Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S 51S

DISCLOSURES: FDA device/drug: Atlantis Plate–Medtronic SofamorDanek. Status: Approved for this indication. FDA device/drug: Zephir Plate–Medtronic Sofamor Danek. Status: Approved for this indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.098

4:2097. Relationship between plate position and neck pain followinginstrumented anterior cervical discectomy and fusionBrian Ipsen, MD1, David Kim, MD1, Brian Kwon, MD1, Louis Jenis,MD1, Jesse Affonso, BA2, Scott Tromanhauser, MD1, Robert Banco,MD1; 1The Boston Spine Group, Boston, MA, USA; 2University ofMassachusetts Medical School, Worcester, MA, USA

BACKGROUND CONTEXT: Anterior cervical plates are commonly usedto provide immediate stabilization following a variety of cervical spineprocedures. Central placement of the plate and avoiding overlap of adjacentunfused motion segments have long been assumed to represent ideal plateposition. However, constraints resulting from local anatomy, limited surgi-cal dissection or individual pathology frequently prevent central placementof the plate. Recommendations regarding ideal plate position have beenbased primarily on biomechanical studies of first-generation plating systemsand anecdotal evidence. There have been no reported systematic studiesexamining the effect of variations in plate position in a large clinicalpopulation.PURPOSE: To study the effect of variation in cervical plate position onclinical outcome in patients undergoing 1- or 2-level instrumented anteriorcervical discectomy and fusion (ACDF).STUDY DESIGN/SETTING: Prospective clinical outcomes study.PATIENT SAMPLE: 96 patients undergoing 1- or 2-level ACDF withinstrumentation for disc herniation or cervical spondylotic radiculopathybetween 1999-2003 with minimum 12 month follow-up.OUTCOME MEASURES: Clinical data collected included pre- and post-operative SF-36, visual analogue scores (VAS) for neck and arm pain, andneck disability index (NDI).METHODS: Early postoperative plain X-rays were analyzed by two inde-pendent examiners utilizing digital image capture and computer-assistedlinear and planar analysis. Plate position was measured as percentage cover-age of superior and inferior vertebral bodies on the lateral view as well asangulation and lateral displacement on the anteroposterior view. Statisti-cal analysis included measurement of Pearson’s correlation coefficient andlinear regression analysis for all demographic, radiographic, and clinicaloutcome variables.RESULTS: Adequate follow-up data were available for 86 pts.(89%) withaverage follow-up in this group of 18.7 months. There was a highly signifi-cant association between lateral plate position and increased postoperativeneck pain (Pearson’s corr. coeff. p�.377, p�0.001, n�86). All other radio-graphic measures [vertical position of the plate, percentage coverage ofsuperior and inferior vertebral bodies, plate angulation, and encroachmenton adjacent segments] failed to demonstrate significant correlation with anyoutcomes measure. Linear regression analysis confirmed a strong correlationbetween lateral plate position in the frontal plane and higher postoperativeneck VAS scores (p�0.001). Smoking history was the only other significantrisk factor associated with increased postoperative neck pain VAS in ourcohort (corr. coeff. p�.391, p�.001, n�87) and higher postoperative NDI(p�.383, p�.003, n�57). Multiple regression analysis revealed that patientage, weight, number of levels fused, plate design, and surgeon werenot associated with neck pain or clinical outcome and were not indepen-dently associated with plate position.CONCLUSIONS: Anterior cervical plate position that deviates by morethan twenty-five percent from midline is strongly associated with increasedpostoperative neck pain reported one year after surgery. All other measuresof plate position in this study population had negligible affect on clinicaloutcome. A long-term follow-up study would be of interest to determinepersistence of neck pain associated with lateral plate position. Biomechani-cal studies of local stress forces in adjacent segments and facet joints

associated with lateral plate position may suggest a potential mechanismfor generation of neck pain in this setting.DISCLOSURES: FDA device/drug: Anterior cervical plates. Status: Ap-proved for this indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.099

4:2698. Anterior cervical discectomy and fusion correlation of fusionstatus with clinical outcomeKevin Foley, MD, John German, MD; Image-Guided Surgery ResearchCenter, Memphis, TN, USA

