Biomedical subjects

K Daniel Riew

Publications and source records attributed to K Daniel Riew.

At least 19 recordsLinked to original sources

PubMed2007

Posterior cervical spine surgery for radiculopathy.

It is now common knowledge that cervical radiculopathy, frequently caused by disc herniation and/or degeneration, will often improve without surgical intervention. Only a small percentage of patients with the severity of symptoms necessitate surgical treatment. Surgery for radiculopathy is indicated for motor weakness, progressive neurological deficits, and progressive symptoms that do not improve with nonoperative treatment. Advantages and disadvantages exist for both ventral and dorsal approaches in the surgical treatment of cervical radiculopathy. Indications and results for dorsal nerve root decompression are discussed, and a review of our preferred techniques, including use of minimally invasive technology, is presented.

Cervical Vertebrae↗

PubMed2006

The feasibility of inserting atlas lateral mass screws via the posterior arch.

STUDY DESIGN: A total of 709 skeletally mature atlas specimens were obtained from the Hamann Todd Collection at the Cleveland Museum of Natural History. Using digital caliper, the thickness of the vertebral artery groove was measured to determine the feasibility of potential screw placement. OBJECTIVE: To determine the feasibility of screw insertion into the atlas lateral mass via the posterior arch. SUMMARY OF BACKGROUND DATA: The originally described starting point for atlas lateral mass screws, at the base of the lateral mass, can be associated with excessive bleeding and irritation of the greater occipital nerve. In order to avoid such problems, we routinely start the screw at a more cranial location on the dorsal, posterior-lateral arch of the atlas, when the anatomy permits. In cases where the arch is too small, we notch the undersurface of the arch so as to recess the screw into the notch. We undertook this cadaveric morphometric study to determine the feasibility of using such techniques in the general population. METHODS: A total of 709 atlas specimens were measured bilaterally to determine the thickness of the posterior-lateral arch at the level of the lateral mass. The presence of the ponticulus posticus was recorded as well. RESULTS: The average minimal thickness of the posterior-lateral atlas was 3.95 mm. There was a total of 157 complete and 34 incomplete ponticuli posticus. Overall, 85.2% of the specimens had a thickness greater than 3 mm, 654 (46.2%) greater than 4 mm, and 194 (13.7%) greater than 5 mm. CONCLUSIONS: Our results suggest that although only a small percentage of patients can accept a screw that is directly inserted via the posterior-lateral arch into the lateral mass, the notching technique is possible in the vast majority of patients. To our knowledge, this is the largest study to examine the possibility of using the posterior-lateral arch as the starting point for these screws. Our results suggest that alternative starting points for these screws are possible in a large percentage of the cases.

Black or African American↗

PubMed2006

The diagnostic effect of various needle tip positions in selective lumbar nerve blocks: an analysis of 1202 injections.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: To determine the effect of various needle tip positions on immediate postinjection pain in selective lumbar nerve blocks. SUMMARY OF BACKGROUND DATA: To our knowledge, no large study has examined the effect of various needle tip positions within or adjacent to the intervertebral foramen on immediate pain outcome. METHODS: A total of 1774 cases of intervertebral lumbar nerve blocks performed by our radiology staff between April 7, 1997 and May 31, 2002, were reviewed. Of the 1774 cases, 1202 met the study criteria (i.e., a single-level injection in an adult). The position of the needle tip and degree of immediate postinjection pain relief were examined. RESULTS: The blocks resulted in an average pain reduction of 4.14 U, as graded on a 0-10 ordinate scale (95% confidence interval 3.98-4.30). The degree of pain reduction was not associated with the needle tip position. CONCLUSIONS: Our results suggest that precise needle tip position within or adjacent to the intervertebral foramen made no difference on immediate pain reduction. These findings allow the practitioner more freedom in performing an injection. This study does not evaluate the long-term effects of various needle tip positions in selective lumbar nerve blocks.

Adolescent↗

PubMed2006

Mastication causing segmental spinal motion in common cervical orthoses.

