Usefulness of Prone Cross-Table Lateral Radiographs in Vertebral Compression Fractures

BACKGROUND: Dynamic radiographs are recommended to investigate non-healing evidence such as the dynamic mobility or intravertebral clefts in osteoporotic vertebral compression fractures (VCFs). However, it is difficult to examine standing flexion and extension lateral radiographs due to severe pain. The use of prone cross-table lateral radiographs (PrLRs) as a diagnostic tool has never been proposed to our knowledge. The purpose of this study is to clarify the usefulness of PrLRs in diagnosis and treatment of VCFs. METHODS: We reviewed 62 VCF patients examined with PrLRs between January 1, 2008 and June 30, 2011. To compare the degree of pain provoked between standing extension lateral radiographs (StLRs) and PrLRs, numeric rating scale (NRS) scores were assessed and compared by a paired t-test. Vertebroplasty was done for 40 patients and kyphoplasty was done for 9 patients with routine manners. To assess the degree of postural reduction, vertebral wedge angles (VWA) and vertebral height ratios (VHR) were calculated by using preoperative StLRs, PrLRs, and postoperative lateral radiographs. Two variables derived from changes in VWA and VHR between preoperative and postoperative radiographs were compared by a paired t-test. RESULTS: The average NRS scores were 6.23 +/- 1.67 in StLRs and 5.18 +/- 1.47 in PrLRs. The degree of pain provocation was lower in using PrLRs than StLRs (p < 0.001). The average changes of VWA between preoperative and postoperative status were 5.24degrees +/- 6.16degrees with PrLRs and 3.46degrees +/- 3.47degrees with StLRs. The average changes of VHR were 0.248 +/- 0.178 with PrLRs and 0.148 +/- 0.161 with StLRs. The comparisons by two variables showed significant differences for both parameters (p = 0.021 and p < 0.001, respectively). The postoperative radiological status was reflected more precisely when using PrLRs than StLRs. CONCLUSIONS: In comparison with StLR, the PrLR was more accurate in predicting the degree of restoration of postoperative vertebral heights and wedge angles, and provoked less pain during examination. The PrLR could be a useful diagnostic tool to detect intravertebral cleft or intravertebral dynamic instability.

Subsidence and Nonunion after Anterior Cervical Interbody Fusion Using a Stand-Alone Polyetheretherketone (PEEK) Cage

BACKGROUND: The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. METHODS: Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as > or = a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being > or = 2 mm in the interspinous distance on the flexion-extension lateral radiographs. RESULTS: The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 +/- 1.46 mm and 0.81 +/- 1.27 mm, respectively. Subsidence > or = 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). CONCLUSIONS: Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.

Differential Diagnosis between Tuberculous Spondylitis and Pyogenic Spondylitis / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study OBJECTIVES: We wanted to make the early differential diagnosis between tuberculous spondylitis and pyogenic spondylitis according to the clinical and MRI findings. SUMMARY OF THE LITERATURE REVIEW: Making an early differential diagnosis between tuberculous spondylitis and pyogenic spondylitis is essential to start prompt and proper treatment. However, the clinical symptoms and MRI findings of both these illnesses can vary considerably. MATERIAL AND METHOD: Ninety-five patients (49 men and 46 women, mean age: 54.5) who were treated from January 2001 to February 2007 and whose diagnosis was confirmed by laboratory or pathological studies were retrospectively reviewed. 50 patients with tuberculous spondylitis and 45 patients with primary pyogenic spondylitis were included. The patients with combined infection or an uncertain diagnosis were excluded. We compared the medical records and MRI findings between the different groups of patients. RESULTS: The patients with tuberculous spondylitis were younger (48.2 years vs. 61.5 years, respectively) and they had a longer symptom duration (4.3 months vs 1.8 months, respectively). The erythrocyte sedimentation rate (ESR) and the C-reactive protein (CRP) level were significantly higher in the patients with pyogenic spondylitis (71.3/49.6 mm/hr and5.74/2.98 mg/dl, respectively). A high fever above 38 degree was more frequent in the patients with pyogenic spondylitis. Intraosseous abscess, epidural abscess, a well-definded paraspinal abscess, focal enhancement and severe destruction of the vertebral body on MRI were more frequent in the patients with tuberculous spondylitis. Four parameters such as a symptom duration longer than 3 months, no fever higher than 38 degree, a well-defined paravertebral abscess and an intraosseous abscess were selected. 42 patients in the tuberculous group had 3 or more of these four parameters. The sensitivity and specificity of these combined 4 parameters were 84% and 97.8%, respectively, for making the differential diagnosis between these 2 maladies. CONCLUSION: These diagnostic criteria might be useful to discriminate between tuberculous spondylitis and pyogenic spondylitis even without definite laboratory or pathological results.

