Radiographic and clinical outcomes following single-level anterior cervical discectomy and allograft fusion without plate placement or cervical collar

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1 J Neurosurg Spine 8: , 2008 Radiographic and clinical outcomes following single-level anterior cervical discectomy and allograft fusion without plate placement or cervical collar JAY JAGANNATHAN, M.D., CHRISTOPHER I. SHAFFREY, M.D., ROD J. OSKOUIAN, M.D., AARON S. DUMONT, M.D., CHRISTIAN HERROLD, M.D., CHARLES A. SANSUR, M.D., AND JOHN A. JANE SR., M.D., PH.D., F.R.C.S.C. Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia Object. Although the clinical outcomes following anterior cervical discectomy and fusion (ACDF) surgery are generally good, 2 major complications are graft migration and nonunion. These complications have led some to advocate rigid internal fixation and/or cervical immobilization postoperatively. This paper examines a single-surgeon experience with single-level ACDF without use of plates or hard collars in patients with degenerative spondylosis in whom allograft was used as the fusion material. Methods. The authors conducted a retrospective review of a prospective database of (Cloward-type) ACDF operations performed by the senior author (J.A.J.) between July 1996 and June Radiographic follow-up included static and flexion/extension radiographs obtained to assess fusion, focal and segmental kyphosis, and change in disc space height. At most recent follow-up, the patients condition was evaluated by an independent physician examiner. The Odom criteria and Neck Disability Index (NDI) were used to assess outcome. Results. One hundred seventy patients underwent single-level ACDF for degenerative pathology during the study period. Their most common presenting symptoms were pain, weakness, and radiculopathy; 88% of patients noted 2 neurological complaints. The mean hospital stay was 1.76 days (range 0 36 days), and 3 patients (2%) had major immediate postoperative complications requiring reoperation. The mean duration of follow-up was 22 months (range months). Radiographic evidence of fusion was present in 160 patients (94%). Seven patients (4%) showed radiographic evidence of pseudarthrosis, and graft migration was seen in 3 patients (2%). All patients had increases in focal kyphosis at the operated level on postoperative radiographs (mean 7.4 ), although segmental alignment was preserved in 133 patients (78%). Mean change in disc space height was 36.5% (range 28 53%). At most recent clinical follow-up, 122 patients (72%) had no complaints referable to cervical disease and were able to carry out their activities of daily living without impairment. The mean postoperative NDI score was 3.2 (median 3, range 0 31). Conclusions. Single-level ACDF without intraoperative plate placement or the use of a postoperative collar is an effective treatment for cervical spondylosis. Although there is evidence of focal kyphosis and loss of disc space height, radiographic evidence of fusion is comparable to that attained with plate fixation, and the rate of clinical improvement is high. (DOI: /SPI/2008/8/5/420) KEY WORDS anterior cervical discectomy and fusion outcome radiograph single-level fusion T HE ACDF operation has gained immense popularity since its introduction in the 1950s by Smith and Robinson 32 as well as Cloward. 9 Today the technique has become a mainstay in the treatment of degenerative cervical spondylosis, intervertebral disc herniation, radiculopathy, and spinal instability. 5,8,31 Abbreviations used in this paper: ACDF = anterior cervical discectomy and fusion; NDI = Neck Disability Index; PLL = posterior longitudinal ligament; SD = standard deviation; VB = vertebral body. Although clinical outcomes following ACDF are generally good, 5,8,11,31 2 of the major complications observed with follow-up are graft migration and nonunion, 16,25,26 leading some to advocate rigid internal fixation and cervical immobilization postoperatively to enhance fusion. 2,7,14 Plate fixation of the cervical spine was initially performed during the early 1980s for the treatment of cervical spine trauma. 6 The theoretical advantages of using a plate are an increase in stability across the treated segment and a decrease in motion between the graft and the endplate. The plate is also intended to act as a buttress, preventing graft extrusion J. Neurosurg.: Spine / Volume 8 / May 2008

