Lateral Flexion-extension Radiographs Research Articles

A Comparative Radiographic Analysis of Fusion Rate between L4-5 and L5-S1 in a Single Level Posterior Lumbar Interbody Fusion.

ObjectiveThis study aimed to investigate radiographic fusion rates at L4-5 and L5-S1 after single level posterior lumbar interbody fusion (PLIF) and evaluate the relationship between fusion rates and preoperative disc slope angle (DSA), lumbar lordosis (LL), segmental angle (SA), and pelvic parameters.MethodsWe conducted a retrospective review of patients who underwent single level PLIF at L4-5 or L5-S1 during May 2003-December 2012 at our institution. 73 patients were finally enrolled. Fusion was assessed by use of the Brantigan-Steffee classification, less than 2mm translation and less than 5° motion on the flexion-extension lateral radiographs. We analyzed the radiographic fusion rates, risk factors, and relationship of fusion rates with DSA, LL, SA, and pelvic parameters.ResultsThere were 59 patients (80.8%) in the L4-5 group and 14 (19.2%) in L5-S1 (average follow-up, 34 months). The radiographic fusion rates were 89.8% in the L4-5 group (53/59) and 42.9% in L5-S1 (6/14) (p<0.001).The preoperative DSA was significantly lesser in the L4-5 group than in the L5-S1 group (13.1±8.1° vs. 27.2±6.7°, p<0.001). The LL, SA, and pelvic parameters were not related with radiographic fusion rates in both groups. Risk factors for non-union were not identified between the two groups except for the surgery level (p<0.001).ConclusionThe radiographic fusion rate at L5-S1 was less than half that at L4-5 after single level PLIF. This may be due to the anatomical and biomechanical differences between the two levels. More vigorous effort to achieve successful fusion at L5-S1 should be considered.

Para-Split Laminotomy: A Rescue Technique for Split Laminotomy Approach in Exploring Intramedullary Midline Located Pathologies

Conventional posterior approaches, which may involve multilevel laminectomies and facetectomies, may lead to spinal deformities, instability, and subluxation. We developed the multilevel spinous process splitting and distraction laminotomy technique, which is an option for approaching midline intramedullary spinal pathologies with preservation of mechanically relevant bone and muscle structures. In some cases, midline splitting is not feasible or convenient because of anatomical differences of spinous processes and laminas. Our objective was to develop a minimally invasive rescue approach technique that makes it possible to remove intramedullary lesions but does not increase the risk of damage to the crucial posterior stabilizers of the spine. We used the para-split laminotomy technique for opening the spinal canal not in the midline but rather in the parasagittal plane. The technique can be combined with the basic split laminotomy technique. This novel technique was used in five adult patients with midline intramedullary pathologies of the cervical and cervicothoracic spine. The operating field under the microscope was sufficient for tumor removal according to the keyhole concept. The approach used did not affect the extent of resection or neurologic outcome. The average number of split laminae was 6 (range: 3-10). Average follow-up was 18 months (range: 13-36 months). Histologic results were as follows: two ependymomas, two astrocytomas, and one primitive neuroectodermal tumor (PNET). To confirm the extension of resection, all patients underwent postoperative magnetic resonance imaging evaluations. The resections were complete in the cases of two ependymomas, subtotal in one astrocytoma, and partial in the other astrocytoma case and the PNET case. Computed tomography scans showed the extension of para-split approaches and the moderately disturbed bony structures. Instability was detected in none of the patients on the flexion-extension lateral radiographs during the follow-up period. The minimally invasive multilevel para-split laminotomy approach as a rescue technique for split laminotomy is a safe and effective surgical procedure, suitable for exploring different intramedullary pathologies located in the midline of the spinal canal. This modified surgical approach fulfills the requirements of other minimally invasive techniques and lowers the risk of damage to the crucial posterior stabilizers of the spine; furthermore, disintegration of the vertebral arches and facet joints is reduced.

