P102. Pedicle subtraction osteotomy with the use of an interbody device for the correction of sagittal imbalance

Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S 25.5⬚⫾8.0⬚ to 16.2⬚⫾6.6⬚ relative to S1 endplate, but reproduced the IAR horizontal motion to the side of the bending. Facet force during lateral bending was unchanged after disc replacement (p⫽0.192), being increased on the side of the bending. CONCLUSIONS: Despite the physical constraints of the ball and socket design, the treated segments demonstrated the normal path of the IAR during motion with a vertical IAR movement in flexion/extension, and a horizontal IAR movement in lateral bending. Disc replacement partially unloaded the facets in flexion/extension and increased coupled rotation in lateral bending. The deviation of the IAR from the center of the spherical bearing surface, and the increased coupled rotation in lateral bending, demonstrate the important role of facets play in constraining movement under combined compression and anterior shear. Also, the decreased facet forces after arthroplasty demonstrates that the implants may distract the facet joints while providing resistance to antero-posterior shear. Of course, because this is a cadaveric, in vitro study, the results are applicapable only to the immediate postoperative period. DISCLOSURES: Device or drug: Prodisic II (Spine Solutions Paoli, PA). Status:Investigational/Not approved. CONFLICT OF INTEREST: Author (MR) Other: financial support: Synthes. doi: 10.1016/j.spinee.2004.05.156 P57. Factors leading to complications in anterior cervical spine surgery Kevin Draxinger, Richard Skolasky, Jr., MA, Lee Riley, III; Johns Hopkins University, Baltimore, MD, USA BACKGROUND CONTEXT: Anterior cervical decompression and fusion (ACDF) spine surgeries are considered safe, short-stay procedures. Previous studies of anterior cervical surgery have studied at the trends and complications using national databases. None have examined possible reasons for the complications, such as co-morbidities, age, yearly volume of both surgeon and hospital, and the associated costs when complications do occur. PURPOSE: To determine what parameters lead to an increase in complication rates in anterior cervical decompression and fusion surgery. STUDY DESIGN/SETTING: A retrospective review of the National Inpatient Survey (NIS) databases from years 1999–2001 of ACDF complications and associated factors. PATIENT SAMPLE: Data from the NIS databases from the years 1999, 2000, and 2001 were subject to statistical analysis. OUTCOME MEASURES: We used statistical analysis to determine if there is a cause for complication rates in ACDF. METHODS: Data from the NIS databases from the years 1999, 2000, and 2001 were subject to analysis. The ICD9-CM codes were utilized to determine patients having elective anterior cervical spine surgery, their admission diagnoses, co-morbidities and peri-operative complications. Entries with one or more complications were analyzed to determine possible factors such as age, surgeon or hospital volume, and other co-morbidities that may lead to an increased length of stay thus probably increased costs. RESULTS: Approximately 52000 anterior cervical spine surgeries were identified from the three years (1999–2001) with a total of 343 patients having one or more complications. There was a significant increase in length of stay for patients having one or more complications. Those surgeons with a high volume (⬍30 cases/year) reported significantly lower complication rates compared to the lowest volume (⬍10 case/year) surgeons. Likewise hospitals with high volumes (⬎84 cases/year) also reported significantly lower complication rates compared to low volume (⬍30 cases/year) hospitals. Complication rates were higher in patients over 60 years old and in patient with one or more co-morbidities. Respiratory complications were the most documented complications; however, iatrogenic pulmonary embolism resulted in the longest length of stay and highest associated cost. CONCLUSIONS: Anterior cervical spine surgery is a safe and simple procedure but is not without complication. Complications are more likely

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to occur in a low volume center or performed by a surgeon with low volumes. Respiratory complications were most frequent but pulmonary embolism led to the longest stay in hospital and increased charges. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.157

P102. Pedicle subtraction osteotomy with the use of an interbody device for the correction of sagittal imbalance John Spears1*, Vinod Podichetty2, Robert Biscup1, Robert Isaacs3; 1 Cleveland Clinic Florida, Weston, FL, USA; 2Weston, FL, USA; 3 Cleveland Clinic Florida Spine Institute, Weston, FL, USA BACKGROUND CONTEXT: Surgical treatment of acquired kyphotic deformity of the spine has included vertebral osteotomies, Smith-Peterson osteotomies, combined anterior and posterior, and pedicle subtraction. PSO has the advantage of three-column correction from a posterior only surgical approach. PURPOSE: A new technique of PSO supplemented by the placement of an anterior column support device would allow for an equal amount of deformity correction with a narrower posterior wedge resection. The addition of the interbody device increases anterior column height, providing a fulcrum while closing the posterior and middle column osteotomy. This is particularly true in the case of revision surgery after cage fusion when the failed device must be removed. STUDY DESIGN/SETTING: A retrospective case control series was performed by one senior surgeon on 26 patients receiving a PSO with placement of an anterior column device augmenting the osteotomy. PATIENT SAMPLE: There were 11 females and 15 males (n=26). The average age was 58.8 years. Five patients had failed cage fusions, thirteen had postlaminectomy instability with acquired kyphosis, three patients had a junctional kyphosis above a previous fusion, and five had post-traumatic or acquired kyphotic deformities. OUTCOME MEASURES: A radiographic analysis of digitized serial plain films to determine fusion, segmental, and regional correction. METHODS: Between March 1998 and January 2004 26 patients had PSO with anterior column device augmentation for correction of kyphotic deformity performed. Hospital records and radiographs were reviewed. Nineteen patients had complete radiographs for review. The kyphotic lumbar segments (the osteotomy angle) and regional lumbar lordosis was measured pre-, postoperatively, and at follow up. Intraoperative data regarding operative time, blood loss, and transfusion requirements was collected. Hospital length of stay, early, and late complications were recorded. RESULTS: Average operative time was 348 minutes. Average blood loss was 2848 ml. Patients received an average of 1930 ml of autologous or allogenic blood intraoperatively. 38.5% of patients required postoperative transfusion. Average length of stay was 6.3 days. Five patients had hypodynamia or ileus that lengthened their hospital stay. One patient experienced an osteoporotic fracture above the fusion level one-month postoperatively requiring extension of the fusion. No patient suffered a permanent neurologic complication. The average improvement in segmental lordosis was 21.6⬚ (⫺11.9 preop to 9.7 postop). The average improvement in regional lumbar lordosis was 18⬚ (2.8 preop to 20.8 postop). All patients began as kyphotic deformities and corrected to normal ranges of regional and segmental lordosis. CONCLUSIONS: The addition of an anterior column device to the pedicle subtraction osteotomy lengthens the anterior column, provides graft material under compression, and limits the amount of wedge resection necessary at the osteotomy site to provide sagittal angular correction. Significant correction of acquired flatback deformities was achieved with this method. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No Conflicts. doi: 10.1016/j.spinee.2004.05.158