2 Single-level ACDF without collar Numerous groups have attempted to demonstrate that rigid plate fixation is associated with better outcomes, particularly in multilevel cervical disc disease, but the outcomes have been equivocal. 20,37,39 There is even less evidence available to support the use of rigid plate fixation for single-level ACDFs, and many of the studies that do exist are limited by low numbers of patients, 11 variable follow-up, and/or differences in the types of instrumentation and allografts used. 20,31, 37,39 This paper describes a single-surgeon experience with the single-level ACDF without plate placement or the use of a hard collar in patients with degenerative spondylosis. Patient Population Clinical Materials and Methods At our institution between July 1996 and June 2005, 750 patients underwent ACDF performed by the senior author (J.A.J.) for degenerative processes, tumors, trauma, and infection. We performed a retrospective analysis of demographic information, fusion outcomes, complications, and quality of life measures using prospectively acquired data pertaining to cases in which single-level ACDF was performed for the treatment of degenerative disease. Patients who required surgery for traumatic or neoplastic disease, and patients who underwent multilevel ACDFs were excluded from the study. Surgical Technique A visual depiction of the operative technique is shown in Fig. 1. Patients underwent ACDF in a manner similar to that described by Cloward, but with slight modifications. 9 In patients without recurrent laryngeal nerve damage or prior surgery, a left-sided transverse skin incision was used. Following dissection through the cervical musculature, the disc space was identified and the level confirmed using intraoperative radiography. Following drilling using a Cloward drill, a thorough decompression was performed by removing all central disc material and endplate osteophyte to the extent of the PLL and uncovertebral joints. A self-retaining distracting apparatus was then inserted into the uncovertebral joint to provide distraction and lordosis at the operative level. The PLL was excised to achieve complete decompression and to ensure that no disc fragments were retained. We favor performing a wide foraminotomy bilaterally. A Cloward interbody graft was then inserted into the disc space. Freeze-dried cortical allograft was used as the interbody graft for all patients. Postoperatively, anteroposterior and lateral cervical spine radiographs were obtained to document proper graft insertion. Cervical plates were not used in any case. Although patients were offered the option of wearing a soft cervical collar for comfort, rigid cervical immobilization was never used. Patients were encouraged to resume normal activities as soon as possible postoperatively. Postoperative Follow-Up Patients were followed up at regular intervals of 6 weeks, 3 months, and 1 year postoperatively. Further clinical follow-up and imaging studies were performed on an as-needed basis. At the time of this study, patients were contacted and quality of life measures were assessed by an independent (physician) examiner, using the criteria of Odom (as described in Zoëga et al. 43 ) and the NDI 35 (Table 1). Radiographic Follow-Up Fusion. A minimum of 12 months radiographic followup was required for inclusion in the study. Follow-up flexion/extension radiographs were obtained in all patients at the time of this study and were evaluated by a radiologist. Fusion was defined as lack of motion on postoperative dynamic images and trabecular bridging of the bone graft interface on postoperative radiographs (Fig. 2). Focal and Segmental Alignment. Focal alignment was defined by the angle formed by lines drawn at the superior margin of the superior VB defining the disc space and the inferior margin of the inferior VB on a lateral radiograph obtained with the patient standing (Fig. 3). The Cobb angles from C-2 to C-7 were also determined. Angles were measured using quantitative measurement analysis software (Eastman Company), which uses extrapolative algorithms to calculate the intersecting angle between 2 lines drawn by the investigator. To allow for investigator error in assessing the margins of the VBs, all angles were measured 3 times and the mean angle was determined. The same investigator produced all computerized measurements. Disc Space Height Changes. To determine changes in disc space height, on each pre- and postoperative lateral radiograph, the posterior height of the C-3 VB (a reference) and the height of the operated disc space were measured (Fig. 3). The initial disc height ratio (Ri) represented the ratio between the operated disc space and the C-3 VB height on the lateral cervical radiograph obtained on the 1st postoperative day. Final disc space height ratio (Rf) was the ratio between the operated disc space and the C-3 VB at most recent follow-up. The narrowing rate was defined as ([Ri Rf] / Ri) 100. Study Population Results One hundred ninety-six patients underwent single-level ACDF