Cervical Disk Arthroplasty Versus ACDF for Preoperative Reducible Kyphosis

Cervical total disk arthroplasty has proven to be an effective and safe alternative for anterior cervical diskectomy and fusion (ACDF) for the treatment of cervical disk degenerative disease. However, whether and when cervical disk arthroplasty is indicated for preoperative cervical spine kyphosis is unclear. In the authors' clinical experiences, preoperative kyphosis can generally be divided into reducible and irreducible forms according to the results of dynamic flexion-extension lateral radiographs. Reducible kyphosis is mostly related to local disk prolapse, clinical symptoms, and musculature weakness, but irreducible kyphosis is always associated with significant cervical degeneration or congenital bone malformation. In this study, 32 patients with preoperative reducible kyphosis were randomized in a 1:1 ratio to either single-level total cervical arthroplasty with the Discover cervical disk prosthesis (DePuy Spine, Raynham, Massachusetts) (arthroplasty group) or single-level ACDF with a polyetheretherketone cage and plate (ACDF group). No significant differences existed in clinical and radiological results at 2-year follow-up between the arthroplasty and ACDF groups. The global and functional spinal unit angles of the arthroplasty group were significantly lower than those of the ACDF group 6 months postoperatively, which was consistent with the result of the comparison in Neck Disability Index score. However, the sagittal alignment of the overall cervical spine and the treated segment and the Neck Disability Index score significantly improved after 6 months in the arthroplasty group but not in the ACDF group. Therefore, preoperative reducible kyphosis is not a contraindication for cervical total disk arthroplasty. However, neck strength-building exercises should be emphasized for the postoperative rehabilitation after cervical total disk arthroplasty.

Soft-Tissue Damage and Segmental Instability in Adult Patients With Cervical Spinal Cord Injury Without Major Bone Injury

A retrospective imaging and clinical study. To evaluate the extraneural soft-tissue damage and its clinical relevance in patients with traumatic cervical spinal cord injury (SCI) without major bone injury. To date, various kinds of cervical discoligamentous injuries have been demonstrated on magnetic resonance images in patients with SCI without bony injury. However, it has not been clear whether these magnetic resonance imaging abnormalities are actually related to spinal segmental instability and the patients' neurological status. Eighty-eight adult patients with acute traumatic cervical SCI without major bone injury were examined by flexion-extension lateral radiographs and magnetic resonance images within 2 days after trauma. We excluded patients with flexion recoil injury; therefore, most of the patients included were considered to have sustained a hyperextension injury. Instability of the injured cervical segment was defined when there was more than 3.5-mm posterior translation and/or more than a 11° difference in the intervertebral angle between the site of interest and adjacent segments. The neurological status was evaluated according to the American Spinal Injury Association motor score. On magnetic resonance images, the damage to the anterior longitudinal ligament and intervertebral disc were apparent in 44 and 37 patients, respectively. Various degrees of prevertebral fluid collection (prevertebral hyperintensity) were demonstrated in 76 patients. These magnetic resonance imaging abnormalities were significantly associated with initial cervical segmental instability as judged by flexion-extension radiographs. Interestingly, the American Spinal Injury Association motor score had a significant association with either magnetic resonance imaging abnormalities or segmental instability but not with the cervical canal diameter. A considerable proportion of the patients with traumatic cervical SCI without major bone injury were shown to have various types of soft-tissue damage associated with cervical segmental instability at the early stages of the injury. The severity of paralysis greatly depended on these discoligamentous injuries.

Posterior Cervical Lateral Mass Screw Fixation and Fusion to Treat Pseudarthrosis of Anterior Cervical Fusion

Retrospective clinical cohort study. To determine the efficacy of posterior lateral mass screw/rod fixation and fusion for the treatment of symptomatic pseudarthrosis of anterior cervical fusion. Both anterior revision and posterior repair of cervical pseudarthrosis have been reported. To date, there is still debate in the literature as how the patient with symptomatic cervical pseudarthrosis should be addressed. Thirty-eight consecutive patients with symptomatic anterior cervical pseudarthrosis were treated with posterior lateral mass screw/rod fixation and fusion. The average follow-up was 28 months (24 to 60 mo) and patients were assessed with clinical examination, questionnaires, flexion-extension lateral radiographs, and/or computed tomography scans. The clinical results were classified as excellent, good, fair, or poor, according to Zdeblick criteria. All patients achieved a solid radiographic fusion at the final follow-up. The result was excellent in 10 patients, good in 22, fair in 6, and poor in none. Patients with symptomatic cervical pseudarthrosis that develops after anterior cervical discectomy and fusion may be managed successfully with posterior lateral mass screw fixation and fusion.

