Lumbar neurogenic claudication, sometimes referred to as pseudoclaudication, is the clinical synd... more Lumbar neurogenic claudication, sometimes referred to as pseudoclaudication, is the clinical syndrome of back pain radiating down one or both legs during ambulation. Classically, the symptoms abate with forward flexion of the lumbar spine and worsen with extension. The condition arises from lumbar spinal stenosis, which is common in the elderly population. Many asymptomatic individuals have lumbar spinal stenosis seen on magnetic resonance imaging (MRI), so this syndrome is a clinical diagnosis. The majority of patients have favorable responses with conservative treatment, which includes physical therapy, bracing, medications, and epidural steroid injections. Patients who do not improve may go on to have surgery. Spinal stenosis has become one of the most common reasons to undergo lumbar spinal surgery in patients older than 65 years of age.
The etiology of axial low back pain is multifactorial and includes pain arising from lumbar facet... more The etiology of axial low back pain is multifactorial and includes pain arising from lumbar facet joints. The facet joints, capsules, and surrounding tissues are innervated by the medial branches of the dorsal rami. Rhizotomy of these nerves can provide pain relief in patients with lumbar facetogenic pain. The reported benefits of endoscopic approaches to the spine include minimal disruption of nonpathologic anatomy while simultaneously allowing for improved visualization of pathologic anatomy. Endoscopic techniques have been described for spinal stenosis, disc herniation, interbody fusion, infection, as well as dorsal medial branch rhizotomy. The goal of medial branch rhizotomy is to denervate lumbar facet joints that are contributing to axial back pain. The previous chapter focused on percutaneous techniques, while this chapter will describe endoscopic rhizotomy.
For patients with multilevel lumbar spondylosis and back pain without leg symptoms, few surgical ... more For patients with multilevel lumbar spondylosis and back pain without leg symptoms, few surgical procedures exist to provide relief of pain. Axial back pain has been attributed in part to pain generated at the facet joints. The lumbar rhizotomy has emerged as an effective method for treatment of axial lumbar back pain in these patients. By performing a limited surgical approach and using an endoscopic method, patients report quick recovery without the pain that typically follows a larger surgical approach. This method provides effective means of ablating the medial branch of the dorsal root, with limited side effects and complications. The history of selective root rhizotomy is discussed, with focus on medial branch neurotomy for treatment of back pain. An endoscopically assisted rhizotomy technique using a minimally invasive approach to the lumbar spine is described. This technique may be expanded for use in other parts of the spine.
Retrospective review of foramen transversarium fracture morphology variables and their relationsh... more Retrospective review of foramen transversarium fracture morphology variables and their relationship to vertebral artery injury. We examined the morphology of foramen transversarium fractures to determine if different patterns of these fractures predicted vertebral artery injury to more specifically identify at risk patterns in which vertebral artery evaluation may be warranted. Risk fractures for vertebral artery injury have been previously reported to include cervical subluxation or dislocations, C1-C3 fractures, and foramen transversarium fractures. There have been no reports determining if specific foramen transversarium fracture patterns are predictive of vertebral artery injuries. We reviewed the initial cervical CT scans of 171 patients seen in our level one trauma center between January 2002 and March 2008 and identified all patients with foramen transversarium fractures. Additionally, CT angiograms were reviewed in these patients to identify patients with vertebral artery injuries. The morphology of the foramen transversarium fractures was compared in those patients with and without vertebral artery injury to identify fracture patterns predictive of arterial injury. Twenty-one (12%) patients were found to have foramen transversarium fractures with 5 (24%) of these patients having associated vertebral artery injury. Multilevel foramen transversarium fractures (P = 0.025) were significantly more frequent in vertebral artery injuries. Logistic regression identified multilevel fractures (odds ratio 17.33) and fracture comminution (odds ratio 10.50) as significant variables influencing vertebral artery injury after foramen transversarium fracture. We found patients presenting with multilevel foramen transversarium fractures and foramen transversarium fracture comminution to be at significantly increased odds of vertebral artery injury. Patients with these fracture patterns should undergo further evaluation with vertebral artery imaging.
