (110 vs 71 morphine milligram equivalents, P = .02). There was an observed reduction in opioid-related adverse events per patient (1.31 vs 0.83, P < .001) and hospital length of stay (4.6 vs 3.9 days, P = .03) after implementation of the protocol. CONCLUSION: Implementation of an evidence-based, multimodal analgesia protocol improved postoperative outcomes, including pain scores, opioid consumption, and length of hospital stay, after posterior lumbar spinal fusion.

Effects of Anterior Plating on Clinical Outcomes of Anterior Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review. OBJECTIVE: To compare surgical outcomes of patients who have undergone anterior lumbar interbody fusion (ALIF) with and without plating. SUMMARY OF BACKGROUND DATA: In biomechanical testing, ALIF constructs supplemented with plating (ALIFP) reduce range of motion and increase construct stiffness compared with ALIF alone. However, whether ALIFP constructs translate into improved clinical outcomes over ALIF alone is unknown. METHODS: From 2004 through 2010, 231 patients underwent ALIF with (146) or without (85) plating. Eight patients lost to follow up were excluded from final evaluation. Patients' records were evaluated retrospectively for demographics, complications, and outcomes. RESULTS: At a mean follow-up of 13.7 months (range, 1-108 mo), the mean Economic, Functional, and Total Prolo scores for ALIF patients were 4.23, 3.63, and 7.87, respectively. The mean Oswestry Disability Index (ODI) was 24%. At a mean follow-up of 11.2 months (range, 1-93 mo), the mean Economic, Functional, and Total Prolo scores for ALIFP patients were 4.28, 3.67, and 7.95, respectively. The mean ODI was 22.9%. There was no significant difference between rate of complications or Prolo scores or ODI between the 2 groups (t test). Neither diabetes, hypertension, smoking, sex, nor age older than 55 years was significantly related to whether patients had higher Prolo scores with or without plating. Patients with a normal body mass index and ALIF had significantly better Prolo Economic scores and total scores than patients with a normal body mass index and ALIFP (P=0.04 and 0.02, independent samples t test). Patients were also stratified by surgical indication for surgery, and there was no significant difference in Prolo scores or ODI for patients who underwent ALIF alone versus ALIFP. CONCLUSIONS: Even when stratified by indication for surgery, anterior plating does not seem to improve Prolo scores or ODI, suggesting that not all patients undergoing ALIF require plating.

The Influence of Common Medical Conditions on the Outcome of Anterior Lumbar Interbody Fusion.

STUDY DESIGN: The authors retrospectively reviewed a consecutive series of 231 patients with anterior lumbar interbody fusion (ALIF). OBJECTIVE: To determine the correlations among common medical conditions, demographics, and the natural history of lumbar surgery with outcomes of ALIF. SUMMARY OF BACKGROUND DATA: Multiple spinal disorders are treated with ALIF with excellent success rates. Nonetheless, adverse outcomes and complications related to patients' overall demographics, comorbidities, or cigarette smoking have been reported. METHODS: The age, sex, body mass index (BMI), comorbidities, history of smoking or previous lumbar surgery, operative parameters, and complications of 231 patients who underwent ALIF were analyzed. Regression analyses of all variables with complications and surgical outcomes based on total Prolo scores were performed. Two models predicting Prolo outcome score were generated. The first model used BMI and sex interaction, whereas the second model used sex, level of surgery, presence of diabetes mellitus, and BMI as variables. RESULTS: At follow-up, the rate of successful fusion was 99%. The overall complication rate was 13.8%, 1.8% of which occurred intraoperatively and 12% during follow-up. The incidence of complications failed to correlate with demographics, comorbidities, smoking, or previous lumbar surgery (P>0.5). ALIF at T12-L4 was the only factor significantly associated with poor patient outcomes (P=0.024). Both models successfully predicted outcome (P=0.05), although the second model did so only for males. CONCLUSIONS: Surgical level of ALIF correlated with poor patient outcomes as measured by Prolo functional scale. BMI emerged as a significant predictor of Prolo total score. Both multivariate models also successfully predicted outcomes. Surgical or follow-up complications were not associated with patients' preoperative status.