Minimally invasive anterior transarticular screw fixation and microendoscopic bone graft for atlantoaxial instability

Even though transarticular screw (TAS) fixation has been commonly used for posterior C1-C2 arthrodesis in both traumatic and non-traumatic lesions, anterior TAS fixation C1-2 is a less invasive technique as compared with posterior TAS which produces significant soft tissue injury, and there were few reports on percutaneous anterior TAS fixation and microendoscopic bone graft for atlantoaxial instability. The goals of our study were to describe and evaluate a new technique for anterior TAS fixation of the atlantoaxial joints for traumatic atlantoaxial instability by analyzing radiographic and clinical outcomes. This was a retrospective study of seven consecutive patients with C1-C2 instability due to upper cervical injury treated by a minimally invasive procedure from May 2007 to August 2009. Bilateral anterior TAS were inserted by the percutaneous approach under Iso-C3D fluoroscopic control. The atlantoaxial joint space was prepared for morselized autogenous bone graft under microendoscopy. The data for analysis included time after the injuries, operating time, intraoperative blood loss, X-ray exposure time, clinical results, and complications. Radiographic evaluation included the assessment of atlantoaxial fusion rate and placement of TAS. Bone fusion of the atlantoaxial joints was assessed by flexion extension lateral radiographs and 1-mm thin-slice computed tomography images as radiographic results. Clinical assessment was done by analyzing the recovery state of clinical presentation from the preoperative period to the last follow-up and by evaluating complications. A total of 14 screws were placed correctly. The atlantoaxial solid fusion without screw failure was confirmed by CT scan in seven cases after a mean follow-up of 27.5 months (range 18-45 months). All patients with associated clinical presentation made a recovery without neurologic sequelae. Postoperative dysphagia occurred and disappeared in two cases within 5 days after surgery. There were no other complications during the follow-up period. Percutaneous anterior TAS fixation and microendoscopic bone graft could be an option for achieving C1-C2 stabilization with several potential advantages such as less tissue trauma and better accuracy. Bilateral TAS fixation and morselized autograft affords effective fixation and solid fusion by a minimally invasive approach.

A radiographic analysis of degenerative spondylolisthesis at the L4–5 level

Lumbar degenerative spondylolisthesis (LDS) is common and has generally been characterized as a homogeneous disease entity in the literature and in clinical practice. Because disease variability has not been carefully characterized, stratification of treatment recommendations based on scientific evidence is currently lacking. In this study, the authors analyzed radiographic parameters of patients with LDS at the L4-5 level to better characterize this entity. Demographic data were collected from 304 patients (200 women and 104 men) with LDS at the L4-5 level. Plain radiographs including anteroposterior, lateral, and flexion-extension lateral radiographs were analyzed for disc height, segmental angulation, segmental translation, and osteophyte formation. Correlations were sought between the variables of age, sex, disc height, segmental angulation, segmental translation, and osteophyte formation. The mean patient age was 63.8 years (range 40-86 years). The mean mid-disc height was 7 mm (range 0-14 mm) on the neutral lateral view. The mean angulation between the superior endplate of L-5 and the inferior endplate of L-4 was 6° of lordosis (range 13° of kyphosis to 23° lordosis) on the neutral lateral view. The mean angular change between flexion and extension lateral radiographs was 5° (range 0°-17°). The mean translation on the neutral lateral view was 6 mm (range 0-15 mm). The mean change in translational between flexion and extension was 2 mm (range 0-11 mm). Twenty patients (7%) exhibited spondylolisthesis only on the flexion view. A significant positive correlation was found between the change in angulation and the change in translation on flexion and extension views (ρ = 0.18, p = 0.001). No significant correlation was found between anterior osteophyte size and mobility with flexion-extension radiographs. The wide range in all radiographic parameters for LDS confirms the heterogeneous nature of this condition and suggests that a grading system to subclassify LDS may be clinically useful. On flexion and extension radiographs, increased translational motion correlated with increased angular motion. Anterior osteophyte size was not found to be predictive of segmental stability. This data set should prove beneficial to those seeking to subcategorize LDS in the future.

Efficacy of anterior odontoid screw fixation in the elderly patient: a CT-based biometrical analysis of odontoid fractures

