Intervertebral Disc Space Research Articles

Surgical Approaches to the Lumbar Hidden Zone: Current Strategies and Future Directions

Surgical Approaches to the Lumbar Hidden Zone: Current Strategies and Future Directions

Pseudarthrosis after lumbar spinal fusion: the role of ¹⁸F-fluoride PET/CT.

PurposePainful pseudarthrosis is one of the most important indications for (revision) surgery after spinal fusion procedures. If pseudarthrosis is the source of recurrent pain it may require revision surgery. It is therefore of great clinical importance to ascertain if it is the source of such pain. The correlation between findings on conventional imaging (plain radiography and CT) and clinical well-being has been shown to be moderate. The goal of this study was to determine the possible role of 18F-fluoride PET in patients after lumbar spinal interbody fusion by investigating the relationship between PET/CT findings and clinical function and pain.MethodsA cohort of 36 patients was retrospectively included in the study after 18F-fluoride PET/CT for either persistent or recurrent low back pain (18 patients) or during routine postoperative investigation (18 patients) between 9 and 76 months and 11 and 14 months after posterior lumbar interbody fusion, respectively. Sixty minutes after intravenous injection of 156 – 263 MBq (mean 199 MBq, median 196 MBq) 18F-fluoride, PET and CT images were acquired using an integrated PET/CT scanner, followed by a diagnostic CT scan. Two observers independently scored the images. The number of bony bridges between vertebrae was scored on the CT images to quantify interbody fusion (0, 1 or 2). Vertebral endplate and intervertebral disc space uptake were evaluated visually as well as semiquantitatively following 18F-fluoride PET. Findings on PET and CT were correlated with clinical wellbeing as measured by validated questionnaires concerning general daily functioning (Oswestry Disability Index), pain (visual analogue scale) and general health status (EuroQol). Patients were divided into three categories based on these questionnaire scores.ResultsNo correlation was found between symptom severity and fusion status. However, 18F-fluoride activity in the vertebral endplates was significantly higher in patients in the lowest Oswestry Disability Index category (i.e. with the worst clinical performance) than in patients in higher categories (p = 0.01 between categories 1 and 2 and 1 and 3). The visual analogue scale and EuroQol results were similar although less pronounced, with only SUVmax between category 1 and 2 being significantly different (p = 0.04).ConclusionWe hypothesize that 18F-fluoride PET/CT may be able to provide support for the diagnosis of painful pseudarthrosis and could serve as a tool to discriminate between symptomatic and asymptomatic pseudarthrosis for revision surgery, as CT defines the consolidation status and PET pinpoints the ‘stress reaction’ at the vertebral endplates which significantly correlates with Oswestry Disability Index score.

Relationship between annular tear and presence of Propionibacterium acnes in lumbar intervertebral disc.

Propionibacterium acnes (P. acnes) in the intervertebral disc may result in low back pain. The purpose of this study was to determine how P. acnes accesses the disc. Patients with low back pain and/or sciatica were examined using X-ray and MRI before surgery. The intervertebral disc space height was measured on X-ray image. Disc and muscle samples were obtained from 46 patients undergoing discectomy at the lumbar spine. The tear of annulus was inspected before discectomy. In the disc and muscle tissue cultures, 16S rDNA gene specific for P. acnes was examined using PCR. The discs from 11 (23.9 %) patients were identified as 16S rDNA positive, in which two patients also had 16S rDNA in their muscles. 16S rDNA gene was significantly more likely to appear in the discs with annular tear than those without tear (P < 0.05). The disc space height was significantly decreased when the disc contained P. acnes. P. acnes is significantly more likely to be present in herniated discs with an annular tear than in herniated discs without such a tear. Since in the vast majority of these cases, no P. acnes was found in control muscle samples, a true infection with P. acnes is far more likely than a contamination.

A Review of Fibrocartilaginous Embolic Myelopathy and Different Types of Peracute Non-Compressive Intervertebral Disk Extrusions in Dogs and Cats.

