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P11. Incidence and Risk Factors for Low Back Pain in Active Duty Military Over a 10 Year Period
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Proceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S
P9. Age as a Key Determinant of Mortality, Impairment and Disability Following Traumatic Spinal Cord Injury: Analysis of the NASCIS-3 Database Julio Furlan, MD, MBA, MSC, PhD1, Michael Bracken, FACE, PhD2, Michael Fehlings, MD, PhD, FACS, FRCSC3; 1Toronto Western Research Institute, Toronto, Ontario, Canada; 2Yale University, New Haven, CT, USA; 3University of Toronto, Toronto, Ontario, Canada BACKGROUND CONTEXT: Despite an increasing incidence of spinal cord injury (SCI) in the elderly, surprisingly little is known regarding outcomes in elderly with an acute SCI. PURPOSE: We sought to evaluate whether age influences mortality, neurological and functional recovery in the acute and chronic stages after traumatic SCI. STUDY DESIGN/SETTING: A retrospective study based on a large, prospectively accrued cohort of SCI adults from 10 trauma centers in the USA. PATIENT SAMPLE: This study included 499 subjects from the National Acute Spinal Cord Injury Study 3 (NASCIS-3) database. The inclusion and exclusion criteria are reported elsewhere (1). OUTCOME MEASURES: Mortality was examined at 6 weeks, 6 and 12 months. Motor, sensory and pain outcomes were assessed using NASCIS scores at 6 weeks, 6 and 12 months. Functional outcome was evaluated using the Functional Independence Measure (FIM) at the same three time points. METHODS: Data were analyzed using Mann-Whitney U test, Fisher’s exact test, Kaplan-Meier curves with log-rank test, Cox regression and regression analyses. The regression analyses included unadjusted models and models controlled for major potential confounders (i.e. sex, ethnicity, Glasgow coma score, blood alcohol concentration on admission, drug protocol, cause, level and severity of SCI). RESULTS: Mortality rates among older people (65 years or older) were significantly greater than younger individuals at 6 weeks, at 6 months and at 1 year following SCI (38.6% versus 3.1%; p!0.0001). Among survivors, age was not significantly correlated with motor recovery or change in pain scores in the acute and chronic stages after SCI based on regression analyses adjusted for major confounders. However, older individuals experienced greater functional impairment (based on FIM scores) than younger individuals, despite experiencing similar rates of sensorimotor recovery (based on NASCIS scores). CONCLUSIONS: Older individuals have a substantially increased mortality rate during the first year following traumatic SCI in comparison with younger patients. Among survivors, the potential of older patients with SCI to neurologically improve within the first year post-injury, this does not appear to translate into similar functional recovery when compared to younger individuals. Given this, rehabilitation protocols that are more focused on functional recovery may reduce disability among older people with acute traumatic SCI. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.267 P10. Fluoroscopic Radiation Exposure in Degenerative Spinal Surgery: In Vivo Evaluation for Operating Room Personnel Daniel Mulconrey, MD; Midwest Orthopaedic Center, Peoria, IL, USA BACKGROUND CONTEXT: No previous study has performed an in vivo examination of fluoroscopic radiation exposure to the spinal surgeon and operating room personnel in a degenerative spine practice. Previous similar studies employed older versions of fluoroscopy and increased fluoro times associated with pedicle screw placement (2.5-6.3 min). Greatest concern for radiation exposure is the unprotected regions of the body including the hands and eyes with recommended annual permissible doses of 15 rem (eye) and 50 rem (hand/body organ). PURPOSE: To quantify the total amount of radiation dosage and identify techniques to maintain safe levels of fluoroscopic exposure in the operating room.