In the elderly population, reported union rates with anterior odontoid screw fixation (AOSF) for odontoid fracture (OF) treatment vary between 23 and 93% when using plain radiographs. However, recent research revealed poor interobserver reliability for fusion assessment using plain radiographs compared to CT scans. Therefore, union rates in patients aged ≥60 years treated with AOSF have to be revisited using CT scans and factors for non-union to be analysed. Prospectively gathered consecutively treated patients using AOSF for odontoid fracture with age ≥60 years were reviewed. Medical charts were assessed for demographics, clinical outcomes and complications. Patients' preoperative radiographs and CT scans were analysed to characterize fracture morphology and type, fracture displacement, presence of atlanto-dental osteoarthritis as well as a detailed morphometric assessment of fracture surfaces (in mm(2)). CT scans performed after a minimum of 3 months postoperatively were analysed for fracture union. Those patients not showing CT-based evidence of completely fused odontoid fracture were invited for radiographic follow-up at a minimum of 6 months follow-up. Follow-up CT-scan were studied for odontoid union as well as the number of screws used and the square surface of screws used for AOSF and the related corticocancellous osseous healing surface of the odontoid fragment (in %) were calculated. Patients were stratified whether they achieved osseous union or fibrous non-union. Patients with a non-union were subjected to flexion-extension lateral radiographs and the non-union defined as stable if no motion was detected. The sample included 13 male (72%) and 5 female (18%) patients. The interval from injury to AOSF was 4.1 ± 5.3 days (0-16 days). Age at injury was 78.1 ± 7.6 years (60-87 years) and follow-up was 75.7 ± 50.8 months (4.2-150.2 months). 10 patients had dislocated fractures, 14 had Type II and 4 "shallow" Type III fractures according to the Anderson classification, 2 had stable C1-ring fractures, 8 had displayed atlanto-dental osteoarthritis. Fracture square surface was 127.1 ± 50.9 mm(2) (56.3-215.9 mm(2)) and osseous healing surface was 84.0 ± 6.8% (67.6-91.1%). CT-based analysis revealed osseous union in 9 (50%) and non-union in 9 patients (50%). Union rates correlated with increased fracture surface (P = 0.02). Statistical analysis revealed a trend that the usage of two screws with AOSF correlates with increased fusion rates (P = 0.06). Stability at C1-2 was achieved in 89% of patients. CT scans are accepted as the standard of reference to assess osseous union. The current study offers an objective insight into the union rates of odontoid fractures treated with AOSF using CT scans in consecutive series of 18 patients ≥60 years. Literature serves evidence that elderly patients with unstable OF benefit from early surgical stabilization. However, although using AOSF for unstable OF yields segmental stability at C1-2 in a high number of patients as echoed in the current study, our analysis stressed that using follow-up CT scans in comparison to biplanar radiographs dramatically reduces osseous union rates compared to those previously reported for AOSF.

The effect of a radiographic solid fusion on clinical outcomes after minimally invasive transforaminal lumbar interbody fusion

Background context The correlation between radiographic solid fusion and favorable clinical outcome has not been fully established. Many surgeons believe that patients who achieve a radiographic solid fusion will exhibit a more positive clinical outcome than those getting an unsuccessful fusion. To our knowledge, there is no study that has evaluated whether a solid fusion influences clinical outcome after minimally invasive lumbar fusion. Purpose This study was designed to evaluate the effect of radiographic solid fusion on clinical outcome after minimally invasive transforaminal lumbar interbody fusion (TLIF). Study design We conducted a retrospective study by comparing the prospectively collecting data. Patient sample The sample comprises 66 patients who had achieved a solid fusion or nonunion at least 2 years after minimally invasive TLIF for the treatment of low-grade spondylolisthesis or degenerative segmental instability. Outcome measures The outcome measures were visual analog scale (VAS) for back pain and radiating leg pain, Oswestry Disability Index (ODI), functional scale (defined as a modified method of Whitecloud et al.), and radiographic fusion status. Methods Two independent spine surgeons reviewed the completed medical records and radiographic data of 66 patients who had undergone minimally invasive TLIF by one surgeon at an institution. Clinical outcome was evaluated using VAS, ODI, and functional scale. The radiographic fusion status was assessed using flexion-extension lateral radiographs and computed tomography scans. Comparison and correlation analyses were performed to examine the relationship between fusion status and clinical outcome. Results There were 51 (77%) patients in the solid fusion (control) group and 15 patients in the nonunion group. The improvement from baseline with regard to VAS scores for back and leg pain as well as ODI scores was significant in both groups (all, p<.0001), with patients in the control group reporting significantly better improvement of back pain scores than those in nonunion group (p=.04). Conversely, the improvement of VAS scores for leg pain and ODI scores was comparable between two groups. Forty-one patients (80%) in the control group and 13 (87%) in the nonunion group demonstrated an excellent or good result in the final functional scale as well. The presence of radiographic solid fusion positively, but not strongly, correlated with the improvement of VAS scores for back pain (r=0.255, p=.039). Conclusions At least 2 years after minimally invasive TLIF, better reduction of back pain was noted in patients who achieved a radiographic solid fusion as opposed to those with nonunion. However, there was no clear evidence that radiographic solid fusion was associated with better clinical outcome scores or improvement in leg pain than nonunion.

