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Optimising lumbar lordosis during PLIF surgery
Proceedings of the BASS 2015 Bath Meeting / The Spine Journal 15 (2015) 50S–85S CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.080
The role of lumbosacral transitional vertebrae in the pathogenesis of degenerative lumbar scoliosis: an in vitro study Alex Torrie, Ian Harding, John Hutchinson, Ian Nelson, Michael Adams, Patricia Dolan; The Department of Comparative and Clinical Anatomy, The University of Bristol, Southwell Road, Bristol, BS2 8EJ, United Kingdom BACKGROUND CONTEXT: Many radiological factors have been linked to curve progression in degenerative lumbar scoliosis (DLS). However, the role of asymmetries at the lumbosacral junction in the development and progression of DLS has been little investigated. PURPOSE: To simulate unilateral lumbosacral transitional vertebrae (LSTV) in lumbar cadaveric spines and to determine whether this increases coronal plane motion. STUDY DESIGN/SETTING: Cadaveric study. PATIENT SAMPLE: Thirteen human cadaveric spinal segments (L4-S1). OUTCOME MEASURES: Coronal plane motion of spinal segments. METHODS: Spinal segments were mounted on a materials testing machine in pure compression at 1000N for 10 minutes. During loading, reflective markers on the vertebral bodies were used to assess coronal plane motion of the specimen using a MacReflex motion analysis system. Attaching a stainless steel plate from the sacrum to the L5 transverse process simulated a unilateral LSTV. This was performed sequentially on both sides, in random order, for each specimen. In each case, the initial loading was repeated and coronal motion was recorded. These series of tests were then repeated after vertebral endplate fracture. Coronal plane motion was compared between baseline values and the simulated right and left LSTV both before and after fracture. RESULTS: Pre-fracture, LSTV affected coronal plane motion by -0.21 and þ0.20 (median values) on right and left sides respectively, compared to baseline, neither were significant (P!0.05). Post-fracture, LSTV decreased coronal plane motion by 0.18 and 0.09 on right and left sides respectively, neither were significant (P!0.05). CONCLUSIONS: These findings provide evidence to refute that unilateral LSTV may be causative in DLS. CONFLICTS OF INTEREST: None. FUNDING SOURCES: Max Biedermann Institute, Germany. http://dx.doi.org/10.1016/j.spinee.2014.12.081
Optimising lumbar lordosis during PLIF surgery Priyan Landham, Angus S. Don, Peter A. Robertson; Auckland City Hospital, 2 Park Road, Grafton, Auckland 1142, New Zealand BACKGROUND CONTEXT: Restoration of sagittal balance during fusion surgery is associated with improved outcome, less adjacent segment degeneration and improved pain scores. PURPOSE: To determine factors associated with mono-segmental lordosis in patients undergoing single level posterior lumbar interbody fusion (PLIF). STUDY DESIGN/SETTING: A retrospective radiological review PATIENT SAMPLE: 83 consecutive patients in a single surgeon series who had undergone single level PLIF with paired lordotic cages. OUTCOME MEASURES: Mono-segmental lordosis and parameters related to intervertebral cage position and size. METHODS: The PLIF technique involved the insertion of identical lordotic cages and posterior decompression to optimize lordosis. The change in lordosis following surgery was related to cage shape and position. All distances were expressed as a ratio to the total length of the superior
67S
endplate of the lower instrumented vertebra to enable comparison between patients. RESULTS: Eighty-three consecutive patients underwent radiographic review. Following surgery, mono-segmental lordosis increased in 83% of cases by a mean of 5.73 (SD 7.21 ). Anterior cage position (as signified by an increasing paired cage centre-point ratio) was significantly correlated with an increase in mono-segmental lordosis (P!0.01). In terms of cage size, increasing anterior cage height had a significant negative correlation with lordosis gain (P!0.01). Asymmetrical cage placement with increasing total cage length showed a non-linear negative trend with lordosis gain. There were no significant correlations between other cage shape parameters and lumbar lordosis. CONCLUSIONS: Anterior cage placement is a key technical factor when trying to improve lumbar lordosis during PLIF surgery. In addition the cage should be of moderate height and length with symmetrical placement. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.082