STUDY DESIGN/SETTING: Prospective in vivo investigation of fluoroscopic radiation exposure during spinal surgery. PATIENT SAMPLE: Thirty-five surgeries were evaluated in 18 males and 17 females (mean age 52.4yrs, range 26.0-79.4). These surgeries included 37 lumbar levels fused, 45 lumbar decompressions, 8 anterior cervical fusions, and 19 TLIF procedures. Spinal instrumentation was implemented in all fusion procedures (104 lumbar pedicle screws, 14 iliac, 22 anterior cervical). All surgeries were performed with a standard, open technique. OUTCOME MEASURES: Dosimetry readings in the operating room would identify techniques to minimize radiation exposure and provide a contrast to accepted annual limits of occupational radiation exposure. The goal was to obtain practical data for extrapolation to the standard degenerative spine practice and establish recommendations for fluoroscopy usage. METHODS: Fluoroscopy was implemented for localization of the level, pedicle screw insertion, verification of decompression, and/or final image. Radiation dosimetry was obtained through unprotected badges placed (1)surgeon’s chest (2)first assistant chest (3,4) cranial and caudal end of operating table. Fluoroscopy images were obtained from an OEC 9800 and data obtained included mA, kVp, total fluoro time, and estimated dose projected to patient. RESULTS: Total fluoroscopic time for all surgeries was 37.01 minutes. Total dose administered to patients was 29.2R (mean mA 5.48, kVp 104.5). Mean fluoroscopic time with lumbar spine instrumentation was greater than decompression alone (instr. 1.74 min vs decomp 0.22 min). Total fluoroscopic radiation exposure was obtained for surgeon (1225 mrem), first assistant (369 mrem), cranial table (92 mrem) and caudal table (150 mrem). Mean dose/min (mrem/min) was calculated for surgeon (33.1), first assistant (9.97), cranial table (2.48), and caudal table (4.05). To remain below the maximum yearly permissible level of radiation, the estimated total number of minutes for the surgeon would be 453 (eye) and 1592 (hand/organ). CONCLUSIONS: Fluoroscopic radiation exposure to the operating room personnel is minimal and the dosage to the spine surgeon remains clearly below an acceptable limit of occupational radiation exposure. Increasing distance from the radiation source led to a significantly diminished dosimetry reading. However, lead shielding for the operating staff remains highly recommended. By minimizing fluoroscopic time and maintaining a safe surgeon distance from the source, radiation contact to the spine surgeon is within safety standards. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.268
P11. Incidence and Risk Factors for Low Back Pain in Active Duty Military Over a 10 Year Period Jeffrey Knox, MD1, Joseph Orchowski, MD1, Philip Belmont, Jr., MD2, Danielle Scher, MD2, Robert Burks, PhD3, Brett Owens, MD2; 1Tripler Army Medical Center, Honolulu, HI, USA; 2William Beaumont Army Medical Center, El Paso, TX, USA; 3US Military Academy, West Point, NY, USA BACKGROUND CONTEXT: Low back pain is among the most common musculoskeletal conditions worldwide and is estimated to affect nearly two-thirds of the US population at some point in their lives. It carries a significant economic burden with an estimated annual cost of $28 billion. Because of the impact this condition has on industry and a significant portion of the general population, it has been the subject of numerous studies to assess its risk factors as well as prognostic indicators for this disease. Low back pain is a multifactorial disease and many risk factors have been implicated including age, race, gender, and marital status. PURPOSE: To investigate the incidence and risk factors for developing low back pain in active duty military population to include age, sex, race, and rank, and military service.
Proceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S STUDY DESIGN/SETTING: Epidemiological study utilizing a database containing demographic information and ICD-9 diagnosis codes for active duty military servicemembers over a 10-year period PATIENT SAMPLE: All individuals serving as active duty military between the years of 1998 and 2008. OUTCOME MEASURES: New onset low back pain requiring a visit to a health care provider. METHODS: To determine the incidence and risk factors for development of low back pain in the active duty military, we conducted a search utilizing the Defense Medical Epidemiology Database (DMED). This database compiles ICD-9-CM coding information for every patient encounter occurring in US military treatment facilities. It also compiles patient demographic information including age, race, gender, rank, and military service. The DMED database was queried using the ICD-9 code 724.2 (Lumbago) and stratified according to these parameters. Our search was limited to first occurrence diagnoses and diagnoses occurring in the ambulatory setting. These data sets were then analyzed using a multivariate Poisson regression analysis. RESULTS: A total of 557,059 cases of low back pain were documented in our population at risk of 13,754,261 person-years. The unadjusted incidence rate of low back pain in our population was 40.5 per 1,000 person-years. Females, compared with males, had a significantly increased adjusted incidence rate ratio (IRR) for low back pain of 1.45 (95% CI 1.44-1.46). Older age groups also were at greater risk of low back pain with the 35-39 (IRR51.19, CI 1.17-1.20) and O40 groups (IRR51.40, CI 1.39-1.42) reaching significance. Servicemembers in the Army (IRR52.17, CI 2.15-2.19) and Air Force (IRR51.52, CI 1.51-1.54) had higher rates when compared with the Marines. Married servicemembers had a higher incidence compared to single servicemembers (IRR51.19, CI1.18-1.19). Junior enlisted servicemembers (E1-E4) had a higher incidence compared to junior officers (O1-O3) (IRR52.0; CI 1.98-2.0). CONCLUSIONS: Female sex, increasing age, service in the Army or Air Force, married status, and junior enlisted rank were all significant risk factors for low back pain. This study constitutes the largest study on this topic to date. An improved understanding of the rate of occurrence of low back pain and the related demographics and risk factors may help formulate diagnostic and preventive strategies. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.269
P12. Testing Minimal Clinically Important Differences: Consensus, Conundrum, or a Red Herring? Robert Gatchel, PhD1, Tom Mayer, MD2; 1University of Texas at Arlington, Arlington, TX, USA; 2University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA BACKGROUND CONTEXT: Various methodologies have been utilized in attempting to develop a standard method for calculating Minimum Clinically Important Difference (MCID) to allow assessment of treatment outcomes. A consensus-based decision (IMPACT group) suggested a 30% reduction from baseline as a means to define the MCID of self-report back pain measures. Vital psychometric issues must be addressed regarding use of an independent measure of the same construct as an external criterion, instead of simply another self-report measure when using an anchor-based approach to MCID. PURPOSE: To test the validity of recently published guidelines regarding MCID using self-report back pain measures and objective socioeconomic outcomes. STUDY DESIGN/SETTING: A prospective study assessing change scores on commonly used spinal pain assessment measures in patients with chronic disabling occupational spinal disorders (CDOSDs) treated in a regional referral rehabilitation center for functional restoration. PATIENT SAMPLE: A consecutive cohort of patients (N51187) with CDOSDs completing a functional restoration program.
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OUTCOME MEASURES: Self-report measures, including the Oswestry Disability Index (ODI) and the SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS) obtained pre- and posttreatment compared to objective socioeconomically-relevant outcomes 1 year post-treatment including work status, health utilization, recurrent injury and case closure were used as external criteria for evaluating MCID. METHODS: Pre- to post-treatment improvement was calculated separately for each measure, and subjects were divided into two groups based on the change in scores relative to baseline: 30% or greater, versus less than 30% improvement. One-year post-treatment objective socioeconomic outcomes were used as independent external criteria relevant to the CDOSD population. That is often studied as the most costly and problematic cohort in spine care. RESULTS: The ODI and SF-36 MCS were not associated with any of the objective one-year outcomes used as external criteria. Reduced post-rehabilitation healthcare utilization (based on percent patients pursuing healthcare from a new provider) was weakly associated with 30% or greater improvement on the SF-36 PCS, relative to patients whose scores changed by less than 30% relative to baseline (15.8% vs. 21.9%). CONCLUSIONS: When objective and independent criteria are used (socioeconomic outcomes), the 30% improvement in the ODI and SF-36 may not be a valid MCID index. This replicates similar conclusions made by an independent research group using a distribution-based approach to MCID. The validity of the anchor-based MCID concept rests on future research using objective external criteria. Moreover, there remains a question whether the term ‘‘important’’ in MCID can be unequivocally and operationally defined as a reliable construct. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.270
