Intra- and extra-capsular ganglia at the gastrocnemius origin and association with meniscal tears and severity of osteoarthritis of the knee joint.

BACKGROUND: The association between size of ganglia or type of ganglia (intra-articular or extra-articular) and meniscal tears or severity of the osteoarthritis (OA) is not evaluated. PURPOSE: To evaluate the prevalence, size, and location of intra- and extra-capsular ganglia at the gastrocnemius origin and to assess their associations with meniscal injury and grades of OA. MATERIAL AND METHODS: This study included 301 consecutive patients who had knee pain and had undergone magnetic resonance imaging (MRI) of the knee. We evaluated presence of ganglia at the gastrocnemius muscle origin site and diagnosed whether it was an intra-capsular located or mixed-capsular located (intra-capsular and extra-capsular) and then measured the diameter of each ganglion. After two weeks, we evaluated whether articular cartilage injury existed. The presence of a meniscal tear was also recorded. RESULTS: A total of 186 patients (93%) had intra- and extra-capsular ganglia. Intra-capsular ganglia were found in 183 cases (91%) and mixed-capsular ganglia were found in 16 cases (8%). In cases with intra- and extra-capsular ganglia, more meniscal tears were found (P = 0.029). Intra-capsular ganglia showed more meniscal tears (P = 0.021). Intra-capsular ganglia were more likely to have high-grade OA (P = 0.043). Patients who had a meniscal tear displayed larger-sized ganglia, especially of the intra-capsular type (P = 0.044). CONCLUSION: Patients with intra- and extra-capsular ganglia, especially of the intra-capsular type, are more likely to have meniscal injury and more severe OA. Patients with a meniscal tear or OA are more likely to have larger intra- and extra-capsular ganglia, especially of the intra-capsular type.

Crowned dens syndrome as a rare cause of anterior neck pain after transurethral resection of the prostate: a case report.

We describe the case of a 79-year-old man who presented with progressive aggravation of severe axial neck pain and fever 3 days after transurethral resection of the prostate (TURP), despite maintaining neutral neck posture during surgery. Laboratory examination revealed markedly elevated C-reactive protein levels and erythrocyte sedimentation rates. Computed tomography revealed crown-like calcifications surrounding the odontoid process. We diagnosed crowned dens syndrome (CDS) as the cause of acute-onset neck pain after TURP. The patient was treated with nonsteroidal anti-inflammatory drugs for 5 days, and his symptoms resolved completely. CDS is a rare disease characterized by calcific deposits around the odontoid process with acute onset of severe neck pain and restricted motion. Evidence of inflammation on serological testing and fever are typical of CDS. However, the prevalence and pathophysiology of CDS remain unclear. We hypothesized that systemic inflammation after prostate surgery may have induced a local inflammatory response involving calcification around the odontoid process.

High reliability and accuracy of dynamic magnetic resonance imaging in the diagnosis of cervical Spondylotic myelopathy: a multicenter study.

BACKGROUND: Cervical spondylotic myelopathy (CSM) is a critical condition that results in significant neurologic deterioration. An accurate diagnosis is essential for determining its outcome and prognosis. The pathology is strongly associated with dynamic factors; therefore, dynamic magnetic resonance (MR) image could be crucial to accurately detect CSM. However, very few studies have evaluated the reliability and accuracy of dynamic MR in CSM. In this study, we aimed to compare intra- and interobserver reliabilities and accuracy of dynamic MR in detecting CSM using sagittal MR scans of the neck in the flexed, neutral, and extended position. METHODS: Out of 131 patients who underwent surgical treatments for CSM, 107 were enrolled in this study. The patient underwent three-types of sagittal MR scans that were obtained separately in different neck positions (neutral, flexion, and extension postures). The MR scans of the cervical spine were evaluated independently by three spine professionals, on the basis of tabled questionnaires. For accuracy, we performed a receiver operator characteristic analysis, and the overall discriminating ability of each method was measured by calculating the area under the ROC curve. The Cohen's kappa coefficient and the Fleiss-generalized kappa coefficient was used to the inter- and intra-observer reliabilities. RESULTS: The intraobserver reliability (using the Cohen's kappa coefficient) and interobserver reliability (using the Fless kappa coefficient) were respectively 0.64 and 0.52 for the neutral sagittal MR. The accuracy of neutral sagittal MR in detecting CSM was 0.735 (95% CI, 0.720 to 0.741) while that of extension sagittal MRI was 0.932 (96% CI, 0.921 to 0.948). CONCLUSIONS: Dynamic MR significantly showed better diagnostic reliability and accuracy in detecting CSM compared to conventional MR. In particular, extension MR scans could provide a more accurate diagnosis than other images.