This review discusses terminology, pathological, clinical, and magnetic resonance imaging (MRI) findings, treatment, outcome, and prognostic factors of fibrocartilaginous embolic myelopathy (FCEM), acute non-compressive nucleus pulposus extrusion (ANNPE), and intradural/intramedullary intervertebral disk extrusion (IIVDE). FCEM, ANNPE, and IIVDE have a similar clinical presentation characterized by peracute onset of neurological dysfunction that is generally non-progressive after the initial 24–48 h. Differentiating between these conditions can be challenging, however, certain clinical and imaging findings can help. FCEM can occur in both adult and immature animals, whereas ANNPE or IIVDE have been reported only in animals older than 1 year. In dogs, ANNPE and IIVDE most commonly occur in the intervertebral disk spaces between T12 and L2, whereas FCEM has not such site predilection. In cats, FCEM occurs more frequently in the cervical spinal cord than in other locations. Data on cats with ANNPE and IIVDE are limited. Optimal MRI definition and experience in neuroimaging can help identify the findings that allow differentiation between FCEM, ANNPE, and IIVDE. In animals with ANNPE and IIVDE, the affected intervertebral disk space is often narrowed and the focal area of intramedullary hyperintensity on T2-weighted images is located above the affected intervertebral disk space. In dogs with ANNPE signal changes associated with the extruded nucleus pulposus and epidural fat disruption can be identified in the epidural space dorsal to the affected intervertebral disk. Identification of a linear tract (predominantly hyperintense on T2-weighted images, iso to hypointense on T1-weighted images and hypointense on T2*-weighted gradient recall echo images) extending from the intervertebral disk into the spinal cord parenchyma is highly suggestive of IIVDE. Treatment of FCEM and ANNPE is conservative. Dogs reported with IIVDE have been managed either conservatively or surgically. Prognostic factors include degree of neurological dysfunction (particularly loss of nociception) and disease-specific MRI variables.

Radiological characteristics and clinical manifestation of isolated lumbar foraminal stenosis

To discuss radiological characteristics and clinical manifestation of isolated lumbar foraminal stenosis. From March 2011 to March 2014, 21 patients with isolated degenerative lumbar foraminal stenosis accepted lumbar decompression and fusion in Beijing Luhe Hospital. Intervertebral disc space was evaluated by measuring the position of joint-body line on preoperative X-ray. Bilateral foraminal area of the corresponding segment in CT (sagittal view of 2D reconstruction) and MRI (T2W1 sagittal view) were measured by Surgimap software. For patients with unilateral symptoms, foraminal area of the affected side was compared with that of the contralateral side. Foraminal area of the same segment on CT was also compared with that on MRI. Preoperatively and at the final follow-up, visual analogue score (VAS) and Oswestry Disability Index (ODI) were used to evaluate clinical outcomes. All patients had a follow-up over 6 months and the average follow-up was 16.8 months (7-42 months). Of the 21 patients (26 segments), 12 segments showed gross narrowing and 14 segments showed slight narrowing. After preoperative measurement on MRI, 6 patients had foraminal stenosis of grade 2, and 15 patients had foraminal stenosis of grade 3, showing no significant difference in clinical outcomes. Compared with the foraminal area of the unaffected side, the affected side showed a decrease of 16% on CT and 28% on MRI, and the difference was statistically significant (t = 3.453, P < 0.05). The foraminal area measured on CT was larger than that measured on MRI (P < 0.05). Compared with that preoperatively, VAS (back pain), VAS (leg pain) and ODI showed significant improvement at the final follow-up (P < 0.05). Radiological examinations as X-ray, CT, MRI and intervertebral foramen block technique play an important role in the diagnosis of foraminal stenosis. Soft oppression caused by hyperplasia and hypertrophy of transforaminal ligment or joint capsule may be important promoters of degenerative lumbar foraminal stenosis. Lumbar foraminal decompression and interbody fusion can satisfactorily improve preoperative symptoms.

