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Subsidence and Fusion Rates Comparing PEEK to Titanium (Ti) Interbody Devices in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MITLIF)
Proceedings of the NASS 28th Annual Meeting / The Spine Journal 13 (2013) 1S–168S ID. Historic studies have recently been used as benchmark data for online ratings of surgeons and institutions and may eventually influence reimbursement. However, these reports may not consider the complexity of factors that predispose to risk of ID. PURPOSE: To conduct a multivariate analysis for risk factors for ID in patients who underwent spine surgery and to develop a risk stratified scoring algorithm for determining risk for incidental durotomy in the context of modern spine surgical procedures at a high volume center. STUDY DESIGN/SETTING: Retrospective multi-variate analysis of a matched-cohort of patients who underwent spine surgery at a single institution between 2010 and 2011. PATIENT SAMPLE: Consecutive adult patients (n54,822) who underwent spine surgery at a single institution between 2010 and 2011. OUTCOME MEASURES: Intra-operative incidental durotomy. METHODS: Patients with ID (n5186) were identified and matched 1:1 with control patients (i.e. no ID) (n5186). Univariate and multiple forward-stepwise regression models of surgeon, demographic, diagnostic, and procedural factors were developed to determine risk factors using relative risk (RR). Using identified risk factors, a predictive probability algorithm for risk stratification of ID was constructed. RESULTS: Posterior surgical approach (RR: 12.5, p!0.002), lumbar operation (RR: 9.0, p!0.005), revision surgery (RR: 3.8, p!0.001), osteoporosis (t-score!2.5) (RR: 2.3, p!0.04), and stenosis requiring surgery (RR: 2.2, p! 0.007) were identified as statistically significant risk factors for ID. These five predictors were utilized to construct our probability profile, which predicted 5.5%, 13.0%, 28.0%, 51.0%, 73.0%, and 88.0% of ID in the presence of 0, 1, 2, 3, 4, and 5 predictors, respectively (p!0.001). Lateral approach was a significant protective factor (RR: 0.45, p50.047). The number of years out of fellowship for surgeons did not significantly correlate with occurrence of ID (r5-0.46, p50.16). However, there was a significant correlation between operative volume and occurrence of ID (r50.63, p50.029). CONCLUSIONS: Our regression model at a high volume spine surgery center with modern spine techniques predicts posterior approach, lumbar operation, revision surgery, osteoporosis, and stenosis requiring surgery increase the patient’s risk for ID and these factors are often additive. These data suggest lateral approaches are protective and surgeon experience does not play a role. This risk stratified profile will help guide the preoperative informed decisionmaking process to counsel a patient about the relative risk for ID. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
153S
(SiHA) fusion material and unilateral pedicle fixation with early patient ambulation. Data were obtained using 8 different IBDs. Six had traditional PLIF designs with vertical walls, 3 PEEK and 3 Titanium (Ti V). Two were special geometric titanium designs (Ti SD). METHODS: Subsidence was studied in 111 patients (47 male, 64 female) ages 16 to 83 (average 56) with digital images on a single PACS system. These were all single level MITLIF with heights of motion segments measured pre op and after confirmed fusion. Careful measurement of each fused level was made independently by two separate individuals with master degrees. When values agreed or differed by only one mm they were accepted (averaging those which varied). Values which varied more than one mm were subjected to detailed reexamination by two separate medical professionals until an accurate value was determined comparing pre and postop midline slice patterns. Fusions were evaluated at 544 levels in 511 patients (241 male, 270 female) ages 15 to 84 (average 57). Fusions were determined by bridging bone seen on reformatted coronal and sagittal images from thin slice CT Scans at 1 year or longer after surgery. RESULTS: Change in Motion Segment Height MITLIF all devices: -0.47mm Males: -0.39mm Females: -0.52mm Age: !60: 0.14* $60: -1.21mm *Positive value indicates increased height due