Degenerative cervical spondylolisthesis: a systematic review

Degenerative cervical spondylolisthesis has received insufficient attention, in contrast to degenerative lumbar spondylolisthesis. In fact, degenerative cervical spondylolisthesis may be more common than previously thought. In order to provide appropriate guidelines for the treatment of degenerative cervical spondylolisthesis, a systematic review of degenerative cervical spondylolisthesis was performed. An English literature search from January 1947 to November 2010 was completed with reference to radiological examination and management of degenerative cervical spondylolisthesis. Of 102 patients with degenerative cervical spondylolisthesis, 52 patients (51%) had neck or occipital pain, 23 patients (22.5%) were referred with radiculopathy and 65 patients (63.7%) presented with myelopathy or myeloradiculopathy. Degenerative cervical spondylolisthesis was most common in C3/4 and C4/5, occurring in 81 patients at C3/4 (46%) and 87 at C4/5 (49.4%). Disc degeneration and facet hypertrophy were the main causes of this clinical entity. Of 123 patients, 57 (46.3%) were found to have segmental instability as shown by flexion-extension lateral radiographs. There are two classification systems for degenerative cervical spondylolisthesis. Surgery was indicated in patients who had radiologically proven cervical spondylolisthesis with instability and/or spinal cord compression. Prospective studies should be designed in the future to draw a more reliable conclusion about the management of degenerative cervical spondylolisthesis.

Os Odontoideum: Rare Cervical Lesion

We report the case of a 22-year-old Marine who presented to the emergency department, after a martial arts exercise, with transient weakness and numbness in all extremities. Computed tomography cervical spine radiographs revealed os odontoideum. Lateral flexion–extension radiographs identified atlanto-axillary instability. This abnormality is rare and can be career ending for military members who do not undergo surgical fusion.

A clinical analysis of 4- and 6-year follow-up results after cervical disc replacement surgery using the Bryan Cervical Disc Prosthesis

In this study, long-term results are presented from clinical studies of the Bryan Cervical Disc Prosthesis at University Hospital Gasthuisberg in Leuven, Belgium. A total of 98 patients (89 with 1-level and 9 with 2-level implantations) agreed to participate in follow-up studies for up to 10 years postoperatively. This article focuses on the 4- and 6-year results. Patients in one of the clinical studies had either radiculopathy or myelopathy associated with spondylosis and/or disc herniations that did not respond to conservative treatment. Patients from the other clinical study received commercially available Bryan devices and the study protocol did not have specific inclusion/exclusion criteria. More than 90% of the patients were considered to have radiculopathy. Clinical measurements discussed in the article include the 36-Item Short Form Health Survey, Neck Disability Index, numerical ratings of neck and arm pain, neurological outcomes, and Odom classification. Angular motion findings from lateral flexion-extension radiographs are also presented. The occurrence of adverse events and second surgeries are examined as an indicator of device safety. The clinical outcomes at 4 and 6 years postoperatively appear consistent with the previously reported results at 1 and 2 years postoperatively. The mean angular motion results at 4 and 6 years postoperatively for 1-level patients were 7.3 and 7.7 degrees, respectively. Two-level patients had slightly less motion at 4 and 6 years postoperatively with mean caudad values of 5.7 and 6.0 degrees, respectively, and cephalad values of 4.2 and 6.2 degrees, respectively. Efforts were made to capture adverse events, regardless of their nature and relatedness to the study surgery. This effort resulted in a relatively high number of recorded events. However, only 6 patients experienced events that were judged by the investigator to be related, either possibly or definitely, to the Bryan device. These events included device migration, device removal, and hoarseness and vocal cord paralysis, as well as 3 cases involving pain and neurological symptoms. Eight patients underwent further neck surgery to treat symptoms. The favorable clinical and angular motion outcomes that were previously noted at 1- and 2-years' follow-up after cervical disc replacement with the Bryan Cervical Disc Prosthesis appear to persist after 4 and 6 years of follow-up.

Changes in cervical range of motion and sagittal alignment in early and late phases after total disc replacement: radiographic follow-up exceeding 2 years