STUDY DESIGN: In vivo fluoroscopic quantification of segmental cervical spinal motion in asymptomatic volunteers during mastication. OBJECTIVE: To quantify the degree of segmental cervical spine motion in patients during mastication and while wearing several commonly used cervical orthoses. SUMMARY OF BACKGROUND DATA: Cervical orthoses are routinely used to stabilize the cervical spine after trauma or cervical fusion and are, in some cases, prescribed to be worn at all times, including during eating. METHODS: Seven volunteers with an average age of 31 years (range, 26-42 years) had 5 seconds of continuous lateral cervical fluoroscopic imaging while they chewed gum without any cervical orthosis (control) and while wearing a soft collar turned forward then backward, a Philadelphia collar, a Miami J collar, or a two-poster brace. Still images were created from the fluoroscopy video, which allowed for quantification of the amount of segmental motion. RESULTS: All cervical collars produced statistically greater motion at occiput-C1 and C1-C2 when compared with no collar. The motion was greatest at the occiput-C1 junction and decreased to the C4 level. No motion was detected in any subject in any brace below C4. The two-poster brace produced the most segmental motion at occiput-C1 (6.3 degrees +/- 2.0 degrees) compared with the soft collar turned backwards (1.9 degrees +/- 1.9 degrees). No subject had any segmental motion below C2 in the soft collar. No segmental spinal motion was observed without a cervical brace. CONCLUSIONS: To limit upper cervical spine segmental motion during mastication, for patients with unstable cervical spines, we propose a two-poster brace with removal of the mandibular component to allow for free mandibular action. For stable spines, we propose a soft collar turned backwards. Patients should be educated with this information.

Adult↗

PubMed2006

Iatrogenic cervical deformity.

Iatrogenic cervical deformity can develop after anterior or posterior procedures. Careful attention to detail can minimize the likelihood of creating a sagittal or coronal plane deformity. Strategies for the prevention and correction of postoperative cervical deformity are presented.

Bone Malalignment↗

PubMed2006

Cervical myelopathy from atlantal hypoplasia and torticollis.

Cervical myelopathy caused by atlantal hypoplasia has been reported in only 11 patients. Atlantal hypoplasia combined with torticollis has not been reported. Rotation of the atlantoaxial joint causes spinal canal narrowing at the atlantoaxial level and stretches the vertebral artery, which may aggravate the symptoms and signs of compressive cervical myelopathy from atlantal hypoplasia. We present a patient with cervical myelopathy from atlantal hypoplasia, retrodental pseudotumor, and torticollis.

Aged↗

PubMed2006

Detection of esophageal perforation using intraesophageal dye injection.

OBJECTIVES: Esophageal perforation complicating anterior cervical spine surgery is a potentially fatal complication. Early identification and immediate treatment may lower adverse effects for the patient. The purpose of this study is to assess the efficacy of intraesophageal dye injection to detect an esophageal injury and to test two novel techniques. METHOD: Ten cadaveric specimens were dissected using an anteromedial Smith-Robinson approach. Each was sequentially tested by a control and three dye injection techniques: technique A: nasogastric tube alone; technique B: nasogastric tube plus a distally placed Foley catheter; technique C: proximal plus a distally placed Foley catheter. Each technique was tested against esophageal perforations created by needle puncture (21-gauge, 18-gauge, and 14-gauge) and by a 2-mm high-speed burr. Dye visualization was independently graded as present or absent by two authors. RESULTS: In the control trial, no dye leak was visualized in any of the 10 specimens. In technique A, 0 of 10 21-gauge perforations, 1 of 10 18-gauge perforations, 2 of 10 14-gauge perforations, and 6 of 10 burr perforations were visualized. In technique B, 1 of 10 21-gauge perforations, 8 of 10 18-gauge perforations, 9 of 10 14-gauge perforations, and 9 of 10 burr perforations were visualized. In technique C, 0 of 10 21-gauge perforations, 9 of 10 18-gauge perforations, 10 of 10 14-gauge perforations, and 7 of 10 burr perforations were visualized. CONCLUSIONS: The study suggests that intraesophageal dye injection via nasogastric tube alone should not be relied upon to exclude the presence of esophageal perforation. Two novel techniques showed an improved, though limited, capability of detecting esophageal perforations.

