Posterior Atalntoaxial Fusion with C1 Lateral Mass Screw and C2 Pedicle Screw Supplemented with Miniplate Fixation for Interlaminar Fusion : A Preliminary Report

Objective

To investigate the feasibility of C1 lateral mass screw and C2 pedicle screw with polyaxial screw and rod system supplemented with miniplate for interlaminar fusion to treat various atlantoaxial instabilities.

Methods

After posterior atlantoaxial fixation with lateral mass screw in the atlas and pedicle screw in the axis, we used 2 miniplates to fixate interlaminar iliac bone graft instead of sublaminar wiring. We performed this procedure in thirteen patients who had atlantoaxial instabilities and retrospectively evaluated the bone fusion rate and complications.

Results

By using this method, we have achieved excellent bone fusion comparing with the result of other methods without any complications related to this procedure.

Conclusion

C1 lateral mass screw and C2 pedicle screw with polyaxial screw and rod system supplemented with miniplate for interlaminar fusion may be an efficient alternative method to treat various atlantoaxial instabilities.     

Inferolateral Entry Point for C2 Pedicle Screw Fixation in High Cervical Lesions

Objective

The purpose of this retrospective study was to evaluate the efficacy and safety of atlantoaxial stabilization using a new entry point for C2 pedicle screw fixation.

Methods

Data were collected from 44 patients undergoing posterior C1 lateral mass screw and C2 screw fixation. The 20 cases were approached by the Harms entry point, 21 by the inferolateral point, and three by pars screw. The new inferolateral entry point of the C2 pedicle was located about 3-5 mm medial to the lateral border of the C2 lateral mass and 5-7 mm superior to the inferior border of the C2-3 facet joint. The screw was inserted at an angle 30° to 45° toward the midline in the transverse plane and 40° to 50° cephalad in the sagittal plane. Patients received followed-up with clinical examinations, radiographs and/or CT scans.

Results

There were 28 males and 16 females. No neurological deterioration or vertebral artery injuries were observed. Five cases showed malpositioned screws (2.84%), with four of the screws showing cortical breaches of the transverse foramen. There were no clinical consequences for these five patients. One screw in the C1 lateral mass had a medial cortical breach. None of the screws were malpositioned in patients treated using the new entry point. There was a significant relationship between two group (p=0.036).

Conclusion

Posterior C1-2 screw fixation can be performed safely using the new inferolateral entry point for C2 pedicle screw fixation for the treatment of high cervical lesions.     

Clinical Outcome of Modified Cervical Lateral Mass Screw Fixation Technique

Objective

The purpose of this study was 1) to analyze clinically-executed cervical lateral mass screw fixation by the Kim''s technique as suggested in the previous morphometric and cadaveric study and 2) to examine various complications and bicortical purchase that are important for b-one fusion.

Methods

A retrospective study was done on the charts, operative records, radiographs, and clinical follow up of thirty-nine patients. One hundred and seventy-eight lateral mass screws were analyzed. The spinal nerve injury, violation of the facet joint, vertebral artery injury, and the bicortical purchases were examined at each lateral mass.

Results

All thirty-nine patients received instrumentations with poly axial screws and rod systems, in which one hundred and seventy-eight screws in total. No vertebral artery injury or nerve root injury were observed. Sixteen facet joint violations were observed (9.0%). Bicortical purchases were achieved on one hundred and fifty-six (87.6%). Bone fusion was achieved in all patients.

Conclusion

The advantages of the Kim''s technique are that it is performed by using given anatomical structures and that the complication rate is as low as those of other known techniques. The Kim''s technique can be performed easily and safely without fluoroscopic assistance for the treatment of many cervical diseases.     

The Clinical Experience of Computed Tomographic-Guided Navigation System in C1-2 Spine Instrumentation Surgery

Objective

To identify the accuracy and efficiency of the computed tomographic (CT)-based navigation system on upper cervical instrumentation, particularly C1 lateral mass and C2 pedicle screw fixation compared to previous reports.

