Anterior Decompression and Fusion for the Treatment of Cervical Myelopathy Caused by Ossification of the Posterior Longitudinal Ligament: A Narrative Review

Occasionally, ossification of the posterior longitudinal ligament (OPLL) causes cord compression, resulting in cervical myelopathy. OPLL differs from other causes of cervical spondylotic myelopathy in several ways, and the surgical strategy should be chosen with OPLL’s characteristics in mind. Although both the anterior and posterior approaches are effective surgical methods for the treatment of OPLL cervical myelopathy, they each have their own set of benefits and drawbacks. Anterior decompression and fusion (ADF) may improve neurological recovery, restore lordosis, and prevent OPLL mass progression. The benefits can be seen in patients with a high canal occupying ratio or kyphotic alignment. We discussed the benefits, limitations, indications, and surgical techniques of ADF for the treatment of OPLL-induced cervical myelopathy in this narrative.

Using Lordotic Cages at the L5–S1 Level Does Not Guarantee the Improvement of Sagittal Alignment in Patients Who Underwent Posterior Lumbar Interbody Fusion

Methods@#Sixty-one patients who underwent 1- or 2-level PLIF, including the L5–S1 level, were divided into two groups based on the lordotic angle of cages (4° and 8° in 41 and 20 patients, respectively). Clinical and radiological parameters were compared. Correlation analyzes were performed to reveal the effect of flexibility and position of cages on the regional sagittal parameters. @*Results@#Pre- and postoperative clinical and radiological parameters were not different between the two groups. Although clinical outcomes improved postoperatively, sagittal parameters did not improve postoperatively in both groups. Patients who underwent 1-level PLIF at the L5–S1 level with the use of 8° cages showed no postoperative improvement (segmental angle: 16.1°–15.9°, p =0.140; lumbar lordosis: 44.8°–47.8°, p =0.740) of regional sagittal parameters. The degree of anterior location of cages showed a positive correlation with the postoperative restoration of the segmental angle (p =0.012 and p =0.050 at 1 and 2 years postoperatively, respectively). @*Conclusions@#Clinical and radiological outcomes based on the lordotic angle of cages were not different. Even with the use of 8° cages and regardless of the more anterior position of cages, sagittal alignment did not improve in cases involving the L5–S1 level. PLIF at the L5–S1 level should be used with caution because improvement in sagittal alignment did not occur.

Posterior Correction of Adolescent Idiopathic Scoliosis with High-Density Pedicle Screw-Only Constructs: 5 Years of Follow-Up

PURPOSE: This study aimed to analyze radiological outcomes in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior correction with high-density pedicle screw-only constructs. We hypothesized that high-density pedicle screw-only constructs in AIS would provide a high correction rate and would facilitate the maintenance of the correction or obviate the loss thereof.MATERIALS AND METHODS: We retrospectively analyzed radiological outcomes over a minimum follow-up period of 5 years in patients with AIS who underwent posterior correction with high-density pedicle screw-only constructs. A total of 124 consecutive patients were included. Demographic data, including age, sex, operated fusion level, numbers of screw, Lenke curve type, Risser stage, and follow-up period were retrospectively collected from electronic medical records and radiological measurements including serial follow-up.RESULTS: The average number of pedicle screws was 1.96/vertebra. The average curve correction was 48.3% for the proximal thoracic (PT) curve, 83.1% for the main thoracic (MT) curve, and 80.2% for the thoracolumbar/lumbar (TL/L) curve at final follow-up. Use of high-density pedicle screw-only constructs helped achieve excellent correction rates, with no significant loss of correction at final follow-up.CONCLUSION: We obtained excellent correction rates of 48.3% for PT, 83.1% for MT, and 80.2% for TL/L curves using high-density pedicle screw-only constructs in AIS, with no significant loss of correction at final follow-up.

Which Criterion Is More Reliable for Selecting the Distal Fusion Level in Cases of Adolescent Idiopathic Scoliosis with Structural Thoracolumbar/Lumbar Curves: Static or Dynamic?