BACKGROUND CONTEXT: Although anterior cervical discectomy andfusion (ACDF) is a common surgical treatment for cervical disc disease,the influence of fusion status on clinical outcome remains unclear. Thisrelationship has not been addressed in the context of a multicenter, prospec-tive, randomized trial using independent radiographic assessment of fusionand patient-derived outcome measures.PURPOSE: The purpose of this study was to investigate the relationshipbetween fusion status and clinical outcome in patients undergoing ACDF.STUDY DESIGN/SETTING: This study was part of a multicenter, pro-spective, randomized, controlled clinical trial of the safety and efficacy ofpulsed electromagnetic field stimulation (PEMF) as an adjunct to cervicalspine fusion.PATIENT SAMPLE: Patients from twelve institutions with symptomaticradiculopathy and correlating radiographic evidence of cervical nerve rootcompression were candidates for entry into the study. All patients wereeither smokers (at least one pack/day) or required multi-level surgery andunderwent anterior cervical discectomy and Smith-Robinson fusion usingallograft bone and anterior cervical plating (single plating system). 323patients were enrolled in the study: 163 were randomized to receive pulsedelectromagnetic field stimulation (PEMF), 160 were randomized to thecontrol group (non-PEMF).OUTCOME MEASURES: Parameters included a focused neurologicalexam, a visual analogue scale (VAS) for pain at rest and with activity, theOswestry Neck Disability Index (NDI) for function, and radiographs.METHODS: Patients were assessed preoperatively and at 1, 3, 6, and 12months postoperatively and annually thereafter until the last patient enrolledhad reached 12 months follow-up. Patient-derived outcome measures wereobtained at each visit. Fusion status was determined in a blinded fashionby two independent orthopedic spine surgeons, as well as an independentradiologist, and rated as fused or not fused based on absence of radiolucency,¡A 50% bony bridging at each graft-vertebra interface, and ¡ 4¬ motionon flexion-extension views. The flexion-extension views were assessedusing computer-assisted, digitized overlay of scaled images. Fusion statuswas then correlated with four previously published definitions of clincalsuccess using the rest and activity VAS and the NDI. Student’s t test andPearson’s Chi square test were used for statistical analysis; significancewas set at p�.05.RESULTS: Power calculations using changes in VAS of 2.0cm and inNDI of 10.0 as clinically significant demonstrated adequate power for theVAS data at both 6 and 12 months and the NDI data at 6 months only.Eight VAS defintions of clinical success and two NDI definitions of clinicalsuccess were investigated. Of the VAS criteria, two proved statisticallysignificant with the remaining six criteria demonstrating numeric supportfor better outcome in fused versus not fused patients. Of the NDI criteria,one proved statistically significant with the other demonstrating numericsupport for better outcome in fused versus not fused patients.CONCLUSIONS: This is the first prospective, randomized, controlledmulticenter trial to investigate the relationship between fusion status andclinical outcome for ACDF. The presence of radiographic fusion followingACDF correlated with defintions of clinical success using patient-derivedoutcome measures.DISCLOSURES: FDA device/drug: Cervical-Stim. Status: Approved forthis indication.

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S52S

Thursday, September 29, 20054:56–5:39 PM

Concurrent Session: Lumbar Fusion

CONFLICT OF INTEREST: Author (KF) Grant Research Support:Orthofix, Inc.

doi: 10.1016/j.spinee.2005.05.100

4:3299. Comparison of conventional and current surgical techniquesof cervical extension osteotomy in ankylosing spondylitisEdward D. Simmons, MD1, Richard Distefano, MD2, Yinggang Zheng,MD1, Edward H. Simmons, MD1; 1University at Buffalo, Buffalo, NY,USA; 2Syracuse Orthopedic Specialists, Dewitt, NY, USA

BACKGROUND CONTEXT: Cervical osteotomy of ankylosing spondy-litis performed in the sitting position and under local anesthesia has beenpracticed in our center for 36 years and several modifications have been doneover the recent 7 years.PURPOSE: This study will compare our conventional and current surgicaltechniques, and their outcomes.STUDY DESIGN/SETTING: Cervical osteotomy has been performed byour two senior authors since the first case performed in 1967. The evolution ofsurgical techniques was divided into two phases: conventional techniqueof 1967–1994 and current technique of 1997–2003.PATIENT SAMPLE: 114 patients underwent cervical osteotomy per-formed with conventional technique and 17 patients with current technique.The average follow-up time was 9.7 years and 26 months respectively.OUTCOME MEASURES: The assessment of flexion deformity pre- andpostoperatively was consistent with the same measurement of chin-browto vertical angle.METHODS: The current group is characterized with larger lateral laminaresection area and external fixation with halo and vest rather than cast. Inboth techniques, the procedure was carried out under local anesthesia withthe patient awake and sitting in a dental chair. The osteotomy site was thesame C7-T1 level and was approached posteriorly.RESULTS: (1) The pre- and postoperative average angle was 56� and4� respectively in the conventional group and 49� and 12� in the currentgroup. (2) In the conventional group, the patients were admitted 2–3 daysprior to surgery and fitted with plaster thoracic cast and a cranial halo.Currently, patients are admitted the day of surgery and the titanium cranialhalo is put on along with thoracic vest in the operating room just prior tosurgery. Average hospital stay was 39 days in the past and 6 days now.(3) Current laminar resection area, differs from conventional resection area,being larger laterally and provides more room for C8 nerve roots bilaterally.The majority of the inferior portion of C6 lamina and superior 50% ofthe T1 lamina, as well as whole C7 lamina are resected. The lateral massjoints of C7-T1 are completely resected and the C7 pedicles are partiallyresected. The patient is given a short sedation and osteoclasis is carriedout to correct flexion deformity and maintain the chin-brow to verticalangle at approximately 10 degrees. Overcorrection beyond this should beavoided. Attachments between cranial halo and vest are connected after-ward. (4) 2 paraplegia occurred in the conventional group; 16 patientsand 2 patients were with transient C8 radiculopathy in the conventionaland current groups respectively. (5) In the conventional group, 4 deathsoccurred postoperatively on days 2, 21, 30 and 77 respectively due tocardio-pulmonary causes, and 6 pseudoarthroses were noted.CONCLUSIONS: Conventional technique has been performed for a largergroup of patients for almost 30 years and reasonably doing well. Thepotential of paraplegia and death alerts us that high risk exists. Even thoughit is a smaller group of patients treated with current technique for 7 years,the larger lateral laminar resection area greatly reduces the possibility ofC8 nerve root impingement. The adjustability of the halo and vest allowsfor modification of head/neck position or postoperative distraction if C8nerve root compression occurs, and quick access to the chest in the eventof a cardiac arrest situation.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.101