Cadaver↗

PubMed2006

Prospective measurement of function and pain in patients with non-neoplastic compression fractures treated with vertebroplasty.

BACKGROUND: There has been an increasing number of reports regarding the benefits of vertebroplasty for the treatment of vertebral compression fractures. In this investigation, validated outcome tools were utilized to document the impact of vertebroplasty on pain and function. METHODS: Fifty patients were recruited at a tertiary university hospital. Patients had been treated for intractable pain due to osteoporotic compression fracture(s) for at least four weeks. The vertebroplasty procedures were performed by a radiologist. The subjects were followed prospectively for one year and received conservative treatment in conjunction with the vertebroplasty. Validated outcome tools, including a visual analog scale, the Oswestry scale, and the Roland-Morris functional activity questionnaire, were used to evaluate changes in pain and functional capabilities. RESULTS: Fifty patients, thirty-one women and nineteen men (mean age, 68.6 years), were followed prospectively for one year. One hundred and three fractures (fifty-nine thoracic and forty-four lumbar) were treated. The visual analog scale showed the greatest improvement between the baseline score (mean, 7.76) and the score at one month (mean, 2.9), and the score remained improved at one year (mean, 2.9). The Oswestry and Roland-Morris questionnaires demonstrated significant (p < 0.0001) functional improvement between the baseline and one-month scores. With the numbers available, there were no significant changes in any variable from one month to one year (p > 0.05). CONCLUSIONS: Vertebroplasty is an effective treatment for patients with intractable pain due to osteoporotic vertebral compression fractures. Improvement in pain scores and functional capabilities that were found at one month were maintained at one year.

Adult↗

PubMed2006

Nerve root blocks in the treatment of lumbar radicular pain. A minimum five-year follow-up.

BACKGROUND: In a previous prospective, randomized, controlled, double-blinded study on the effect of nerve root blocks on the need for operative treatment of lumbar radicular pain, we found that injections of corticosteroids were more effective than bupivacaine for up to thirteen to twenty-eight months. We performed a minimum five-year followup of those patients who had avoided surgery. METHODS: All of the patients were considered to be operative candidates by the treating surgeon, and all had initially requested operative intervention. They had then been randomized to be treated with a selective nerve-root block with either bupivacaine or bupivacaine and betamethasone. Both the treating physician and the patient were blinded to the type of medication. Of fifty-five randomized patients, twenty-nine avoided an operation in the original study. Twenty-one of those twenty-nine patients were reevaluated with a follow-up questionnaire at a minimum of five years after the initial block. RESULTS: Seventeen of the twenty-one patients still had not had operative intervention. There was no difference between the group treated with bupivacaine alone and the group treated with bupivacaine and betamethasone with regard to the avoidance of surgery for five years. At the five-year follow-up evaluation, all of the patients who had avoided operative treatment had significant decreases in neurological symptoms and back pain compared with the baseline values. CONCLUSIONS: The majority of patients with lumbar radicular pain who avoid an operation for at least one year after receiving a nerve root injection with bupivacaine alone or in combination with betamethasone will continue to avoid operative intervention for a minimum of five years.

Follow-Up Studies↗

PubMed2006

Anti-apoptotic effects of caspase inhibitors on rat intervertebral disc cells.