STUDY DESIGN: Retrospective comparative study.OBJECTIVES: To compare the reliability of 2 criteria to predict the radiological outcomes of corrective surgery in cases of adolescent idiopathic scoliosis (AIS) with structural thoracolumbar/lumbar (TL/L) curves.SUMMARY OF LITERATURE REVIEW: Distal fusion level selection in AIS with structural TL/L curves is debatable.MATERIALS AND METHODS: This study included 131 AIS patients with structural TL/L curves who underwent corrective surgery in which distal fusion was stopped at L3. Whole-spine standing radiographs and bending radiographs were obtained preoperatively. The patients were divided into 2 groups according to their findings on bending radiographs (dynamic criterion) and by the last touching vertebra and the lower end vertebra (static criterion). Radiological outcomes were assessed by reviewing postoperative radiographs. Reliability tests were conducted to compare the predictability of radiological outcomes using these 2 methods. In addition, radiological parameters were compared between both criteria.RESULTS: Among 131 patients, 25 showed radiologically poor outcomes (19.1%). The sensitivity of the dynamic and static criteria was 0.69 and 0.50, respectively. The specificity of each criterion was 0.49 and 0.64, respectively. Overall, the dynamic criterion showed superior reliability (p=0.03). However, no significant difference in radiological parameters could be found in a comparison of both criteria.CONCLUSIONS: Although the dynamic criterion was more sensitive for predicting poor radiological outcomes when stopping fusion at L3 in patients with structural TL/L curves, its specificity was lower than that of the static criterion. Thus, both dynamic and static criteria should be considered when selecting the distal fusion level in cases of AIS with structural TL/L curves.

Which Criterion Is More Reliable for Selecting the Distal Fusion Level in Cases of Adolescent Idiopathic Scoliosis with Structural Thoracolumbar/Lumbar Curves: Static or Dynamic?

OBJECTIVES@#To compare the reliability of 2 criteria to predict the radiological outcomes of corrective surgery in cases of adolescent idiopathic scoliosis (AIS) with structural thoracolumbar/lumbar (TL/L) curves.SUMMARY OF LITERATURE REVIEW: Distal fusion level selection in AIS with structural TL/L curves is debatable.@*MATERIALS AND METHODS@#This study included 131 AIS patients with structural TL/L curves who underwent corrective surgery in which distal fusion was stopped at L3. Whole-spine standing radiographs and bending radiographs were obtained preoperatively. The patients were divided into 2 groups according to their findings on bending radiographs (dynamic criterion) and by the last touching vertebra and the lower end vertebra (static criterion). Radiological outcomes were assessed by reviewing postoperative radiographs. Reliability tests were conducted to compare the predictability of radiological outcomes using these 2 methods. In addition, radiological parameters were compared between both criteria.@*RESULTS@#Among 131 patients, 25 showed radiologically poor outcomes (19.1%). The sensitivity of the dynamic and static criteria was 0.69 and 0.50, respectively. The specificity of each criterion was 0.49 and 0.64, respectively. Overall, the dynamic criterion showed superior reliability (p=0.03). However, no significant difference in radiological parameters could be found in a comparison of both criteria.@*CONCLUSIONS@#Although the dynamic criterion was more sensitive for predicting poor radiological outcomes when stopping fusion at L3 in patients with structural TL/L curves, its specificity was lower than that of the static criterion. Thus, both dynamic and static criteria should be considered when selecting the distal fusion level in cases of AIS with structural TL/L curves.

Association between Sacral Slanting and Adjacent Structures in Patients with Adolescent Idiopathic Scoliosis

