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Howard S An

Publications and source records attributed to Howard S An.

67 records · Page 4Linked to original sources
PubMedDate not supplied

Does rigid instrumentation increase the fusion rate in one-level anterior cervical discectomy and fusion?

BACKGROUND CONTEXT: Although plate fixation enhances the fusion rate in multilevel anterior cervical discectomy and fusion (ACDF), debate exists regarding the efficacy of nonplating to rigid plate fixation in one-level ACDF. PURPOSE: To determine the efficacy of nonplating to rigid plate fixation in regards to fusion rate and clinical outcome in patients undergoing one-level ACDF with autograft. STUDY DESIGN: A review of 69 consecutive patients who underwent one-level ACDF with autograft and with or without rigid anterior cervical plate fixation. PATIENT SAMPLE: Sixty-nine patients who underwent one-level ACDF (mean age, 45 years) were evaluated for radiographic evidence of fusion (mean, 14 months) and for clinical outcome. All patients received tricortical iliac crest autografts. Disc space distraction was 2 mm, the grafts were inserted with the cortical surface positioned anteriorly, and each graft was countersunk 2 mm from the anterior vertebral border. Thirty-eight patients underwent nonplated ACDF and 31 patients underwent plated ACDF. Eighteen Orion (Sofamor-Danek, Memphis, TN), eight Atlantis (Sofamor-Danek) and five PEAK polyaxial (Depuy-Acromed, Rayham, MA) anterior cervical plating systems were used. Rigid plate fixation was used in all patients with instrumentation. Postoperatively, hard collars were worn 6 to 8 weeks in nonplated patients and soft collars were worn for 3 to 4 weeks in plated patients. Twenty-four patients were smokers (54.2% nonplating; 45.8% plating) and work-related injuries entailed 23 patients (47.8% nonplating; 52.2% plating). OUTCOME MEASURES: Fusion was assessed based on last follow-up of lateral neutral, flexion and extension radiographs. Radiographs were evaluated blindly to assess fusion and instrumentation integrity between nonplated and plated patients. Clinical outcomes were assessed with the Cervical Spine Outcomes Questionnaire and also assessed on last follow-up as excellent, good, fair or poor based on Odom's criteria. METHODS: Fusion rate and postoperative clinical outcome were assessed in 69 patients who underwent one-level ACDF with autograft and with or without rigid anterior plate fixation. Additional risk factors were also analyzed. Statistical significance was established at p<.05. RESULTS: Sixty-six patients (95.7%) achieved a solid fusion (100% nonplated; 90.3% plated). Nonunions occurred in three patients (1 smoker; 2 nonsmokers) with Orion instrumentation. Slight screw penetration into the involved and uninvolved interbody spaces occurred in one patient who was a nonsmoker and did not achieve fusion. One superficial cervical wound infection was noted in a nonplated patient. No other intraoperative or postoperative complications were noted. No statistically significant difference was noted between nonplating to rigid plating upon fusion rate (p>.05). All nonunions occurred at the C5-C6 level. Mean estimated intraoperative blood loss was significantly greater in plated patients (p=.043). Revision surgery involved 9.7% of the plated patients, whereas none of the nonplated patients required reoperation. Postoperative clinical outcome was assessed in all patients (mean, 21 months). Excellent results were noted in 18.8%, good results in 72.5% and fair results in 8.7% of the patients. Nonunion patients reported satisfactory clinical outcome. No statistical significance was noted between clinical outcome of fused and nonfused patients, the presence of a work-related injury and the use of plating (p>.05). Demographics and history of smoking were not factors influencing fusion or clinical outcome in this series (p>.05). The effect on fusion by various plate types could not be discerned from this study. CONCLUSION: A 100% and 90.3% fusion rate was obtained for one-level nonplated and plated ACDF procedures with autograft, respectively. The effects of smoking or level of fusion could not be discerned from these one-level cases. Excellent and good clinical outcome results were obtained for 91.3%. Nonplating or rigid plate fixation for ACDF in properly selected patients to treat radiculopathy with or without myelopathy has a high fusion rate and yields a satisfactory clinical outcome. Although controversy exists as to the efficacy of rigid plate fixation in one-level ACDF, solid bone fusion can be adequately obtained without plate fixation and instrumentation-related complications can be avoided. In line with the literature, plate fixation should be reserved for patients unwilling or unable to wear a hard orthosis postoperatively for an extended period of time or for those patients who seek a quicker return to normal activities. Proper patient selection, meticulous operative technique and postoperative care is essential to promote optimal graft-host incorporation.