This was a retrospective clinical study in which the follow-up period exceeded 2 years. The authors investigated the time course of radiographic changes in the cervical range of motion (ROM) and sagittal alignment after cervical total disc replacement involving the ProDisc-C artificial disc. Eighteen patients who underwent C5-6 total disc replacement were followed for an average of 27 months. Cervical neutral and flexion-extension lateral radiographs were obtained before and at 1 and 3 months after surgery for early-phase observations and at the last follow-up for late-phase observation. Segmental ROM values in the treated, superior, and inferior adjacent segments were measured. For whole-neck motion, C2-7 ROM was also measured. The percentage contributions of ROM at functional and adjacent segments to whole-neck motion were calculated. For evaluating sagittal alignment, C2-7 and C5-6 Cobb angles were measured. All data from ProDisc-C arthroplasty were compared with the results obtained in 22 patients who underwent C5-6 interbody fusion in which a Solis cage was used and who were followed for an average of 25 months. In the ProDisc-C group, C2-7 and C5-6 ROM significantly decreased in the early phase after surgery and returned to preoperative levels in the late phase. Both superior and inferior adjacent segments showed significantly decreased ROM in the acute phase after surgery and returned to the preoperative values in the late phase. In terms of contributions to whole-neck motion, the ROM of the functional and adjacent segments did not change significantly compared with the preoperative ROM. In the cage group, C2-7 ROM was also significantly decreased in the early phase after surgery and returned to preoperative levels at the late phase. Both superior and inferior adjacent segments exhibited significantly increased ROM and percentage contributions to whole-neck motion in the early and late phases. Sagittal alignment of the whole cervical spine became significantly more lordotic in the late phase in the ProDisc-C group. The C5-6 Cobb angle became significantly lordotic in the ProDisc-C group, whereas there was no significant change in C5-6 Cobb angle in the cage group. In the early phase after ProDisc-C replacement, the ROM of the entire neck as well as functional and adjacent segments decreased but, at the late phase, they returned to the preoperative state. Contributions of functional and adjacent segments to whole-neck motion were not changed after ProDisc-C replacement. Adjacent-segmental motion could be saved by ProDisc-C replacement instead of interbody cage fusion. Segmental degenerative kyphosis was significantly corrected in patients who underwent ProDisc-C replacement.

Three dimensional computed tomography (3D-CT) and radiographs assessment of interbody fusion after posterior lumbar intervertabral fusion.

Objective To evaluate the clinical application of three dimensional computed tomography (3D-CT) and radiographs in assessment of interbody fusion after posterior lumbar intervertebral fusion (PLIF). Methods Forty-three patients, consisting of 19 males and 24 females were treated with PLIF in single segment from March 2000 to June 2007. The mean age was 47.2 years. The interbody fusion was performed by autograft in 26 cases and autograft plus PEEK cages in 17 cases. The preoperative diagnosis were isthmus spondylolisthesis in 21 cases, degenerative spondylolisthesis in 15 cases, Lumbar disc herniation associated with instability in 3 cases, revision after primary lumbar discectomy in 3 cases, and far lateral disc herniation in 1 cases. The interbody fusion levels were L_(3,4) in 6 cases, L_(4,5) in 17 cases,and L_5S_1 in 20 cases. Twenty-four patients underwent two-level internal fixation, while 19 cases accepted three-level fixation. The posterior, lateral static radiograph, flexion-extension radiographs and 3D-CT were performed at follow-up visit . The modified Brantigan grade was used to assess the fusion rate. The interbody stability was assessed by the flexion-extension radiographs. Results The mean follow-up was 18 months (12-85 months). The fusion rates in X-rays and 3D-CT were 64% and 40%, respectively. The mean Brantigan grade in X-rays and 3D-CT were 2.70±1.10 and 2.19±1.16, respectively. The grade was significantly lower in 3D-CT (P< 0.05). The Brantigan grades in 3D-CT were also significantly lower than those in X-ray between the groups of isthmus spondylolisthesis and degenerative spondylolisthesis, two-level and three-level internal fixation, and autograft only and autograft plus PEEK cages. There were only 3 cases showing dynamic instability. The other cases (93%) had no instability according to dynamic X-rays ,even those were comfirmed of nonunion of the bone graft . Conclusion The lumbar 3D-CT is more accurate in assessment of interbody fusion. It is necessary to perform the 3D-CT before removal of the internal fixation. Key words: Lumbar vertebrae ; Spinal fusion ; Radiography ; Tomography ; X-ray computed ;

Imaging correlation of the degree of degenerative L4–5 spondylolisthesis with the corresponding amount of facet fluid