The Frequency of Axial Deposition in Korean Patients With Gout at a Tertiary Spine Center.

Objectives: This study aimed to describe the frequency of axial deposition (axial gout) and determine the associated factors in patients with gout who presented to a spine clinic in Korea. Methods: We enrolled 95 Korean patients who visited our spine center from March 2012 to February 2016 and who had been previously diagnosed with gout and had available computed tomography (CT) images of the vertebral columns. Axial gout was defined as the presence of erosions or tophi in the vertebral endplate or facet joint. The clinical and laboratory data of these patients were retrieved from medical records. Results: Out of 95 patients, 15 [15.8%; 95% confidence interval (CI), 9.4-25.0%] had a conventional CT evidence suggestive of axial gout. In these 15 patients, 12 (80%) had lumbar spine involvement (95% CI, 51.4-94.7%). Fifteen patients had erosions of the vertebral column, and two presented with tophi that exhibited erosive changes of the facet joints. The presence of axial gout was not associated with the patients' age, duration of gout, laboratory findings, inflammatory back pain symptoms, identification of monosodium urate crystals in the peripheral joints, current use of urate-lowering drugs, hypertension, and end-stage renal disease; however, there was a significant association with the presence of diabetes (P = 0.008). Conclusions: The frequency of axial deposition in Korean patients with gout and spinal symptoms was 15.8%, with the lumbar region being the most commonly involved section of the spine. In addition, diabetes was associated with evidence of axial gout on imaging.

Lumbar Epidural Varix Causing Radicular Pain: A Case Report and Differential Diagnosis of Lumbar Cystic Lesions.

Lumbar epidural varices are a rare cause of radicular pain mimicking lumbar disc herniation or other cyst-like masses including sequestrated disc herniation, facet joint synovial cyst, or perineural cyst. We report a case of a 36-year-old woman presenting with lumbar radicular pain caused by a lumbar epidural varix. Lumbar magnetic resonance imaging (MRI) revealed a cystic lesion in the ventral epidural space posterior to the right L4 body. Surgery was conducted and histopathology confirmed the diagnosis of an epidural varix. Lumbar epidural varices and other lumbar cystic lesions can commonly cause radicular pain. Physicians will benefit from increased awareness of epidural varices as a cause of lumbosacral radicular pain and the associated radiologic findings supporting differential diagnosis. In particular, careful interpretation of MRI scans may help ensure proper diagnosis of an epidural varix versus other cystic lesions. LEVEL OF EVIDENCE: V.

Osteochondroma of the Distal Clavicle: A Rare Cause of Impingement and Biceps Tear of the Shoulder.

Hereditary multiple exostosis (HME) is an autosomal dominant disorder manifested by the presence of multiple osteochondromas. Although the lesions are benign in nature, exostoses are often associated with characteristic progressive skeletal deformity and displaying clinical symptoms such as mechanical irritation or impingement. We present the successful arthroscopic resection in a 24-year-old HME male with impingement syndrome and long head tendon tear of the biceps caused by osteochondroma arising from the distal clavicle.

Analysis of Migration Patterns of Disk Fragments and Contributing Factors in Extruded Lumbar Disk Herniation.