Methods

Between May 2005 and March 2014, 25 patients underwent upper cervical instrumentation via a CT-based navigation system. Seven patients were excluded, while 18 patients were involved. There were 13 males and five females; resulting in four degenerative cervical diseases and 14 trauma cases. A CT-based navigation system and lateral fluoroscopy were used during the screw instrumentation procedure. Among the 58 screws inserted as C1-2 screws fixation, their precise positions were evaluated by postoperative CT scans and classified into three categories : in-pedicle, non-critical breach, and critical breach.

Results

Postoperatively, the precise positions of the C1-2 screws fixation were 81.1% (47/58), and 8.6% (5/58) were of non-critical breach, while 10.3% (6/58) were of critical breach. Most (5/6, 83.3%) of the critical breaches and all of non-critical breaches were observed in the C2 pedicle screws and there was only one case of a critical breach among the C1 lateral mass screws. There were three complications (two vertebral artery occlusions and a deep wound infection), but no postoperative instrument-related neurological deteriorations were seen, even in the critical breach cases.

Conclusion

Although CT-based navigation systems can result in a more precise procedure, there are still some problems at the upper cervical spine levels, where the anatomy is highly variable. Even though there were no catastrophic complications, more experience are needed for safer procedure.     

Analysis of Measurement Accuracy for Craniovertebral Junction Pathology : Most Reliable Method for Cephalometric Analysis

Objective

This study was designed to determine the most reliable cephalometric measurement technique in the normal population and patients with basilar invagination (BI).

Methods

Twenty-two lateral radiographs of BI patients and 25 lateral cervical radiographs of the age, sex-matched normal population were selected and measured on two separate occasions by three spine surgeons using six different measurements. Statistical analysis including intraclass correlation coefficient (ICC) was carried out using the SPSS software (V. 12.0).

Results

Redlund-Johnell and Modified (M)-Ranawat had a highest ICC score in both the normal and BI groups in the inter-observer study. The M-Ranawat method (0.83) had a highest ICC score in the normal group, and the Redlund-Johenll method (0.80) had a highest ICC score in the BI group in the intra-observer test. The McGregor line had a lowest ICC score and a poor ICC grade in both groups in the intra-observer study. Generally, the measurement method using the odontoid process did not produce consistent results due to inter and intra-observer differences in determining the position of the odontoid tip. Opisthion and caudal point of the occipital midline curve are somewhat ambiguous landmarks, which induce variable ICC scores.

Conclusion

On the contrary to other studies, Ranawat method had a lower ICC score in the inter-observer study. C2 end-plate and C1 arch can be the most reliable anatomical landmarks.     

T1 Slope and Cervical Sagittal Alignment on Cervical CT Radiographs of Asymptomatic Persons

Objective

We performed a retrospective analysis of medical records and radiographic images of patients who never underwent spinal treatment including diagnosis. The objective of this study is to explain the biomechanical and physiologic characteristics of cervical alignment related to thoracic inlet angle including T1 slope changes in each individual.

Methods

We reviewed the cervical CT radiographs of 80 patients who visited ENT outpatient clinic without any symptom, diagnosis and treatment of cervical spine from January 2011 to September 2012. All targeted people were randomized without any prejudice. We assessed the data-T1 slope, Cobb''s angle C2-7, neck tilt, sagittal vertical axis (SVA) C2-7 and thoracic inlet angle by the CT radiographs.

Results

The relationships between each value were analyzed and we concluded that Cobb''s angle C2-7 gets higher as the T1 slope gets higher, while the SVA C2-7 value decreases.

Conclusion

We propose that the T1 slope is background information in deciding how much angle can be made in the cervical spinal angle of surgical lordotic curvature, especially severe cervical deformity.     