BACKGROUND: Sacral slanting is a frequent unique phenomenon in patients with adolescent idiopathic scoliosis (AIS) and may be important for selecting the distal fusion level. However, the reason of the phenomenon remains unknown. The purpose of this study was to determine the association between sacral slanting and adjacent structures in patients with AIS. METHODS: A total of 303 AIS patients who underwent both whole spine standing anteroposterior (AP) and whole leg standing AP radiography were included. The degree of sacral slanting, pelvic obliquity, lumbar curve angles (L1-L4), and L4 tilt were assessed on whole spine standing AP radiographs. Whole leg standing AP radiographs were used to assess the degree of leg length discrepancy (LLD). Demographic data and radiological parameters were analyzed descriptively. Pearson correlation analysis and partial correlation analysis of the parameters were performed. A p-value of less than 0.05 was considered statistically significant. RESULTS: The proportion of patients with ≥ 5° of sacral slanting among those with < 3° of pelvic obliquity was 8.9% (27/303). Thirty-two patients (10.6%, 32/303) showed more than 10 mm of LLD. Sacral slanting was positively correlated with pelvic obliquity and lumbar curve (r = 0.445 and r = 0.325, respectively). Pelvic obliquity was also correlated with LLD and L4 tilt (r = 0.123 and r = 0.311, respectively). However, partial correlation analysis showed that LLD was not directly correlated with sacral slanting (r = −0.034). CONCLUSIONS: Sacral slanting can be thought to be a compensatory mechanism for large lumbar curves, which is accompanied by pelvic obliquity. In contrast, a congenitally slanted upper sacrum may contribute to scoliosis in some cases. LLD was not directly correlated with sacral slanting.

Preoperative Magnetic Resonance Imaging Evaluation in Patients with Adolescent Idiopathic Scoliosis

STUDY DESIGN: Retrospective case series. PURPOSE: The purpose of this study was to examine the incidence of neural axis abnormalities and the relevant risk factors in patients with adolescent idiopathic scoliosis (AIS). OVERVIEW OF LITERATURE: The use of preoperative magnetic resonance imaging (MRI) to assess the whole spine in patients with idiopathic scoliosis is controversial, and indications for such MRI evaluations have not been definitively established. However, we routinely use whole-spine MRI in patients with scoliosis who are scheduled to undergo surgical correction. METHODS: A total of 378 consecutive patients with presumed AIS who were admitted for spinal surgery were examined for neural axis abnormalities using MRI. To differentiate patients with normal and abnormal MRI findings, the following clinical parameters were evaluated: age, sex, menarcheal status, rotation angle (using a scoliometer), coronal balance, shoulder height difference, and low back pain. We radiographically evaluated curve type, thoracic or thoracolumbar curve direction, curve magnitude and flexibility, apical vertebral rotation, curve length, coronal balance, sagittal balance, shoulder height difference, thoracic kyphosis, and the Risser sign. RESULTS: Neural axis abnormalities were detected in 24 patients (6.3%). Abnormal MRI findings were significantly more common in males than in females and were associated with increased thoracic kyphosis. However, there were no significant differences in terms of the other measured parameters. CONCLUSIONS: Among the patients with presumed AIS who received preoperative whole-spine MRI, 6.3% had neural axis abnormalities. Males and patients with increased thoracic kyphosis were at a higher risk.

Agreement on the Level Selection in Laminoplasty among Experienced Surgeons: A Survey-Based Study

STUDY DESIGN: Survey based study. PURPOSE: To assess the degree of agreement in level selection of laminoplasty (LP) for the selected cervical myeloradiculopathy cases between experienced spine surgeons. OVERVIEW OF LITERATURE: Although, cervical LP is a widely used surgical technique for multi-level spinal cord compression, until now there is no consensus about how many segments or which segments should be opened to achieve a satisfactory decompression. METHODS: Thorough clinical and radiographic data (plain X-ray, computed tomography, and magnetic resonance imaging) of 30 patients who had cervical myelopathy were prepared. The data were provided to three independent spine surgeons with over 10 years experience in operation of their own practices. They were questioned about the most preferable surgical method and suitable decompression levels. The second survey was carried out after 6 months with the same cases. If the level difference between respondents was a half level or below, agreement was considered acceptable. The intraobserver and interobserver agreements in level selection were assessed by kappa statistics. RESULTS: Three respondents selected LP as an option for 6, 8, and 22 cases in the first survey and 10, 21, and 24 cases in the second survey. The reasons for selection of LP were levels of ossification of the posterior longitudinal ligament (p=0.004), segmental kyphotic deformity (p=0.036) and mean compression score (p=0.041). Intraobserver agreement showed variable results. Interobserver agreement was poor to fair by perfect matching (kappa=0.111–0.304) and fair to moderate by acceptable matching (kappa=0.308–0.625). CONCLUSIONS: The degree of agreement for level selection of LP was not high even though experienced surgeons would choose the opening segments on the basis of same criteria. These results suggest that more specific guidelines in determination of levels for LP should be required to decrease unnecessary wide decompression according to individual variance.