Posterior Lumbar Interbody Fusion Using New Hydroxyapatite Block: Comparison with Metal and PEEK Cages / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study OBJECTIVES: This study compared the clinical outcomes of posterior lumbar interbody fusion (PLIF) using hydroxyapatite blocks with PLIF using a metal or poly-ether-ether-ketone (PEEK) cage. SUMMARY OF THE LITERATURE REVIEW: There are few reports on the clinical outcomes of PLIF using a hydroxyapatite block for treating lumbar degenerative disease. MATERIALS AND METHODS: The 27 PLIF cases (62 units, HA block) that were followed up for 1-year were compared with 13 cases using a metal cage and 13 cases using a PEEK cage. Pedicle screw fixation was performed for all the cases. If the local bone is deficient, then an additional bone graft with autogeous iliac bone or bone substitute was used. The visual analog scale(VAS) for low back pain and radiating pain, the Oswestry disability index (ODI), the intervertebral height and the halo sign around the cages and pedicle screws were comparatively analyzed. RESULTS: The mean VAS score for low back pain before PLIF and using the HA block, the metal cage and the PEEK cage was 7.5, 8.3 and 6.2, respectively, and this was 3.3, 2.9 and 4.8 after PLIF (P0.05, One-way ANOVA). CONCLUSION: PLIF using a HA block showed improvements, including the back pain, and the ODI was satisfactory and this didn't fall below those ODIs of using metal or PEEK cages. Although a HA block may have higher tendency to break, there was no breakage at the 1-year follow up.

Prevalence and Morphologic Features of Ponticulus Posticus in Koreans: Analysis of 312 Radiographs and 225 Three-dimensional CT Scans

STUDY DESIGN: A retrospective review of three-dimensional CT scan images and radiographs. PURPOSE: To investigate the prevalence and morphologic features of ponticulus posticus in Koreans. OVERVIEW OF LITERATURE: There has been little reported on the prevalence or morphologic characteristics of ponticulus posticus in Asians, predisposing them to vertebral artery injury during screw placement in the lateral mass of the atlas. METHODS: The presence and types of ponticulus posticus were investigated on 225 consecutive cervical three-dimensional CT scans and 312 consecutive digital lateral cephalometric head radiographs. RESULTS: Various spectra of ponticulus posticus were found in 26% of the CT scans and 14% of the radiographs. CONCLUSIONS: Ponticulus posticus is a relatively common anomaly in Koreans. Therefore, the presence of this anomaly should be carefully examined for on radiographs before lateral mass screw placement. If ponticulus posticus is suspected or confirmed on radiographs, three-dimensional CT scanning should be considered before placement of lateral mass screws into the posterior arch, especially given its wide variation of size and shape.