Anterior exposure has become an increasingly popular procedure for the general and vascular surge... more Anterior exposure has become an increasingly popular procedure for the general and vascular surgeon due to the increased use of anterior lumbar interbody fusion and artificial disc replacement for the treatment of many spinal problems. Because of this increase, revision operations have become increasing necessary. Despite this, there is almost no literature dealing with the issues related to these complex revision operations. A retrospective review of charts was performed on patients operated on from April 2002 until October 2004 in two tertiary care hospitals. In total, 218 open exposures for anterior lumbar spinal approaches were performed of which 9 patients required revision lumbar spinal operations. Seven patients were approached again anteriorly (78%), and 2 (22%) patients required a combined anterior and posterior approach. The nine cases were the number of revision procedures performed over the 16-month period of this study. The average age was 44 overall (range, 25-89) and 53 (33-73) for the revision operations, p>.05. All revision operations attempted were successful. Seven (78%) of the secondary procedures could be approached retroperitoneally whereas 2 (22%) patients required transperitoneal approaches owing to the degree of adhesions. The average length until revision surgery was 13 months (range 6-24). No patients required early revision defined as surgery within 30 days from the primary surgery. Early complications occurred in 4 patients (44%), and included dural tear, median nerve dysthesia, left common femoral nerve palsy further complicated by prolonged postoperative ileus and retrograde ejaculation. Late complications occurred in one patient and consisted of a deep venous thrombosis and urinary tract infection. The average length of stay was 6 days (SD 2.7 days) (range 4-12) compared with 4 days (SD 2.3 days) (range 2-22) for the index operations, p>.05. Revision anterior open exposure to the lumbar and lumbosacral vertebral bodies can be performed safely, but is associated with an increased rate of early complications. Nonetheless, these complications are self-limited and highlight the importance of a multidisciplinary approach in maximizing the various surgical skills of spine (orthopedic and neurosurgical) and exposure (vascular and general) surgeons in reducing serious complications in revision anterior lumbar spinal surgery.
... 10 University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA. 11Booth, Barto... more ... 10 University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA. 11Booth, Bartolozzi, Balderston Orthopaedics/ Pennsylvania Hospital, Philadelphia, PA, USA. 12 Hospital for Special Surgery, New York, NY, USA. ...
Anterior cervical decompression and fusion has become a very widely used procedure for the treatm... more Anterior cervical decompression and fusion has become a very widely used procedure for the treatment of cervical degenerative disc disease with clinical symptoms of radiculopathy or myelopathy. Even with a high success rate, anterior cervical decompression and fusion is associated with numerous complications including adjacent-segment degeneration, pseudoarthrosis, and donor site morbidity. One serious long term risk associated with cervical arthrodesis is the increased biomechanical stress at adjacent segments that may hasten degeneration at these levels. Alternatively, artificial disc replacement provides a solution in the cervical spine which may maintain motion at the operated level. Motion at the adjacent levels are maintained reducing the rate of adjacent level degeneration when compared with fusion. The fate of the segments adjacent to a fusion has driven the need for better methods of treatment which may possess superior long term results compared to fusion operations.
The goal of this study was to compute the dynamic neck loads during simulated high-speed bilatera... more The goal of this study was to compute the dynamic neck loads during simulated high-speed bilateral facet dislocation and investigate the injury mechanism. Ten osteoligamentous functional spinal units (C3/4, n = 4; C5/6, n = 3; C7/T1, n = 3) were prepared with muscle force replication, motion tracking flags, and a 3.3-kg mass rigidly attached to the upper vertebra. Frontal impacts of increasing severity were applied to the lower vertebra until dislocation was achieved. Inverse dynamics was used to calculate the dynamic neck loads during dislocation. Average peak impact acceleration required to cause dislocation ranged between 7.6 and 11.6 g. This resulted in dynamic neck loads applied at average peak rates of 906 Nm/s for flexion moment, 8017 N/ for anterior shear, and 8100 N/s for axial compression. To determine the temporal event patterns, the average occurrence times of the load and motion peaks were statistically compared (P <0.05). Among average peak loads, axial compression of 233.6 N was first to occur followed by anterior shear force of 73.1 N and flexion moment of 30.7 Nm. Among average peak motions, axial separation of 5.3 mm was first to occur followed by flexion rotation of 63.1 degrees and anterior shear of 21.5 mm. Subsequently, average peak posterior shear force of 110.3 N was observed as the upper facet became locked in the intervertebral foramina. Average peak axial compression of 6.6 mm occurred significantly later than all preceding events. During bilateral facet dislocation, the main loads included flexion moment and forces of axial compression and anterior shear. These loads caused flexion rotation, facet separation, and anterior translation of the upper facet relative to the lower. The present data help elucidate the injury mechanism of cervical facet dislocation.