BACKGROUND: The exact location of migrated extruded lumbar disk fragments is an important consideration in selecting a treatment plan. However, few descriptive reports of the migration pattern of extruded lumbar disk fragments are available. OBJECTIVE: To examine the distribution of disk fragments and possible contributing factors that affect their migration. DESIGN: Retrospective descriptive study. SETTING: Tertiary university outpatient and inpatient clinic. PATIENTS: A total of 164 patients diagnosed with a symptomatic extruded lumbar disk from January 2011 to December 2012. METHODS: Lumbar spine magnetic resonance imaging scans of patients were retrospectively reviewed. The term "migration" was defined as the horizontal and vertical displacement of extruded material away from the opening in the annulus through which the material has extruded. Migration of the disk material was recorded in both the horizontal and vertical plane. In the horizontal plane, migration was recorded as central, paracentral, subarticular, or foraminal. In the vertical plane, migration was recorded as rostral or caudal. MAIN OUTCOME MEASUREMENTS: The pattern of migration and the associated factors (age and the level of herniation) were analyzed. RESULTS: Rostral and caudal migration was observed in 27% (95% confidence interval [CI], 21%-35%) and 73% (95% CI, 66%-79%) of the patients. Central, paracentral, subarticular, and foraminal migration was observed in 6% (95% CI, 3%-11%), 67% (95% CI, 60%-74%), 18% (95% CI, 13%-25%), and 9% (95% CI, 5%-14%) of the patients, respectively. A significant increase was observed in the incidence of rostral migration with increasing age (P = .048). A significant association was also noted between migration in the horizontal plane and increasing age (P = .01). A significant increase occurred in the incidence of foraminal extrusion with increasing age (P = .01). A significant association was found between migration in the vertical plane and horizontal plane; in patients with foraminal herniations, migration was always rostral (P < .001). CONCLUSION: The migration of extruded lumbar disk materials follows some general patterns. The results of this study may help spine interventionists and surgeons choose appropriate treatments for patients who have radiculopathy associated with lumbar disk extrusions. LEVEL OF EVIDENCE: IV.

Does C5 or C6 Radiculopathy Affect the Signal Intensity of the Brachial Plexus on Magnetic Resonance Neurography?

Patients with C5 or C6 radiculopathy complain of shoulder area pain or shoulder girdle weakness. Typical idiopathic neuralgic amyotrophy (INA) is also characterized by severe shoulder pain, followed by paresis of shoulder girdle muscles. Recent studies have demonstrated that magnetic resonance neurography (MRN) of the brachial plexus and magnetic resonance imaging (MRI) of the shoulder in patients with INA show high signal intensity (HSI) or thickening of the brachial plexus and changes in intramuscular denervation of the shoulder girdle. We evaluated the value of brachial plexus MRN and shoulder MRI in four patients with typical C5 or C6 radiculopathy. HSI of the brachial plexus was noted in all patients and intramuscular changes were observed in two patients who had symptoms over 4 weeks. Our results suggest that HSI or thickening of the brachial plexus and changes in intramuscular denervation of the shoulder girdle on MRN and MRI may not be specific for INA.

Radiological Stability after Revision of Infected Total Knee Arthroplasty Using Modular Metal Augments.

PURPOSE: To evaluate the radiological stability according to the number of modular augments after revision of infected total knee arthroplasty (TKA). MATERIALS AND METHODS: Between February 2006 and September 2013, 37 patients (39 knees) followed ≥2 years after revision of infected TKA using modular metal augments for bone defects were reviewed retrospectively. We divided the patients into 3 groups according to the number of augments into group A (≤2 augments, 14 knees), group B (3-4 augments, 18 knees), and group C (5≥ augments, 7 knees) and evaluated the width of radiolucent zones around the implant at the last follow-up. RESULTS: There were 3 Anderson Orthopedic Research Institute type I, 33 type II, and 3 type III bone defects. The mean number of radiolucent zones of group A was 3 and the sum of width averaged 4.4 mm. In group B, the values were 4.8 and 6.2 mm, respectively. In group C, the values were 8.1 and 12.9 mm, respectively. The differences between the three groups were statistically significant. CONCLUSIONS: In revision TKA with modular metal augmentation caused by infected TKA, increased modularity can result in radiological instability.