for degenerative disease during the study period. Twenty-six patients were lost to follow-up, leaving 170 patients who formed the basis for this study. Seventy-three patients (43%) were women and 97 (57%) were men. Their mean age at surgery was 53 years (median 56 years, range years). Seventy-eight patients (46%) underwent surgery only for degenerative spondylosis, 55 (32%) patients had cervical disc protrusion, and 37 patients (21%) had radiographic evidence of both. Ten patients had undergone previous single-level posterior cervical discectomies (6%), and 5 patients (3%) had undergone multilevel cervical hemilaminectomies and had recurrent or residual symptoms. A summary of the levels treated is depicted in Table 2. Surgery was performed at the C3 4 level in 28 patients (16%); at the C4 5 level in 29 (17%); at the C5 6 level in 71 (42%); and at the C6 7 level in 42 (25%). Fifteen patients (9%) had undergone posterior cervical hemilaminectomies previously. The mean duration of clinical and radiographic follow-up was 22 months (range months). J. Neurosurg.: Spine / Volume 8 / May

3 J. Jagannathan et al. FIG. 1. Illustration showing the Jane modification to the Cloward technique. In patients without recurrent laryngeal nerve damage or prior surgery, a left-sided transverse skin incision is used (A). Following the dissection through the cervical musculature, the disc space is identified and the level is confirmed using an intraoperative radiograph. The disc space is then drilled using a Cloward drill (B), and a distraction apparatus that fits into the uncovertebral joint is placed to allow lordosis of the spine (C). Thorough decompression is then performed by removing all central disc material and endplate osteophyte to the extent of the PLL and uncovertebral joints (D). The PLL is also excised to achieve complete decompression and to be certain that no disc fragments are retained. We favor performing wide foraminotomies bilaterally, with a wider decompression on the side with pain (E). A Cloward interbody graft is then inserted into the disc space (F). Preoperative Neurological Condition All patients noted either neck pain or extremity pain preoperatively. Weakness was noted by 151 patients (89%), although only 110 patients (65%) had clinical evidence of diminished strength on physical examination. Sensory disturbances were noted by 142 patients (83%), and were con422 firmed by electromyographic examination in 67 patients (48% of those with sensory disturbance). One hundred and thirty-one patients (77%) noted neck pain. Sixty patients (35%) had evidence of myelopathy on physical examination. One hundred fifty patients (88%) noted $ 2 neurological complaints; 130 patients (76%) noted 3; and 30 patients (18%) had $ 4. J. Neurosurg.: Spine / Volume 8 / May 2008

4 Single-level ACDF without collar TABLE 1 Clinical outcome ratings in 170 patients who underwent ACDF Odom No. of Pa- Criteria NDI Rating tients (%) excellent 0 4 (no disabil- no complaints referable 122 (72) ity) to disease good 5 14 (mild dis- intermittent discomfort 31 (18) ability) referable to disease fair (moder- subjective improvement 10 (6) ate disability) in symptoms; activity impaired poor (severe no improvement in symp- 7 (4) disability) toms or worsening 35 (complete incapacitated 0 (0) disability) Hospital Course Hospital stay is depicted graphically in Fig. 4. Mean length of hospital stay was 1.76 days (range 0 36 days). One hundred and twenty-seven patients (75%) were discharged home on postoperative Day 1. The majority of patients (164) were transferred directly to the floor postoperatively. Four patients (2%) required care in the intensive care unit, and in 3 cases this was due to a postoperative myocardial infarction. Pulmonary edema developed postoperatively in the fourth patient and intubation was required. Two patients were discharged home directly from the recovery area. Complications Postoperative complications are summarized in Table 3. Most complications following single-level ACDF were related to the surgical approach and were self limited. The most common postoperative complaint was dysphagia, seen in 15 patients (9%), although in 10 (67%) of these 15 the symptoms improved within 12 weeks of the initial operation. The presence of postoperative dysphagia appeared to be unrelated to the side of the approach, with a left-sided approach having been used in 8 of the 15 patients and a right-sided approach in 7. All of these patients underwent swallowing and speech evaluations by an ear, nose, and throat surgeon. Only 1 of these patients (0.5%) was noted to have new paresis of the recurrent laryngeal nerve, but 4 patients had residual hoarseness. Three patients (2%) had slight protrusion of the allograft