Adult↗
PubMedDate not supplied

Rheumatoid arthritis: evaluation and surgical management of the cervical spine.

BACKGROUND CONTEXT: Rheumatoid arthritis is a debilitating polyarthropathic degenerative condition. Eighty-six percent of patients with rheumatoid arthritis have cervical spine involvement. Often these lesions are clinically asymptomatic or symptoms are erroneously attributed to peripheral manifestation of the patient's rheumatoid disease. Because these lesions are common and missed diagnosis can result in death, early recognition is vital. PURPOSE: The purpose of this literature review is to identify common lesions present in the rheumatoid neck and review diagnostic methods as well as treatment options for those requiring surgical intervention. STUDY DESIGN: A review of the English medical literature with focus on more recent studies on the presentation, diagnosis, management, surgical treatment and clinical outcomes of rheumatoid arthritis of the cervical spine. METHODS: A comprehensive literature review of the English medical literature obtained through Medline up to November 2003 was performed identifying relevant and more recent articles that addressed the presentation, evaluation, surgical management and outcomes of rheumatoid patients with cervical spine involvement. RESULTS: If left untreated, a large percentage of rheumatoid patients with cervical spine involvement progress toward complex instability patterns resulting in significant morbidity and mortality. Once myelopathy occurs, prognosis for neurologic recovery and long-term survival is poor. In properly selected patients, anterior and/or posterior cervical procedures can prevent neurologic injuries and preserve remaining function. CONCLUSION: Cervical spine involvement in the rheumatoid patient is common and progressive. Early diagnosis and treatment is imperative; however, surgical intervention should be considered carefully because associated morbidity and mortality is high.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Growth factors and the intervertebral disc.

BACKGROUND CONTEXT: The concept of biologically regenerating the intervertebral disc (IVD) using growth factor injection was first proposed in early 1990. Since that time, the technology to produce recombinant proteins, including growth factors, on an industrial scale has been developed. Currently, the effects of recombinant growth factors on IVD cells are less well known than those on articular cartilage chondrocytes. STUDY DESIGN: Literature review. PURPOSE: The purpose of this review is to summarize the most recent findings of the effects of growth factors on the IVD and, further, to discuss trends in the biological repair of the degenerated intervertebral disc. METHODS: A literature search was conducted using available databases, such as the National Library of Medicine, as well as data presented at scientific conferences held in the past 2 years, primarily in the United States. RESULTS: Herein, we report increasing evidence for the biological regeneration of the IVD. The effect of growth factors on the metabolism of IVD cells or tissues was studied using in vitro and in vivo approaches. In addition to using recombinant growth factor proteins, the gene transfer technique was also applied to study the effect of growth factors on the IVD. For in vivo studies, the availability of recombinant proteins and the use of gene transfer techniques accelerated progress in this field of research. CONCLUSIONS: The results from these in vitro and in vivo studies clearly suggest the potential usefulness of recombinant growth factors as therapeutic drugs or as medical devices.

Animals↗
PubMedDate not supplied

Neurofibromatosis type I with severe dystrophic kyphoscoliosis and its operative management via a simultaneous anterior-posterior approach: a case report and review of the literature.