Spondylolysis outcomes in adolescents after direct screw repair of the pars interarticularis.

OBJECT: Isthmic spondylolysis can significantly decrease functional abilities, especially in adolescent athletes. Although treatment can range from observation to surgery, direct screw placement through the fractured pars, or Buck's procedure, may be a more minimally invasive procedure than the more common pedicle screw-hook construct. METHODS: Review of surgical databases identified 16 consecutive patients treated with Buck's procedure from 2004 to 2010. Twelve patients were treated at Miami Children's Hospital and 4 at Barrow Neurological Institute. Demographics and clinical and radiographic outcomes were recorded and analyzed retrospectively. RESULTS: The 16 patients had a median age of 16 years, and 14 were 20 years or younger at the time of treatment. Symptoms included axial back pain in 100% of patients with concomitant radiculopathy in 38%. Pars defects were bilateral in 81% and unilateral in 19% for a total of 29 pars defects treated using Buck's procedure. Autograft or allograft augmented with recombinant human bone morphogenetic protein as well as postoperative bracing was used in all cases. Postoperatively, symptoms resolved completely or partially in 15 patients (94%). Of 29 pars defects, healing was observed in 26 (89.6%) prior to 1 revision surgery, and an overall fusion rate of 97% was observed at last radiological follow-up. There were no implant failures. All 8 athletes in this group had returned to play at last follow-up. CONCLUSIONS: Direct screw repair of the pars interarticularis defect as described in this series may provide a more minimally invasive treatment of adolescent patients with satisfactory clinical and radiological outcomes, including return to play of adolescent athletes.

Cervical spinal cord infarction after cervical spine decompressive surgery.

OBJECTIVE: To report five patients who underwent cervical decompressive surgeries and developed persistent postoperative neurologic deficits compatible with spinal cord infarctions and evaluate causes for these rare complications. METHODS: The clinical courses and imaging studies of five patients were retrospectively analyzed. Imaging findings, types of surgeries, vascular compromise or risk factors, hypotensive episodes, intraoperative somatosensory evoked potentials, concomitant brain infarctions, and clinical degree and radiographic extent of spinal cord infarction were studied. The presence of spinal cord infarction was determined by clinical course and imaging evaluation. RESULTS: All five patients had antecedent cervical cord region vascular compromise or generalized vascular risk factors. Four patients developed hypotensive episodes, two intraoperatively and two postoperatively. None of the four patients with hypotensive episodes had imaging or clinical evidence of concomitant brain infarctions. CONCLUSIONS: Neuroimaging evaluation of spinal cord infarction after decompressive surgery is done to exclude spinal cord compression, to ensure adequate surgical decompression, and to confirm infarction by imaging. Antecedent, unrecognized preoperative vascular compromise may be a significant contributor to spinal cord infarction by itself or in combination with hypotension.

Tumoral calcinosis presenting as a deformity of the thoracic spine.

The authors describe a rare case of tumoral calcinosis (TC) of the thoracic spine in a 13-year-old boy with thoracic scoliosis. The patient presented with a 2-year history of back pain. He had no personal or family history of bone disease, deformity, or malignancy. Magnetic resonance imaging revealed a heterogeneously enhancing mass involving the T-7 vertebral body and the left pedicle. Computed tomography findings suggested that the mass was calcified and that this had resulted in scalloping of the vertebral body. The lesion was resected completely by using a left T-7 costotransversectomy and corpectomy. The deformity was corrected with placement of a vertebral body cage and pedicle screw fixation from T-5 to T-9. Pathological analysis of the mass demonstrated dystrophic calcification with marked hypercellularity and immunostaining consistent with TC. This represents the third reported case of vertebral TC in the pediatric population. Pediatric neurosurgeons should be familiar with lesions such as TC, which may be encountered in the elderly and in hemodialysis-dependent populations, and may not always require aggressive resection.