on postoperative radiographic imaging, but dynamic radiographs demonstrated fusion in all 3. Postoperative neuroimaging studies demonstrated ventral cord compression in 3 patients, but only 1 patient developed clinical symptoms that warranted repeated surgery (described in the next section). The other 2 patients were observed with periodic follow-up neuroimaging and remain free of symptoms at 14 and 48 months follow-up. Three patients developed postoperative hematomas, 2 of whom required repeated surgery (see next section), and 1 of whom was managed expectantly. Intraoperative cerebrospinal fluid leaks were encountered in 3 patients (2%). All of these patients had signs of ossification of the PLL, and the leak was incurred in all cases during the removal of the PLL. In 2 cases the leaks were treated with lumbar drainage; in the other case, the leak was managed conservatively by means of bedrest with the head of the bed elevated to 45. Wound infections were seen in 3 patients (2%), and in all cases these were treated with a short (1-week course) of oral antibiotics. In 1 patient undergoing a C6 7 fusion, Horner syndrome developed postoperatively; this was thought to be related to injury to sympathetic fibers during the initial dissection. Complication rates were not statistically related to age, sex, or primary pathological condition (p 0.05, Cox proportional-hazards regression). FIG. 2. Upright anteroposterior (left) and lateral (right) radiographs obtained 2 years after C5 6 ACDF in a 41-yearold man with degenerative spondylosis demonstrating solid fusion (white arrow). J. Neurosurg.: Spine / Volume 8 / May

5 J. Jagannathan et al. FIG. 3. Radiographs showing measurements obtained 24 months after a C6 7 ACDF. A: Focal alignment was defined by the angle formed by lines drawn at the superior margin of the superior VB defining the disc space and the inferior margin of the inferior body on a lateral radiograph obtained with the patient standing. B: The Cobb angles from C- 2 to C-7 were also determined. Angles were measured using quantitative measurement analysis software, which uses extrapolative algorithms to calculate the intersecting angle between 2 lines drawn by the investigator. C: Changes in disc space height were determined using pre- and postoperative lateral radiographs. The posterior height of the body of C-3 (a reference) and the height of the operated disc space were measured. The initial disc height ratio (Ri) represented the ratio between the operated disc space and the height of the C-3 VB on the lateral cervical radiograph obtained on the 1st postoperative day. Final disc height ratio (Rf) was the ratio between the operated disc space and the C-3 VB at most recent follow-up. The narrowing rate was defined as the ([Ri Rf]/Ri) 100. Repeated Surgery A total of 7 patients (4%) required reoperation. Three patients (2%) required repeated surgery for immediate postoperative complications: postoperative hematomas developed in 2 patients, and 1 patient had ventral compression from her allograft and presented with new-onset weakness postoperatively. All 3 of these patients were ultimately discharged home after a mean hospital stay of 4.8 days (range 3 7 days). Four patients required repeated surgery due to failure of the initial surgery and presence of adjacent-segment disease. One patient experienced worsening weakness and myelopathy and had evidence of nonunion on radiographs obtained 36 months postoperatively. This patient had undergone multilevel laminectomies at another facility following his ACDF and had evidence of instability when he presented again at our institution. He ultimately required anterior and posterior cervical decompression with lateral mass fusion 41 months after the initial ACDF surgery at our institution (Fig. 5) and had stabilization of symptoms at 50 months follow-up. Two patients had residual disc postoperatively, requiring repeated surgery with multilevel ACDF and plate placement 8 weeks after initial surgery (postoperative radiographs also demonstrated early adjacent-segment degeneration in both cases). One patient had complete extrusion of his bone plug and ultimately underwent multilevel ACDF with plate placement (due to degeneration at the level above the previous surgery) at 27 months postoperatively. The mean interval between the initial procedure and the second operation in patients with long-term complications was 18 months. Neurological Outcome and Quality of Life Table 4 summarizes neurological outcome at the most recent clinical follow-up (mean 22 months). One hundred and eleven patients (85%) who had neck pain preoperatively experienced an improvement in pain level. One hundred sixty-seven patients (98%) had either improved or stable