Cervical Pedicle Screw Insertion Using the Technique with Direct Exposure of the Pedicle by Laminoforaminotomy

Objective

To present the accuracy and safety of cervical pedicle screw insertion using the technique with direct exposure of the pedicle by laminoforaminotomy.

Methods

We retrospectively reviewed 12 consecutive patients. A total of 104 subaxial cervical pedicle screws in 12 patients had been inserted. We also assessed the clinical and radiological outcomes and analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1: <25%, 2: 20% to 50%, 3: >50% of screw diameter) on the postoperative vascular-enhanced computed tomography scans. Grade 2 and 3 were considered as incorrect position.

Results

The correct position was found in 95 screws (91.3%); grade 0-75 screws, grade 1-20 screws and the incorrect position in 9 screws (8.7%); grade 2-6 screws, grade 3-3 screws. There was no neurovascular complication related with cervical pedicle screw insertion.

Conclusion

This technique (technique with direct exposure of the pedicle by laminoforaminotomy) could be considered relatively safe and easy method to insert cervical pedicle screw.     

Comparative Analysis of Three Different Cervical Lateral Mass Screw Fixation Techniques by Complications and Bicortical Purchase : Cadaveric Study

Objective

The purpose of this study is to compare the incidence of possible complications of cervical lateral screw fixation and the achievements of bicortical purchase using the Roy-Camille, Magerl and the modified methods.

Methods

Six fresh-frozen cervical spine segments were harvested. The Roy-Camille technique was applied to C3 and C4, and the Magerl technique was applied to C5, C6, and C7 of one side of each cadaver. The modified technique was applied to the other side of each cadaver. The nerve root injury, violation of the facet joint, vertebral artery injury, and the bicortication were examined at each screwing level.

Results

No vertebral artery injury was observed in any of the three methods. One nerve root injury was observed in each cervical spine segment using the Roy-Camille method (8.3%), the Magerl method (5.6%), and the modified method (3.3%). Facet joint injuries were observed in two cervical spinal segments using the Roy-Camille method (16.7%) and three with the Magerl method (16.7%), while five facet joint violations occurred when using the modified method (16.7%). Bicortical purchases were achieved on ten cervical spinal segments with the Roy-Camille method (83.3%) and Magerl method (55.6%), while twenty bicortical purchases were achieved in the modified method (66.7%).

Conclusion

The advantages of the modified method are that it is performed by using given anatomical structures and that the complication rate is as low as those of other known methods. This modified method can be performed easily and safely without fluoroscopic assistance for the treatment of many cervical diseases.     

Posterior Cervical Fixation with a Nitinol Shape Memory Loop for Primary Surgical Stabilization of Atlantoaxial Instability: A Preliminary Report

Objective

To evaluate a new posterior atlantoaxial fixation technique using a nitinol shape memory loop as a simple method that avoids the risk of vertebral artery or nerve injury.

Methods

We retrospectively evaluated 14 patients with atlantoaxial instability who had undergone posterior C1-2 fusion using a nitinol shape memory loop. The success of fusion was determined clinically and radiologically. We reviewed patients'' neurologic outcomes, neck disability index (NDI), solid bone fusion on cervical spine films, changes in posterior atlantodental interval (PADI), and surgical complications.

Results

Solid bone fusion was documented radiologically in all cases, and PADI increased after surgery (p<0.05). All patients remained neurologically intact and showed improvement in NDI score (p<0.05). There were no surgical complications such as neural tissue or vertebral artery injury or instrument failure in the follow-up period.

Conclusion

Posterior C1-2 fixation with a nitinol shape memory loop is a simple, less technically demanding method compared to the conventional technique and may avoid the instrument-related complications of posterior C1-2 screw and rod fixation. We introduce this technique as one of the treatment options for atlantoaxial instability.     