BACKGROUND CONTEXT: Neurofibromatosis is an autosomal-dominant hereditary disorder with two subtypes: NF-1 (type I) and NF-2 (type II). NF-1 is a complex disorder with a constellation of manifestations that can also entail skeletal abnormalities, including spinal deformity of a noncongenital nature with early age onset. The short, sharp, angular curve usually present in the thoracic region, as exhibited in NF-1, presents a quandary in its surgical management. Various studies have reported on the efficacy of anterior correction as opposed to posterior alone, whereas others have advocated a sequential, combined approach to diminish the degree of deformity and achieve solid arthrodesis. However, despite solid arthrodesis, curve progression may still ensue. Nonetheless, a simultaneous anterior-posterior approach to treat such a condition of NF-1 with severe dystrophic kyphoscoliosis is a rare occurrence. PURPOSE: To describe the presentation and operative management of a patient with NF-1 and severe dystrophic kyphoscoliosis. STUDY DESIGN: A case report and review of the literature. METHODS: A clinical and radiographic review of a 51-year-old male patient who presented with NF-1, a 165-degree thoracic kyphotic deformity, associated scoliosis, varied degree of vertebral destruction of T9-T11, and paraparesis below T10. RESULTS: Operative intervention of the deformity consisted of a simultaneous anterior-posterior approach and entailed posterior cord exposure, anterior vertebrectomy of T9-T11, cord decompression, posterior osteotomy (posterior elements were auto-fused), anterior distraction and kyphosis correction, anterior strut grafting, anterior rod instrumentation, and posterior compression instrumentation and fusion from T6-L2. The deformity was reduced, sold fusion was noted, and the patient was asymptomatic. CONCLUSIONS: A simultaneous anterior-posterior approach for the surgical treatment of severe dystrophic kyphoscoliosis in neurofibromatosis type I is an avenue to properly visualize the spinal cord, achieve solid arthrodesis, and to minimize as well as prevent the progression of deformity.

Humans↗
PubMedDate not supplied

Osteogenic protein-1 is most effective in stimulating nucleus pulposus and annulus fibrosus cells to repair their matrix after chondroitinase ABC-induced in vitro chemonucleolysis.

BACKGROUND CONTEXT: Chondroitinase ABC (C-ABC) is used in chemonucleolysis to degrade, with great specificity, the chondroitin sulfate and dermatan sulfate chains of proteoglycans (PGs). A recent study showed that osteogenic protein-1 (OP-1) is very effective in stimulating the production and formation of the extracellular matrix by rabbit intervertebral disc cells. PURPOSE: To test the hypothesis that the repair of the extracellular matrix of the intervertebral disc after chemonucleolysis by C-ABC can be stimulated by exposure to a low dose of a growth factor, OP-1. STUDY DESIGN: An alginate bead cell culture system was used to monitor the effects of OP-1 on the repair of damaged matrices after in vitro chemonucleolysis with C-ABC. METHODS: Rabbit nucleus pulposus (NP) or annulus fibrosus (AF) cells cultured for 2 weeks in alginate gel were briefly exposed to low concentrations of C-ABC and then cultured in the presence or absence of OP-1. The control group was cultured without enzyme treatment for the same period in the absence of OP-1. At each time point, the contents of DNA and proteoglycan accumulation and proteoglycan synthesis were measured. RESULTS: NP or AF cells cultured in alginate beads, which were digested with C-ABC and then treated with OP-1, recover PG content more rapidly than those cultured in the absence of OP-1. The major contributor to the superior matrix repair in the cells treated with OP-1 was an up-regulation of proteoglycan synthesis. CONCLUSIONS: OP-1 was effective in stimulating matrix repair by NP and AF cells after their matrices were nearly totally depleted of sulfated glycosaminoglycans. The use of OP-1 after chemonucleolysis might help the disc to regain biomechanical strength, weakened by enzyme digestion, by stimulating matrix metabolism.

Alginates↗
PubMedDate not supplied

Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar spine model: a pilot study.