Surgical management of coccidioidomycosis of the spine: clinical article.

OBJECT: Coccidioides immitis is a dimorphous fungus endemic in the southwestern US and northern Mexico. While its primary presentation is pulmonary, it can have devastating neurological sequelae. METHODS: The authors provide a retrospective review with long-term follow-up between 1986 and 2008 at a single institution. RESULTS: The authors identified 27 patients between 13 and 81 years old (mean 41.4 years) with spinal coccidioides who were treated surgically at the Barrow Neurological Institute between 1986 and 2008. There were 24 males (89%) and 3 females (11%). Eleven patients (41%) had cervical spine involvement, 15 (56%) had thoracic involvement, 7 (26%) had lumbar involvement, and 2 (7%) had sacral involvement. All 27 patients presented with localized or radiating pain. Nine patients (33%) had myelopathic symptoms at presentation, 5 (19%) had radiculopathy, 4 (15%) had fever, and 12 (44%) had progressive kyphosis. The disease was most frequently seen among African American patients (14 patients [52%]), followed by Caucasians (5 patients [19%]), Asians (3 patients [11%]), and Hispanics (3 patients [11%]). Ten patients (37%) required multiple operations at the same level. Follow-up was available in 19 patients (70%) (mean 9.8 months, range 1-39 months). Sixteen (84%) of these 19 patients improved from their preoperative baseline states, 1 (5%) was stable on examination, 1 patient's condition (5%) deteriorated compared with the preoperative examination, and 1 patient (5%) died in the postoperative period. CONCLUSIONS: Although spinal involvement of coccidioidomycosis is relatively uncommon, a high index of suspicion and aggressive therapy are warranted to prevent devastating neurological injury, and lifelong antifungal therapy is often warranted.

Pott disease in a 13-month-old: case report.

BACKGROUND AND IMPORTANCE: Tuberculosis (TB) is a common disease worldwide that is caused by Mycobacterium tuberculosis. TB of the spine is the most common site of bony infection and is often referred to as Pott disease. To the best of our knowledge, our case represents the youngest patient with naturally acquired Pott disease in the United States. CLINICAL PRESENTATION: A 13-month-old boy presented with paraplegia and a known diagnosis of TB. His evaluation revealed a kyphotic gibbus deformity in the midthoracic region associated with severe spinal cord compression. The patient underwent urgent decompressive laminectomies, T2-T4 transpedicular corpectomies, placement of an anterior tibial strut graft, and posterior instrumentation with sublaminar wires and a Steinmann pin. At his 18-month follow-up, the patient was ambulating 5 steps at a time independently, and his kyphotic deformity showed no sign of progression. CONCLUSION: Pott disease can occur in very young children and presents a unique challenge when a patient presents with a neurological deficit and unstable deformity requiring surgical intervention.

Surgical technique and outcomes in the treatment of spinal cord ependymomas: part II: myxopapillary ependymoma.

BACKGROUND: Myxopapillary ependymomas usually occur in the filum terminale of the spinal cord. OBJECTIVE: This report summarizes our experience treating myxopapillary ependymomas. METHODS: The records of 34 patients (14 men, 20 women; mean age 45.5 years; age range, 14-88 years) who underwent resection of a myxopapillary ependymoma between 1983 and 2006 were reviewed for age, sex, tumor location, symptoms at diagnosis, duration of symptoms, treatment before presentation, extent of surgical resection, adjuvant therapy, length of follow-up, evidence of recurrence, and complications. Neurological examinations performed at presentation, immediately after surgery, and last follow-up were graded according to the McCormick grading scale. RESULTS: The average duration of symptoms before diagnosis was 22.2 months. The most common symptom was pain followed by weakness, bowel/bladder symptoms, and numbness. The rate of gross total resection was 80%. All patients with a subtotal resection (20%) underwent postoperative radiation therapy. Presentation and outcomes of patients who underwent subtotal resection followed by radiation therapy were compared with those who underwent gross total resection. There was no significant difference in neurological grade between the groups at presentation or final follow-up. The overall recurrence rate was 10% (3/34 patients). CONCLUSION: The goal of surgical treatment of myxopapillary ependymomas is resection to the greatest extent possible with preservation of function. In cases of subtotal resection, postoperative radiation therapy may improve outcome. If neurological function is maintained at treatment, these indolent lesions allow years of good function.