Can spino-pelvic parameters predict hardware failure in Scheuermann’s kyphosis patients? Eyal Behrbalk, Ofir Uri, Bronek Boszczyk, Hossein Mehdian, Michael Grevitt; The Centre for Spinal Studies and Surgery, Queen’s Medical Centre BACKGROUND CONTEXT: Proximal junction failure (e.g. screw pullout, rod breaking and junctional kyphosis) are of the most common complications following surgical correction of Scheuermann’s Kyphosis (SK). PURPOSE: This study investigates the relationship between patients’ spino-pelvic characteristics and occurrence of proximal junctional complications. STUDY DESIGN/SETTING: Retrospective case series. PATIENT SAMPLE: 29 patients. OUTCOME MEASURES: Measurement were performed on whole spine lateral unsupported standing radiographs preoperatively, at the first early postoperative follow-up (24615 days) and at the latest follow-up (32612 months). METHODS: Spino-pelvic characteristics of 8 patients (age 2065 years, 7 males) who developed proximal-junction complications after surgical correction of SK were compared to those of 21 patients (age 2166 years, 18 males) who did not have complication after similar operation. RESULTS: The preoperative and postoperative magnitude of the thoracickyphosis and lumbar-lordosis were similar in the complication and noncomplication groups (p5ns). However, the pelvic-incidence and the preoperative sacral-slope were significantly higher in the complications group (52611 vs. 42610 and 3869 vs. 2767 respectively; p!0.05). Similarly, the preoperative sagittal-vertical-axis was significantly more positive in patients who developed proximal-junction complications (24629cm vs. -16629cm; p50.002). CONCLUSIONS: Patients who developed proximal-junction complications had higher pelvic-incidence, higher sacral-slope and more positive preoperative sagittal-vertical-axis. Patients with higher pelvic-incidence (and sacral-slope) should have higher expected lumbar-lordosis. When thoracic-kyphosis is corrected a compensatory decrease in lumbar-lordosis occurs. It is our opinion that as both groups had the same thoracic-kyphosis and lumbar-hyper-lordosis and underwent the same magnitude of correction. The reduction in lumbar-lordosis beyond the expected values caused spino-pelvic mismatch and failure. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.083
The role of lumbosacral transitional vertebrae in the pathogenesis of degenerative lumbar scoliosis: an in vitro study Alex Torrie, Ian Harding, John Hutchinson, Ian Nelson, Michael Adams, Patricia Dolan; The Department of Comparative and Clinical Anatomy, The University of Bristol, Southwell Road, Bristol, BS2 8EJ, United Kingdom BACKGROUND CONTEXT: Many radiological factors have been linked to curve progression in degenerative lumbar scoliosis (DLS). However, the role of asymmetries at the lumbosacral junction in the development and progression of DLS has been little investigated. PURPOSE: To simulate unilateral lumbosacral transitional vertebrae (LSTV) in lumbar cadaveric spines and to determine whether this increases coronal plane motion. STUDY DESIGN/SETTING: Cadaveric study. PATIENT SAMPLE: Thirteen human cadaveric spinal segments (L4-S1). OUTCOME MEASURES: Coronal plane motion of spinal segments. METHODS: Spinal segments were mounted on a materials testing machine in pure compression at 1000N for 10 minutes. During loading, reflective markers on the vertebral bodies were used to assess coronal plane motion of the specimen using a MacReflex motion analysis system. Attaching a stainless steel plate from the sacrum to the L5 transverse process simulated a unilateral LSTV. This was performed sequentially on both sides, in random order, for each specimen. In each case, the initial loading was repeated and coronal motion was recorded. These series of tests were then repeated after vertebral endplate fracture. Coronal plane motion was compared between baseline values and the simulated right and left LSTV both before and after fracture. RESULTS: Pre-fracture, LSTV affected coronal plane motion by -0.21 and þ0.20 (median values) on right and left sides respectively, compared to baseline, neither were significant (P!0.05). Post-fracture, LSTV decreased coronal plane motion by 0.18 and 0.09 on right and left sides respectively, neither were significant (P!0.05). CONCLUSIONS: These findings provide evidence to refute that unilateral LSTV may be causative in DLS. CONFLICTS OF INTEREST: None. FUNDING SOURCES: Max Biedermann Institute, Germany. http://dx.doi.org/10.1016/j.spinee.2014.12.081