The aim of this study was to correlate the degree of L4-5 spondylolisthesis on plain flexion-extension radiographs with the corresponding amount of L4-5 facet fluid visible on MR images. Patients underwent evaluation at the Neurosurgical Spine Clinics of Stanford University Medical Center and National Health Insurance Medical Center (Goyang, South Korea) between January 2006 and December 2007. Only patients who were diagnosed with L4-5 degenerative spondylolisthesis (DS) and who had both lumbosacral flexion-extension radiographs and MR images available for review were eligible for this study. Each patient's dynamic motion index (DMI) was measured using the lateral lumbosacral plain radiograph and was the percentage of the degree of anterior slippage seen on flexion versus that seen on extension. Axial T2-weighted MR images of the L4-5 facet joints obtained in each patient was analyzed for the amount of facet fluid, using the image showing the widest portion of the facets. The facet fluid index was calculated from the ratio of the sum of the amounts of facet fluid found in the right plus left facets over the sum of the average widths of the right plus left facet joints. Fifty-four patients with L4-5 DS were included in this study. Of these 54 patients, facet fluid was noted on MR images in 29 patients (53.7%), and their mean DMI was 6.349 +/- 2.726. Patients who did not have facet fluid on MR imaging had a mean DMI of 1.542 +/- 0.820; this difference was statistically significant (p < 0.001). There was a positive linear association between the facet fluid index and the DMI in the group of patients who exhibited facet fluid on MR images (Pearson correlation coefficient 0.560, p < 0.01). In the subgroup of 29 patients with L4-5 DS who showed facet fluid on MR images, flexion-extension plain radiographs in 10 (34.5%) showed marked anterolisthesis, while the corresponding MR images did not. There is a linear correlation between the degree of segmental motion seen on flexion-extension plain radiography in patients with DS at L4-5 and the amount of L4-5 facet fluid on MR images. If L4-5 facet fluid in patients with DS is seen on MR images, a corresponding anterolisthesis on weight-bearing flexion-extension lateral radiographs should be anticipated. Obtaining plain radiographs will aid in the diagnosis of anterolisthesis caused by an L4-5 hypermobile segment, which may not always be evident on MR images obtained in supine patients.

Clinical and radiological instability following standard fenestration discectomy

Background:Post-surgical lumbar instability is an established complication but there is limited evidence in the literature regarding the incidence of lumbar instability following fenestration and discectomy. We analyzed our results following fenestration discectomy with a special focus on instability.Materials and Methods:Eighty-three patients between the age of 17 and 52 years who had undergone fenestration discectomy for a single-level lumbar intervertebral disc prolapse were followed-up for a period of 1–5 years. The criteria for instability included “instability catch,”, “painful catch,” and “apprehension.” The working capacity of the patient and the outcome score of the surgery were assessed by means of the Oswestry disability score and the Prolo economic and functional outcome score. Flexion-extension lateral radiographs were taken and analyzed for abnormal tilt and translation.Results:Of the 83 patients included, 70 were men and 13 were women, with an average age of 37.35 years (17–52 years) at 5 years follow-up. Clinical instability was seen in 10 (12.04%) patients. Radiological instability was noted in 29 (34.9%) patients. Only six (60%) of the 10 patients who demonstrated clinical instability had radiological evidence of instability. Twenty (68.96%) patients with radiological instability were asymptomatic. Three (10.34%) patients with only radiological instability had unsatisfactory outcome. The Oswestry scoring showed an average score of 19.8%. Mild disability was noted in 59 (71.08%) patients and moderate disability was seen in 24 (28.91%) patients. None of the patients had severe disability. These outcomes were compared with the outcomes in other studies in the literature for microdiscectomy and the results were found to be comparable.Conclusion:The favorable outcome of this study is in good agreement with other studies on microdiscectomy. Clinical instability in 12.04% of the patients is in agreement with other studies. Radiological signs of instability are seen even in asymptomatic patients and so are not as reliable as clinical signs of instability. Standard fenestration discectomy does not destabilize the spine more than microdiscectomy.

The role of standing flexion-extension radiographs for spondylolisthesis following single level disk surgery

Objectives: Spondylolisthesis is the forward displacement of a lumbar vertebra relative to the adjacent vertebra, occurs as result degeneration or surgery and is a special type of lumbar instability. There is no consensus about which radiologic modality or findings truly reflect the lumbar instability and the exact incidence after single level disk surgery is unknown.Methods: In this prospective study, we have included 90 patients who were operated by the same surgeon with single level disk herniation. We aimed at evaluating the post-operative lumbar spondylolisthesis, with flexion and extension lateral radiographs in addition to standard magnetic resonance imaging (MRI).Results: We have seen spondylolisthesis in six of 90 cases with standing lateral flexion-extension radiographs, which were undefinable with MRI. Pain intensity and functional-economic rating scale (Prolo scale) were unremarkable.Discussion: We have concluded that standing flexion-extension radiographs should be routinely combined in patients with failed back surgery syndrome and even if lumbar instability is clinically suspected, especially when conventional MR examination is normal. When the MR examination showed spondylolisthesis, standing flexion-extension radiographs could not give additional information.