BACKGROUND: Apoptosis is thought to be a critical component of disc degeneration. Two main pathways of Fas-mediated apoptosis have been identified: Type I, which is the death-inducing signaling complex pathway, and Type II, which is the mitochondrial pathway. The apoptotic pathway for anulus fibrosus cells, which is phenotypically different from that of nucleus pulposus cells, has not been elucidated to our knowledge. The ultimate initiators or executioners of apoptosis are caspases. There are also inhibitors of caspases, which have the potential of being used as anti-apoptotic therapeutic agents. We therefore undertook this study to determine (1) the apoptotic pathway of anulus fibrosus cells and (2) the anti-apoptotic potential of caspase inhibitors. METHODS: Rat anulus fibrosus cells were isolated, cultured, and placed in either 0% (apoptosis-promoting condition) or 10% (normal control) fetal bovine serum. We identified and quantified the presence of apoptotic cell death, caspase activities, and loss of mitochondrial membrane potential. In addition, we examined the cells for the expression of Fas, procaspases, and cytochrome-c. Finally, we analyzed the degree of anti-apoptotic effects of caspase inhibitors on the cells in 1% fetal bovine serum. RESULTS: The percentage of apoptosis and Fas expression in the cells incubated in 0% fetal bovine serum were increased compared with those in the cells incubated in 10% fetal bovine serum (both p < 0.001). Caspase-8, 9, and 3 activities were increased and expression of procaspases was decreased in the 0% fetal bovine serum compared with those in the 10% fetal bovine serum (all p < 0.001). In contrast, the loss of mitochondrial membrane potential and cytochrome-c release into the cytosol were unchanged in the 0% fetal bovine serum. Pancaspase and caspase-8 inhibitors reduced apoptotic cell death (p < 0.001 and p < 0.05, respectively), but caspase-9 inhibitor did not reduce apoptotic cell death. CONCLUSIONS: Our results suggest that, unlike nucleus pulposus cells, anulus fibrosus cells are Fas Type-I cells, which undergo apoptosis through the death-inducing signaling complex. We also found that apoptosis of intervertebral disc cells can be attenuated by caspase inhibitors.

Animals↗

PubMed2006

Management of recalcitrant osteoarthritis of the atlanto-axial joint.

The medical records and radiographs of 17 patients with recalcitrant pain secondary to C1-C2 osteoarthritis were independently reviewed. All patients were treated by the senior author (K.D.R.). Initial treatment included physical therapy, nonsteroidal anti-inflammatory drugs, and soft collar immobilization. If non-responsive, patients were referred to a single radiologist for injection of the involved C1-C2 joint(s). If symptoms persisted, then transarticular screw fixation and Magerl wire fixation with structural iliac crest bone graft was performed. Postoperatively, all patients were placed in a soft collar. Postoperative anteroposterior (AP), lateral, flexion/extension, and open-mouthed odontoid radiographs were taken at 6 weeks, 3 months, and 1 year. Three independent observers assessed all radiographs for fusion. Fusion was noted by radiographic evidence of bridging bony trabeculae across the C1-C2 joint and/or bridging bone from the posterior arch of C1 to the C2 spinous process. Patient satisfaction improved significantly whether they were treated by corticosteroid injection or surgically.

Adrenal Cortex Hormones↗

PubMed2005

Evaluation of pedicle screw placement in the deformed spine using intraoperative plain radiographs: a comparison with computerized tomography.