strength compared with their preoperative examination findings, and 53 (48%) of the patients with preoperative weakness had improvement in strength on follow-up examination. All 3 of the patients who developed increased weakness postoperatively had some weakness preoperatively as well. Eighty-five percent of patients who had neck pain preoperatively noted improvement on most recent follow-up. Results of clinical outcome ratings using the Odom criteria and NDI and performed by the physicians examining the patients are summarized in Table 1. One hundred twenty-two patients (72%) had no complaints referable to cervical disease and were able to carry on their activities of daily living without impairment. Thirty-one patients (18%) had intermittent discomfort referable to cervical disease; 10 patients (6%) had subjective improvement in their symptoms 424 J. Neurosurg.: Spine / Volume 8 / May 2008

6 Single-level ACDF without collar TABLE 3 Summary of postoperative complications Complication No. of Cases FIG. 4. Graph depicting length of hospital stay following singlelevel ACDF. dysphagia 15 hoarseness 4 extrusion of bone plug 3 cerebrospinal fluid leak 3 kyphosis w/ bone resorption 5 wound hematoma 3 ventral compression from bone plug 3 wound infection 3 Horner syndrome 1 but remained impaired. Seven patients (4%) had worsening of symptoms, and previous surgery had failed in 3 of these patients (43%). The mean postoperative NDI score was 3.2 (median 3, range 0 31). Radiographic Outcome Fusion. Postoperative radiographs demonstrated fusion in 160 patients (94%). The fusion rate did not appear to vary significantly with the cervical level fused (Table 2). In 7 patients (4%) there was partial fusion of the graft and pseudarthrosis developed. All of these patients experienced amelioration in their clinical symptoms. Two patients (1%) had either no fusion or extrusion of their allograft postoperatively. One patient with partial fusion had partial bone plug extrusion. Angle of Segmental Kyphosis. The angle of segmental kyphosis worsened postoperatively in all cases, although in 133 patients segmental alignment was preserved. Preoperatively, 36 patients (21%) had segmental kyphosis, with an angle of less than 0. The mean change ( SD) for the cohort was (median 8.2, range 3.3 to 15.4 ). No statistically significant relationship could be determined between the angle change and surgical level, or postoperative functional status (p = 0.24 for level, p = 0.33 for functional status, Student t-test). Cobb Angle. There was significant variation in the preoperative Cobb angles, from 34.2 of lordosis to 19.2 of kyphosis. No statistically significant change in the mean Cobb angles between the pre- and postoperative measurement could be determined (p = 0.32, Student t-test). In 84 TABLE 2 Characteristics of cervical levels treated Mean change SD Focal Segmental Disk Space Cervical No. of % w/ Kyphosis Kyphosis Height Loss Levels Patients Fusion ( ) ( ) (%) C C C C of 102 patients (82%) with lordotic alignment preoperatively (defined as 10 ), the spinal alignment remained lordotic postoperatively, while the remaining 18 patients developed kyphosis. Twenty patients had straight (0 10 ) preoperative alignment; postoperatively, kyphosis developed in 7 of these 20, the spine remained straight in 2, and lordosis developed in 1. Forty-eight patients had preoperative kyphosis ( 0 ) and all of these patients remained kyphotic postoperatively. The mean change in Cobb angle between pre- and postoperative measurements was (range 2 16 ; Table 2). Change in Disc Space Height. The mean percentage of disc space height loss was found to be % at most recent follow-up (median 34%, range 28 53%). There was no statistically significant relationship between reduction in disc space height and the level of surgery or postoperative functional status (p = 0.24 for level, p = 0.45 for postoperative status, Student t-test). Discussion Both anterior and posterior approaches have been used in the treatment of cervical spondylosis. 40,41 Initially, the posterior approach was used, and although effective, it presented challenges in exposing midline disc fragments and osteophytic changes. 17 Because the primary pathology in cervical spondylosis is related to changes at the intervertebral disc space, including ligamentous hypertrophy, reactive endplate growth, and facet joint calcification, an anterior approach provides the surgeon the maximal ability to decompress around the disc space, with the opportunity to decompress laterally to the neuroforamina if needed. 3,9 Although not always correlated with clinical outcome following ACDF, 12 the fusion of a motion segment is generally viewed as critical in determining the success of the operation. 