- Email: [email protected]
P67. Correlation of radiographic parameters and clinical symptoms
138S
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S
RESULTS: Overall mean pre-operative pain score improved significantly at 3 months post-surgery (5.02⫾0.68 vs 3.43⫾1.07, p⬍0.001) with further significant improvement over the course of the first year. Pain ratings remained significantly improved compared to pre-operative values throughout the 6-year assessment. Function was also significantly improved relative to pre-op baseline over the course of the study, with maintenance of this improvement at each follow-up. At six years, 83.5% of all patients were fused with no device migration or new lucencies after two years; lowest fusion rate (74.3%) was seen with 2-level PLIF group. At six years, cumulative likelihood of freedom from subsequent reoperation remained high (⬎90%). The rate of additional surgery at the index level was 7.3% with all but one revision/removal occuring within the first 2 years. The incidence of adjacent level pathology was 3.7%. A comparison of the rate of additional surgery within the first 3 years (10.9%) versus in years three to six (5.4%) further demonstrated a decreasing rate of necessary re-operation. DISCUSSION: This carefully-selected patient cohort demonstrates that fusion for DDD with threaded interbody cages (e.g., BAK/L) resulted in continued clinical improvement over the first 12 months which is similar to previous reports. Pain and function measures remained significantly better than preoperative levels to six years. At six years, fusion rates were acceptably high with a concomitant low probability of reoperation or complications. There was a slight advantage to an anterior approach versus a posterior approach. CONCLUSIONS: Interbody fusion with threaded cages remains a successful operation long-term. DISCLOSURES: Device or drug: BAK/L interbody fusion cage. Status: not applicable. CONFLICT OF INTEREST: John Sherman, MD, consultant: Centerpulse Spine-Tech; Speaker’s Bureau. Rose Griffith, previous employee: Centerpulse Spine-Tech. Steven Griffith, PhD, employee: Centerpulse Spine-Tech. doi: 10.1016/S1529-9430(03)00328-0 P62. Effectiveness of spinal release and halo-femoral traction in the management of severe spinal deformity Alvin Crawford, MD1, Moahammed Al-Sayyad, MD1, Charles Mehlman, DO1; 1Children’s Hospital Medical Center, Cincinnati, OH, USA HYPOTHESIS: The occurrence of neurologic complications following correction of spinal deformity is directly proportional to curve magnitude. Halo-femoral traction has been suggested as a useful tool for gradual safe correction. The purpose of this study was to assess the effectiveness of spinal release and halo-femoral traction in the management of severe spinal deformity. METHODS: We conducted a hospital database search (1979–2000) to identify all spinal deformity patients whose treatment had included halofemoral traction. Analysis of chart and X-ray information focused on pretraction curve magnitude, preoperative curve magnitude in bending or hyperextension films, final traction curve magnitude, traction weight as a percent of body weight, and complications associated with traction treatment. For patients with multiple curves, only the largest curve was included for analysis. Twenty-three patients had pre-traction anterior release, four of which had a posterior release at the same setting. One patient had posterior release only and the remaining patient had no surgical release before traction. RESULTS: We identified 25 patients (17 girls and 8 boys) whose average age was 14 years (range 7–24 years) who underwent an average period of 9 days of halo-femoral traction (range 5–13 days). There were 11 idiopathic and 10 non-idiopathic scoliosis curves. In addition four kyphosis patients were studied. Average pre-traction curve magnitude was 95 degrees (range 60–150 degrees) and the average preoperative curve magnitude in bending was 73 degrees a (range 42–143 degrees while post-traction average curve magnitude was 44 degrees (range 22–65 degrees). The difference between the magnitude of curve correction in bending and traction films was statistically significant (p⬍0.001). Traction weight was incrementally increased to an average of 54% of body weight (range 33%–114%). The only traction