Biomechanics of a lumbar interspinous anchor with transforaminal lumbar interbody fixation.

OBJECT: To study the stability offered by a clamping lumbar interspinous anchor (ISA) for transforaminal lumbar interbody fusion (TLIF). METHODS: Seven human cadaveric lumbosacral specimens were tested: 1) intact; 2) after placing ISA; 3) after TLIF with ISA; 4) with TLIF, ISA, and unilateral pedicle screws-rod; 5) with TLIF and unilateral pedicle screws-rod (ISA removed); and 6) with TLIF and bilateral pedicle screws-rods. Pure moments (7.5 Nm maximum) were applied in each plane to induce flexion-extension, axial rotation, and lateral bending while recording angular motion optoelectronically. Compression (400 N) was applied while upright foraminal height was measured. RESULTS: All instrumentation reduced angular range of motion (ROM) significantly from normal. The loading modes in which the ISA limited ROM most effectively were flexion and extension, where the ROM allowed was equivalent to that of pedicle screws-rods (P > .08). The ISA was least effective in reducing lateral bending, with this mode reduced to 81% of normal. TLIF with unilateral pedicle screws-rod was the least stable configuration. Addition of the ISA to this construct significantly improved stability during flexion, extension, lateral bending, and axial rotation (P < .008). Constructs that included the ISA increased the foraminal height an average of 0.7 mm more than the other constructs (P < .05). CONCLUSIONS: In cadaveric testing, the ISA limits flexion and extension equivalently to pedicle screws-rods. It also increases foraminal height. When used with TLIF, a construct of ISA or ISA plus unilateral pedicle screws-rod may offer an alternative to bilateral pedicle screws-rods for supplemental posterior fixation.

Microsurgical treatment of pediatric intracranial aneurysms: long-term angiographic and clinical outcomes.

BACKGROUND: Pediatric aneurysms are rare and complex to treat. Long-term angiographic and clinical data after microsurgical or endovascular therapies are lacking. OBJECTIVE: To study the clinical and radiographic outcomes in aneurysms in pediatric patients treated with microsurgery. METHODS: Between 1989 and 2005, 48 patients

Treatment of distal posterior cerebral artery aneurysms: a critical appraisal of the occipital artery-to-posterior cerebral artery bypass.

OBJECTIVE: This is the largest contemporary series of distal posterior cerebral artery (PCA) aneurysms treated by use of endovascular coiling and stenting as well as surgical clipping, clip wrapping, and bypass techniques. We propose a new treatment paradigm. METHODS: The location, size, type of aneurysm, clinical presentation, treatment, complications, and outcomes associated with 34 distal PCA aneurysms in 33 patients (15 females, 18 males; mean age, 44 years) were reviewed retrospectively. RESULTS: The most common presenting symptom was headache in 19 (58%) followed by contralateral weakness or numbness in 6 (18%) and visual changes in 4 (12%). Eight aneurysms were giant. Of the remaining 26 aneurysms, 17 were fusiform/dissecting, 5 were saccular, and 4 were mycotic. Treatment was primarily endovascular in 22 patients, 12 of whom also had a concomitant surgical bypass procedure. Nine patients underwent microsurgical clipping, and 3 underwent combined treatment of clipping and coiling and/or stenting. There were no significant differences in outcomes between the groups (P=.078). The recurrence rate in patients undergoing coiling was 22% and 0% in patients undergoing clipping. Fourteen aneurysms (41%) involved treatment with an occipital artery-to-PCA bypass or an onlay graft. Compared with their preoperative status, these patients had significantly worse outcomes than those without a bypass (P=.013). CONCLUSION: Bypass techniques for the treatment of distal PCA aneurysms are associated with a higher rate of complications than once thought. In our new treatment paradigm, bypass is a last resort and reserved for patients in whom balloon-test occlusion fails, who refuse parent-vessel sacrifice, and who cannot undergo primary stenting with coiling or clip wrapping.