27,30 Application of a cervical plate has gained acceptance as a means of increasing fusion rates and preventing graft dislodgement, but it can be expensive and has been associated with complications such as dysphagia, infection, and instrumentation failure. 4,13,23,24 Instrumented fusion is also associated with a significantly higher amount of intraoperative blood loss when compared with procedures in which plate fixation is not used. 31 The effectiveness of plate fixation in single-level ACDF is controversial, and there are significant differences in fusion rates among published studies. Connolly et al. 11 reported a 100% fusion rate in a series of 14 cases in which pa- J. Neurosurg.: Spine / Volume 8 / May

7 J. Jagannathan et al. TABLE 4 Neurological outcomes on most recent postoperative follow-up* Symptom Improved Stable Worse neck pain 111 (85) 20 (15) 0 (0) sensory disturbance 51 (36) 89 (63) 2 (1) strength 53 (32) 114 (68) 3 (2) * Values represent number of patients (%) with symptoms on postoperative physical examination. FIG. 5. Postoperative lateral radiograph obtained in a 71-yearold man who experienced progressive weakness and cervical instability postoperatively. This patient had undergone ACDF but had persistent symptoms, requiring multilevel cervical laminectomies (arrows), which were performed at another institution. Approximately 24 months after the laminectomies were performed, the patient presented again at our institution with evidence of instability and required posterior and anterior fixation. tients underwent ACDF with autografts; instrumentation was placed in 8 of the 14 cases. Wang et al. 38 demonstrated a fusion rate of 91.7% in patients who underwent ACDF without instrumentation and 95.5% in patients who underwent ACDF with plate fixation and reported a higher rate of pseudarthrosis in the patients who were treated without instrumentation (although no statistical significance was demonstrated). Kaiser et al. 20 reported on 157 patients who underwent single-level ACDF with plate fixation and compared the results with those achieved in 242 controls in whom plates were not used, finding fusion rates of 96% for the patients in whom cervical plates were applied and 90% in those who were treated without plates. In this series, however, the control group consisted of a historical cohort, making direct comparison difficult. Describing one of the larger case series involving singlelevel ACDF with and without fixation, Samartzis et al. 31 reported a solid fusion rate in 100% of cases in which plates were not applied, compared with 90.3% of those in which plate fixation was used. The clinical outcomes were excellent or good in 91.3% of the patients in the series, overall. All instances of nonunion involved a single-plate fixation device, indicating that the rigidity of the plate system itself may actually eliminate some of the normal compressive forces at the graft bone interface and inhibit fusion. 18,33 Our data indicate a high level of cervical kyphotic angulation on follow-up imaging (mean change 7.4 ) and loss of disc space height following ACDF. The fact that the overall alignment between C-2 and C-7 did not change significantly in spite of kyphosis indicates that the untreated segments of the cervical spine compensated for focal kyphosis. The significance of these findings is unclear because it is controversial whether cervical kyphosis or loss of disc space height influences clinical outcome after anterior cervical discectomy with or without fusion. 1,21,34 It is possible that with longer follow-up, symptoms could develop in some of the patients with kyphosis. Hilibrand et al. 19 demonstrated that up to 25% of patients undergoing anterior fusion develop new disease due to the degeneration of the adjacent segment within 10 years. Achieving fusion in these patients can be particularly challenging when an anterior cervical arthrodesis is performed adjacent to the existing fusion. The results of our study suggest that plate placement adds little to the ACDF procedure alone for the management of single-level cervical spondylosis. The fusion rate of 94% following single-level ACDF is comparable to rates reported in case series in which cervical instrumentation was used. 22,31 Although we have noted a risk of graft subsidence when plates are not used, none of our patients with graft subsidence developed symptoms. Furthermore, the rate of graft subsidence in these patients was comparable to or less than the rate of plate-related complications reported by other groups. Proponents of cervical plate fixation point to the fact that internal fixation with a plate may obviate the need for rigid external immobilization. Our data indicate that a cervical collar is unnecessary, as the immediate and long-term fusion rates did not appear to be affected by the lack of immobilization. Indeed, in terms of comfort, not having to wear a collar has been the most important difference for our patients. Of the 10 patients who did not achieve complete fusion, 7 (78%) experienced an improvement in clinical symptoms. Also of note was the fact that 5 of these patients (including both patients in whom there was no fusion) were smokers, further supporting the findings of previous groups who have correlated smoking with worse fusion outcomes and higher rates of pseudarthrosis. 