BACKGROUND CONTEXT: In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic spine. PURPOSE: To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. STUDY DESIGN/SETTING: Mechanical and pathological investigations in the lumbar spine. METHODS: Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm2) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar spines were removed en bloc for screw pull-out testing and histological evaluation. RESULTS: The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549+/-0.087 g/cm2, which was significantly less than the pre-OVX mean BMD of 0.603+/-0.092 g/cm2 (p < 0.001). The mean resistance against the pull-out force for the HA-PS was significantly greater at 165.6+/-26.5N than in the Ti-PS (103.1+/-30.2N, p < .001). The histological sections in the HA-PS clearly revealed new bone bonding with the apatite coating but only fibrous tissue bonding in the Ti-PS. CONCLUSIONS: The results of this study showed that the resistance to the pull-out force of HA-PS is 1.6 times that of Ti-PS. Furthermore, HA-PS has superior biological bonding to the surrounding bone, as early as 10 days after surgery in this osteoporotic spine model. Thus, in patients with osteoporosis, coating of the pedicle screw with HA may provide better stability and bonding between the pedicle screw and bone in the early postoperative period.

Absorptiometry, Photon↗
PubMedDate not supplied

Cell technologies for spinal fusion.

For a successful spinal fusion to occur, several vital elements are necessary. They consist of the presence of the bone-forming cell (osteoblast) or its precursor, the appropriate biological signals directing bone synthesis, and a biocompatible scaffold on which the process can occur. The most critical of these components is the osteoblast or its precursor, the mesenchymal stem cell (MSC), both of which possess the ability to form bone. As a result, many current techniques attempt to maximize the benefits derived from harvesting the ready source of MSCs from bone marrow, while minimizing the associated complications. These cellular technologies seek to improve on the harvest and concentration of the MSCs or enhance their delivery and action. This review focuses on the terminology, historical underpinnings, and current research rationale and techniques and discusses the possible future of these technologies.

Animals↗
PubMedDate not supplied

Animal models for human disc degeneration.

Despite the significant impairment associated with degenerative disc disease, a clear understanding of its pathogenesis is still lacking. Currently, no particular model parallels the complex nature of human disc degeneration. Naturally occurring animal models have the drawback that the basis for the high rate of disc degeneration is not known. Although the interventions in artificial animal models that create disc degeneration are known, the relationship of those to the events leading to disc degeneration in humans is not. With the recent progress in biomechanics, cell biology and molecular biology, an easily reproducible and valid animal model may help unlock the complex cascade of events surrounding human disc degeneration.

Animals↗
PubMedDate not supplied

Congenital lumbar spinal stenosis: a prospective, control-matched, cohort radiographic analysis.