related complication was a bilateral lower extremity sensory and motor deficit that occurred when total traction reached 58% of body weight. This resolved following traction weight decrease to 35% of body weight. There were no long term traction related complications. With a minimum follow up of one year, the average final correction was 71%. DISCUSSION: Spinal cord injury is the most feared complication of spinal deformity surgery. Patients with severely rigid and/or large curves are felt to be at increased risk for this complication. Our results show that halofemoral traction is an effective adjunct in the treatment of these challenging patients. Spinal release and halo-femoral traction offer a controlled approach to pre-surgical fusion reduction of severe spinal deformities. CONCLUSIONS: Average pre-traction curves of almost 95 degrees a were safely corrected by about 50% using halo-femoral traction for an average of 9 days. Halo-femoral traction is an effective adjunct in the treatment of severe spinal deformities. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00329-2
P67. Correlation of radiographic parameters and clinical symptoms Steven Glassman, MD1,5, Keith Bridwell2, William Horton, MD3, Sigurd Berven, MD4, John Dimar, MD5; 1Leatherman Spine Center, Louisville, KY, USA; 2Washington University in St. Louis, St. Louis, MO, USA; 3 Emory University, Atlanta, GA, USA; 4University of California, San Francisco, San Francisco, CA, USA; 5University of Louisville, Louisville, KY, USA HYPOTHESIS: The purpose of this study is to correlate radiographic measures of deformity with patient-based outcome measures in adult scoliosis. The initial study hypotheses were major curve location, rotatory subluxation, coronal shift, and positive sagittal balance will correlate with increased pain, and decreased function and self-image; and curve magnitude will not correlate with pain or function. METHODS: We utilized a multi-center database to provide sufficient sample size for meaningful statistical analysis. The study cohort includes patients over 18 years of age with scoliosis greater than 30 degrees, and patients who have undergone previous surgical treatment of spinal deformity greater than 18 months prior to enrollment. All patients were enrolled in 2002. The assessment consisted of standard demographics, 36 AP and lateral radiographs, and quality of life measures including the SRS-22, SF12, and Oswestry (ODI) profiles. RESULTS: The 298 patients studied include 176 with no prior surgery and 126 with prior spine fusion. Mean age was 48 (range 18–87) years in the no prior surgery group and 51 (range 20–81) years in the prior surgery group. Both groups were 84% female. No prior surgery group comparison based on curve location revealed more favorable scores for thoracic curves versus all other curves (SRS-22 pain and function [p⫽.01], SF-12 bodily pain and physical function [p⫽.03], and ODI [p⫽.04]). Patients with coronal shift greater than 4 cm. reported poorer function based on the SRS-22 (p⫽.03) and greater pain on the SF-12 and ODI (p⫽.05). Patients with positive global sagittal balance reported greater pain (SRS-22 [p⫽.01], SF12 and ODI [p⫽.00]), diminished physical function (SRS-22 and SF-12 [p⫽.00]), poorer self image (SRS-22 [p⫽.03]), and social function (SF12 [p⫽.02]). Prior Surgery Group Thoracic curves were associated with less pain on ODI (p⫽.03), better function (SRS-22 and SF-12 [p⫽.01]) and better self-image on SRS-22 (p⫽.02) versus thoracolumbar or lumbar curves. Analysis of sagittal balance demonstrated a dramatic effect on outcome parameters for patients with positive sagittal balance after surgery. Poorer outcomes were noted in pain, function, and self-image domains of the SRS-22 (p⫽.00), as well as bodily pain, physical function, vitality (p⫽.00) and social function (p⫽.02) on the SF-12. Greater pain was also reported on the ODI scale (p⫽.00). DISCUSSION: Neither group demonstrated any correlation between curve magnitude or rotatory subluxation and any outcome parameters. A positive sagittal balance was associated with poorer clinical measures of pain;
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S function and self-image in patients with and without prior spine surgery. Coronal balance correlated with clinical symptoms only in patients who had no prior surgery. For both groups, thoracolumbar and lumbar curve location yielded less favorable scores versus thoracic curves. CONCLUSIONS: The findings of this study underline the overriding importance of sagittal balance in assessment and management of adult spinal deformity. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: Steven Glassman, MD, John Dimar, MD, consultant: royalties from Medtronic Sofamor Danek. Keith Bridwell, MD, William Horton, MD, consultant: Research only funds for Medtronic Sofamor Danek. doi: 10.1016/S1529-9430(03)00330-9