STUDY DESIGN: A retrospective study. OBJECTIVE: To develop an accurate and reliable method to detect malpositioned pedicle screws during thoracic and lumbar spinal deformity operations using intraoperative plain radiographs. SUMMARY OF BACKGROUND DATA: The reliability of pedicle screw assessment using plain radiographs is more difficult during scoliosis operations compared to nondeformed spine operations. Methodology is necessary to document and improve the accuracy of interpretation of intraoperative plain radiographs for deformity surgeries. METHODS: A total of 789 pedicle screws, including 632 thoracic and 157 lumbar, inserted from T1 to L4 in 49 patients with spinal deformity with postoperative computerized tomography (CT) data were investigated. According to the diagnoses, the number of screws placed was 683 for scoliosis in 43 patients and 106 for kyphosis in 6 patients. The position of the pedicle screw inserted was graded with CT as an acceptable screw (n = 724) versus violated screw (n = 65), defined as the central axis of the inserted pedicle screw out of the outer cortex of the pedicle wall. There were 3 plain radiographic criteria used to judge the accuracy of screw position after minor screw tip position adjustment according to the relative length of the screws in the lateral radiograph: (1) violation of the harmonious segmental change of the tips of the inserted screws with reference to vertebral rotation using the posterior upper spinolaminar junction in the posteroanterior (PA) radiograph (medial or lateral out); (2) no crossing of the medial pedicle wall by the tip of the pedicle screw inserted with reference to the vertebral rotation using the posterior upper spinolaminar junction in the PA radiograph (lateral out); and (3) violation of the imaginary midline of the vertebral body using the posterior upper spinolaminar junction in the PA radiograph by the position of the tip of the inserted pedicle screw (medial out). RESULTS: Comparative analysis of these pedicle screws using postoperative CT and intraoperative plain radiographs confirmed 65 violated pedicle screws, including 15 medial violations and 50 lateral violations. Of 15 pedicle screws with medial wall violation, 13 showed a loss of harmonious segmental change in the screw tips and violation of the imaginary midline of the vertebral body (sensitivity 0.87, specificity 0.97, and accuracy 0.98). One case showed only a loss of harmonious change in the screw tip, and the other one case did not show any significant plain radiograph findings. Of the 50 pedicle screws with lateral wall violation, 47 cases showed a loss of harmonious segmental change in the screw tips and no crossing of medial pedicle wall by the pedicle screw inserted (sensitivity 0.94, specificity 0.90, and accuracy 0.96). Two cases did not show any significant plain radiograph findings, and the other one case showed only violation of the harmonious segmental change in the screw tips. CONCLUSIONS: Intraoperative plain radiographs alone using 3 radiographic criteria were very sensitive to detect lateral wall pedicle screw violations, specific for assessing for medial wall violations, and highly accurate for both. This result confirms the ability of careful intraoperative plain radiographic assessment after pedicle screw insertion to detect malpositioned screws, to allow for possible revision during the index operation.

Adolescent↗

PubMed2005

Increased risk of postoperative neurologic deficit for spinal surgery patients with unobtainable intraoperative evoked potential data.

STUDY DESIGN: This was a retrospective study of 4,310 patients undergoing spinal surgery between 1994 and 2003. OBJECTIVES: To examine the incidence and potential causality of unobtainable somatosensory evoked potential (SSEP) and neurogenic mixed evoked potential (NMEP) data for a population of spinal surgery patients. SUMMARY OF BACKGROUND DATA: Patients with absent or unobtainable evoked potential data may increase the risk of undetected neurologic injury. To date, a comprehensive review of this patient population has not been reported. METHODS: A total of 4,310 consecutive orthopedic spinal surgeries at one institution from January 1994 through December 2003 were reviewed. Cases lacking sufficient monitoring data, despite functional neural integrity (ambulators, intact sensation), were identified. Diagnoses were divided into six general categories. The association between absent evoked potential data and associated neurologic and/or medical pathology was evaluated. RESULTS: A total of 59 of 4,310 cases (1.37%) had absent SSEP and/or NMEP intraoperative data despite functional neural integrity (44 ambulators/15 nonambulators)" 5.08% of study patients awoke with increased neurologic deficit (3 of 59), 2 global deficits, and 1 nerve root deficit. The incidence of postoperative neurologic deficit in the entire surgical population was 0.77% (33 of 4,310), 8 global (0.19%), and 25 nerve root deficits (0.058%). A Fisher's exact test demonstrated a statistically significant difference between the incidence in these two populations (P = 0.0121) and the incidence of global paraplegic deficits (P = 0.0075). CONCLUSION: Patients with unobtainable data pose a much higher risk (P = 0.0121) for postoperative neurologic deficits. Multiple Stagnara wake-up tests are strongly recommended when evoked potential data cannot be obtained.

Adolescent↗

PubMed2005

Development of adjacent-level ossification in patients with an anterior cervical plate.