A Comparative Experimental Study of Allograft andPorous Hydroxyapatite as Bone Substitutes / 대한정형외과학회잡지

PURPOSE: An experimental animal study was performed to compare the bone fusion capacity of an allograft and porous hydroxyapatite. MATERIALS AND METHODS: Three milliliters of allograft or porous hydroxyapatite particles were inserted between the 4th and 5th lumbar transverse processes of New Zealand white rabbits weighing 3-3.5 kg. The total number of rabbits was 30, which were divided randomly into 2 groups. The bone formation and fusion capacity were evaluated 12 weeks after surgery through the gross findings and manual palpation, as well as radiological, biomechanical, and histological studies. Six rabbits in the allograft group died during breeding but the autopsy finding did not show any evidence suggesting an infection or graft rejection. The allograft was harvested from the iliac crest of the rabbits of the same species aseptically and was preserved at ??80oC for at least 7 days before implantation. RESULTS: The fusion rates were 55.6% (5/9) and 66.7% (10/15) in the allograft and porous hydroxyapatite groups, respectively. The mean values of the tensile strengths were 140.7 N in the allograft group and 189.6 N in the porous hydroxyapatite group. Histological analysis of 2 specimens from each group revealed theporous hydroxyapatite group to show a slightly better osteoconduction capacity. CONCLUSION: The porous hydroxyapatite group showed better bony union capacity even though there was no significant difference between the 2 groups.

Indirect Decompression using Segmental Screw Fixation for Cervical Myelopathy Caused by C1-2 Subluxation: Technical Note / 대한정형외과학회잡지

The main aims of surgery for severe cord compression and myelopathy caused by atlantoaxial subluxation are decompression of the spinal cord and achievement of rigid fixation and fusion. Direct decompression by resecting the bony structures that compress the spinal cord includes transoral decompression and resection of the posterior arch of the atlas. The shortcomings of these procedures are a high complication rate and a relatively low rate of union. Indirect decompression can be performed by a reduction of the subluxation and fixation without bone resection. To the best of our knowledge, there are no domestic reports on the use of indirect decompression for severe cord compression and myelopathy for atlantoaxial subluxation. We report a case of a patient that had atlantoaxial subluxation and severe myelopathy; satisfactory reduction of the subluxation and decompression with an improvement in the myelopathy symptoms was achieved by indirect decompression using segmental screw fixation.

Old Atlantoaxial Rotary Subluxation Associated with High-riding Vertebral Arteries: Arthrodesis Using C1 Lateral Mass Screws and C2 Laminar Screws: A Case Report

To the best of our knowledge, there has been no domestic report on posterior atlantoaxial fusion with segmental screw fixation using C2 laminar screws and C1 lateral mass screws for atlantoaxial subluxation. We report the result of this operation performed in a patient with old atlantoaxial rotary subluxation who required posterior fusion. We chose this technique in this patient because wire fixation was not suitable due to osteoporosis, and transarticular screw fixation and use of C2 pedicle screws were not feasible due to the peculiar bony anatomy of the axis.

Revision of Atlantoaxial Fusion using Segmental Screw Fixation: Experience in Bilateral Posterior Arch Fracture of the Atlas Complicating Atlantoaxial Halifax Clamp Fixation: A Case Report / 대한척추외과학회지

A fracture of the posterior arch of the atlas is a rare complication of Halifax clamp fixation for atlantoaxial fusion. To the best of our knowledge, there is only one case reported reporting the English literature. Revision for this condition is challenging because of the difficulty in the surgical approach, internal fixation, and fusion. We report a case of bilateral fractures and nonunion of the posterior arch of the atlas and atlantoaxial nonunion after an atlantoaxial fusion procedure using Halifax clamp fixation, which resulted in persistent atlantoaxial instability and progressive myelopathy. Segmental screw fixation was performed using C1 lateral mass screws and C2 subarticular screws, along with intraarticular and extraarticular atlantoaxial inter-facet fusion.