Ultrasound-Guided Percutaneous Removal of Wooden Foreign Bodies in the Extremities with Hydro-Dissection Technique.

OBJECTIVE: We described the technique of ultrasound (US)-guided percutaneous removal of the foreign bodies (FB) with hydro-dissection in the radiologic department and presented video files of several cases. MATERIALS AND METHODS: Four patients referred to the radiology department for US evaluation and US-guided percutaneous removal of the FBs in the upper and lower extremities between November, 2006 and November, 2013 were included in this study. The procedures started with US evaluation for the exact location and shape of the FB. A 5 mm-sized skin incision was made at the site of the nearest point from the FB where no passing arteries or tendons were present. We adopted a hydrodissection technique to separate the FB from adjacent tissue using a 2% lidocaine solution. Injected anesthetics detached the FBs from surrounding tissue and thereby facilitated removal. After the tip of the mosquito forceps reached the FB, the wooden FBs were removed. RESULTS: The mean time required for the entire procedure was approximately 20 minutes. There were no significant complications during the US-guided removal or long-term complications after the procedure. All 4 FBs were successfully removed from the soft tissue under US guidance. CONCLUSION: Ultrasound-guided percutaneous removal of the FBs with hydro-dissection in the radiology department is a less invasive and safe method over surgical removal in the operating room. Additionally, the use of a guide wire and serial dilator may help minimize soft tissue injury and facilitate the introduction of forceps.

Three Different Methods in Deformity Correction of Degenerative Flat Back: A Single Surgeon's Experience with 64 Consecutive Cases.

STUDY DESIGN: Retrospective study. PURPOSE: To evaluate the radiological and clinical results of three different methods in the deformity correction of a degenerative flat back. OVERVIEW OF LITERATURE: There are no comparative studies about different procedures in the treatment of degenerative flat back. METHODS: Sixty-four patients who consecutively underwent corrective surgery for degenerative flat back were reviewed. The operations were performed by three different methods: posterior-only (group P, n=20), one-stage anterior-posterior (group AP, n=12), and two-stage anterior-posterior with iliac screw fixation (group AP-I, n=32). Medical and surgical complications were examined and radiological and clinical results were compared. RESULTS: The majority of medical and surgical complications were found in group AP (5/12) and group P (7/20). The sagittal vertical axes were within normal range immediately postoperatively in all groups, but only group AP-I showed normal sagittal alignment at the final follow-up. Postoperative lumbar lordosis was also significantly higher in group AP-I than in group P or group AP and the finding did not change through the last follow-up. The Oswestry disability index was significantly lower in groups AP and AP-I than in group P at the final follow-up. Meanwhile, the operating time was the longest in group AP-I, and total amount of blood loss was larger in group AP-I and group AP than in group P. CONCLUSIONS: Anterior-posterior correction showed better clinical results than posterior-only correction. Two-staged anterior-posterior correction with iliac screw fixation showed better radiological results than posterior-only or one-staged anterior-posterior correction. Two-staged anterior-posterior correction with iliac screw fixation also showed a lower complication rate than one-staged anterior-posterior correction.

Surgical correction in patients with lumbar degenerative kyphosis who had low bone mineral density: an analysis of 40 patients with a minimum follow-up of two years.