BACKGROUND CONTEXT: Degenerative lumbar spinal stenosis manifests primarily after the sixth decade of life as a result of facet hypertrophy and degenerative disc disease. Congenital stenosis, on the other hand, presents earlier in age with similar clinical findings but with multilevel involvement and fewer degenerative changes. These patients may have subtle anatomic variations of the lumbar spine that may increase the likelihood of thecal sac compression. However, to the authors' knowledge, no quantitative studies have addressed various radiographic parameters of symptomatic, congenitally stenotic individuals to normal subjects. PURPOSE: To radiographically quantify and compare the anatomy of the lumbar spine in symptomatic, congenitally stenotic individuals to age- and sex-matched, asymptomatic, nonstenotic controlled individuals. STUDY DESIGN/SETTING: A prospective, control-matched, cohort radiographic analysis. PATIENT SAMPLE: Axial and sagittal magnetic resonance imaging (MRI) and lateral, lumbar, plain radiographs of 20 surgically treated patients who were given a clinical diagnosis of congenital lumbar stenosis by the senior author were randomized with images of 20, asymptomatic age- and sex-matched subjects. OUTCOME MEASURES: MRIs and lateral, lumbar, plain radiographs were independently quantitatively assessed by two individuals. Measurements obtained from the axial MRIs included: midline anterior-posterior (AP) vertebral body diameter, vertebral body width, midline AP canal diameter, canal width, spinal canal cross-sectional area, pedicle length, and pedicle width. From the sagittal MRIs, the following measurements were calculated: AP vertebral body diameter, vertebral body height, and AP canal diameter at the mid-vertebral level. On the lateral, lumbar, plain radiograph (L3 level), the AP diameters of the vertebral body spinal canal were measured. METHODS: The images of these 40 individuals were then randomized and distributed in a blinded fashion to five separate spine surgeons who graded the presence and severity of congenital stenosis utilizing a five-tier scale. Images consisting of 15 symptomatic individuals, graded definitely congenitally stenotic (mean age, 51.7 years; range, 43-65 years), and 15 asymptomatic individuals, graded definitely not stenotic (mean age, 50.7 years; range, 41-55 years), were age- and sex-matched and included for further review. From these 30 patients, a lateral, lumbar, plain radiograph and axial and sagittal MRIs (T1/T2 weighted) from L2-L5 were quantitatively analyzed. Rater reliability was assessed by Kappa coefficient testing. RESULTS: The cross-sectional area of the canal was significantly smaller in the congenitally stenotic patients at all lumbar levels measured (L2: 176 mm(2) vs. 259 mm(2), L3: 177 mm(2) vs. 275 mm(2), L4: 183 mm(2) vs. 283 mm(2), L5: 213 mm(2) vs. 323 mm(2), p<.05). Pedicle length was markedly shorter in the stenosis group at each lumbar level (L2: 5.9 mm vs. 8.9 mm, L3: 6.0 mm vs. 8.8 mm, L4: 6.5 mm vs. 9.2 mm, L5: 5.8 mm vs. 9.1 mm, p<.05). Furthermore, midline, axial AP canal diameter, vertebral body width, and sagittal AP canal diameter were all significantly smaller than the control patients (p<.05). A ratio of the AP diameter of the pedicle length to the vertebral body was also noted to be statistically significant on both the lateral plain radiographs (L3: 0.426 vs. 0.704) and sagittal MRI (L2: 0.343 vs. 0.461, L3: 0.361 vs. 0.461, L4: 0.362 vs. 0.481, L5: 0.354 vs. 0.452, p<.05). No difference was noted comparing the AP diameter of the vertebral body (axial and sagittal images), vertebral body height, canal width, and pedicle width. Kappa testing coefficient indicated a strong rater reliability (k=0.81, 95% confidence interval: 0.62-0.94). CONCLUSIONS: Congenital lumbar stenosis has not been clearly defined radiographically. Clinically, congenitally stenotic patients present at a younger age with fewer degenerative changes and multiple levels of involvement. Radiographically, these patients have a shorter pedicular length and as a result a smaller cross-sectional spinal canal area (mean critical values of 6.5 mm and 213 mm(2) were observed, respectively). The mean critical ratios were 0.43 (2:1 AP vertebral body: pedicle length) on the lateral lumbar radiograph and 0.36 on the sagittal MRI. The altered canal anatomy resulting from a decreased pedicle length may anatomically predispose these patients to earlier complaints of symptomatic neurogenic claudication. Identification of the presence of congenital stenosis should increase the treating surgeon's awareness of the potential need for multilevel treatment.

Adult↗
PubMedDate not supplied

Plain radiography of the lumbosacral spine in Marfan syndrome.