15,28,29 Because radiographic evidence of fusion has been shown to be unreliable at times, both in human and animal models, 10,42 we believe that clinical follow-up is critical in validating the success of our operations. An independent thirdparty observer completed the outcomes assessments in this study. The use of such adjudicated outcomes is important, as it removes surgeon bias as a confounder. The overwhelming majority of patients had improvement in clinical outcomes following surgery, with 96% of patients noting unchanged or improved symptoms in the areas of sensory 426 J. Neurosurg.: Spine / Volume 8 / May 2008

8 Single-level ACDF without collar disturbance (including radiculopathy), strength, and neck pain, based on the Odom criteria. This finding contrasts with the findings of previously published reports, which have noted more favorable clinical outcomes in patients treated with cervical plate application following singlelevel fusion. 36 There are limitations to our study design. The data were collected retrospectively, and thus it was impossible to completely control for selection bias. Furthermore, the fact that patients were not evaluated by the same examiner preand postoperatively makes it difficult to accurately quantify the degree of improvement the patients experienced. A randomized controlled trial will be essential in determining the true benefit of external or internal fixation in patients who undergo single-level ACDF for cervical spondylosis. Conclusions The high fusion rate (94%) and overall favorable neurological outcomes (96%) associated with noninstrumented single-level ACDF with no postoperative collar indicates that this is an efficacious option in treating cervical spondylosis. Acknowledgments We thank Athlene Harrup, Tom Szabo, and Kaitlin Mussomeli for their invaluable help in coordinating patient follow-up for this study. References 1. Abd-Alrahman N, Dokmak AS, Abou-Madawi A: Anterior cervical discectomy (ACD) versus anterior cervical fusion (ACF), clinical and radiological outcome study. Acta Neurochir (Wien) 141: , Aebi M, Zuber K, Marchesi D: Treatment of cervical spine injuries with anterior plating. Indications, techniques, and results. Spine 16 (3 Suppl):S38 S45, Bailey RW, Badgley CE: Stabilization of the cervical spine by anterior fusion. J Bone Joint Surg Am 42: , Bazaz R, Lee MJ, Yoo JU: Incidence of dysphagia after anterior cervical spine surgery: a prospective study. 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9 J. Jagannathan et al. my with titanium intervertebral cage fusion. Acta Neurochir (Wien) 145: , Vernon H, Mior S: The Neck Disability Index: a study of reliability and validity. J Manipulative Physiol Ther 14: , Wang JC, McDonough PW, Endow KK, Delamarter RB: A comparison of fusion rates between single-level cervical corpectomy and two-level discectomy and fusion. J Spinal Disord 14: , Wang JC, McDonough PW, Endow KK, Delamarter RB: Increased fusion rates with cervical plating for two-level anterior cervical discectomy and fusion. Spine 25:41 45, Wang JC, McDonough PW, Endow K, Kanim LE, Delamarter RB: The effect of cervical plating on single-level anterior cervical discectomy and fusion. J Spinal Disord 12: , Wang JC, McDonough PW, Kanim LE, Endow KK, Delamarter RB: Increased fusion rates with cervical plating for three-level anterior cervical discectomy and fusion. Spine 26: , White AA III, Panjabi MM: Biomechanical considerations in the surgical management of cervical spondylotic myelopathy. Spine 13: , Wiberg J: Effects of surgery on cervical spondylotic myelopathy. Acta Neurochir (Wien) 81: , Zdeblick TA, Cooke ME, Wilson D, Kunz DN, McCabe R: Anterior cervical discectomy, fusion, and plating. A comparative animal study. Spine 18: , Zoëga B, Kärrholm J, Lind B: Outcome scores in degenerative cervical disc surgery. Eur Spine J 9: , 2000 Manuscript submitted July 30, Accepted January 24, Address correspondence to: Jay Jagannathan, M.D., Department of Neurological Surgery, University of Virginia Health System, Box , Charlottesville, Virginia jj5a@hscmail. mcc.virginia.edu. 428 J. Neurosurg.: Spine / Volume 8 / May 2008