Femoral Neurogram Before Transpsoas Spinal Access at L4–5 Intervertebral Disk Space

Observational study. To illustrate the variability of the course of the femoral nerve across the L4-5 disk space, and to present a novel application of transforaminal epidural steroid injections (TFESI) in the visualization of femoral nerve roots. A concern regarding the lateral retroperitoneal transpsoas approach is the proximity of the lumbar plexus. Current techniques of assessing the proximity of neural tissue to the L4-5 disk space have limited capabilities. A total of 100 patients were selected for L4-5 TFESI (L4 selective nerve root blocks) because of lumbar radiculopathy. L4 neurograms were obtained while performing L4-5 TFESI under flouroscopic guidance, using a retroneural technique. The course of the L4 root/femoral nerve was then evaluated under fluoroscopy in the anteroposterior and lateral planes. Images were then reviewed by a radiologist, physiatrist, and 2 orthopedic spine surgeons. Fluoroscopic evaluation revealed that the pattern of location of the femoral nerve was highly variable. In males, it was located 4.7% in zone 2, 32.5% in zone 3, 53.5% in zone 4, and 9.3% in zone P. In female patients, it was located 7.0% in zone 2, 14% in zone 3, 54.4% in zone 4, and 24.6% in zone P. An L4 neurogram will provide an accurate trajectory of L4 root/femoral nerve as it crosses the L4-5 intervertebral disk space. An accurate assessment is essential to help minimize the increasing frequency of thigh pain, paresthesias, and weakness associated with the lateral access to the L4-5 intervertebral disk space. Femoral nerves that fall within zones 2 and 3 will require more manipulation during retraction and may be better suited with a different surgical approach.

Use of vertebral body units to locate the cavoatrial junction for optimum central venous catheter tip positioning

Central venous catheter (CVC) placement plays an important role in clinical practice; however, optimal positioning of the CVC tip remains a controversial issue. The objective of this study was to evaluate the use of vertebral body unit (VBUs), to locate the cavoatrial junction (CAJ), for optimal CVC tip placement based on chest radiography (CXR) using the carina as a landmark. 524 patients who underwent coronary computed tomographic angiography (CTA) and CXR were included. The position of the CAJ was identified using VBUs, and the efficacy of VBUs for locating the CAJ with the carina as a landmark was analysed using multiple regression analysis. A VBU was defined as the distance between two adjacent vertebral bodies, including the inter-vertebral disk space. The mean (sd) distance from the carina to the superior CAJ was 54.3 (9.7) mm on CTA; the mean distance in VBUs at the level of the carina was 21.4 (1.7) mm on CTA and 22.6 (2.1) mm on CXR. The mean CAJ position was 2.5 VBUs below the carina on CTA and 2.4 VBUs below on CXR with 95% limits of agreement between -0.6 and +0.3. The position of the CVC tip in relation to the carina can be described using the thoracic spine as an internal ruler, and the position of the CAJ in adults was reliably estimated to be 2.4 VBUs below the carina. KCT0001319.

Combined magnetic fields provide robust coverage for interbody and posterolateral lumbar spinal fusion sites.

Electromagnetic fields generated by spinal bone growth stimulation devices have been computationally modelled to determine coverage of the lumbar spinal vertebrae. The underlying assumption of these models was that the electric field, but not the magnetic field, was therapeutically relevant. However, there are no published studies examining the therapeutic coverage of spinal fusion sites by stimulators utilizing combined magnetic fields. To assess the coverage, an anatomical model of the vertebrae and discs of the lumbar spine was developed to represent interbody and posterolateral fusion sites. Computer simulations of the induced electromagnetic fields were analysed to determine coverage of the fusion sites. For both interbody and posterolateral fusion models, combined magnetic fields provided 100 % coverage of the fusion sites for all intervertebral disc spaces and for all posterior planes from L1 to L5, respectively. Within the vertebral column, the magnitude of the electric field reached a maximum value of 3.6 × 10−4 V/m, which is several orders of magnitude less than any reported study demonstrating a biological effect. Given its clinical efficacy, a bone growth stimulator utilizing combined magnetic fields must rely on the action of its magnetic field rather than its electric field for a therapeutic effect.

Minimally invasive percutaneous endoscopic 2 levels adjacent lumbar discectomy through 1 portal skin incision: Preliminary study.