Comparative Analysis of Cervical Lateral Mass Screw Insertion among Three Techniques in the Korean Population by Quantitative Measurements with Reformatted 2D CT Scan Images: Clinical Research

Objective

Our purpose of this study is to compare insertion angles and screw lengths from Roy-Camille, Magerl, and our designed method for cervical lateral mass screw fixation in the Korean population by quantitative measurement of reformatted two dimensional (2D) computed tomography (CT) images.

Methods

We selected thirty Korean patients who were evaluated with thin section CT scans and reconstruction program to obtain reformatted 2D-CT images of the transversal plane passing the cranio-caudal angle using three different techniques. We measured the minimum angle to avoid vertebral artery (VA) injury, the ideal angle and depth for bicortical screwing of cervical lateral mass. Morphometric measurements of the lateral masses from C3-C7 were also taken.

Results

In all three techniques, the mean safety angles from the VA were less than 8 degrees and the necessary depth of the screw was about 14 mm for safety to the VA and for the bicortical purchase. In our designed technique, the mean β angles of each level from C3 to C7 were 29.0, 29.8, 29.5, 26.3, and 23.9 degrees, respectively.

Conclusion

Results of this study and data from the literature indicate that differences may exist between the Korean and Western people in the length and angle for ideal lateral mass screw fixation. In addition, our technique needs further cadaveric and clinical study for safety and efficacy for being performed as alternative method for cervical lateral mass fixation.     

The Incidence and Clinical Implications of Congenital Defects of Atlantal Arch

Objective

Atlantal arch defects are rare. Few cadaveric and imaging studies have been reported on the variations of such anomalies. Our goal in this study was to examine the incidence and review the clinical implications of this anomaly.

Methods

A retrospective review of 1,153 neck or cervical spine computed tomography (CT) scans was performed to identify patients with atlantal arch defects. Neck CT scans were performed in 650 patients and cervical spine CT scans were performed in 503 patients. Posterior arch defects of the atlas were grouped in accordance with the classification of Currarino et al. In patients exhibiting this anomaly, special attention was given to defining associated anomalies and neurological findings.

Results

Atlantal arch defects were found in 11 (11/1153, 0.95%) of the 1,153 patients. The type A posterior arch defect was found in nine patients and the type B posterior arch defect was found in two patients. No type C, D, or E defects were observed. One patient with a type A posterior arch defect had an anterior atlantal-arch midline cleft (1/1153, 0.087%). Associated cervical spine anomalies observed included one C_6-7 fusion and two atlantal assimilations. None of the reviewed patients had neurological deficits because of atlantal arch anomalies.

Conclusion

Most congenital anomalies of the atlantal arch are found incidentally during investigation of neck mass, neck pain, radiculopathy, and after trauma.     

Morphometric Study of the Nerve Roots Around the Lateral Mass for Posterior Foraminotomy

Objective

Morphometric data on dorsal cervical anatomy were examined in an effort to protect the nerve root near the lateral mass during posterior foraminotomy.

Methods

Using 25 adult formalin-fixed cadaveric cervical spines, measurements were taken at the lateral mass from C3 to C7 via a total laminectomy and a medial one-half facetectomy. The morphometric relationship between the nerve roots and structures of the lateral mass was investigated. Results from both genders were compared.

Results

Following the total laminectomy, from C3 to C7, the mean of the vertical distance from the medial point of the facet (MPF) of the lateral mass to the axilla of the root origin was 3.2-4.7 mm. The whole length of the exposed root had a mean of 4.2-5.8 mm. Following a medial one-half facetectomy, from C3 to C7, the mean of the vertical distance to the axilla of the root origin was 2.1-3.4 mm, based on the MPF. Mean vertical distances from the MPF to the medial point of the root that crossed the inferior margin of the intervertebral disc were 1.2-2.7 mm. The mean distance of the exposed root was 8.2-9.0 mm, and the mean angle between the dura and the nerve root was significantly different between males and females, at 53.4-68.4°.

Conclusion

These data will aid in reducing root injuries during posterior cervical foraminotomy.     