to operative restoration of disc height Effects of Material PEEK: -0.31mm Ti: -0.60mm Effects of Design Vertical Wall (PEEK & Ti V): -0.59mm Special Design (Ti SD): -0.04mm Fusion Rates Fused Non Union Uncertain PEEK 91.8% 6.6% 1.6% Ti 98.3% 1.2% 0.5% CONCLUSIONS: Subsidence from MITLIF with unilateral fixation is less than ½ mm. Subsidence is affected by age but not by gender. Subsidence is not significantly different between PEEK and Ti. Special geometric designs have significantly less subsidence than vertical straight walled PLIF type devices (p5.03) Fusion and nonunion rates are significantly better with Ti than PEEK (p5.003). Risk of failure of fusion with PEEK (8.2%) compared to Ti (1.7%) is statistically significant (p5.003). Design is more important than material to reduce subsidence. Material is more important than design to promote fusion. Titanium and PEEK IBDs with Vertical Walls Special Geometric Titanium Designs. FDA DEVICE/DRUG STATUS: Unilateral pedicle fixation (Not approved for this indication), ‘‘PLIF type’’ Titanium and PEEK devices (Not approved for this indication), Titanium Geo Structure (Unknown), TiSD device (Approved for this indication), BMP2 (Not approved for this indication), SiHA (Not approved for this indication). http://dx.doi.org/10.1016/j.spinee.2013.07.389
http://dx.doi.org/10.1016/j.spinee.2013.07.388
P115. Subsidence and Fusion Rates Comparing PEEK to Titanium (Ti) Interbody Devices in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MITLIF) Walter W. Eckman, MD, Lynda G. Hester, PT, Michelle McMillen, RN; Aurora Spine Center, Tupelo, MS, US BACKGROUND CONTEXT: PEEK interbody devices have been popularized due to radiolucency and speculation that subsidence would be less with a low modulus of elasticity. PEEK is very weak (3.6 GPa) while bone is 3 to 8 times stronger (10-30 GPa) and Ti is 3 to 8 times stronger than bone (100 GPa). Fracturing and fragmentation of PEEK devices is under-reported but has recently caused at least one PEEK device to be removed from the market by the FDA. Weak interbody devices and the inherent nature of interbody fusion procedures, which increase likelihood of subsidence, lessen motion segment stability and may reduce fusion rates. Unilateral MITLIF with a single interbody device and unilateral pedicle screw fixation presents a significant challenge when trying to prevent subsidence and achieve fusion. PURPOSE: To study subsidence and fusion rates in MITLIF with unilateral pedicle fixation comparing PEEK, titanium and special geometric titanium designs. STUDY DESIGN/SETTING: All patients had one or two level unilateral MITLIF by a single surgeon using a closed 21mm working channel, single interbody devices with BMP2 or Silicate Substituted Hydroxyapatite
P116. Degenerative Changes in the Lumbar Spine Correlate with Spino-Pelvic Alignment in Patients with Low Back Pain Dominique A. Rothenfluh1, Julia Lebschi, MD2, Esin Rothenfluh, MD3; 1 Nottingham, UK; 2University of Zurich, Zurich, Switzerland; 3Nottingham University Hospitals NHS Trust, Nottingham, UK BACKGROUND CONTEXT: In a previous study [submitted] we have derived a model to assign patients to either a higher or lower risk group for symptomatic adjacent segment degeneration (ASD) after lumbar spinal fusion based on their spino-pelvic alignment described by the difference of pelvic incidence and lumbar lordosis. Logistic regression has determined a cut off value of 15 to divide patients into two groups. Patients with a difference in pelvic incidence and lumbar lordosis of more than 15 had a 20times higher risk for developing symptomatic ASD with a sensitivity of 75% and specificity of 87%. A subsequent biomechanic modeling study [submitted] has shown that in this patient group, joint reaction forces in the unfused spine and in the adjacent segment are significantly higher especially for shear stress. PURPOSE: Based on the above findings we hypothesized that as a result of different segmental joint loads, spino-pelvic alignment correlates with degenerative changes seen on MRI in patients with low back pain. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Out of 1638 clinical reports of first consultations in 2010 with primary diagnosis low back pain, 274 patients had MRI
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.