Patterns of Treatment for Metastatic Pathological Fractures of the Spine: The Efficacy of Each Treatment Modality

BACKGROUND: Metastatic pathological fractures of the spine are a major problem for cancer patients; however, there is no consensus on treatment strategy. The purpose of this study was to evaluate various treatment options by analyzing their patterns for metastatic pathological fractures of the spine. METHODS: In this study, 54 patients (male:female = 36:18) who were diagnosed with metastatic pathological fractures of spine were recruited. Demographic data, origin of cancer, type of treatment, and results were obtained from electronic medical records. Treatment options were divided into radiotherapy (RT), vertebroplasty (VP) or kyphoplasty (KP), operation (OP), and other treatments. Treatment results were defined as aggravation, no response, fair response, good response, and unknown. The survival time after detection of pathologic fractures was analyzed with the Kaplan-Meier method. RESULTS: The mean age of the patients was 62.3 years. Hepatocellular carcinoma was the most common cancer of primary origin (n = 9), followed by multiple myeloma (n = 8). RT was the most common primary choice of treatment (n = 29, 53.7%), followed by OP (n = 13, 24.1%), and VP or KP (n = 10, 18.5%). Only 13 of 29 RT cases and 7 of 13 OP cases demonstrated a fair or good response. The mean survival time following detection of pathological spinal fractures was 11.1 months for 29 patients, who died during the study period. CONCLUSIONS: RT was the most common primary choice of treatment for metastatic pathological fractures of the spine. However, the response rate was suboptimal. Although OP should be considered for the relief of mechanical back pain or neurologic symptoms, care should be taken in determining the surgical indication. VP or KP could be considered for short-term control of localized pain, although the number of cases was too small to confirm the conclusion. It is difficult to determine the superiority of the treatment modalities, hence, a common guideline for the diagnosis and treatment of metastatic pathological fractures of the spine is required.

Thoracic Vertebral Fracture due to Spinal Tuberculosis which was Misdiagnosed as Matastatic Cancer: A Case Report

STUDY DESIGN: A case report. OBJECTIVES: To report the case of a patient whose preoperative imaging results seemed to show metastatic spine tumor but who actually had a vertebral pathologic fracture caused by spine tuberculosis. SUMMARY OF LITERATURE REVIEW: Tuberculosis spondylitis is classified into peridiscal, central, anterior, and posterior spondylitis according to the portion involved, and central spondylitis can be mistaken as a tumor. MATERIALS AND METHODS: Imaging studies were performed in a 79-year-old female with progressive lower extremity weakness. We found a T12 pathologic vertebral fracture, which was suspected to be metastatic cancer. RESULTS: We performed surgery and found spine tuberculosis in the pathological and immunological examinations. Two weeks postoperatively, the patient could walk with crutches and underwent anti-tuberculosis therapy. CONCLUSIONS: Even when the results of imaging studies predict spinal metastasis, we should keep in mind the possibility of spinal tuberculosis.

Lumbar Cryptococcal Osteomyelitis Mimicking Metastatic Tumor

Cryptococcus is an encapsulated, yeast-like fungus that rarely causes infection in immunocompetent patients. We present the case report of a 66-year-old female patient with a history of rectal cancer with an isolated lumbar vertebral cryptococcosis proven by biopsy performed during operation. The patient was not an immunocompromised host and did not have any other risk factors except the history of cured rectal cancer. The presumptive diagnosis based on imaging studies was metastatic spine cancer, so operation was performed. However, cryptococcal osteomyelitis was diagnosed in the pathologic examination. This case report emphasizes that we should be aware that lumbar cryptococcosis can be a rare cause of mimicking lesions with metastatic cancer.