Subsidence of Cylindrical Cage (AMSLU? Cage) : Postoperative 1 Year Follow-up of the Cervical Anterior Interbody Fusion

Objective

There are numerous reports on the primary stabilizing effects of the different cervical cages for cervical radiculopathy. But, little is known about the subsidence which may be clinical problem postoperatively. The goal of this study is to evaluate subsidence of cage and investigate the correlation between radiologic subsidence and clinical outcome.

Methods

To assess possible subsidence, the authors investigated clinical and radiological results of the one-hundred patients who underwent anterior cervical fusion by using AMSLU™ cage during the period between January 2003 and June 2005. Preoperative and postoperative lateral radiographs were measured for height of intervertebral disc space where cages were placed. Intervertebral disc space was measured by dividing the sum of anterior, posterior, and midpoint interbody distance by 3. Follow-up time was 6 to 12 months. Subsidence was defined as any change in at least one of our parameters of at least 3 mm.

Results

Subsidence was found in 22 patients (22%). The mean value of subsidence was 2.21 mm, and mean subsidence rate was 22%. There were no cases of the clinical status deterioration during the follow-up period. No posterior or anterior migration was observed.

Conclusion

The phenomenon of subsidence is seen in substantial number of patients. Nevertheless, clinical and radiological results of the surgery were favorable. An excessive subsidence may result in hardware failure. Endplate preservation may enables us to control subsidence and reduce the number of complications.     

Surgical Treatment of Craniovertebral Junction Instability : Clinical Outcomes and Effectiveness in Personal Experience

Objective

Craniovertebral junction (CVJ) consists of the occipital bone that surrounds the foramen magnum, the atlas and the axis vertebrae. The mortality and morbidity is high for irreducible CVJ lesion with cervico-medullary compression. In a clinical retrospective study, the authors reviewed clinical and radiographic results of occipitocervical fusion using a various methods in 32 patients with CVJ instability.

Methods

Thirty-two CVJ lesions (18 male and 14 female) were treated in our department for 12 years. Instability resulted from trauma (14 cases), rheumatoid arthritis (8 cases), assimilation of atlas (4 cases), tumor (2 cases), basilar invagination (2 cases) and miscellaneous (2 cases). Thirty-two patients were internally fixed with 7 anterior and posterior decompression with occipitocervical fusion, 15 posterior decompression and occipitocervical fusion with wire-rod, 5 C1-2 transarticular screw fixation, and 5 C1 lateral mass-C2 transpedicular screw. Outcome (mean follow-up period, 38 months) was based on clinical and radiographic review. The clinical outcome was assessed by Japanese Orthopedic Association (JOA) score.

Results

Nine neurologically intact patients remained same after surgery. Among 23 patients with cervical myelopathy, clinical improvement was noted in 18 cases (78.3%). One patient died 2 months after the surgery because of pneumonia and sepsis. Fusion was achieved in 27 patients (93%) at last follow-up. No patient developed evidence of new, recurrent, or progressive instability.

Conclusion

The authors conclude that early occipitocervical fusion to be recommended in case of reducible CVJ lesion and the appropriate decompression and occipitocervical fusion are recommended in case of irreducible craniovertebral junction lesion.     

C7 Posterior Fixation Using Intralaminar Screws : Early Clinical and Radiographic Outcome

Objective

The use of segmental instrumentation technique using pedicle screw has been increasingly popular in recent years owing to its biomechanical stability. Recently, intralaminar screws have been used as a potentially safer alternative to traditional fusion constructs involving fixation of C2 and the cervicothoracic junction including C7. However, to date, there have been few clinical series of C7 laminar screw fixation in the literature. Thus, the purpose of this study is to report our clinical experiences using C7 laminar screw and the early clinical outcome of this rather new fixation technique.

Methods

Thirteen patients underwent C7 intralaminar fixation to treat lesions from trauma or degenerative disease. Seventeen intralaminar screws were placed at C7. The patients were assessed both clinically and radiographically with postoperative computed tomographic scans.