BACKGROUND: It has been our experience that ossification occurs adjacent to anterior cervical plates. Our hypothesis was that the closer the plate is to the adjacent disc space, the greater the ossification. METHODS: We retrospectively reviewed the lateral radiographs of the cervical spine of 118 patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the treatment of a degenerative cervical condition; none of the patients had had cervical spine surgery prior to the index arthrodesis. The plate-to-disc distance was measured on the postoperative lateral radiograph and was used to divide the patients into two groups for each of the two adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was >/=5 mm. The mean duration of follow-up was 25.7 months. The severity of the ossification at the two adjacent disc spaces was classified on a scale ranging from grade 0 (no ossification) to grade 3 (complete bridging). Eighteen patients were excluded from the measurement of the severity of the caudal ossification because overlapping by the bone of the shoulder precluded adequate visualization of the caudal level. RESULTS: Ossification developed in seventy (59%) of the 118 cephalad adjacent disc spaces and twenty-nine (29%) of the 100 caudal adjacent disc spaces (p < 0.001). The mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001). The rate of ossification was higher in group A than in group B, both at the cephalad adjacent disc spaces (67% compared with 24%) and at the caudal adjacent disc spaces (45% compared with 5%) (both p < 0.001). In addition, 93% (twenty-six) of the twenty-eight cases of moderate-to-severe ossification developed in group A. CONCLUSIONS: We found a positive association between adjacent-level ossification following anterior cervical plate procedures and the plate-to-disc distance. We now strive to place anterior cervical plates at least 5 mm away from the adjacent disc spaces in order to decrease the likelihood of moderate-to-severe adjacent-level ossification.

Adult↗

PubMed2005

Complications of fluoroscopically guided extraforaminal cervical nerve blocks. An analysis of 1036 injections.

BACKGROUND: A number of serious complications associated with fluoroscopically guided extraforaminal cervical nerve blocks have been reported in the literature. The purpose of the present study was to determine the rate of complications associated with these blocks and to determine whether needle positioning during the procedure affected the prevalence of complications at one institution. METHODS: Between October 1999 and June 2003, we performed 1036 fluoroscopically guided extraforaminal cervical nerve blocks in 844 patients. Plain radiographs documenting the procedure were made as part of the standard quality-assurance protocol. An independent observer who was uninvolved with the procedures reviewed a prospectively kept database on all patients. We subsequently reviewed the patient records to identify complications. RESULTS: There were no catastrophic complications such as vessel damage, paralysis, or death. Overall, fourteen patients (1.66%) had a minor complication in association with the procedure. With the numbers available, the rate of complications associated with pdeep injection (798 blocks) was not significantly different from that associated with shallow injection (238 blocks) (1.89% compared with 0.84%). However, the rate of complications associated with anterior placement of the needle tip (thirty-three blocks) was higher than that associated with ideal placement of the needle tip (904 blocks) (6.06% compared with 1.55%) (p = 0.04). CONCLUSIONS: No catastrophic complications occurred in this series of 1036 nerve blocks. We found that the medial-lateral needle depth as seen on frontal-view radiographs was not associated with complications, although the anterior positioning of the needle as seen on lateral-view radiographs was associated with minor complications. Our results suggest that, with our technique, cervical nerve blocks are relatively safe procedures.

Anti-Inflammatory Agents↗

PubMed2005

Mitochondrial involvement in fas-mediated apoptosis of human lumbar disc cells.

BACKGROUND: Two main pathways of Fas-mediated apoptosis have been identified: the Type-I (death-inducing signaling complex) pathway and the Type-II (mitochondrial) pathway. While apoptotic cell death has been implicated in lumbar degenerative disc disease, we are not aware of any studies in which surgically removed discs from live humans have been examined to determine which of the two pathways is involved in the apoptosis of disc cells. As an initial step in the development of therapies to inhibit inappropriate or premature apoptosis of disc cells, our objective was to determine which pathway is involved. METHODS: We examined thirty-two samples of herniated lumbar disc tissue with use of immunohistochemical staining and Western blot analysis to determine the presence of several proteins, including caspase-8 (associated with the Type-I pathway); BID (BH3 interacting domain death agonist), cytochrome-c, and caspase-9 (associated with the Type-II pathway); and caspase-3 (an executioner of apoptosis). The TUNEL (terminal deoxynucleotidyl transferase [TDT]-mediated dUTP nick end labeling) assay was performed to confirm the occurrence of apoptosis of the disc cells. RESULTS: The proteins associated with the Type-II pathway (BID, cytochrome-c, and caspase-9) stained positively in all samples. Although the protein associated with the Type-I pathway (caspase-8) was not detected on immunohistochemical analysis, a small amount of caspase-8 was detected on Western blot analysis. However, the expression of Type-II proteins was still higher than the expression of caspase-8 on Western blot analysis. The expression of caspase-3 was identified in all samples with immunohistochemical and Western blot analysis. TUNEL-positive disc cells were identified in all samples. CONCLUSIONS: The results of the present study suggest that human disc cells are Type-II cells, which undergo apoptotic cell death through mitochondrial involvement.