BACKGROUND CONTEXT: Marfan syndrome is a connective tissue disorder that results from a defect in the production of fibrillin. These patients tend to have several osseous anomalies of the lumbosacral spine. PURPOSE: This study examines the effectiveness of plain radiographic findings in predicting Marfan syndrome. STUDY DESIGN/SETTING: Case-control study. PATIENT SAMPLE: Fourteen height-matched controls and 33 patients with Marfan syndrome were obtained from our genetics clinic or through the National Marfan Foundation. OUTCOME MEASURES: Determined using measurements taken on plain radiographs. METHODS: Five measurements were acquired of the lumbosacral spine from the radiographs of both groups: interpedicular distance, scalloping value, sagittal canal diameter, vertebral body width and transverse process width. RESULTS: The following measurements were significantly larger in patients with Marfan syndrome: interpedicular distance at L1-L5 (p<.0001); sagittal diameters of the vertebral canal at L4-S2 (p<.01); transverse process to vertebral body width ratio at L2-L5 (p<.01). There was no significant difference in the scalloping values from L1-L5 between the patients with Marfan syndrome and the controls. A multivariate regression analysis generated the following criteria for plain film diagnosis of Marfan syndrome (two criteria need to be met for diagnosis): interpedicular distance at L5 greater than or equal to 36.0 mm, sagittal diameter at L5 greater than or equal to 13.5 mm or transverse process to vertebral width ratio at L3 greater than or equal to 2.25. CONCLUSION: Based on this criteria, patients can be diagnosed with Marfan syndrome with a high sensitivity (81.8%) but a low specificity (58.3%). Thus, plain radiography can be a useful means of screening patients with Marfan syndrome.

Adult↗
PubMedDate not supplied

Comparing outcomes of anterior cervical discectomy and fusion in workman's versus non-workman's compensation population.

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) is an accepted surgical procedure to treat degenerative conditions, including disc herniations and spinal stenosis. The literature on lumbar spine surgery reports that patients with a workman's compensation claim have less successful clinical results. Regarding the cervical spine, however, different conclusions have been drawn. PURPOSE: The purpose of this study was to directly compare the functional outcomes of ACDF in patients with and without a workman's compensation claim and to determine whether a compensation claim adversely affected the clinical outcome. STUDY DESIGN: This is a retrospective study examining the long-term results of ACDF in the workman's and non-workman's compensation populations. PATIENT SAMPLE: Eighty consecutive patients undergoing ACDF were retrospectively analyzed. The patients were divided into two groups: 30 patients in Group 1 (workman's compensation) and 50 patients in Group 2 (non-workman's compensation). The average age of Group 1 was 45 years (range, 31 to 57) and Group 2 was 45 years (range, 30 to 79). The patients were followed for an average length of 4 years (range, 2 to 7 years). OUTCOME MEASURES: We evaluated the surgical results using a functional outcome scoring system (Odom's Criteria), visual analog scale and a radiographic grading scale. The questionnaire was independently administered in a standard question-answer format at the 1-year follow-up. Statistical analyses was performed using a Levene's test. METHODS: All surgeries were performed by the same attending physician. A left-sided approach and Smith-Robinson fusion technique with autograft or allograft without instrumentation was used in all cases. A hard cervical orthosis was used postoperatively for 8 weeks. Radiographic examination including lateral flexion and extension views were obtained at a minimum of 12 months postoperatively. Furthermore, radiographic analysis was performed each subsequent postoperative year. The radiographs were analyzed by two independent physicians in a blind fashion for evidence of radiographic fusion. RESULTS: At follow-up no discernible difference was noted for functional outcomes. Eighty-three percent of patients in Group 1 and 90% of patients in Group 2 noted excellent or good results. This was not statistically significant (p=.280). In Group 1, 97% of patients returned to work at an average of 18 weeks, whereas 98% of patients in Group 2 returned to work at an average of 10 weeks postoperatively. Upon radiographic evaluation, 64% of patients in Group 1 were determined to have a solid fusion (Grade 3). The fusion rate in Group 2 was 72%. This was not statistically significant. However, the fusion rate among smokers was 50%, and among nonsmokers it was 80%. This was statistically significant (p=.001). CONCLUSIONS: Workman's compensation claims did not adversely affect the functional outcome of ACDF. It should be noted that a significant increase in pseudarthroses was noted with the smoking population. Patient selection is a critical factor in determining functional outcome, with 83% good to excellent results if the pathology, clinical presentation and radiographic findings correlate

Adult↗
PubMedDate not supplied

Comparison of allograft to autograft in multilevel anterior cervical discectomy and fusion with rigid plate fixation.