P72. Correction of neuromuscular scoliosis and pelvic obliquity without lumbosacral fusion Richard McCall1; 1Shriners Hospitals for Children–Shreveport, Shreveport, LA, USA HYPOTHESIS: Surgical correction of scoliosis and pelvic obliquity in neuromuscular diseases using spinal instrumentation is an accepted surgical procedure. Controversy exists as to the caudad extent of fusion and instrumentation: to lumbar 5 or to the sacrum. Instrumentation to lumbar 5 has been associated with lesser degrees of correction and postoperative progression of scoliosis and pelvic obliquity. Instrumentation with a URod terminating in pedicle screws at lumbar 5 has demonstrated correction of scoliosis and pelvic obliquity equal to that accomplished with Unit-Rod instrumentation with maintenance of correction. METHODS: Patients with progressive neuromuscular scoliosis underwent spinal fusion and instrumentation using a U-Rod terminating in pedicle screw fixation at lumbar 5 with no attempt to fuse or instrument across the lumbosacral joint. Scoliosis correction occurred either with segmental wiring or segmental instrumentation, pelvic obliquity correction occurring through stability of the lumbar 5 S-1 disc and the iliolumbar ligaments. RESULTS: From 1998 to 2002, 25 patients with neuromuscular scoliosis underwent instrumentation and fusion only to lumbar 5 using a U-Rod terminating in pedicle screws. Twenty patients were reviewed with an average follow-up of 2.8 years. Average age at surgery was 13.9 years (9.5–17.5) Surgery was either anterior posterior or posterior alone Table 1. DISCUSSION: Correction of scoliosis of 74% and pelvic obliquity of 68% with instrumentation only to lumbar 5 compares favorably with results of authors using Unit-Rod instrumentation to the sacrum. Previous studies have shown good correction of scoliosis and pelvic obliquity with instrumentation to lumbar 5 in small curves (⬍40) and mild pelvic obliquity (⬍20) with maintenance of correction. Larger curves or greater degrees of pelvic obliquity have resulted in poorer initial correction and greater loss of long term correction. A continuous U-Rod with pedicle screw fixation at lumbar 5 can correct larger degrees of scoliosis and pelvic obliquity and maintain long term correction. CONCLUSIONS: Instrumentation and fusion at lumbar 5 is a simpler procedure with less technical difficulty decreased surgical time, risk and blood loss compared to instrumentation and fusion to the pelvis. Postoperative and long-term follow-up indicated that fusion at lumbar 5 can both correct scoliosis and pelvic obliquity and maintain this correction. DISCLOSURES: Device or drug: U-Rod. Status: approved. CONFLICT OF INTEREST: No conflicts. Table 1 Average Cobb (deg) Pelvic Obliquity (deg) Measurements Pre-op Post-op (1 year) Latest follow-up
60 (35–110) 17.9 (5–40) 16 (5–40)
doi: 10.1016/S1529-9430(03)00331-0
139S
P77. Increasing the stability of unilateral transverse lumbar interbody fusions Andrew V. Slucky, MD2, Darrel S. Brodke, MD1, John A. Droge, MS1, Kent N. Bachus, PhD1; 1University of Utah, Salt Lake City, UT, USA; 2 Peralta Orthopaedic Associates, Oakland, CA, USA HYPOTHESIS: Applying recent hardware minimization trends to the current transverse lumbar interbody fusion construct (TLIF), it may be possible to reduce the surgical exposure needed for lumbar motion segment fusion and hence, minimize paraspinal muscle damage during fusion procedures. Specifically, it would be advantageous if the TLIF’s bilateral posterior pedicle screw construct could be achieved using a unilateral pedicle screw construct (UTLIF) or even a hybrid construct incorporating a unilateral pedicle screw with percutaneous contralateral facet screw construct (SUTLIF). The goal of this study was to compare and contrast the stability of these three lumbar interbody fusion techniques. METHODS: Seven human cadaveric lumbar spines were prepared by removing all skin and musculature, while keeping all ligamentous structures intact. The spines were then fastened into a 7-axis spine simulator, and tested in flexion/extension, lateral bending, and axial torsion using ⫾5.0 Nm torque in each direction with a 50 N compressive load (1,2). Displacement of the vertebral bodies during testing was measured with an optoelectronic motion measurement system. Paired statistical methods were done (a) between the TLIF and the UTLIF, (b) between the TLIF and the SUTLIF, and (c) between the UTLIF and the SUTLIF using the non-parametric Wilcoxon Signed Ranks Test, using a Holm-Sida´k