153S
(SiHA) fusion material and unilateral pedicle fixation with early patient ambulation. Data were obtained using 8 different IBDs. Six had traditional PLIF designs with vertical walls, 3 PEEK and 3 Titanium (Ti V). Two were special geometric titanium designs (Ti SD). METHODS: Subsidence was studied in 111 patients (47 male, 64 female) ages 16 to 83 (average 56) with digital images on a single PACS system. These were all single level MITLIF with heights of motion segments measured pre op and after confirmed fusion. Careful measurement of each fused level was made independently by two separate individuals with master degrees. When values agreed or differed by only one mm they were accepted (averaging those which varied). Values which varied more than one mm were subjected to detailed reexamination by two separate medical professionals until an accurate value was determined comparing pre and postop midline slice patterns. Fusions were evaluated at 544 levels in 511 patients (241 male, 270 female) ages 15 to 84 (average 57). Fusions were determined by bridging bone seen on reformatted coronal and sagittal images from thin slice CT Scans at 1 year or longer after surgery. RESULTS: Change in Motion Segment Height MITLIF all devices: -0.47mm Males: -0.39mm Females: -0.52mm Age: !60: 0.14* $60: -1.21mm *Positive value indicates increased height due to operative restoration of disc height Effects of Material PEEK: -0.31mm Ti: -0.60mm Effects of Design Vertical Wall (PEEK & Ti V): -0.59mm Special Design (Ti SD): -0.04mm Fusion Rates Fused Non Union Uncertain PEEK 91.8% 6.6% 1.6% Ti 98.3% 1.2% 0.5% CONCLUSIONS: Subsidence from MITLIF with unilateral fixation is less than ½ mm. Subsidence is affected by age but not by gender. Subsidence is not significantly different between PEEK and Ti. Special geometric designs have significantly less subsidence than vertical straight walled PLIF type devices (p5.03) Fusion and nonunion rates are significantly better with Ti than PEEK (p5.003). Risk of failure of fusion with PEEK (8.2%) compared to Ti (1.7%) is statistically significant (p5.003). Design is more important than material to reduce subsidence. Material is more important than design to promote fusion. Titanium and PEEK IBDs with Vertical Walls Special Geometric Titanium Designs. FDA DEVICE/DRUG STATUS: Unilateral pedicle fixation (Not approved for this indication), ‘‘PLIF type’’ Titanium and PEEK devices (Not approved for this indication), Titanium Geo Structure (Unknown), TiSD device (Approved for this indication), BMP2 (Not approved for this indication), SiHA (Not approved for this indication). http://dx.doi.org/10.1016/j.spinee.2013.07.389
http://dx.doi.org/10.1016/j.spinee.2013.07.388
P115. Subsidence and Fusion Rates Comparing PEEK to Titanium (Ti) Interbody Devices in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MITLIF) Walter W. Eckman, MD, Lynda G. Hester, PT, Michelle McMillen, RN; Aurora Spine Center, Tupelo, MS, US BACKGROUND CONTEXT: PEEK interbody devices have been popularized due to radiolucency and speculation that subsidence would be less with a low modulus of elasticity. PEEK is very weak (3.6 GPa) while bone is 3 to 8 times stronger (10-30 GPa) and Ti is 3 to 8 times stronger than bone (100 GPa). Fracturing and fragmentation of PEEK devices is under-reported but has recently caused at least one PEEK device to be removed from the market by the FDA. Weak interbody devices and the inherent nature of interbody fusion procedures, which increase likelihood of subsidence, lessen motion segment stability and may reduce fusion rates. Unilateral MITLIF with a single interbody device and unilateral pedicle screw fixation presents a significant challenge when trying to prevent subsidence and achieve fusion. PURPOSE: To study subsidence and fusion rates in MITLIF with unilateral pedicle fixation comparing PEEK, titanium and special geometric titanium designs. STUDY DESIGN/SETTING: All patients had one or two level unilateral MITLIF by a single surgeon using a closed 21mm working channel, single interbody devices with BMP2 or Silicate Substituted Hydroxyapatite
P116. Degenerative Changes in the Lumbar Spine Correlate with Spino-Pelvic Alignment in Patients with Low Back Pain Dominique A. Rothenfluh1, Julia Lebschi, MD2, Esin Rothenfluh, MD3; 1 Nottingham, UK; 2University of Zurich, Zurich, Switzerland; 3Nottingham University Hospitals NHS Trust, Nottingham, UK BACKGROUND CONTEXT: In a previous study [submitted] we have derived a model to assign patients to either a higher or lower risk group for symptomatic adjacent segment degeneration (ASD) after lumbar spinal fusion based on their spino-pelvic alignment described by the difference of pelvic incidence and lumbar lordosis. Logistic regression has determined a cut off value of 15 to divide patients into two groups. Patients with a difference in pelvic incidence and lumbar lordosis of more than 15 had a 20times higher risk for developing symptomatic ASD with a sensitivity of 75% and specificity of 87%. A subsequent biomechanic modeling study [submitted] has shown that in this patient group, joint reaction forces in the unfused spine and in the adjacent segment are significantly higher especially for shear stress. PURPOSE: Based on the above findings we hypothesized that as a result of different segmental joint loads, spino-pelvic alignment correlates with degenerative changes seen on MRI in patients with low back pain. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Out of 1638 clinical reports of first consultations in 2010 with primary diagnosis low back pain, 274 patients had MRI
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.