Transforaminal Epidural Steroid Injection for Lumbosacral Radiculopathy: Preganglionic versus Conventional Approach

OBJECTIVE: The present study was undertaken to evaluate the effectiveness of transforaminal epidural steroid injection (TFESI) with using a preganglionic approach for treating lumbar radiculopathy when the nerve root compression was located at the level of the supra-adjacent intervertebral disc. MATERIALS AND METHODS: The medical records of the patients who received conventional TFESI at our department from June 2003 to May 2004 were retrospectively reviewed. TFESI was performed in a total of 13 cases at the level of the exiting nerve root, in which the nerve root compression was at the level of the supra-adjacent intervertebral disc (the conventional TFESI group). Since June 2004, we have performed TFESI with using a preganglionic approach at the level of the supra-adjacent intervertebral disc (for example, at the neural foramen of L4-5 for the L5 nerve root) if the nerve root compression was at the level of the supra-adjacent intervertebral disc. Using the inclusion criteria described above, 20 of these patients were also consecutively enrolled in our study (the preganglionic TFESI group). The treatment outcome was assessed using a 5-point patient satisfaction scale and by using a VAS (visual assessment scale). A successful outcome required a patient satisfaction scale score of 3 (very good) or 4 (excellent), and a reduction on the VAS score of > 50% two weeks after performing TFESI. Logistic regression analysis was also performed. RESULTS: Of the 13 patients in the conventional TFESI group, nine showed satisfactory improvement two weeks after TFESI (69.2%). However, in the preganglionic TFESI group, 18 of the 20 patients (90%) showed satisfactory improvement. The difference between the two approaches in terms of TFESI effectiveness was of borderline significance (p = 0.056; odds ratio: 10.483). CONCLUSION: We conclude that preganglionic TFESI has the better therapeutic effect on radiculopathy caused by nerve root compression at the level of the supra-adjacent disc than does conventional TFESI, and the diffence between the two treatments had borderline statistical significance.

Atlanto-occipital Assimilation Associated with Basilar Invagination, C1-2 Instability, C2-3 Block Vertebra,and C3-4 Retrolisthesis : A Case Report / 대한정형외과학회잡지

Congenital atlanto-occipital assimilation is frequently accompanied by basilar invagination and C1-2 instability. Occipitocervical fusion is required if these conditions cause neurological symptoms. Recently posterior fusion using occipitocervical screw fixation in the extension position has been introduced for the simultaneous decompression of the cervicomedullary junction compressed by basilar invagination, a reduction of atlantoaxial subluxation, and rigid fixation. However, it is a technically demanding procedure, and there is no domestic report of an experience with this procedure. We report a case of a patient with C2-3 block vertebra and C3-4 retrolisthesis in addition to congenital atlanto-occipital assimilation, basilar invagination and C1-2 instability. The patient underwent posterior fusion using occipitocervical screw fixation in the extension position.

Atlantoaxial Fixation using C2 Subarticular Screws and C1 Lateral Mass Screws : A Technical Report / 대한정형외과학회잡지

Segmental screw fixation is a useful procedure for the surgical treatment of atlantoaxial subluxation. Currently, C1 lateral mass screws and C2 pedicle screws are the standard screws used in this procedure. However, the C2 pedicle screw can cause serious complications such as vertebral artery injury. Recently we suggested a new trajectory for the C2 screw, the subarticular screw, which has a lower probability of vertebral artery injury compared with the pedicle screw, based on a study using 1 mm-sliced CT scan images and simulation software. We report the first case of segmental screw fixation using C2 subarticular screws along with C1 lateral mass screws. The patient had atlantoaxial subluxation and myelopathy and showed satisfactory results after surgery.