multiple comparison procedure (1) using an alpha of 0.05. RESULTS: Each specimen was tested with the three different hardware constructs (TLIF, UTLIF, and SUTLIF) in flexion/extension, lateral bending, and axial torsion. The TLIF instrumentation being the current standard, all other hardware constructs were normalized to the TLIF to obtain a “percent of TLIF.” Flexion extension: each specimen was tested with all three hardware constructs in random order. The mean stiffness⫾95% confidence interval are as follows: the UTLIF instrumentation was 52%⫾13% of TLIF instrumentation, and the SUTLIF was 98%⫾15% of TLIF. Paired analyses showed significant differences in flexion extension between the UTLIF and TLIF techniques (p⫽0.027), the UTLIF and SUTLIF techniques (p⫽0.027), but did not show a difference between TLIF and SUTLIF techniques (p⫽0.735). Lateral bending: The UTLIF instrumentation was 48%⫾9% of TLIF instrumentation, and the SUTLIF was 89%⫾16% of TLIF instrumentation in lateral bending. A statistical difference was shown between the UTLIF and TLIF techniques (p⫽0.027), the UTLIF and SUTLIF techniques (p⫽0.027), but no difference was seen between TLIF and SUTLIF techniques (p⫽0.091). Axial Torsion: When comparing the stiffness of each hardware construct in axial torsion, the UTLIF instrumentation was 74%⫾14% of TLIF instrumentation, and the SUTLIF was 100%⫾13% of TLIF instrumentation. In axial torsion significant differences were shown between the UTLIF and TLIF (p⫽0.041) and the UTLIF and SUTLIF techniques (p⫽0.042). However, no significant difference was shown between the TLIF and SUTLIF techniques (p⫽0.735). DISCUSSION: Data from this study showed that supplementing the unilateral construct with a trans facet screw increased the stability to nearly that of a bilateral construct. CONCLUSIONS: In each direction no significant differences in stiffness were measured between the TLIF and SUTLIF constructs. However, the UTLIF construct had a significantly lower stiffness than both the TLIF construct and the SUTLIF construct in all directions. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: Darrel S. Brodke, MD, John A. Droge, MS, Andrew V. Slucky, MD, Kent N. Bachus, PhD, grant research support: Medtronic Sofamor-Danek.
14 (0–50 d) 5.8 d (0–23) 4.5 d (0–23) doi: 10.1016/S1529-9430(03)00332-2
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S
RESULTS: Overall mean pre-operative pain score improved significantly at 3 months post-surgery (5.02⫾0.68 vs 3.43⫾1.07, p⬍0.001) with further significant improvement over the course of the first year. Pain ratings remained significantly improved compared to pre-operative values throughout the 6-year assessment. Function was also significantly improved relative to pre-op baseline over the course of the study, with maintenance of this improvement at each follow-up. At six years, 83.5% of all patients were fused with no device migration or new lucencies after two years; lowest fusion rate (74.3%) was seen with 2-level PLIF group. At six years, cumulative likelihood of freedom from subsequent reoperation remained high (⬎90%). The rate of additional surgery at the index level was 7.3% with all but one revision/removal occuring within the first 2 years. The incidence of adjacent level pathology was 3.7%. A comparison of the rate of additional surgery within the first 3 years (10.9%) versus in years three to six (5.4%) further demonstrated a decreasing rate of necessary re-operation. DISCUSSION: This carefully-selected patient cohort demonstrates that fusion for DDD with threaded interbody cages (e.g., BAK/L) resulted in continued clinical improvement over the first 12 months which is similar to previous reports. Pain and function measures remained significantly better than preoperative levels to six years. At six years, fusion rates were acceptably high with a concomitant low probability of reoperation or complications. There was a slight advantage to an anterior approach versus a posterior approach. CONCLUSIONS: Interbody fusion with threaded cages remains a successful operation long-term. DISCLOSURES: Device or drug: BAK/L interbody fusion cage. Status: not applicable. CONFLICT OF INTEREST: John Sherman, MD, consultant: Centerpulse Spine-Tech; Speaker’s Bureau. Rose Griffith, previous employee: Centerpulse Spine-Tech. Steven Griffith, PhD, employee: Centerpulse Spine-Tech. doi: 10.1016/S1529-9430(03)00328-0 P62. Effectiveness of spinal release and halo-femoral traction in the management of severe spinal deformity Alvin Crawford, MD1, Moahammed Al-Sayyad, MD1, Charles Mehlman, DO1; 