A radiographic study of the pedicle rib unit morphology as compared with measurements of the pedi... more A radiographic study of the pedicle rib unit morphology as compared with measurements of the pedicle in cadaveric thoracic spines. To evaluate the morphology of pedicle rib units in the thoracic spine in normal thoracic human spines, with particular attention to T4-T9, and to compare the dimensions of the pedicle rib unit with corresponding dimensions of the adjacent pedicles. Despite the clinical successes reported with thoracic pedicle screw-rod constructs, controversy exists as to the safety of this technique in pedicles that are anatomically too small for transpedicular fixation. An alternative method of extrapedicular screw fixation within the pedicle rib unit was evaluated in a previous study and found to be anatomically feasible. Although the morphology of the pedicle rib unit was described in two previous studies, the measurements were obtained in scoliotic spines. Therefore, no study has sought to define the transverse dimension and chord length of the pedicle rib unit, and compare it with the corresponding pedicle dimensions. Six fresh unfixed adult cadavers were obtained randomly. No history of spine disease was noted, and cause of death was unrelated to spinal disorder or trauma. The mean age was 84, with a range of 76 to 90. There were two females and four males. Computerized tomographic (CT) images of the thoracic spine were obtained. For cadavers in which the gantry resulted in oblique axial sections, reformatting was performed for more accurate measurements. Measurements of the transverse diameter and chord length of the pedicle rib unit were obtained and compared with measurements of the transverse pedicle width and chord length. The transverse width and chord length of the pedicle rib unit were significantly larger than corresponding pedicle measurements at all levels, a consistent finding when comparing the mean of all levels, the mean of T4-T9, and the mean of each individual level T4-T7. This study confirms the marked difference in size of the pedicle rib unit as compared with the pediclein both transverse width and chord length. This allows for a space that accommodates much larger major screw diameters, longer screw lengths, and because of the nature of screw placement, a greater screw convergence. Thus, there is anatomic potential for extrapedicular vertebral body fixation in the thoracic spine. However, care must be taken in placement of screws following precisely our previously described method of extrapedicular screw insertion. Penetration of surrounding structures, most notably the aorta on the left, is a potential risk when deviating from the method. Biomechanical evaluations are presently being conducted to evaluate the use of extrapedicular thoracic screw fixation.
A radiographic and anatomic study of an extrapedicular method of screw placement in cadaveric tho... more A radiographic and anatomic study of an extrapedicular method of screw placement in cadaveric thoracic spines. To evaluate an alternative method of thoracic vertebral body screw fixation using an extrapedicular screw technique. To evaluate the anatomic safe zones and proper starting point for this alternative approach to the placement of screw fixation in the thoracic spine. Despite the clinical successes reported with thoracic pedicle screw-rod constructs, controversy exists about the safety of this technique in pedicles that are anatomically too small for transpedicular fixation. An alternative method of extrapedicular screw fixation was evaluated in this present study. Two fresh, unfixed, adult cadavers were obtained randomly; 6.0-mm AO Synthes pedicle screws were placed using an extrapedicular approach bilaterally from T3 to T10. The screws were placed according to one defined method described later. Computerized tomographic (CT) images were obtained. The position of each screw was analyzed. The cadavers were then dissected with the screw pathway exposed and the relation of the screw to surrounding anatomy documented. All screws did not penetrate the spinal canal. All screws were within the pedicle rib unit and did not penetrate the neural foramen or pleura. This study, although only introductory, indicates the potential for extrapedicular vertebral body fixation in the thoracic spine. Biomechanical evaluations are presently being conducted to evaluate the use of extrapedicular thoracic screw fixation.