Adult↗

PubMed2005

The ponticulus posticus: implications for screw insertion into the first cervical lateral mass.

BACKGROUND: The arcuate foramen is an important osseous anomaly of the first cervical vertebra (the atlas) that must be taken into consideration during placement of lateral mass screws into the atlas. METHODS: The prevalence of this anomaly in our patient population was determined through a retrospective review of 464 lateral radiographs of the neck. The anatomy of the arcuate foramen was identified in a study of cadavers. RESULTS: Seventy-two arcuate foramina, complete or incomplete, were identified on the 464 lateral radiographs of the neck; thus, the prevalence was 15.5% in our patient population. CONCLUSIONS: Although the arcuate foramen is a common anomaly, it is often not recognized. Proper identification of this anomaly on preoperative lateral radiographs should alert the surgeon to avoid using the ponticulus posticus as a starting point for a lateral mass screw in order to not injure the vertebral artery.

Bone Screws↗

PubMed2005

Hypertrophy of ligamentum flavum in lumbar spinal stenosis associated with increased proteinase inhibitor concentration.

BACKGROUND: It is well known that age-related fibrosis, or decreases in the elastin-to-collagen ratio of the ligamentum flavum, along with hypertrophy of the ligamentum flavum, are associated with lumbar spinal stenosis. However, the molecular mechanism by which this fibrosis and hypertrophy develop is unknown. Tissue inhibitors of matrix metalloproteinase (TIMPs) are proteinase inhibitors that suppress extracellular matrix degradation. Elevated TIMP-1 and TIMP-2 expression has been implicated in various fibrotic diseases of the liver, kidney, lung, and heart. These TIMPs can also induce cellular proliferation and inhibit apoptosis in a wide range of cell types. These findings led us to postulate that TIMP-1 and TIMP-2 might also be associated with hypertrophy and fibrosis of the ligamentum flavum in lumbar spinal stenosis. METHODS: We quantified and localized TIMP expression in ligamentum flavum tissues that had been obtained during surgery from thirty patients with spinal stenosis and from thirty gender-matched control patients with disc herniation. The thickness of the ligamentum flavum at the level of the facet joint was measured on axial T1-weighted magnetic resonance images. In addition, we examined ligamentum flavum tissues for the expression of markers of cellular proliferation and apoptosis. RESULTS: The ligamentum flavum was significantly thicker in the patients with spinal stenosis (mean, 5.68 mm) than in the patients with disc herniation (mean, 2.70 mm) (p < 0.001). The concentration of TIMP-2 in the ligamentum flavum was significantly higher in the patients with spinal stenosis (mean, 12.62 ng/mL) than in those with disc herniation (mean, 8.85 ng/mL) (p = 0.028). TIMP-1 and TIMP-2 were detected in the cytoplasm of ligamentum flavum fibroblasts. TIMP-1 and TIMP-2 concentrations were associated with hypertrophy of the ligamentum flavum (p = 0.015 and p = 0.003, respectively). None of the samples from the patients with stenosis had evidence of proliferation of ligamentum flavum fibroblasts. The expression of markers for apoptosis was significantly higher in the patients with spinal stenosis (58.8%) than in those with disc herniation (26.6%) (p < 0.001). CONCLUSIONS: Increased TIMP expression has been implicated in fibrosis and hypertrophy of the extracellular matrix of several organs. Our results suggest that increased expression of TIMP-2 in ligamentum flavum fibroblasts is associated with fibrosis and hypertrophy of the ligamentum flavum in patients with spinal stenosis.

Aged↗