BACKGROUND CONTEXT: A relatively high pseudarthrosis rate is associated with multilevel anterior cervical discectomy and fusion (ACDF). Anterior plate fixation increases fusion rate in multilevel ACDF. A debate still exists between the effectiveness of allograft versus autograft in plated multilevel ACDF. PURPOSE: To determine the efficacy of allograft versus autograft in fusion rate and clinical outcome in patients undergoing two- and three-level ACDFs with rigid anterior plate fixation. STUDY DESIGN: A retrospective radiographic and clinical review to assess fusion, risk factors and clinical outcome of 80 consecutive patients who underwent ACDF with rigid anterior plate fixation involving two and three levels with either allograft or autograft. PATIENT SAMPLE: There were 45 patients (56%) who had autogenous iliac crest tricortical grafts and 35 patients (44%) who received tricortical allograft with an average age of 49 years who were treated by multilevel ACDF with rigid anterior plate fixation at a single institution. Thirty-three Peak polyaxial (Depuy-Acromed, Rayham, MA), 26 Orion (Sofamor-Danek, Memphis, TN), 16 Atlantis (Sofamor-Danek, Memphis, TN) and 5 Synthes (Paoli, PA) anterior cervical plating systems were used. All patients underwent ACDF (61 two-level, 19 three-level) by a Smith Robinson technique. All patients had burring of the end plates, 2-mm distraction of the motion segment and graft countersunk 2 mm from the anterior vertebral border. Anterior cervical plate with unicortical screw purchase was used in all cases. Segmental screw fixation was performed in 46 patients. Soft collars were worn postoperatively for 3 to 4 weeks. OUTCOME MEASURES: Follow-up lateral neutral, flexion and extension radiographs were used to assess fusion. The radiographs were reviewed by an independent blinded observer in assessing fusion grades between autograft versus allograft. Clinical outcomes were rated excellent, good, fair and poor based on Odom's criteria. METHODS: Fusion rate and postoperative clinical outcome were assessed in 80 patients who underwent two- or three-level ACDF with rigid anterior plate fixation. Additional risk factors were also analyzed. RESULTS: Radiographic fusion was assessed in all patients (mean, 16 months). Seventy-eight patients (97.5%) achieved solid arthrodesis. Pseudarthrosis occurred in two patients who had allograft for two-level and three-level fusions. Nonsegmental screws were used in the two-level nonunion case. Postoperative dysphagia developed in one two-level nonunion patient, and revision surgery was performed in the other nonunion three-level patient. Twenty-three patients were smokers, and 26 patients had work-related injuries. Clinical outcome (mean, 20 months) was excellent in 23, good in 48 and fair in 9 patients. No statistical significance was noted between demographics, history of tobacco use, graft-type, end plate preparation technique, intermediate segmental screws, plate-type, clinical outcome of fused and nonfused patients and presence of work-related injuries (p>.05). CONCLUSIONS: A high fusion rate of 97.5% was obtained for multilevel ACDF with rigid plating with either autograft or allograft. In this study, nonunion occurred in patients with allograft but this difference was not statistically significant. Fusion was obtained in 97.8% of patients with segmental screw fixation and 97.1% with nonsegmental screw fixation. Nonsegmental screw fixation may contribute to less than adequate stability and contribute to a higher rate of nonunion, but such effects could not be discerned from this study. Excellent and good clinical outcome was noted in 88.8% of the patients. Proper patient selection and meticulous operative technique is essential to obtain high fusion rates and optimal clinical outcome, which is more important than graft type.

Adult↗