STUDY DESIGN: Retrospective study. PURPOSE: To investigate influence of bone mineral density (BMD) on the surgical correction of lumbar degenerative kyphosis (LDK). OVERVIEW OF LITERATURE: No studies so far have reported the influence of BMD on the surgical correction of LDK. METHODS: Forty LDK patients with more than 2 years follow-up were studied. Pelvic incidence (PI), pelvic tilt, sacral slope, sagittal vertical axis (SVA), lumbar lordosis (LL), and thoracic kyphosis were measured preoperatively, immediate postoperatively and at final follow-up. Adverse outcomes: proximal adjacent fractures, sagittal decompensation, pseudoarthrosis, and cage subsidence were documented. RESULTS: There were 37 females and 3 males. Average age was 65.1±4.5 years and mean follow-up was 34.2±16.7 months. 42.5% were Takemitsu type 3 curves, 27.5% type 2, 20.0% type 4 and 10.0% type 1. 37.5% had osteopenia, 40.0% osteoporosis and 22.5% had severe osteoporosis. SVA improved from 237.0±96.7 mm preoperatively to 45.3±41.8 mm postoperatively (p=0.000). LL improved from 10.5°±14.7° to -40.6°±10.9° postoperatively (p=0.000). At final follow-up SVA deteriorated to 89.8±72.2 mm and LL to 34.7°±15.8° (p=0.000). The association between late sagittal decompensation, pseudoarthrosis, or proximal adjacent fractures and osteoporosis was insignificant. The difference between immediate postoperative LL and PI (PIDiff) had a significant association with sagittal decompensation and pseudoarthrosis. CONCLUSIONS: Osteoporosis did not influence the degree of correction, late sagittal decompensation, proximal adjacent fractures, and pseudoarthrosis in LDK. PIDiff had a significant association with sagittal decompensation and pseudoarthrosis.

Factors determining cervical spine sagittal balance in asymptomatic adults: correlation with spinopelvic balance and thoracic inlet alignment.

BACKGROUND CONTEXT: Based on the previous studies, cervical lordosis (CL) is a parameter influenced by thoracic kyphosis (TK); however, the correlations still remain unclear. Few studies have analyzed the correlations between the cervical spine lordosis and global spinopelvic balance. To date, there has been no study focused on the factors determining cervical spine sagittal balance. PATIENT SAMPLE: Seventy-seven asymptomatic volunteers without the history of symptoms related to whole spine. OUTCOME MEASURES: Statistical significance of correlations of radiographic parameters on cervical spine and whole-spine standing lateral radiograph. PURPOSE: To analyze the factors determining cervical spine sagittal balance, including global spinopelvic balance and thoracic inlet (TI) alignment in asymptomatic adults. STUDY DESIGN: A prospective radiographic study. METHODS: Cervical and whole-spine standing lateral radiographs were taken to analyze the following parameters: spinopelvic parameters pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), and TK; TI parameters thoracic inlet angle (TIA) and T1 slope; and cervical spine parameters C0-C2, C2-C7, and C0-C7 angles and cervical tilting. Statistical analysis was performed using the Pearson correlation coefficients and multiple regression analysis. RESULTS: All the parameters showed a normal distribution. There was a significant sequential linkage between PI and SS (r=0.653), SS and LL (r=0.807), LL and TK (r=-0.516), and TK and C0-C7 angle (r=-0.322). There was a significant relationship between TK and T1 slope (r=0.351) but no significant relationship between TK and TIA. There were significant sequential relationships between TIA and T1 slope (r=0.694), T1 slope and C2-C7 angle (r=-0.624), and C2-C7 and C0-C2 angles (r=-0.547). T1 slope was the only parameter that demonstrated a significant correlation with both SP and TI parameters. A linear regression model showed that T1 slope had a stronger relationship with TIA (r=0.694) than TK (r=0.351). CONCLUSIONS: T1 slope was a key factor determining cervical spine sagittal balance. Both spinopelvic balance and TI alignment have a significant influence on cervical spine sagittal balance via T1 slope, but TIA had a stronger effect than TK. An individual with large T1 slope required large CL to preserve physiologic sagittal balance of the cervical spine. The results of the present study could serve as baseline data for further studies on the cervical spine sagittal balance in various clinical conditions including the surgical reconstruction of lordosis.

Efficacy of intra-articular injection of thrombin-based hemostatic agent in the control of bleeding after primary total knee arthroplasty.