Results

There was no violation of the screw into the spinal canal during the procedure and no neurological worsening or vascular injury from screw placement. The mean clinical and radiographic follow up was about 19 months, at which time there were no cases of screw pull-out, screw fracture or non-union. Complications included two cases of dorsal breech of intralaminar screw and one case of postoperative infection.

Conclusion

Intralaminar screws can be potentially safe alternative technique for C7 fixation. Even though this technique cannot be used in the cases of C7 laminar fracture, large margin of safety and the ease of screw placement create a niche for this technique in the armamentarium of spine surgeons.     

Comparison of Outcomes after Atlantoaxial Fusion with Transarticular Screws and Screw-Rod Constructs

Objective

The purpose of this study was to compare the radiological and neurological outcomes between two atlantoaxial fusion method for atlantoaxial stabilization; C1 lateral mass-C2 pedicle screws (screw-rod constructs, SRC) versus C1-2 transarticular screws (TAS).

Methods

Forty-one patients in whom atlantoaxial instability was treated with atlantoaxial fixation by SRC group (27 patients, from March 2005 to May 2011) or TAS group (14 patients, from May 2000 to December 2005) were retrospectively reviewed. Numeric rating scale (NRS) for pain assessment, Oswestry disability index (ODI), and Frankel grade were also checked for neurological outcome. In radiologic outcome assessment, proper screw position and fusion rate were checked. Perioperative parameters such as blood loss during operation, operation time, and radiation exposure time were also reviewed.

Results

The improvement of NRS and ODI were not different between both groups significantly. Good to excellent response in Frankel grade is shown similarly in both groups. Proper screw position and fusion rate were also observed similarly between two groups. Total bleeding amount during operation is lesser in SRC group than TAS group, but not significantly (p=0.06). Operation time and X-ray exposure time were shorter in SRC group than in TAS group (all p<0.001).

Conclusion

Both TAS and SRC could be selected as safe and effective treatment options for C1-2 instability. But the perioperative result, which is technical demanding and X-ray exposure might be expected better in SRC group compared to TAS group.     

The effect of radiofrequency neurotomy of lower cervical medial branches on cervicogenic headache

Objective

Cervicogenic headache (CGH) is known to be mainly related with upper cervical problems. In this study, the effect of radiofrequency neurotomy (RFN) for lower cervical (C4-7) medial branches on CGH was evaluated.

Methods

Eleven patients with neck pain and headache, who were treated with lower cervical RFN due to supposed lower cervical zygapophysial joint pain without symptomatic intervertebral disc problem or stenosis, were enrolled in this study. CGH was diagnosed according to the diagnostic criteria of the cervicogenic headache international study group. Visual analogue scale (VAS) score and degree of VAS improvement (VASi) (%) were checked for evaluation of the effect of lower cervical RFN on CGH.

Results

The VAS score at 6 months after RFN was 2.7±1.3, which were significantly decreased comparing to the VAS score before RFN, 8.1±1.1 (p<0.001). The VASi at 6 months after RFN was 63.8±17.1%. There was no serious complication.

Conclusion

Our data suggest that lower cervical disorders can play a role in the genesis of headache in addition to the upper cervical disorders or independently.     

The Clinical Significance of Ossification of Ligamentum Nuchae in Simple Lateral Radiograph : A Correlation with Cervical Ossification of Posterior Longitudinal Ligament

Objective

Ossification of the ligamentum nuchae (OLN) is usually asymptomatic and incidentally observed in cervical lateral radiographs. Previous literatures reported the correlation between OLN and cervical spondylosis. The purpose of this study was to elucidate the clinical significance of OLN with relation to cervical ossification of posterior longitudinal ligament (OPLL).