Lumbar neurogenic claudication, sometimes referred to as pseudoclaudication, is the clinical synd... more Lumbar neurogenic claudication, sometimes referred to as pseudoclaudication, is the clinical syndrome of back pain radiating down one or both legs during ambulation. Classically, the symptoms abate with forward flexion of the lumbar spine and worsen with extension. The condition arises from lumbar spinal stenosis, which is common in the elderly population. Many asymptomatic individuals have lumbar spinal stenosis seen on magnetic resonance imaging (MRI), so this syndrome is a clinical diagnosis. The majority of patients have favorable responses with conservative treatment, which includes physical therapy, bracing, medications, and epidural steroid injections. Patients who do not improve may go on to have surgery. Spinal stenosis has become one of the most common reasons to undergo lumbar spinal surgery in patients older than 65 years of age.
The etiology of axial low back pain is multifactorial and includes pain arising from lumbar facet... more The etiology of axial low back pain is multifactorial and includes pain arising from lumbar facet joints. The facet joints, capsules, and surrounding tissues are innervated by the medial branches of the dorsal rami. Rhizotomy of these nerves can provide pain relief in patients with lumbar facetogenic pain. The reported benefits of endoscopic approaches to the spine include minimal disruption of nonpathologic anatomy while simultaneously allowing for improved visualization of pathologic anatomy. Endoscopic techniques have been described for spinal stenosis, disc herniation, interbody fusion, infection, as well as dorsal medial branch rhizotomy. The goal of medial branch rhizotomy is to denervate lumbar facet joints that are contributing to axial back pain. The previous chapter focused on percutaneous techniques, while this chapter will describe endoscopic rhizotomy.
For patients with multilevel lumbar spondylosis and back pain without leg symptoms, few surgical ... more For patients with multilevel lumbar spondylosis and back pain without leg symptoms, few surgical procedures exist to provide relief of pain. Axial back pain has been attributed in part to pain generated at the facet joints. The lumbar rhizotomy has emerged as an effective method for treatment of axial lumbar back pain in these patients. By performing a limited surgical approach and using an endoscopic method, patients report quick recovery without the pain that typically follows a larger surgical approach. This method provides effective means of ablating the medial branch of the dorsal root, with limited side effects and complications. The history of selective root rhizotomy is discussed, with focus on medial branch neurotomy for treatment of back pain. An endoscopically assisted rhizotomy technique using a minimally invasive approach to the lumbar spine is described. This technique may be expanded for use in other parts of the spine.
Retrospective review of foramen transversarium fracture morphology variables and their relationsh... more Retrospective review of foramen transversarium fracture morphology variables and their relationship to vertebral artery injury. We examined the morphology of foramen transversarium fractures to determine if different patterns of these fractures predicted vertebral artery injury to more specifically identify at risk patterns in which vertebral artery evaluation may be warranted. Risk fractures for vertebral artery injury have been previously reported to include cervical subluxation or dislocations, C1-C3 fractures, and foramen transversarium fractures. There have been no reports determining if specific foramen transversarium fracture patterns are predictive of vertebral artery injuries. We reviewed the initial cervical CT scans of 171 patients seen in our level one trauma center between January 2002 and March 2008 and identified all patients with foramen transversarium fractures. Additionally, CT angiograms were reviewed in these patients to identify patients with vertebral artery injuries. The morphology of the foramen transversarium fractures was compared in those patients with and without vertebral artery injury to identify fracture patterns predictive of arterial injury. Twenty-one (12%) patients were found to have foramen transversarium fractures with 5 (24%) of these patients having associated vertebral artery injury. Multilevel foramen transversarium fractures (P = 0.025) were significantly more frequent in vertebral artery injuries. Logistic regression identified multilevel fractures (odds ratio 17.33) and fracture comminution (odds ratio 10.50) as significant variables influencing vertebral artery injury after foramen transversarium fracture. We found patients presenting with multilevel foramen transversarium fractures and foramen transversarium fracture comminution to be at significantly increased odds of vertebral artery injury. Patients with these fracture patterns should undergo further evaluation with vertebral artery imaging.