PURPOSE: To evaluate the hemostatic effect of intraarticular injection of a thrombin-based hemostatic agent in total knee arthroplasty (TKA). MATERIALS AND METHODS: We performed a prospective randomized controlled trial on the use of a thrombin-based hemostatic agent in patients undergoing unilateral TKA. A total of 100 TKA patients were enrolled, with 50 patients randomized into the study group and the other 50 patients into the controlled group. Drain output, hemoglobin level, total red blood cell loss for 24 hours after surgery, transfusion rates, and complications were assessed. RESULTS: Postoperative drain output was 525 mL in the study group and 667 mL in the control group (p=0.01). Nine patients in the study group and eighteen in the control group received blood transfusion (p=0.043). But, there was no significant difference between two groups in terms of hemoglobin level change and total red blood cell loss (p>0.05). CONCLUSIONS: The thrombin-based hemostatic agent demonstrated efficacy in reducing drain output and blood transfusion rates. Thus, we believe the use of a thrombin-based hemostatic agent should be considered as an option in orthopedic surgery that involves massive bleeding.

Ipsilateral femoral neck and shaft fracture in children: a report of two cases and a literature review.

Concomitant ipsilateral fractures of the neck and shaft of the femur in children are rare. The most recent report in this context found a total of only nine reported cases (<12 years of age) following a search of the indexed English literature. These injuries occur in children due to high-velocity trauma, and there is no generally accepted method of treatment. We report three additional cases from the literature and two cases of our own. In our cases, one had a residual 10° varus deformity at the subtrochanteric level in the femur, but this did not affect hip function. Another patient exhibited a limp at final follow-up due to leg length discrepancy, and peroneal nerve palsy at the time of injury. We advocate operative stabilization of the femoral shaft fracture first to reduce the risk of further displacement and simplify the subsequent reduction of the femoral neck. The series shows that these rare injuries have a poor prognosis, with high rates of incidence of avascular necrosis, coxa vara, and leg length discrepancy.

Surgical treatment of t1-2 disc herniation with t1 radiculopathy: a case report with review of the literature.

The prevalence of intervertebral disc herniation (IDH) of the thoracic spine is rare compared to the cervical or lumbar spine. In particular, IDH of the upper thoracic spine is extremely rare. We report the case of T1-2 IDH and its treatment, with a literature review. A 37-year-old male patient visited our hospital due to radiating pain at the left upper extremity and weakness of grip power. In cervical spine magnetic resonance images, T1-2 disc space showed herniated disc material and compressed T1 root was identified. Laminoforaminotomy was performed with a posterior approach. The radiating pain and weakness of grip power improved immediately after the surgery. Of patients who show radiating pain or numbness at the medial aspect of forearm, or weakness of intrinsic muscle of hand, can be suspected to have T1 radiculopathy. A detailed physical examination and a radiologic evaluation including this area should be required for the T1 radiculopathy.

Indirect reduction of the radial head in children with chronic Monteggia lesions.

OBJECTIVE: The purpose of this study was to report the long-term follow-up results of chronic Monteggia fractures treated with angulation-translation osteotomy of ulna and closed reduction of the radial head. DESIGN: Retrospective. SETTING: Level 1 trauma center. PATIENTS: We retrospectively reviewed 10 missed Monteggia fractures in children. The mean age of the patients was 7.5 years (range, 6-10 years), and there were 2 girls and 8 boys. The mean duration of time between initial injury and initial presentation was 1.7 years (range, 6 weeks to 5 years). INTERVENTION: Closed reduction with ulna osteotomy or lengthening was performed in all 10 cases. Annular ligament reconstruction (ALR) was done in 2 cases. Final follow-up ranged from 3 to 20 years (mean 10 years). MAIN OUTCOME MEASUREMENT: We assessed preoperative and postoperative radiographs to evaluate the quality of the radial head reduction. Clinical results were assessed according to the functional elbow score devised by Kim et al. RESULTS: Radial head reduction was achieved and maintained in 8 of 10 cases after primary or secondary surgery. The radial head was mildly subluxated in one case and dislocated in another case at final follow-up. ALR was performed in only 2 cases. Open reduction and ALR is not required in every case, and its need should depend on intraoperative stability of radial head.