Value of Preoperative Cervical Discography

PURPOSE: The aim of this study was to describe the method and the value of cervical discography as correlated with the MR findings. MATERIALS AND METHODS: Twenty-one discs in 11 consecutive patients who underwent cervical discography were analyzed. MR and CT discography (CTD) were performed in all patients. Discography was performed after swallowing barium for visualizing the pharynx and the esophagus to prevent penetration. We also analyzed the preceding causes of the subjects' cervical pain. The results of the pain provocation test were classified into concordant pain, discordant pain and a negative test. MRI was analyzed according to the T2-signal intensity (SI) of the disc, disc height, annular bulging and disc herniation. The CTD was analyzed for degeneration or radial tear of the disc, epidural leakage of the contrast agent and pooling of the contrast agent at the periphery of the disc. The pain provocation tests were correlated with the MR and CTD findings. We used the chi-square test to analyze the results. RESULTS: Concordant pain was observed in 14 cases, discordant pain in 3 cases and there were negative tests in 4 cases. There were no complications related to the procedure. Four patients had undergone anterior cervical fusion and four patients had pain that developed after traffic injuries. The decreased T2-SI and annular bulging on MRI, disc degeneration and peripheral pooling of the contrast agent on CT were significantly correlated with pain provocation. CONCLUSION: When the diagnosis of disc disease is difficult with performing MRI, cervical discography with using swallowed barium solution to reduce the penetration of the esophagus or hypopharynx may play be helpful. The decreased T2-SI and annular bulging on MRI correlated significantly with a positive result on the pain provocation test.

The Subarticular Screw: a New Trajectory for the C2 Screw / 대한척추외과학회지

STUDY DESIGN: Surgical simulation using CT images and computer software. OBJECTIVES: We wanted to determine a new trajectory for the C2 screw, and then we wanted to evaluate its safety and accuracy. Summary of Literature REVIEW: There have been a few suggestions for trajectories of the C2 pedicle screws. However, their safety is somewhat unsatisfactory as all of them have some possibility of vertebral artery injury. MATERIALS AND METHODS: Using 1 mm-sliced CT scan images of 158 patients and an A-view spine surgery simulator 1.0, we determined a new trajectory for the C2 screw with which 4.0 mm screws can be inserted with a minimal number of breaches of the bone cortices. The percentage of cortical perforations by the suggested trajectory was compared with that by the pedicle screws by means of simulation. RESULTS: The medial angulation of the determined trajectory is the same as that of the pedicle on the axial CT images: it usually is between 30 and 40 degrees. The screw is angled toward the antero-superior end of the superior articular process of C2, as observed on lateral fluoroscopy. The entry point is 3 mm inferior to the posterior aspect of the superior articular surface, and this point should allows the screw (ED note: check this and it wasn't clear.)the screw to be inserted close to the superomedial border of the superior articular process. Using this trajectory, 2.5% (8/316) of the screws breached the vertebral grooves, while 6.0% (19/316) of the pedicle screws breached them (p=0.030, chi-square test). CONCLUSIONS: The subarticular screw has improved safety compared with the pedicle screws. However, there are still some casesin which screws can not be inserted without breaching the vertebral groove. Therefore, preoperative thin-slice CT scanning with three-dimensional reconstruction and/or three-dimensional CT-angiography is recommended.

Two Simple Tests for Adequate Needle Positioning in Vertebroplasty / 대한척추외과학회지

STUDY DESIGN: We analyzed the diagnostic values of two simple tests for adequate needle positioning in vertebroplasty. OBJECTIVES: We wanted to suggest performing the aspiration test and patency test, which can replace some of the roles of intraosseous venography (IOV) in vertebroplasty, and we also wanted to analyze the two tests' diagnostic values. SUMMARY OF LITERATURE REVIEW: Intra-osseous venography is an existing safety test for vertebroplasty, but it is less frequently performed nowadays because of its drawbacks. MATERIALS AND METHODS: The aspiration test is defined as positive if blood is easily aspirated through a vertebroplasty needle, and a positive aspiration test means that the needle tip is communicating with the venous system. This and IOV were carried out on a total of 114 sides of 61 vertebrae of 40 consecutive patients. Agreement between the two tests was evaluated with using Cohen's kappa coefficient, and the diagnostic values of the aspiration test, with using IOV as the gold standard, were also evaluated. The patency test is done in the intra-vertebral vacuum cleft cases. After bipedicular insertion of needles, saline is injected into one needle. If the saline gushes out of the other needle, the test is positive, and it means that both needles are inserted in the vacuum cleft. The patency test was performed in 25 vertebrae, and the positive rate and causes of the negative result were investigated. RESULTS: Cohen's kappa coefficient between the aspiration test and IOV was 0.88. The sensitivity of the aspiration test was 88%, the specificity was 99%, the positive predictive value was 97%, and the negative predictive value was 93%. The patency test was positive in 88% of the vacuum clefts. In all the positive cases, both needles were located within the vacuum cleft. In all the negative cases, one of the two needles was located outside the cleft. CONCLUSIONS: The aspiration test is a simple and reliable test that has high agreement with IOV. The patency test can be a better choice than IOV for the vacuum cleft cases because it does not leave contrast media in the clefts.