P13. Comparison of Motion Patterns of an Elastomeric Disc Prosthesis to a Sliding Bearing Disc Prosthesis: Effects on the Facet Joint Motion/Stress During Flexion/Extension Casey Lee, MD1, Luiz Pimenta, MD, PhD2, James Dwyer, MD3; 1 Roseland, NJ, USA; 2Santa Rita Hospital, Sao Paolo, Brazil; 3New Jersey Spine Institute, Bedminster, NJ, USA BACKGROUND CONTEXT: Artificial disc replacement (ADR) with the current generation provides satisfactory pain relief and functional recovery. However, the first generation disc prostheses with sliding core design present increasing concerns of abnormal biomechanics at the posterior structures evidenced by early facet joints degeneration and of stress fractures of pars or pedicles after ADR. PURPOSE: To compare the motion patterns of the vertebral bodies and facet joints of ADR with sliding core prosthesis (SB Charite) to ADR of elastomeric disc prosthesis (Physio-L) during flexion and extension. STUDY DESIGN/SETTING: Comparison of motion patterns of vertebral bodies on lateral x-rays during flexion/extension; Physio-L VS Charite disc prosthesis. PATIENT SAMPLE: Post-operative flexion and extension x-rays of 14 patients with Physio-L disc prosthesis and of 10 patients with Charite prosthesis were evaluated for motion patterns of vertebral bodies and facet joints. OUTCOME MEASURES: Translational displacements in the AP and vertical directions of vertebral bodies of ADR during flexion/extension were compared between the Physio-L and Charite disc prosthesis. METHODS: The magnitude of AP and vertical translation of the posterior-inferior corner (A1 at extension and A2 at flexion) and the anterior-inferior corner (B1-extension and B2-flexion) of the superior vertebral body (VB) of ADR in reference to the inferior VB during flexion/extension. The measurement was normalized to 4 cm AP distance to eliminate variables of x-ray magnification. The point P is the crossing point of two lines of
Proceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S
P9. Age as a Key Determinant of Mortality, Impairment and Disability Following Traumatic Spinal Cord Injury: Analysis of the NASCIS-3 Database Julio Furlan, MD, MBA, MSC, PhD1, Michael Bracken, FACE, PhD2, Michael Fehlings, MD, PhD, FACS, FRCSC3; 1Toronto Western Research Institute, Toronto, Ontario, Canada; 2Yale University, New Haven, CT, USA; 3University of Toronto, Toronto, Ontario, Canada BACKGROUND CONTEXT: Despite an increasing incidence of spinal cord injury (SCI) in the elderly, surprisingly little is known regarding outcomes in elderly with an acute SCI. PURPOSE: We sought to evaluate whether age influences mortality, neurological and functional recovery in the acute and chronic stages after traumatic SCI. STUDY DESIGN/SETTING: A retrospective study based on a large, prospectively accrued cohort of SCI adults from 10 trauma centers in the USA. PATIENT SAMPLE: This study included 499 subjects from the National Acute Spinal Cord Injury Study 3 (NASCIS-3) database. The inclusion and exclusion criteria are reported elsewhere (1). OUTCOME MEASURES: Mortality was examined at 6 weeks, 6 and 12 months. Motor, sensory and pain outcomes were assessed using NASCIS scores at 6 weeks, 6 and 12 months. Functional outcome was evaluated using the Functional Independence Measure (FIM) at the same three time points. METHODS: Data were analyzed using Mann-Whitney U test, Fisher’s exact test, Kaplan-Meier curves with log-rank test, Cox regression and regression analyses. The regression analyses included unadjusted models and models controlled for major potential confounders (i.e. sex, ethnicity, Glasgow coma score, blood alcohol concentration on admission, drug protocol, cause, level and severity of SCI). RESULTS: Mortality rates among older people (65 years or older) were significantly greater than younger individuals at 6 weeks, at 6 months and at 1 year following SCI (38.6% versus 3.1%; p!0.0001). Among survivors, age was not significantly correlated with motor recovery or change in pain scores in the acute and chronic stages after SCI based on regression analyses adjusted for major confounders. However, older individuals experienced greater functional impairment (based on FIM scores) than younger individuals, despite experiencing similar rates of sensorimotor recovery (based on NASCIS scores). CONCLUSIONS: Older individuals have a substantially increased mortality rate during the first year following traumatic SCI in comparison with younger patients. Among survivors, the potential of older patients with SCI to neurologically improve within the first year post-injury, this does not appear to translate into similar functional recovery when compared to younger individuals. Given this, rehabilitation protocols that are more focused on functional recovery may reduce disability among older people with acute traumatic SCI. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.267 P10. Fluoroscopic Radiation Exposure in Degenerative Spinal Surgery: In Vivo Evaluation for Operating Room Personnel Daniel Mulconrey, MD; Midwest Orthopaedic Center, Peoria, IL, USA BACKGROUND CONTEXT: No previous study has performed an in vivo examination of fluoroscopic radiation exposure to the spinal surgeon and operating room personnel in a degenerative spine practice. Previous similar studies employed older versions of fluoroscopy and increased fluoro times associated with pedicle screw placement (2.5-6.3 min). Greatest concern for radiation exposure is the unprotected regions of the body including the hands and eyes with recommended annual permissible doses of 15 rem (eye) and 50 rem (hand/body organ). PURPOSE: To quantify the total amount of radiation dosage and identify techniques to maintain safe levels of fluoroscopic exposure in the operating room.
STUDY DESIGN/SETTING: Prospective in vivo investigation of fluoroscopic radiation exposure during spinal surgery. PATIENT SAMPLE: Thirty-five surgeries were evaluated in 18 males and 17 females (mean age 52.4yrs, range 26.0-79.4). These surgeries included 37 lumbar levels fused, 45 lumbar decompressions, 8 anterior cervical fusions, and 19 TLIF procedures. Spinal instrumentation was implemented in all fusion procedures (104 lumbar pedicle screws, 14 iliac, 22 anterior cervical). All surgeries were performed with a standard, open technique. OUTCOME MEASURES: Dosimetry readings in the operating room would identify techniques to minimize radiation exposure and provide a contrast to accepted annual limits of occupational radiation exposure. The goal was to obtain practical data for extrapolation to the standard degenerative spine practice and establish recommendations for fluoroscopy usage. METHODS: Fluoroscopy was implemented for localization of the level, pedicle screw insertion, verification of decompression, and/or final image. Radiation dosimetry was obtained through unprotected badges placed (1)surgeon’s chest (2)first assistant chest (3,4) cranial and caudal end of operating table. Fluoroscopy images were obtained from an OEC 9800 and data obtained included mA, kVp, total fluoro time, and estimated dose projected to patient. RESULTS: Total fluoroscopic time for all surgeries was 37.01 minutes. Total dose administered to patients was 29.2R (mean mA 5.48, kVp 104.5). Mean fluoroscopic time with lumbar spine instrumentation was greater than decompression alone (instr. 1.74 min vs decomp 0.22 min). Total fluoroscopic radiation exposure was obtained for surgeon (1225 mrem), first assistant (369 mrem), cranial table (92 mrem) and caudal table (150 mrem). Mean dose/min (mrem/min) was calculated for surgeon (33.1), first assistant (9.97), cranial table (2.48), and caudal table (4.05). To remain below the maximum yearly permissible level of radiation, the estimated total number of minutes for the surgeon would be 453 (eye) and 1592 (hand/organ). CONCLUSIONS: Fluoroscopic radiation exposure to the operating room personnel is minimal and the dosage to the spine surgeon remains clearly below an acceptable limit of occupational radiation exposure. Increasing distance from the radiation source led to a significantly diminished dosimetry reading. However, lead shielding for the operating staff remains highly recommended. By minimizing fluoroscopic time and maintaining a safe surgeon distance from the source, radiation contact to the spine surgeon is within safety standards. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.268
P11. Incidence and Risk Factors for Low Back Pain in Active Duty Military Over a 10 Year Period Jeffrey Knox, MD1, Joseph Orchowski, MD1, Philip Belmont, Jr., MD2, Danielle Scher, MD2, Robert Burks, PhD3, Brett Owens, MD2; 1Tripler Army Medical Center, Honolulu, HI, USA; 2William Beaumont Army Medical Center, El Paso, TX, USA; 3US Military Academy, West Point, NY, USA BACKGROUND CONTEXT: Low back pain is among the most common musculoskeletal conditions worldwide and is estimated to affect nearly two-thirds of the US population at some point in their lives. It carries a significant economic burden with an estimated annual cost of $28 billion. Because of the impact this condition has on industry and a significant portion of the general population, it has been the subject of numerous studies to assess its risk factors as well as prognostic indicators for this disease. Low back pain is a multifactorial disease and many risk factors have been implicated including age, race, gender, and marital status. PURPOSE: To investigate the incidence and risk factors for developing low back pain in active duty military population to include age, sex, race, and rank, and military service.
Proceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S STUDY DESIGN/SETTING: Epidemiological study utilizing a database containing demographic information and ICD-9 diagnosis codes for active duty military servicemembers over a 10-year period PATIENT SAMPLE: All individuals serving as active duty military between the years of 1998 and 2008. OUTCOME MEASURES: New onset low back pain requiring a visit to a health care provider. METHODS: To determine the incidence and risk factors for development of low back pain in the active duty military, we conducted a search utilizing the Defense Medical Epidemiology Database (DMED). This database compiles ICD-9-CM coding information for every patient encounter occurring in US military treatment facilities. It also compiles patient demographic information including age, race, gender, rank, and military service. The DMED database was queried using the ICD-9 code 724.2 (Lumbago) and stratified according to these parameters. Our search was limited to first occurrence diagnoses and diagnoses occurring in the ambulatory setting. These data sets were then analyzed using a multivariate Poisson regression analysis. RESULTS: A total of 557,059 cases of low back pain were documented in our population at risk of 13,754,261 person-years. The unadjusted incidence rate of low back pain in our population was 40.5 per 1,000 person-years. Females, compared with males, had a significantly increased adjusted incidence rate ratio (IRR) for low back pain of 1.45 (95% CI 1.44-1.46). Older age groups also were at greater risk of low back pain with the 35-39 (IRR51.19, CI 1.17-1.20) and O40 groups (IRR51.40, CI 1.39-1.42) reaching significance. Servicemembers in the Army (IRR52.17, CI 2.15-2.19) and Air Force (IRR51.52, CI 1.51-1.54) had higher rates when compared with the Marines. Married servicemembers had a higher incidence compared to single servicemembers (IRR51.19, CI1.18-1.19). Junior enlisted servicemembers (E1-E4) had a higher incidence compared to junior officers (O1-O3) (IRR52.0; CI 1.98-2.0). CONCLUSIONS: Female sex, increasing age, service in the Army or Air Force, married status, and junior enlisted rank were all significant risk factors for low back pain. This study constitutes the largest study on this topic to date. An improved understanding of the rate of occurrence of low back pain and the related demographics and risk factors may help formulate diagnostic and preventive strategies. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.269
P12. Testing Minimal Clinically Important Differences: Consensus, Conundrum, or a Red Herring? Robert Gatchel, PhD1, Tom Mayer, MD2; 1University of Texas at Arlington, Arlington, TX, USA; 2University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA BACKGROUND CONTEXT: Various methodologies have been utilized in attempting to develop a standard method for calculating Minimum Clinically Important Difference (MCID) to allow assessment of treatment outcomes. A consensus-based decision (IMPACT group) suggested a 30% reduction from baseline as a means to define the MCID of self-report back pain measures. Vital psychometric issues must be addressed regarding use of an independent measure of the same construct as an external criterion, instead of simply another self-report measure when using an anchor-based approach to MCID. PURPOSE: To test the validity of recently published guidelines regarding MCID using self-report back pain measures and objective socioeconomic outcomes. STUDY DESIGN/SETTING: A prospective study assessing change scores on commonly used spinal pain assessment measures in patients with chronic disabling occupational spinal disorders (CDOSDs) treated in a regional referral rehabilitation center for functional restoration. PATIENT SAMPLE: A consecutive cohort of patients (N51187) with CDOSDs completing a functional restoration program.