Causes and Clinical Manifestations of Cauda Equina Syndrome

STUDY DESIGN: A literature review. OBJECTIVES: To describe the causes and clinical characteristics of cauda equina syndrome. SUMMARY OF LITERATURE REVIEW: The cauda equina syndrome, complex symptoms and signs expressed as variable clinical manifestation, has rare incidence but needs attention since it can bring about serious complications and sequales if neglected. MATERIALS AND METHODS: The Author reviewed articles reporting the causes and clinical manifestation of cauda equina syndrome. RESULTS: There are marked inconsistencies in the current evidence base surrounding the definition due to various clinical presentation of cauda equina syndrome. CONCLUSION: As there is no symptom or sign which has an absolute diagnostic value in establishing the diagnosis of cauda equina syndrome, any patient in whom a clinical suspicion of cauda equina syndrome arises must undergo urgent magnetic resonance imaging for diagnosis.

Fusion Rates of Instrumented Lumbar Spinal Arthrodesis according to Surgical Approach: A Systematic Review of Randomized Trials

BACKGROUND: Lumbar spine fusion rates can vary according to the surgical technique. Although many studies on spinal fusion have been conducted and reported, the heterogeneity of the study designs and data handling make it difficult to identify which approach yields the highest fusion rate. This paper reviews studies that compared the lumbosacral fusion rates achieved with different surgical techniques. METHODS: Relevant randomized trials comparing the fusion rates of different surgical approaches for instrumented lumbosacral spinal fusion surgery were identified through highly sensitive and targeted keyword search strategies. A methodological quality assessment was performed according to the checklist suggested by the Cochrane Collaboration Back Review Group. Qualitative analysis was performed. RESULTS: A literature search identified six randomized controlled trials (RCTs) comparing the fusion rates of different surgical approaches. One trial compared anterior lumbar interbody fusion (ALIF) plus adjunctive posterior transpedicular instrumentation with circumferential fusion and posterolateral fusion (PLF) with posterior lumbar interbody fusion (PLIF). Three studies compared PLF with circumferential fusion. One study compared three fusion approaches: PLF, PLIF and circumferential fusion. CONCLUSIONS: One low quality RCT reported no difference in fusion rate between ALIF with posterior transpedicular instrumentation and circumferential fusion, and PLIF and circumferential fusion. There is moderate evidence suggesting no difference in fusion rate between PLF and PLIF. The evidence on the fusion rate of circumferential fusion compared to PLF from qualitative analysis was conflicting. However, no general conclusion could be made due to the scarcity of data, heterogeneity of the trials included, and some methodological defects of the six studies reviewed.

Prevalence And Risk Factor of Degenerative Disease of Adjacent Segment after Anterior Cervical Arthrodesis

STUDY DESIGN: A retrospective radiologic and clinical analysis of 48 patients following anterior cervical fusion. OBJECTIVES: To examine the prevalence of symptomatic adjacent segment disease after anterior cervical fusion and determine the risk factors affecting its progression. SUMMARY OF LITERATURE REVIEW: Symptomatic adjacent segment disease appears to occur at a rate of 2% to 3% per year. MATERIALS AND METHODS: Forty-eight patients, who were followed up for more than 3 years after anterior cervical arthrodesis, were enrolled in this study. A modification of the Robinson criteria was used for the clinical evaluation and the radiographic grading of Hilibrand was used for the radiology evaluation. Kaplan-Meier survival analysis was used to examine the survival rate. Age, gender, number of fusion segments, preoperative ROM, angle of lordosis, spinal canal diameter and radiologic degeneration of adjacent segments were selected as potential risk factors. The subjects were divided into two groups according to their clinical symptoms. RESULTS: Symptomatic adjacent segment disease developed in 11 of the 48 patients(22.9%). The disease free survival rates were 88.7%, 82.4% and 58.7% at 5, 10 and 15 years, respectively. A study of the risk factors showed that preoperative degenerative changes and narrow spinal canal in the adjacent segments were significant. However, there were no significant associations with age, gender, number of fusion segments, preoperative ROM and angle of lordosis. CONCLUSION: The prevalence of symptomatic adjacent segment disease after anterior cervical fusion was considerable and higher when the patients had preoperative degenerative changes and a narrow spinal canal in the adjacent segments.