Methods

We retrospectively compared the prevalence of OPLL in 105 patients with OLN and without OLN and compared the prevalence of OLN in 105 patients with OPLL and without OPLL. We also analyzed the relationship between the morphology of OLN and involved OPLL level. The OPLL level was classified as short (1-3) or long (4-6), and the morphologic subtype of OLN was categorized as round, rod, or segmented.

Results

The prevalence of OPLL was significantly higher in the patients with OLN (64.7%) than without OLN (16.1%) (p=0.0001). And the prevalence of OLN was also higher in the patients with OPLL (54.2%) than without OPLL (29.5%) (p=0.0002). In patients with round type OLN, 5 of 26 (19.2%) showed long level OPLL, while in patients with larger type (rod and segmented) OLN, 22 of 42 (52.3%) showed long level OPLL (p=0.01).

Conclusion

There was significant relationship between OLN and OPLL prevalence. This correlation indicates that there might be common systemic causes as well as mechanical causes in the formation of OPLL and OLN. The incidentally detected OLN in cervical lateral radiograph, especially larger type, might be helpful to predict the possibility of cervical OPLL.     

Unilateral C1 Lateral Mass and C2 Pedicle Screw Fixation for Atlantoaxial Instability in Rheumatoid Arthritis Patients: Comparison with the Bilateral Method

Objective

Bilateral C1 lateral mass and C2 pedicle screw fixation (C1LM-C2P) is an ideal technique for correcting atlantoaxial instability (AAI). However, the inevitable situation of vertebral artery injury or unfavorable bone structure may necessitate the use of unilateral C1LM-C2P. This study compares the fusion rates of the C1 lateral mass and C2 pedicle screw in the unilateral and bilateral methods.

Methods

Over five years, C1LM-C2P was performed in 25 patients with AAI in our institute. Preoperative studies including cervical X-ray, three-dimensional computed tomography (CT), CT angiogram, and magnetic resonance imaging were performed. To evaluate bony fusion, measurements of the atlanto-dental interval (ADI) and CT scans were performed in the preoperative period, immediate postoperative period, and postoperatively at 1, 3, 6, and 12 months.

Results

Unilateral C1LM-C2P was performed in 11 patients (44%). The need to perform unilateral C1LM-C2P was due to anomalous course of the vertebral artery in eight patients (73%) and severe degenerative arthritis in three patients (27%). The mean ADI in the bilateral group was 2.09 mm in the immediate postoperative period and 1.75 mm in 12-months postoperatively. The mean ADI in the unilateral group was 1.82 mm in the immediate postoperative period and 1.91 mm in 12-months postoperatively. Comparison of ADI measurements showed no significant differences in either group (p=0.893), and the fusion rate was 100% in both groups.

Conclusion

Although bilateral C1LM-C2P is effective for AAI from a biomechanical perspective, unilateral screw fixation is a useful alternative in patients with anatomical variations.     

Myelopathy Caused by Soft Cervical Disc Herniation : Surgical Results and Prognostic Factors

Objective

The purpose of this study was to investigate the surgical results and prognostic factors for patients with soft cervical disc herniation with myelopathy.

Methods

During the last 7 years, 26 patients with cervical discogenic myelopathy were undertaken anterior discectomy and fusion. Clinical and radiographic features were reviewed to evaluate the surgical results and prognostic factors. The clinical outcome was judged using two grading systems (Herkowitz''s scale and Nurick''s grade).

Results

Male were predominant (4:1), and C5-6 was the most frequently involved level. Gait disturbance, variable degree of spasticity, discomfort in chest and abdomen, hand numbness were the most obvious signs. Magnetic resonance(MR) images showed that central disc herniation was revealed in 16 cases, and accompanying cord signal changes in 4. Postoperatively, 23 patients showed favorable results (excellent, good and fair) according to Herkowitz''s scale.

Conclusion

Anterior cervical discectomy and fusion effectively reduced myelopathic symptoms due to soft cervical disc herniation. The authors assured that the shorter duration of clinical attention, the lesser the degree of myelopathy and better outcome in discogenic myelopathy.