C1-2 Instability associated with Duplicated Vertebral Artery: A Case Report / 대한척추외과학회지

A vertebral artery injury is one of the most critical complications of atlantoaxial fixation. Abnormal courses or congenital anomalies of the vertebral artery increase its risk. The authors report a case of a patient who had an atlantoaxial subluxation associated with severe spinal cord compression and a duplicated vertebral artery. The atlantoaxial subluxation, which was not reduced satisfactorily by an intraoperative head position change or direct manipulation of the atlas and axis, precluded a transarticular screw fixation. The lack of free space around the spinal cord precluded a sublaminar wiring. The duplicated vertebral artery made it difficult to insert C1 lateral mass screws and C2 pedicle screws with Harms' technique.

Augmentation of Anterior Vertebral Screws Using Direct Anterior Vertebroplasty in the Porcine Model / 대한척추외과학회지

STUDY DESIGN: A biomechanical study using the porcine spine. OBJECTIVES: To investigate the efficacy of direct anterior vertebroplasty [Polymethylmetacrylic acid (PMMA) augmentation] with anterior vertebral screw fixation. SUMMARY AND LITERATURE REVIEW: We are not aware of any previous reports that described this technique. MATERIALS AND METHODS: Thirty out of 35 fresh porcine lumbar vertebral bodies (L1-5) were instrumented with single anteriorvertebral screws using different augmentation methods. In group 1 (n=10), the non-augmented group, each vertebral body was pre-drilled and an anterior vertebral screw was inserted unicortically at 90 degrees laterally. In groups 2 (n=10) and 3 (n=10), after the unicortical pre-drilling, 2 ml of PMMA were injected through an 11-gauge bone biopsy needle. The screw was inserted immediately after the cement injection in group 2, and after complete consolidation of the cement in group 3. Axial pullout loads to loosen the screws were measured. Conventional vertebroplasties via bilateral pedicles were performed in the other 5 vertebral bodies, the cement distribution areas of which were compared with the 5 specimens of groups 2 and 3, respectively, using radiomorphometry. The data were analyzed using the Mann-Whitney test. RESULTS: The mean pullout loads were 459+/-111N in group 1, 1510+/-165N in group 2, and 1241+/-189N in group 3. The PMMA augmented anterior vertebral screws (groups 2 and 3) provided more than 100% of an increase in pullout strength compared with non-augmented screws (group 1) (P 0.05) CONCLUSIONS: Direct anterior vertebroplasty is another effective augmentation method for anterior vertebral screw fixation. With this technique, we avoided an unnecessary posterior procedure and achieved a more rigid fixation because we could insert the screws during the consolidation of PMMA.

The Usefulness of Selective Nerve Root Block as a Predictor of Prognosis of Lumbar Disc Herniation / 대한척추외과학회지