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OUTCOME MEASURES: Self-report measures, including the Oswestry Disability Index (ODI) and the SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS) obtained pre- and posttreatment compared to objective socioeconomically-relevant outcomes 1 year post-treatment including work status, health utilization, recurrent injury and case closure were used as external criteria for evaluating MCID. METHODS: Pre- to post-treatment improvement was calculated separately for each measure, and subjects were divided into two groups based on the change in scores relative to baseline: 30% or greater, versus less than 30% improvement. One-year post-treatment objective socioeconomic outcomes were used as independent external criteria relevant to the CDOSD population. That is often studied as the most costly and problematic cohort in spine care. RESULTS: The ODI and SF-36 MCS were not associated with any of the objective one-year outcomes used as external criteria. Reduced post-rehabilitation healthcare utilization (based on percent patients pursuing healthcare from a new provider) was weakly associated with 30% or greater improvement on the SF-36 PCS, relative to patients whose scores changed by less than 30% relative to baseline (15.8% vs. 21.9%). CONCLUSIONS: When objective and independent criteria are used (socioeconomic outcomes), the 30% improvement in the ODI and SF-36 may not be a valid MCID index. This replicates similar conclusions made by an independent research group using a distribution-based approach to MCID. The validity of the anchor-based MCID concept rests on future research using objective external criteria. Moreover, there remains a question whether the term ‘‘important’’ in MCID can be unequivocally and operationally defined as a reliable construct. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2009.08.270
P13. Comparison of Motion Patterns of an Elastomeric Disc Prosthesis to a Sliding Bearing Disc Prosthesis: Effects on the Facet Joint Motion/Stress During Flexion/Extension Casey Lee, MD1, Luiz Pimenta, MD, PhD2, James Dwyer, MD3; 1 Roseland, NJ, USA; 2Santa Rita Hospital, Sao Paolo, Brazil; 3New Jersey Spine Institute, Bedminster, NJ, USA BACKGROUND CONTEXT: Artificial disc replacement (ADR) with the current generation provides satisfactory pain relief and functional recovery. However, the first generation disc prostheses with sliding core design present increasing concerns of abnormal biomechanics at the posterior structures evidenced by early facet joints degeneration and of stress fractures of pars or pedicles after ADR. PURPOSE: To compare the motion patterns of the vertebral bodies and facet joints of ADR with sliding core prosthesis (SB Charite) to ADR of elastomeric disc prosthesis (Physio-L) during flexion and extension. STUDY DESIGN/SETTING: Comparison of motion patterns of vertebral bodies on lateral x-rays during flexion/extension; Physio-L VS Charite disc prosthesis. PATIENT SAMPLE: Post-operative flexion and extension x-rays of 14 patients with Physio-L disc prosthesis and of 10 patients with Charite prosthesis were evaluated for motion patterns of vertebral bodies and facet joints. OUTCOME MEASURES: Translational displacements in the AP and vertical directions of vertebral bodies of ADR during flexion/extension were compared between the Physio-L and Charite disc prosthesis. METHODS: The magnitude of AP and vertical translation of the posterior-inferior corner (A1 at extension and A2 at flexion) and the anterior-inferior corner (B1-extension and B2-flexion) of the superior vertebral body (VB) of ADR in reference to the inferior VB during flexion/extension. The measurement was normalized to 4 cm AP distance to eliminate variables of x-ray magnification. The point P is the crossing point of two lines of