CT guided Epidural Steroid Injection / 신경중재치료의학

PURPOSE: CT guided epidural steroid injection (ESI) is not commonly used for the management of lumbar pain in Korea. Therefore, we evaluated a short term improvement as defined by the scale of pain after CT guided ESI. MATERIALS AND METHODS: We prospectively followed 29 consecutive patients (average age, 62 years; range, 38-78 years; 10 men, 19 women) with lumbar radiculopathy for a minimal follow-up period of 1 month. The intensity of radicular pain was scored by the patient on the visual analog scan (VAS), from 0 (no pain) to 10 (maximal intensity). Scores before and after the procedure were compared by using the Wilcoxon signed-rank test for paired values. Pain relief was classified as "0" when the pain was completely resolved or had diminished, "1" for not changing, "2" for an increase in pain. RESULTS: The mean VAS scores were 8 (range, 2-10) before and 5 (range, 1-10) 1 month after the procedure, with significant pain relief (p < .001). Pain relief was divided as 0 in 21 patients (72%), 1 in 8 patients (28%) without anyone of grade 2. There was no procedure-related complication except one patient with temporary left side weakness and sensory change which lasted 1-2 hours and subsided thereafter propably due to temporary route compression caused by previous postoperative adhesion or inadvertent intrathecal injection. CONCLUSION: Good pain relief can be expected after CT guided ESI. CT guided ESI may have some difficulties in postoperative patient with metal devices or adhesion.

Change of Deformity due to Position and Anesthesia in Adolescent Idiopathic Scoliosis / 대한정형외과학회잡지

PURPOSE: To determine changes in the end vertebra and neutral vertebra as well as in the magnitudes of coronal and rotational deformities according to position and anesthesia in patients with adolescent idiopathic scoliosis. MATERIALS AND METHODS: Sixty-two structural curves in 31 patients were evaluated using standing, supine, side bending, post-anesthesia, and postoperative anteroposterior plain radiographs. Cobb angles and rotation angles by perdriolle torsionmeter were measured, and the end vertebra and neutral vertebra were identified in each radiograph. RESULTS: Coronal cobb angles decreased significantly with correction rates of 25.0%, 31.7%, 59.5%, and 74.0%, and rotational deformities decreased with correction ratesof 6.1%, 24.5%, 6.2%, and 25.7% by supine position, anesthesia, side bending and surgery, respectively.The end vertebrae changed in 18 patients (58.1%) in both supine and post-anesthesia radiographs, and the neutral vertebrae changed in 10 patients (32.3%) in supine radiographs and in 20 patients (64.5%) in post-anesthesia radiographs. CONCLUSION: Coronal deformities are significantly corrected by supine position and anesthesia. Anesthesia significantly corrects axial rotation, but more correction cannot be achieved by rod derotation. The end vertebra and neutral vertebra have a tendency to vary by position and anesthesia, which gives rise to confusion in the determination of fusion level.

Early-Onset Facioscapulohumeral Muscular Dystrophy: Significance of Pelvic Extensor in Sagittal Spinal Imbalance / 대한정형외과학회잡지

An 11-year-old girl with early-onset facioscapulohumeral muscular dystrophy (FSHD) presented with progressive gait disturbance and lumbar hyperlordosis. The motor power of her pelvic extensor muscles was grade 3. Pelvic tilt and hip flexion were markedly increased as determined by gait analysis. This FSHD case is an impressive example of a patient demonstrating the concept that weak pelvic extensor muscles cannot keep the spine upright and balanced. The most important factor in the development of hyperlordosis is the weakness of the pelvic extensor muscles, and the results of gait analysis exquisitely explain the pathophysiology. The patient stands with her spine hyperextended to maintain upright posture by a compensatory mechanism of relatively strong back extensor muscles. Corrective surgery for lumbar hyperlordosis was not considered as it could eliminate the compensatory lumbar hyperextension, thus making the spine of the patient stoop forward through the hip joint during walking, being caused by the weakness of her pelvic extensor muscles.