Intracranial hemorrhage and spinal cord injury from a fractured C1-C2 sublaminar cable: case report.

OBJECTIVE: This is a unique case report of a fractured atlantoaxial interspinous multistranded cable leading to intracranial hemorrhage and spinal cord injury. CLINICAL PRESENTATION: A 61-year-old woman, with a history of rheumatoid arthritis and C1-C2 interspinous wiring with allograft for atlantoaxial instability, presented with neck pain and progressive decline in mental status. Prior to transfer to our institution from a referral hospital, imaging studies revealed progressive hydrocephalus with interval development of subarachnoid and fourth ventricular hemorrhage. Initial and repeat angiographic work-up was negative for vascular lesions. Magnetic resonance imaging revealed a subdural hematoma and signal changes at the cervicomedullary junction. Computed tomography of the cervical spine revealed a fractured interspinous cable, intradural penetration, and atlantoaxial instability. INTERVENTION: After ventriculostomy, both the patient's mental status and quadriparesis improved to a C on the American Spinal Injury Association (ASIA) scale. During surgery, the fractured cable and subdural hematoma were removed revealing an area of spinal cord impalement. She underwent C1-C3 lateral mass fixation with iliac crest autograft for fusion and was discharged to rehabilitation after a ventriculoperitoneal shunt was placed. At her 6-month follow-up, she was independent and had improved to ASIA E. Computed tomography confirmed fusion. CONCLUSION: Spinal instrumentation eventually fails from pseudarthrosis and can cause neurological injury. In patients with atlantoaxial instability, direct C1-C2 screw fixation with posterior interspinous wiring using autograft offers the best chance for fusion. Cervical spine pathology can cause intracranial hemorrhage, and unconventional causes of injury must be considered when routine workup is negative.

Formation of painful seroma and edema after the use of recombinant human bone morphogenetic protein-2 in posterolateral lumbar spine fusions.

BACKGROUND: The use of bone morphogenetic proteins for fusion augmentation in spine surgery has increased dramatically in recent years. Information is continually emerging regarding the effectiveness and safety profile of these compounds. OBJECTIVE: We have noted an increased incidence in sterile seroma formation and painful edema after the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) for posterolateral lumbar fusion. We present a retrospective review to determine the incidence of seroma formation and to discuss its clinical implications. METHODS: We retrospectively reviewed the operative reports of patients who underwent posterolateral lumbar fusion with the addition of rhBMP-2. We identified all patients who required surgical exploration of a postoperative sterile seroma. RESULTS: Of the 130 patients who underwent posterolateral lumbar fusion with rhBMP-2, 6 (4.6%) were returned to the operating room for exploration of a sterile seroma. The total amount of rhBMP-2 delivered to the posterolateral space per patient was 2.1 to 14.7 mg (mean, 8.4 mg per patient). The patients were returned to the operating room 5 to 13 days (mean, 7.7 days) after their initial surgery, and infection was ruled out in all cases by intraoperative cultures. CONCLUSION: There seems to be an increased incidence of formation of sterile seroma and painful edema in the lumbar region after posterolateral fusion with rhBMP-2. This report, along with other series highlighting the potential complications of bone morphogenetic proteins, suggests that more caution should be used when these compounds are used. Further studies are required to better define the risks and benefits of using bone morphogenetic proteins for spine surgery.

Biomechanics of a lumbar interspinous anchor with anterior lumbar interbody fusion.