1Children’s Hospital Medical Center, Cincinnati, OH, USA HYPOTHESIS: The occurrence of neurologic complications following correction of spinal deformity is directly proportional to curve magnitude. Halo-femoral traction has been suggested as a useful tool for gradual safe correction. The purpose of this study was to assess the effectiveness of spinal release and halo-femoral traction in the management of severe spinal deformity. METHODS: We conducted a hospital database search (1979–2000) to identify all spinal deformity patients whose treatment had included halofemoral traction. Analysis of chart and X-ray information focused on pretraction curve magnitude, preoperative curve magnitude in bending or hyperextension films, final traction curve magnitude, traction weight as a percent of body weight, and complications associated with traction treatment. For patients with multiple curves, only the largest curve was included for analysis. Twenty-three patients had pre-traction anterior release, four of which had a posterior release at the same setting. One patient had posterior release only and the remaining patient had no surgical release before traction. RESULTS: We identified 25 patients (17 girls and 8 boys) whose average age was 14 years (range 7–24 years) who underwent an average period of 9 days of halo-femoral traction (range 5–13 days). There were 11 idiopathic and 10 non-idiopathic scoliosis curves. In addition four kyphosis patients were studied. Average pre-traction curve magnitude was 95 degrees (range 60–150 degrees) and the average preoperative curve magnitude in bending was 73 degrees a (range 42–143 degrees while post-traction average curve magnitude was 44 degrees (range 22–65 degrees). The difference between the magnitude of curve correction in bending and traction films was statistically significant (p⬍0.001). Traction weight was incrementally increased to an average of 54% of body weight (range 33%–114%). The only traction
related complication was a bilateral lower extremity sensory and motor deficit that occurred when total traction reached 58% of body weight. This resolved following traction weight decrease to 35% of body weight. There were no long term traction related complications. With a minimum follow up of one year, the average final correction was 71%. DISCUSSION: Spinal cord injury is the most feared complication of spinal deformity surgery. Patients with severely rigid and/or large curves are felt to be at increased risk for this complication. Our results show that halofemoral traction is an effective adjunct in the treatment of these challenging patients. Spinal release and halo-femoral traction offer a controlled approach to pre-surgical fusion reduction of severe spinal deformities. CONCLUSIONS: Average pre-traction curves of almost 95 degrees a were safely corrected by about 50% using halo-femoral traction for an average of 9 days. Halo-femoral traction is an effective adjunct in the treatment of severe spinal deformities. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00329-2
P67. Correlation of radiographic parameters and clinical symptoms Steven Glassman, MD1,5, Keith Bridwell2, William Horton, MD3, Sigurd Berven, MD4, John Dimar, MD5; 1Leatherman Spine Center, Louisville, KY, USA; 2Washington University in St. Louis, St. Louis, MO, USA; 3 Emory University, Atlanta, GA, USA; 4University of California, San Francisco, San Francisco, CA, USA; 5University of Louisville, Louisville, KY, USA HYPOTHESIS: The purpose of this study is to correlate radiographic measures of deformity with patient-based outcome measures in adult scoliosis. The initial study hypotheses were major curve location, rotatory subluxation, coronal shift, and positive sagittal balance will correlate with increased pain, and decreased function and self-image; and curve magnitude will not correlate with pain or function. METHODS: We utilized a multi-center database to provide sufficient sample size for meaningful statistical analysis. The study cohort includes patients over 18 years of age with scoliosis greater than 30 degrees, and patients who have undergone previous surgical treatment of spinal deformity greater than 18 months prior to enrollment. All patients were enrolled in 2002. The assessment consisted of standard demographics, 36 AP and lateral radiographs, and quality of life measures including the SRS-22, SF12, and Oswestry (ODI) profiles. RESULTS: The 298 patients studied include 176 with no prior surgery and 126 with prior spine fusion. Mean age was 48 (range 18–87) years in the no prior surgery