Surgical treatment of "chin-on-pubis" deformity in a patient with ankylosing spondylitis: a case report of consecutive cervical, thoracic, and lumbar corrective osteotomies.

STUDY DESIGN: A case report. OBJECTIVE: To report the successful consecutive spinal osteotomies of multiple segments performed on a patient with extremely severe kyphotic deformity. SUMMARY OF BACKGROUND DATA: There have been no reports on the experience and surgical strategy of spinal osteotomy on multiple segments for severe global spine deformity. METHODS: A 48-year-old man, a patient with ankylosing spondylitis with "chin-on-pubis" deformity, underwent consecutive spinal osteotomies to correct the severe, fixed global kyphosis. The axial skeletons from the skull, all vertebrae, and both sacroiliac joints and hip joint were fused into a single bone. After both hip resectional arthroplasties for the first step, staged, sequential spinal osteotomies, including pedicle subtraction osteotomy (PSO) on C6, posterior vertebral column resection on T11-T12, and PSO on L3, were performed. Finally, both total hip arthoroplasties were performed. RESULTS: The chin-brow vertical angle improved from 140° to 15°. Correction angles of 45°, 70°, and 30° in the cervical, thoracic, and lumbar spines, respectively, were achieved without complication. At the last follow-up, excellent improvement in activities of daily living and horizontal gaze were achieved. CONCLUSION: This is the first report on C6 PSO and spinal osteotomies in whole spine segments. For patients with a severe global kyphotic deformity, it is important to place the patient in a stable prone position so that corrective surgery can be performed on the thoracolumbar spine. To accomplish this, initially correcting the deformities in the hip joints and the cervical spine can yield excellent clinical results.

Assessment of pedicle perforation by the cervical pedicle screw placement using plain radiographs: a comparison with computed tomography.

STUDY DESIGN: A retrospective study. OBJECTIVE: To suggest methods for detecting pedicle perforation on the basis of cervical pedicle screw (CPS) position on plain radiographs. SUMMARY OF BACKGROUND DATA: No studies have reported correlations between CPS position and pedicle perforation as observed on plain radiographs. This study was performed under the assumption that the detection of pedicle perforation would help to minimize the risks of neurovascular injury and help to obtain stable fixation. METHODS: A total of 48 subjects (with 205 screws) who had undergone CPS placement from C3 to C7 were enrolled in this study. To evaluate CPS position, the positions of the screw heads (neutral; the lateral margin of lateral mass cross the polyaxial screw head core, medial, or lateral) and tips (medial to uncovertebral joint [UVJ], within UVJ, or lateral to UVJ) on anteroposterior (AP) radiographs were analyzed. On the postoperative computed tomography, we analyzed the grade of pedicle perforation (grade 0: no PF; 1: < 25%; 2: 20%-50%; 3: > 50% of the screw diameter violation). Grades 0 and 1 were considered to be the correct position. RESULTS: Correct positioning was found for 174 screws (84.9%), and incorrect positioning was found for 31 screws (15.1%). The screw head was placed in a neutral position for 182 screws (88.8%), in the lateral position for 15 screws (7.3%), and in the medial position for 8 screws (3.9%). Of the 182 screws whose heads were in neutral position, 151 (83%) screws whose tips were located medial to the UVJ area were correctly positioned (sensitivity 0.89, specificity 1.0). A significant correlation was observed between the position of the screw tip and the grade of pedicle perforation (P = 0.000). CONCLUSION: A screw with a head that is located in a neutral position and a tip that is placed medial to the UVJ area on plain radiographs is considered to be in the safest position. A tip positioned lateral to the UVJ area or a head located out of the neutral position is expected to increase the risk of perforation. The use of intraoperative radiographs during CPS placement will help to identify the screws that are expected to cause pedicle perforation and allow the appropriate corrections to be made.