Anterior exposure has become an increasingly popular procedure for the general and vascular surge... more Anterior exposure has become an increasingly popular procedure for the general and vascular surgeon due to the increased use of anterior lumbar interbody fusion and artificial disc replacement for the treatment of many spinal problems. Because of this increase, revision operations have become increasing necessary. Despite this, there is almost no literature dealing with the issues related to these complex revision operations. A retrospective review of charts was performed on patients operated on from April 2002 until October 2004 in two tertiary care hospitals. In total, 218 open exposures for anterior lumbar spinal approaches were performed of which 9 patients required revision lumbar spinal operations. Seven patients were approached again anteriorly (78%), and 2 (22%) patients required a combined anterior and posterior approach. The nine cases were the number of revision procedures performed over the 16-month period of this study. The average age was 44 overall (range, 25-89) and 53 (33-73) for the revision operations, p>.05. All revision operations attempted were successful. Seven (78%) of the secondary procedures could be approached retroperitoneally whereas 2 (22%) patients required transperitoneal approaches owing to the degree of adhesions. The average length until revision surgery was 13 months (range 6-24). No patients required early revision defined as surgery within 30 days from the primary surgery. Early complications occurred in 4 patients (44%), and included dural tear, median nerve dysthesia, left common femoral nerve palsy further complicated by prolonged postoperative ileus and retrograde ejaculation. Late complications occurred in one patient and consisted of a deep venous thrombosis and urinary tract infection. The average length of stay was 6 days (SD 2.7 days) (range 4-12) compared with 4 days (SD 2.3 days) (range 2-22) for the index operations, p>.05. Revision anterior open exposure to the lumbar and lumbosacral vertebral bodies can be performed safely, but is associated with an increased rate of early complications. Nonetheless, these complications are self-limited and highlight the importance of a multidisciplinary approach in maximizing the various surgical skills of spine (orthopedic and neurosurgical) and exposure (vascular and general) surgeons in reducing serious complications in revision anterior lumbar spinal surgery.
... 10 University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA. 11Booth, Barto... more ... 10 University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA. 11Booth, Bartolozzi, Balderston Orthopaedics/ Pennsylvania Hospital, Philadelphia, PA, USA. 12 Hospital for Special Surgery, New York, NY, USA. ...
Anterior cervical decompression and fusion has become a very widely used procedure for the treatm... more Anterior cervical decompression and fusion has become a very widely used procedure for the treatment of cervical degenerative disc disease with clinical symptoms of radiculopathy or myelopathy. Even with a high success rate, anterior cervical decompression and fusion is associated with numerous complications including adjacent-segment degeneration, pseudoarthrosis, and donor site morbidity. One serious long term risk associated with cervical arthrodesis is the increased biomechanical stress at adjacent segments that may hasten degeneration at these levels. Alternatively, artificial disc replacement provides a solution in the cervical spine which may maintain motion at the operated level. Motion at the adjacent levels are maintained reducing the rate of adjacent level degeneration when compared with fusion. The fate of the segments adjacent to a fusion has driven the need for better methods of treatment which may possess superior long term results compared to fusion operations.
The goal of this study was to compute the dynamic neck loads during simulated high-speed bilatera... more The goal of this study was to compute the dynamic neck loads during simulated high-speed bilateral facet dislocation and investigate the injury mechanism. Ten osteoligamentous functional spinal units (C3/4, n = 4; C5/6, n = 3; C7/T1, n = 3) were prepared with muscle force replication, motion tracking flags, and a 3.3-kg mass rigidly attached to the upper vertebra. Frontal impacts of increasing severity were applied to the lower vertebra until dislocation was achieved. Inverse dynamics was used to calculate the dynamic neck loads during dislocation. Average peak impact acceleration required to cause dislocation ranged between 7.6 and 11.6 g. This resulted in dynamic neck loads applied at average peak rates of 906 Nm/s for flexion moment, 8017 N/ for anterior shear, and 8100 N/s for axial compression. To determine the temporal event patterns, the average occurrence times of the load and motion peaks were statistically compared (P <0.05). Among average peak loads, axial compression of 233.6 N was first to occur followed by anterior shear force of 73.1 N and flexion moment of 30.7 Nm. Among average peak motions, axial separation of 5.3 mm was first to occur followed by flexion rotation of 63.1 degrees and anterior shear of 21.5 mm. Subsequently, average peak posterior shear force of 110.3 N was observed as the upper facet became locked in the intervertebral foramina. Average peak axial compression of 6.6 mm occurred significantly later than all preceding events. During bilateral facet dislocation, the main loads included flexion moment and forces of axial compression and anterior shear. These loads caused flexion rotation, facet separation, and anterior translation of the upper facet relative to the lower. The present data help elucidate the injury mechanism of cervical facet dislocation.