group and 51 (range 20–81) years in the prior surgery group. Both groups were 84% female. No prior surgery group comparison based on curve location revealed more favorable scores for thoracic curves versus all other curves (SRS-22 pain and function [p⫽.01], SF-12 bodily pain and physical function [p⫽.03], and ODI [p⫽.04]). Patients with coronal shift greater than 4 cm. reported poorer function based on the SRS-22 (p⫽.03) and greater pain on the SF-12 and ODI (p⫽.05). Patients with positive global sagittal balance reported greater pain (SRS-22 [p⫽.01], SF12 and ODI [p⫽.00]), diminished physical function (SRS-22 and SF-12 [p⫽.00]), poorer self image (SRS-22 [p⫽.03]), and social function (SF12 [p⫽.02]). Prior Surgery Group Thoracic curves were associated with less pain on ODI (p⫽.03), better function (SRS-22 and SF-12 [p⫽.01]) and better self-image on SRS-22 (p⫽.02) versus thoracolumbar or lumbar curves. Analysis of sagittal balance demonstrated a dramatic effect on outcome parameters for patients with positive sagittal balance after surgery. Poorer outcomes were noted in pain, function, and self-image domains of the SRS-22 (p⫽.00), as well as bodily pain, physical function, vitality (p⫽.00) and social function (p⫽.02) on the SF-12. Greater pain was also reported on the ODI scale (p⫽.00). DISCUSSION: Neither group demonstrated any correlation between curve magnitude or rotatory subluxation and any outcome parameters. A positive sagittal balance was associated with poorer clinical measures of pain;
Proceedings of the NASS 18th Annual Meeting / The Spine Journal 3 (2003) 67S–171S function and self-image in patients with and without prior spine surgery. Coronal balance correlated with clinical symptoms only in patients who had no prior surgery. For both groups, thoracolumbar and lumbar curve location yielded less favorable scores versus thoracic curves. CONCLUSIONS: The findings of this study underline the overriding importance of sagittal balance in assessment and management of adult spinal deformity. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: Steven Glassman, MD, John Dimar, MD, consultant: royalties from Medtronic Sofamor Danek. Keith Bridwell, MD, William Horton, MD, consultant: Research only funds for Medtronic Sofamor Danek. doi: 10.1016/S1529-9430(03)00330-9
P72. Correction of neuromuscular scoliosis and pelvic obliquity without lumbosacral fusion Richard McCall1; 1Shriners Hospitals for Children–Shreveport, Shreveport, LA, USA HYPOTHESIS: Surgical correction of scoliosis and pelvic obliquity in neuromuscular diseases using spinal instrumentation is an accepted surgical procedure. Controversy exists as to the caudad extent of fusion and instrumentation: to lumbar 5 or to the sacrum. Instrumentation to lumbar 5 has been associated with lesser degrees of correction and postoperative progression of scoliosis and pelvic obliquity. Instrumentation with a URod terminating in pedicle screws at lumbar 5 has demonstrated correction of scoliosis and pelvic obliquity equal to that accomplished with Unit-Rod instrumentation with maintenance of correction. METHODS: Patients with progressive neuromuscular scoliosis underwent spinal fusion and instrumentation using a U-Rod terminating in pedicle screw fixation at lumbar 5 with no attempt to fuse or instrument across the lumbosacral joint. Scoliosis correction occurred either with segmental wiring or segmental instrumentation, pelvic obliquity correction occurring through stability of the lumbar 5 S-1 disc and the iliolumbar ligaments. RESULTS: From 1998 to 2002, 25 patients with neuromuscular scoliosis underwent instrumentation and fusion only to lumbar 5 using a U-Rod terminating in pedicle screws. Twenty patients were reviewed with an average follow-up of 2.8 years. Average age at surgery was 13.9 years (9.5–17.5) Surgery was either anterior posterior or posterior alone Table 1. DISCUSSION: Correction of scoliosis of 74% and pelvic obliquity of 68% with instrumentation only to lumbar 5 compares favorably with results of authors using Unit-Rod instrumentation to the sacrum. Previous studies have shown good correction of scoliosis and pelvic obliquity with instrumentation to lumbar 5 in small curves (⬍40) and mild pelvic obliquity (⬍20) with maintenance of correction. Larger curves or greater degrees of pelvic obliquity have resulted in poorer initial correction and greater loss of long term correction. A continuous U-Rod with pedicle screw fixation at lumbar 5 can correct larger degrees of scoliosis and pelvic obliquity and maintain long term correction. CONCLUSIONS: Instrumentation and fusion at lumbar 5 is a simpler procedure with less technical difficulty decreased surgical time, risk and blood loss compared to instrumentation and fusion to the pelvis. Postoperative and long-term follow-up indicated that fusion at lumbar 5 can both correct scoliosis and pelvic obliquity and maintain this correction. DISCLOSURES: Device or drug: U-Rod. Status: approved. CONFLICT OF INTEREST: No conflicts. Table 1 Average Cobb (deg) Pelvic Obliquity (deg) Measurements Pre-op Post-op (1 year) Latest follow-up