Herpes Zoster Confused with Radiculopathy / 대한정형외과학회잡지

PURPOSE: To describe the clinical features of herpes zoster that can be easily misdiagnosed as cervical or lumbar radiculopathy. MATERIALS AND METHODS: We retrospectively reviewed the medical records and diagnostic studies of 7 patients with herpes zoster-related arm or leg pain. RESULTS: Except one immunocompromised patient with suspected postherpetic neuralgia or sequelae of herpetic myelitis, the other 6 patients with herpes zoster complained of very severe initial pain of sudden onset. Three patients did not show skin lesions on initial examination, and 2 of 5 patients with an MRI of the cervical or lumbar spine had findings consistent with their arm or leg pain and may have been confused with radiculopathy. Conservative treatment, including antiviral agents, improved the symptoms of all patients except the immunocompromised one. Selective nerve root blocks of the corresponding dermatomes were performed in 5 patients and extremity pain decreased over 50% in 4 of them. CONCLUSION: Herpes zoster can be confused with radiculopathy in patients with arm or leg pain if the typical skin lesions have not been developed. Unnecessary treatments including surgery should be avoided by early, correct diagnosis through prudent history taking and physical examination.

The Comparison of the Results Between AO Internal Fixator (Long lever-arm) and Screw-Rod System (Short lever-arm) Through Posterior Approach in Unstable Thoracolumbar Fractures / 대한척추외과학회지

STUDY DESIGN: Prospective study. OBJECTIVES: To analyze the outcome of posterior reduction and fixation with the AO internal fixator and with the screw-rod system in unstable thoracolumbar fractures and to investigate differences in effectiveness between the two methods. SUMMARY OF LITERATURE REVIEW: In unstable thoracolumbar fractures, fixation with the AO internal fixator is an effective method for posterior reduction. However, the results of correction are quite variable. MATERIALS AND METHODS: We analyzed 51 patients with unstable thoracolumbar fractures who underwent correction through posterior approach between 1997 and 2003. We divided the patients into two groups: Patients in Group A (25 cases) were treated with the AO internal fixator, and patients in Group B (26 cases) were treated with the screw-rod system. We added transpedicular bone grafts for 17 patients in Group A. We evaluated correction of deformity (anterior and posterior height of vertebral body, sagittal index, disc height), loss of correction, spinal canal clearance, and neurological recovery. RESULTS: Comparing correction of deformity, we saw better results in Group A than in Group B in regards to sagittal index and anterior height of vertebral body. However, we saw a higher degree of correction loss in the anterior height of the vertebral body in Group A. We grafted autogenous bone into the fracture site by transpedicular approach for 17 patients in Group A. We saw less correction loss in the anterior vertebral body height and sagittal index. In regard to spinal canal clearance, we saw better results in Group A (18%) than in Group B (10%). As for neurological recovery, we could not find any statistically significant difference between the two groups. CONCLUSIONS: Through an operative procedure, we could achieve better results in restoration of anterior vertebral height and canal clearance with the AO internal fixator system. Further study is necessary to keep the reduced state of vertebral height.

A Novel Concept for the Best Coronal Alignment of Pedicle Screws in Multilevel Lumbar Posterior Instrumentation - A Technical Note / 대한척추외과학회지

Correct alignment of pedicle screws is imperative in multilevel instrumentation. However, there has been no report addressing the technical aspects of this subject. If the head diameter of a pedicle screw is D, the head height is H, and the convergence angle of the screw being inserted is alpha, then the distance between the extension line of the medial borders of the inserted screw heads and the insertion point of the adjacent screw (A) is described by the following formula: A = 1/2Dcos alpha- Hsin alpha If an L3 pedicle screw (D=13 mm, H=15 mm) is to be inserted with a convergence angle of 14 degrees after the insertion of L4 and L5 screws, its insertion point should be 3.6 mm medial to the extension line of the centers of the L4 and L5 screws and 2.7 mm lateral to the extension line of their medial borders for all screw heads, so it can be aligned in the coronal plane. In order to achieve the best alignment, a pedicle screw is inserted between the extended line of the centers and that of the medial borders of the inserted adjacent screw heads. For the routine range of convergence angles, it is essential to move the entry point medially toward the extended line connecting the medial borders of the inserted adjacent screw heads.