STUDY DESIGN: A prospective study. OBJECTIVES: To investigate the usefulness of selective nerve root block (SNRB) as a prognosis predictor of a lumbar disc herniation. SUMMARY OF LITERATURE REVIEW: The biochemical factors of radiculopathy, as opposed to the biomechanical factors, are more reversible and responsive to a corticosteroid injection. MATERIALS AND METHODS: Fifty patients underwent SNRB for the radiculopathy caused by a herniated lumbar disc and were followed for at least 1 year. The straight leg raising (SLR) angle, visual analog scale (VAS) and the patients' subjective satisfaction, using the Weber criteria, were initially investigated, and again at 1 week and 1 month after the procedure, and finally at the final follow-up. The patients were divided into two groups according to the final satisfaction. Group 1 (satisfactory prognosis, N=32) had Excellent/Good results at the final follow-up, whereas Group 2(unsatisfactory prognosis, N=18) had Fair/Poor final results, or underwent surgical treatment. The improvements in the SLR and VAS at 1 week and 1 month were compared between two groups. The subjective satisfaction each time was compared to the final outcome; the relative risks were also calculated. RESULTS: The improvements in the SLR and VAS for Group 1 were significantly better than those for Group 2 at both 1 week and 1 month (p<0.05). Those patients with Excellent/Good results at 1 week and 1 month manifested satisfactory final outcomes (p<0.05). The risks of the patients with Fair/Poor results at 1 week and 1 month manifesting unsatisfactory final outcomes were 6.8 and 15.2 times higher than those with Excellent/Good results. CONCLUSION: Selective nerve root block could be a useful method, not only to relieve acute leg pain, but also to predict the longterm prognosis of a herniated lumbar disc. Early surgical treatment could be considered for the patients not manifesting significant improvement until 1 month after SNRB.

The Usefulness of Selective Nerve Root Block as a Predictor of Prognosis of Lumbar Disc Herniation / 대한척추외과학회지

STUDY DESIGN: A prospective study. OBJECTIVES: To investigate the usefulness of selective nerve root block (SNRB) as a prognosis predictor of a lumbar disc herniation. SUMMARY OF LITERATURE REVIEW: The biochemical factors of radiculopathy, as opposed to the biomechanical factors, are more reversible and responsive to a corticosteroid injection. MATERIALS AND METHODS: Fifty patients underwent SNRB for the radiculopathy caused by a herniated lumbar disc and were followed for at least 1 year. The straight leg raising (SLR) angle, visual analog scale (VAS) and the patients' subjective satisfaction, using the Weber criteria, were initially investigated, and again at 1 week and 1 month after the procedure, and finally at the final follow-up. The patients were divided into two groups according to the final satisfaction. Group 1 (satisfactory prognosis, N=32) had Excellent/Good results at the final follow-up, whereas Group 2(unsatisfactory prognosis, N=18) had Fair/Poor final results, or underwent surgical treatment. The improvements in the SLR and VAS at 1 week and 1 month were compared between two groups. The subjective satisfaction each time was compared to the final outcome; the relative risks were also calculated. RESULTS: The improvements in the SLR and VAS for Group 1 were significantly better than those for Group 2 at both 1 week and 1 month (p<0.05). Those patients with Excellent/Good results at 1 week and 1 month manifested satisfactory final outcomes (p<0.05). The risks of the patients with Fair/Poor results at 1 week and 1 month manifesting unsatisfactory final outcomes were 6.8 and 15.2 times higher than those with Excellent/Good results. CONCLUSION: Selective nerve root block could be a useful method, not only to relieve acute leg pain, but also to predict the longterm prognosis of a herniated lumbar disc. Early surgical treatment could be considered for the patients not manifesting significant improvement until 1 month after SNRB.

C1-2 Fixation Using Polyaxial Screws and Rods Assisted by Computer Simulation for Revision of Failed Posterior Fusion: A Technical Report / 대한정형외과학회잡지

Segmental C1-2 screw fixation using C1 lateral mass screws and C2 pedicle screws is a technically demanding procedure which can cause injuries to the vertebral artery or neural structures as well as massive bleeding from the epidural venous plexus. In particular, this procedure is more difficult in revision cases because of the lack of normal anatomical landmarks, adhesion, and bleeding. The authors report a case of a patient in whom preoperative surgical simulation and planning using computer software was very helpful in the direct screwing of the atlas and axis for a revision of atlantoaxial fusion.