60 (35–110) 17.9 (5–40) 16 (5–40)
doi: 10.1016/S1529-9430(03)00331-0
139S
P77. Increasing the stability of unilateral transverse lumbar interbody fusions Andrew V. Slucky, MD2, Darrel S. Brodke, MD1, John A. Droge, MS1, Kent N. Bachus, PhD1; 1University of Utah, Salt Lake City, UT, USA; 2 Peralta Orthopaedic Associates, Oakland, CA, USA HYPOTHESIS: Applying recent hardware minimization trends to the current transverse lumbar interbody fusion construct (TLIF), it may be possible to reduce the surgical exposure needed for lumbar motion segment fusion and hence, minimize paraspinal muscle damage during fusion procedures. Specifically, it would be advantageous if the TLIF’s bilateral posterior pedicle screw construct could be achieved using a unilateral pedicle screw construct (UTLIF) or even a hybrid construct incorporating a unilateral pedicle screw with percutaneous contralateral facet screw construct (SUTLIF). The goal of this study was to compare and contrast the stability of these three lumbar interbody fusion techniques. METHODS: Seven human cadaveric lumbar spines were prepared by removing all skin and musculature, while keeping all ligamentous structures intact. The spines were then fastened into a 7-axis spine simulator, and tested in flexion/extension, lateral bending, and axial torsion using ⫾5.0 Nm torque in each direction with a 50 N compressive load (1,2). Displacement of the vertebral bodies during testing was measured with an optoelectronic motion measurement system. Paired statistical methods were done (a) between the TLIF and the UTLIF, (b) between the TLIF and the SUTLIF, and (c) between the UTLIF and the SUTLIF using the non-parametric Wilcoxon Signed Ranks Test, using a Holm-Sida´k multiple comparison procedure (1) using an alpha of 0.05. RESULTS: Each specimen was tested with the three different hardware constructs (TLIF, UTLIF, and SUTLIF) in flexion/extension, lateral bending, and axial torsion. The TLIF instrumentation being the current standard, all other hardware constructs were normalized to the TLIF to obtain a “percent of TLIF.” Flexion extension: each specimen was tested with all three hardware constructs in random order. The mean stiffness⫾95% confidence interval are as follows: the UTLIF instrumentation was 52%⫾13% of TLIF instrumentation, and the SUTLIF was 98%⫾15% of TLIF. Paired analyses showed significant differences in flexion extension between the UTLIF and TLIF techniques (p⫽0.027), the UTLIF and SUTLIF techniques (p⫽0.027), but did not show a difference between TLIF and SUTLIF techniques (p⫽0.735). Lateral bending: The UTLIF instrumentation was 48%⫾9% of TLIF instrumentation, and the SUTLIF was 89%⫾16% of TLIF instrumentation in lateral bending. A statistical difference was shown between the UTLIF and TLIF techniques (p⫽0.027), the UTLIF and SUTLIF techniques (p⫽0.027), but no difference was seen between TLIF and SUTLIF techniques (p⫽0.091). Axial Torsion: When comparing the stiffness of each hardware construct in axial torsion, the UTLIF instrumentation was 74%⫾14% of TLIF instrumentation, and the SUTLIF was 100%⫾13% of TLIF instrumentation. In axial torsion significant differences were shown between the UTLIF and TLIF (p⫽0.041) and the UTLIF and SUTLIF techniques (p⫽0.042). However, no significant difference was shown between the TLIF and SUTLIF techniques (p⫽0.735). DISCUSSION: Data from this study showed that supplementing the unilateral construct with a trans facet screw increased the stability to nearly that of a bilateral construct. CONCLUSIONS: In each direction no significant differences in stiffness were measured between the TLIF and SUTLIF constructs. However, the UTLIF construct had a significantly lower stiffness than both the TLIF construct and the SUTLIF construct in all directions. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: Darrel S. Brodke, MD, John A. Droge, MS, Andrew V. Slucky, MD, Kent N. Bachus, PhD, grant research support: Medtronic Sofamor-Danek.
14 (0–50 d) 5.8 d (0–23) 4.5 d (0–23) doi: 10.1016/S1529-9430(03)00332-2