OBJECT: An interspinous anchor (ISA) provides fixation to the lumbar spine to facilitate fusion. The biomechanical stability provided by the Aspen ISA was studied in applications utilizing an anterior lumbar interbody fusion (ALIF) construct. METHODS: Seven human cadaveric L3-S1 specimens were tested in the following states: 1) intact; 2) after placing an ISA at L4-5; 3) after ALIF with an ISA; 4) after ALIF with an ISA and anterior screw/plate fixation system; 5) after removing the ISA (ALIF with plate only); 6) after removing the plate (ALIF only); and 7) after applying bilateral pedicle screws and rods. Pure moments (7.5 Nm maximum) were applied in flexion and extension, lateral bending, and axial rotation while recording angular motion optoelectronically. Changes in angulation as well as foraminal height were also measured. RESULTS: All instrumentation variances except ALIF alone reduced angular range of motion (ROM) significantly from normal in all directions of loading. The ISA was most effective in limiting flexion and extension (25% of normal) and less effective in reducing lateral bending (71% of normal) and axial rotation (71% of normal). Overall, ALIF with an ISA provided stability that was statistically equivalent to ALIF with bilateral pedicle screws and rods. An ISA-augmented ALIF allowed less ROM than plate-augmented ALIF during flexion, extension, and lateral bending. Use of the ISA resulted in flexion at the index level, with a resultant increase in foraminal height. Compensatory extension at the adjacent levels prevented any significant change in overall sagittal balance. CONCLUSIONS: When used with ALIF at L4-5, the ISA provides immediate rigid immobilization of the lumbar spine, allowing equivalent ROM to that of a pedicle screw/rod system, and smaller ROM than an anterior plate. When used with ALIF, the ISA may offer an alternative to anterior plate fixation or bilateral pedicle screw/rod constructs.

Four-level anterior cervical discectomy and fusion with plate fixation: radiographic and clinical results.

OBJECTIVE: Anterior cervical discectomy and fusion with plating is a common procedure performed for cervical spondylosis by spine surgeons. However, data on procedures involving 4 disc spaces are lacking. We report the outcomes of patients who underwent 4-level anterior cervical discectomy and fusion with plating at a single institution. METHODS: Between 1997 and 2006, 34 patients (19 females, 15 males; mean age, 58 years; age range, 38-83 years) underwent 4-level anterior cervical discectomy and fusion with plating based on a surgical database search. Only patients undergoing surgery at 4 contiguous disc levels were included. Data were collected in a retrospective fashion. Patients' demographics, symptoms, neurologic findings, and radiographic findings at admission were recorded. Long-term clinical and radiographic outcomes at last follow-up were analyzed. RESULTS: Twenty-nine patients (85%) underwent anterior cervical discectomy and fusion with plating at C3-C7. Sixteen patients presented with neurologic deficits, of which 14 (88%) improved. None worsened after surgery. Minor complications occurred in 26 patients, including transient dysphagia in 18 (53%) and hoarseness in 3 (9%). Radiographic outcomes were available in 27 patients (median follow-up, 15 months; range, 4-71 months). The overall fusion rate was 92.6%. Stable fibrous nonunions were present in 2 patients; the chance of nonunion was 1.9% per level and 7% per patient. Adjacent-level disease occurred in 2 patients. CONCLUSION: In carefully selected patients, 4-level anterior cervical discectomy and fusion with plating can be associated with high rates of fusion. The technique is safe and effective for managing multilevel cervical spondylotic myelopathy and may obviate the need for circumferential procedures.

Occipitoatlantal dislocation.

Occipitoatlantal dislocation (OAD) can be devastating. This injury may be fatal in many cases, but more survivors are reported because of improvements in diagnosis and treatment. This article describes the diagnosis and treatment of OAD. To diagnose and treat OAD appropriately, neurosurgeons must have a detailed understanding of the anatomy of the craniocervical junction. Various radiographic criteria are used to establish the diagnosis of OAD. A destabilizing injury such as OAD requires surgical fixation. Many surgical techniques are available for fixation of the craniocervical junction. Future studies will continue to refine the diagnostic criteria for OAD and to develop improved methods for craniocervical stabilization.