A radiographic study of the pedicle rib unit morphology as compared with measurements of the pedi... more A radiographic study of the pedicle rib unit morphology as compared with measurements of the pedicle in cadaveric thoracic spines. To evaluate the morphology of pedicle rib units in the thoracic spine in normal thoracic human spines, with particular attention to T4-T9, and to compare the dimensions of the pedicle rib unit with corresponding dimensions of the adjacent pedicles. Despite the clinical successes reported with thoracic pedicle screw-rod constructs, controversy exists as to the safety of this technique in pedicles that are anatomically too small for transpedicular fixation. An alternative method of extrapedicular screw fixation within the pedicle rib unit was evaluated in a previous study and found to be anatomically feasible. Although the morphology of the pedicle rib unit was described in two previous studies, the measurements were obtained in scoliotic spines. Therefore, no study has sought to define the transverse dimension and chord length of the pedicle rib unit, and compare it with the corresponding pedicle dimensions. Six fresh unfixed adult cadavers were obtained randomly. No history of spine disease was noted, and cause of death was unrelated to spinal disorder or trauma. The mean age was 84, with a range of 76 to 90. There were two females and four males. Computerized tomographic (CT) images of the thoracic spine were obtained. For cadavers in which the gantry resulted in oblique axial sections, reformatting was performed for more accurate measurements. Measurements of the transverse diameter and chord length of the pedicle rib unit were obtained and compared with measurements of the transverse pedicle width and chord length. The transverse width and chord length of the pedicle rib unit were significantly larger than corresponding pedicle measurements at all levels, a consistent finding when comparing the mean of all levels, the mean of T4-T9, and the mean of each individual level T4-T7. This study confirms the marked difference in size of the pedicle rib unit as compared with the pediclein both transverse width and chord length. This allows for a space that accommodates much larger major screw diameters, longer screw lengths, and because of the nature of screw placement, a greater screw convergence. Thus, there is anatomic potential for extrapedicular vertebral body fixation in the thoracic spine. However, care must be taken in placement of screws following precisely our previously described method of extrapedicular screw insertion. Penetration of surrounding structures, most notably the aorta on the left, is a potential risk when deviating from the method. Biomechanical evaluations are presently being conducted to evaluate the use of extrapedicular thoracic screw fixation.
A radiographic and anatomic study of an extrapedicular method of screw placement in cadaveric tho... more A radiographic and anatomic study of an extrapedicular method of screw placement in cadaveric thoracic spines. To evaluate an alternative method of thoracic vertebral body screw fixation using an extrapedicular screw technique. To evaluate the anatomic safe zones and proper starting point for this alternative approach to the placement of screw fixation in the thoracic spine. Despite the clinical successes reported with thoracic pedicle screw-rod constructs, controversy exists about the safety of this technique in pedicles that are anatomically too small for transpedicular fixation. An alternative method of extrapedicular screw fixation was evaluated in this present study. Two fresh, unfixed, adult cadavers were obtained randomly; 6.0-mm AO Synthes pedicle screws were placed using an extrapedicular approach bilaterally from T3 to T10. The screws were placed according to one defined method described later. Computerized tomographic (CT) images were obtained. The position of each screw was analyzed. The cadavers were then dissected with the screw pathway exposed and the relation of the screw to surrounding anatomy documented. All screws did not penetrate the spinal canal. All screws were within the pedicle rib unit and did not penetrate the neural foramen or pleura. This study, although only introductory, indicates the potential for extrapedicular vertebral body fixation in the thoracic spine. Biomechanical evaluations are presently being conducted to evaluate the use of extrapedicular thoracic screw fixation.
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