Optimising lumbar lordosis during PLIF surgery Priyan Landham, Angus S. Don, Peter A. Robertson; Auckland City Hospital, 2 Park Road, Grafton, Auckland 1142, New Zealand BACKGROUND CONTEXT: Restoration of sagittal balance during fusion surgery is associated with improved outcome, less adjacent segment degeneration and improved pain scores. PURPOSE: To determine factors associated with mono-segmental lordosis in patients undergoing single level posterior lumbar interbody fusion (PLIF). STUDY DESIGN/SETTING: A retrospective radiological review PATIENT SAMPLE: 83 consecutive patients in a single surgeon series who had undergone single level PLIF with paired lordotic cages. OUTCOME MEASURES: Mono-segmental lordosis and parameters related to intervertebral cage position and size. METHODS: The PLIF technique involved the insertion of identical lordotic cages and posterior decompression to optimize lordosis. The change in lordosis following surgery was related to cage shape and position. All distances were expressed as a ratio to the total length of the superior
67S
endplate of the lower instrumented vertebra to enable comparison between patients. RESULTS: Eighty-three consecutive patients underwent radiographic review. Following surgery, mono-segmental lordosis increased in 83% of cases by a mean of 5.73 (SD 7.21 ). Anterior cage position (as signified by an increasing paired cage centre-point ratio) was significantly correlated with an increase in mono-segmental lordosis (P!0.01). In terms of cage size, increasing anterior cage height had a significant negative correlation with lordosis gain (P!0.01). Asymmetrical cage placement with increasing total cage length showed a non-linear negative trend with lordosis gain. There were no significant correlations between other cage shape parameters and lumbar lordosis. CONCLUSIONS: Anterior cage placement is a key technical factor when trying to improve lumbar lordosis during PLIF surgery. In addition the cage should be of moderate height and length with symmetrical placement. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.082
Can spino-pelvic parameters predict hardware failure in Scheuermann’s kyphosis patients? Eyal Behrbalk, Ofir Uri, Bronek Boszczyk, Hossein Mehdian, Michael Grevitt; The Centre for Spinal Studies and Surgery, Queen’s Medical Centre BACKGROUND CONTEXT: Proximal junction failure (e.g. screw pullout, rod breaking and junctional kyphosis) are of the most common complications following surgical correction of Scheuermann’s Kyphosis (SK). PURPOSE: This study investigates the relationship between patients’ spino-pelvic characteristics and occurrence of proximal junctional complications. STUDY DESIGN/SETTING: Retrospective case series. PATIENT SAMPLE: 29 patients. OUTCOME MEASURES: Measurement were performed on whole spine lateral unsupported standing radiographs preoperatively, at the first early postoperative follow-up (24615 days) and at the latest follow-up (32612 months). METHODS: Spino-pelvic characteristics of 8 patients (age 2065 years, 7 males) who developed proximal-junction complications after surgical correction of SK were compared to those of 21 patients (age 2166 years, 18 males) who did not have complication after similar operation. RESULTS: The preoperative and postoperative magnitude of the thoracickyphosis and lumbar-lordosis were similar in the complication and noncomplication groups (p5ns). However, the pelvic-incidence and the preoperative sacral-slope were significantly higher in the complications group (52611 vs. 42610 and 3869 vs. 2767 respectively; p!0.05). Similarly, the preoperative sagittal-vertical-axis was significantly more positive in patients who developed proximal-junction complications (24629cm vs. -16629cm; p50.002). CONCLUSIONS: Patients who developed proximal-junction complications had higher pelvic-incidence, higher sacral-slope and more positive preoperative sagittal-vertical-axis. Patients with higher pelvic-incidence (and sacral-slope) should have higher expected lumbar-lordosis. When thoracic-kyphosis is corrected a compensatory decrease in lumbar-lordosis occurs. It is our opinion that as both groups had the same thoracic-kyphosis and lumbar-hyper-lordosis and underwent the same magnitude of correction. The reduction in lumbar-lordosis beyond the expected values caused spino-pelvic mismatch and failure. CONFLICTS OF INTEREST: None. FUNDING SOURCES: None. http://dx.doi.org/10.1016/j.spinee.2014.12.083