Utility of Flexion-Extension Radiographs in Evaluating the Degenerative Cervical Spine

Retrospective cohort of 258 consecutive patients. The purpose of this study is to determine the: (1) percentage of flexion-extension radiographs that revealed pathology not appreciated on neutral radiographs in the nontrauma population, and (2) frequency that these views led to a change in the management of these patients. The utility of flexion-extension radiographs in the evaluation of the spine trauma or preoperative patient is well accepted, but the role of dynamic radiographs in the degenerative population is not well defined. Consecutive patients presenting with axial cervical, upper extremity radicular, or myelopathic symptoms underwent upright anteroposterior, neutral lateral, and flexion-extension lateral radiographs. Patients with recent trauma, rheumatoid arthritis, prior cervical fracture, prior cervical surgery, inadequate radiographs, or congenital anomalies were excluded. Three observers reviewed all radiographs after determining the best measurement method by a priori analysis of interobserver reliability. Listhesis was observed on 23 of the neutral lateral images; 6 of these were found to have changes between flexion and extension (2-4 mm). Two patients (1%) had spondylolisthesis on flexion-extension radiographs not visualized on neutral lateral radiographs. A subsequent review of these patients' charts revealed no change in management based on these findings. Cervical flexion-extension radiographs are a method of assessing potential instability. In the degenerative population studied here, 1% had spondylolisthesis noted only on the flexion-extension images, and 3% had a change in spondylolisthesis. None of these, however, led to a changes in clinical management. These data, in conjunction with the extra cost and radiation exposure associated with additional views, led us to no longer regard dynamic radiographs as a useful part of the initial imaging for the patient with degenerative cervical conditions.

Clinical Experiences and Usefulness of Cervical Posterior Stabilization with Polyaxial Screw-Rod System

The objective of this study is to investigate the safety, surgical efficacy, and advantages of a polyaxial screw-rod system for posterior occipitocervicothoracic arthrodesis. Charts and radiographs of 32 patients who underwent posterior cervical fixation between October 2004 and February 2006 were retrospectively reviewed. Posterior cervical polyaxial screw-rod fixation was applied on the cervical spine and/or upper thoracic spine. The surgical indication was fracture or dislocation in 18, C1-2 ligamentous injury with trauma in 5, atlantoaxial instability by rheumatoid arthritis (RA) or diffuse idiopathic skeletal hyperostosis (DISH) in 4, cervical spondylosis with myelopathy in 4, and spinal metastatic tumor in 1. The patients were followed up and evaluated based on their clinical status and radiographs at 1, 3, 6 months and 1 year after surgery. A total of 189 screws were implanted in 32 patients. Fixation was carried out over an average of 3.3 spinal segment (range, 2 to 7). The mean follow-up interval was 20.2 months. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-7 lateral masses, as well as the lower cervical and upper thoracic pedicles. Satisfactory bony fusion and reduction were achieved and confirmed in postoperative flexion-extension lateral radiographs and computed tomography (CT) scans in all cases. Revision surgery was required in two cases due to deep wound infection. One case needed a skin graft due to necrotic change. There was one case of kyphotic change due to adjacent segmental degeneration. There were no other complications, such as cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, or implant failure, and there were no cases of postoperative radiculopathy due to foraminal stenosis. Posterior cervical stabilization with a polyaxial screw-rod system is a safe and reliable technique that appears to offer several advantages over existing methods. Further biomechanical testings and clinical experiences are needed in order to determine the true benefits of this procedure.

Three-Dimensional In Vivo Measurement of Lumbar Spine Segmental Motion

Fifteen asymptomatic volunteers were externally rotated and CT scanned to determine lumbar segmental motion. To measure three-dimensional segmental motion in vivo using a noninvasive measurement technique. Spinal instability has been implicated as a potential cause of low back pain, especially, axial rotational instability. Typically, flexion-extension lateral radiographs were used to quantify instability, but inaccurately measured translations and inability to capture out-of-plane rotations are limitations. Using a custom-calibrated rotation jig, L1-S1 CT reconstructions were created of volunteers in each of 3 positions: supine and left and right rotations of the torso with respect to the hips. Segmental motions were calculated using Euler angles and volume merge methods in three major planes. Segmental motions were small (< 4 degrees or 6 mm) with the greatest motions seen in axial rotation (range, 0.6 degrees to 2.2 degrees ), lateral bending (range, -3.6 degrees to 3.0 degrees ), and frontal translation (-1.2 mm to 5.4 mm). Largest motions were in the levels: L1-L2 to L3-L4. Complex coupled motions were measured due to external torsion and could be indicative of instability chronic patients with low back pain. The presented data provide baseline segmental motions for future comparisons to symptomatic subjects.