4:56100. Rate of total disability after lumbar discogenic fusion in theWorkmen’s Compensation populationNicholas Ahn, MD1, Uri Ahn, MD2, Carolien De Roode, MD3,Steven Kline, MD3, William Hopkins, MD4, Alexander Bailey4,William Reed, Jr.4, Glenn Amundson, MD4; 1Case WesternReserve University, Cleveland, OH, USA; 2New Hampshire SpineInstitute, Bedford, NH, USA; 3University of Missouri-Kansas City,Kansas City, MO, USA; 4Heartland Spine and Specialty Hospital,Overland Park, KS, USA

BACKGROUND CONTEXT: Lumbar discogenic fusion is a procedurewhich, even in the ideal candidate, has a limited success rate which is atbest approximately 70%. The results of lumbar fusion for mechanical backpain have been inferior in the Workmen’s Compensation (WC) population.PURPOSE: This study was performed to determine the improvement inpain and functional outcome, as well as the rate of total disability afterlumbar discogenic fusion in this population.STUDY DESIGN/SETTING: Retrospective review of WC patients whohad undergone single- or multi-level lumbar discogenic fusion with 2 yearfollow-up.PATIENT SAMPLE: 63 WC patients who had undergone lumbar disco-genic fusion for mechanical low back pain were studied. Exclusion criteriaincluded patients with neurogenic symptoms and patients who had under-gone previous lumbar fusion. All patients underwent combined interbody(ALIF or PLIF) and posterior fusion with instrumentation. Two year follow-up was available for all subjects.OUTCOME MEASURES: VAS and Oswestry scores were retrospectivelycalculated both pre- and postoperatively in all subjects. In addition, allpatients were evaluated for work capacity after surgery. Total disability wasdefined as a patient who was completely unable to return to any meaningfulwork 2 years after surgery.METHODS: Patients were also divided into three groups. Group 1 con-sisted of 39 patients who underwent single-level discogenic fusion. Group2 consisted of 19 patients underwent two-level discogenic fusion. Group 3consisted of 5 patients who underwent three-level discogenic fusion. Allmulti-level fusions were performed by 3 of the authors (ASB, WOR, GMA).Paired t tests were used to compare VAS and Oswestry scores before andafter surgery in each of the groups. t tests were also used to compare meanimprovement in VAS and Oswestry between Groups 1 and 2. Fisher’sexact test was used to compare the proportion of patients on total disabilityin Groups 1 and 2. Group 3 could not be tested as the rate of totaldisability was 100%.RESULTS: Group 1: Mean improvement in VAS was 4.1 (on a 1–10scale), and in Oswestry was 23 points. Paired t test demonstrated the changein VAS and Oswestry after fusion was significant (p�.05). 23% (9/39) ofthese patients went on to file for total disability after fusion. Group 2:Mean improvement in VAS was 1.1, and in Oswestry was 6 points. Pairedt test demonstrated the change in VAS was significant (p�.05), but thatthe change in Oswestry after fusion was not (p�.19). 74% (14/19) of thesepatients went on to file for total disability after fusion. Group 3: All patientswent on to total disability after fusion (5/5). No improvement in VAS orOswestry was noted (p�.05). Comparison of Groups 1 and 2: Fisher’sexact test comparing proportion of patients filing for total disability demon-strated the proportion was significantly higher in Group 2 than in Group 1(p�.01).CONCLUSIONS: Total disability is substantial in the WC patient undergo-ing lumbar discogenic fusion. After single level fusion, the total disabilityrate approaches 25%. In the WC patient undergoing multi-level lumbardiscogenic fusion, the rates of total disability were high (over 70% for 2level fusions and 100% for 3 level fusions). In addition, no significant