Background:Acute lumbar disc herniation can occur in every lumbar intervertebral disc space and in multiple levels simultaneously. In the cases of 2 levels adjacent lumbar disc herniations of severe unilateral radiculopathic leg pain caused by compression of the nerve roots, respectively, multiple incision or long incision is generally needed for simultaneous removal of disc fragment in 2 levels.Objectives:We proposed the minimally invasive one portal skin incision endoscopic discectomy is effective and safe method to treat 2 levels adjacent lumbar disc herniation.Materials and Methods:We have experimented total 8 cases of 2 levels adjacent lumbar disc herniation having unilateral radiculopathic pain respectively. All cases are 2 levels adjacent lumbar disc herniation. We have tried a percutaneous endoscopic transforaminal approach through minimal one portal skin incision and remove the two herniated disc materials in the adjacent levels.Results:The L2-L3 level was involved in 2 patients, L3-L4 level in 6 patients, while the L4-L5 level was involved in 7 patients, L5-S1 level in 1 patient. The mean follow-up was 18.5 months. The mean visual analogue score (VAS) of the patients prior to surgery was 7.75, and the mean postoperative VAS was 2.375. According to Macnab's criteria, 3 patients had excellent results, 4 patients had good results, 1 patient had fair results, and no patient had a poor result; satisfactory results were obtained in 87.5% of the cases.Conclusion:The percutaneous endoscopic transforaminal approach through 1 skin portal incision could be effective surgical method in unilateral adjacent 2 levels lumbar disc herniation.

Adjacent Segment Degeneration after Cervical Disc Surgery: Comparison of One-Level Cervical Disc Arthroplasty versus Anterior Cervical Interbody Fusion: 7-Year Radiological Follow-Up

Introduction Cervical disc arthroplasty and anterior cervical interbody fusion provide the same clinical result in the surgical treatment of degenerative disc disease. The main theoretical advantage of motion preservation is its preventive effect on the adjacent disc degeneration. The aim of our study was to compare the radiological results at the 7-year follow-up after disc replacement and after fusion. Patients and Methods Since January 2006 to December 2007, 17 patients underwent one-level cervical disc arthroplasty (group A), and 17 patients were operated with one-level interbody fusion (group B). ROM of the adjacent segment, dimensions of the adjacent intervertebral disc space, ROM and alignment of the whole cervical spine, and presence of heterotopic ossification were evaluated preoperatively and at 7-year follow-up. All the measurements were done by independent radiologist on the digital anteroposterior, lateral, and flexion/extension X-rays. Results The adjacent disc height decreased in both groups, but the decrease was more significant in the fusion group. Mean disc height was 4.13 mm (preoperative) and 4.03 mm (postoperative) in group A, and 4.02 mm (preoperative) and 3.83 mm (postoperative) in group B. The sagittal ROM of the adjacent segment was higher in the arthroplasty group (group A: 10.89 degrees, group B: 9.5 degrees). The cervical lordosis was significantly higher in the fusion group (group A: 11.81 degrees, group B: 18.59 degrees, p &lt; 0.05). In the arthroplasty group, the mean ROM of the operated level was 11.4 degrees preoperatively and 11.12 degrees postoperatively ( p &gt; 0.05). A total of 64.7% of the patients had any sign of heterotopic ossification. Conclusion The segment of the prosthesis ultimately showed preservation of the preoperative motion. The decrease of the intervertebral disc height, and the ROM (flexion/extension) in the adjacent segments was more significant in the fusion group, so the disc degeneration process seems to be faster after fusion than arthroplasty. The restoration of the lordosis is more effective with fusion than arthroplasty. The early experience is promising but long-term follow-up studies are required to prove the theoretical advantages of the arthroplasty in the prevention of the adjacent segment degeneration.

Pediatric Spontaneous Discitis: A Case Report

Discitis in children is a benign self-limiting inflammatory or infectious lesion of the intervertebral disc space. Spondylitis/spondylodiscitis is still an uncommon diagnosis, often with delay in diagnosis and treatment due to uncharacteristic symptoms. The aim of this study is to increase the awareness and outline a pattern of investigation and treatment. The clinical signs were general irritability, abdominal or hip pain, and refusal to walk or to sit. The unspecificity of the symptoms, laboratory findings, and the late plain radiology detection does often delay the final diagnosis.

Cervical intervertebral foraminal disc extrusion in dogs: clinical presentation, MRI characteristics and outcome after medical management

The aim of the present study was to retrospectively evaluate the clinical signs, MRI characteristics, interobserver agreement and outcome after medical treatment in dogs affected by cervical intervertebral foraminal disc...

Neurological signs and pre- and post-traction low-field MRI findings in Dobermanns with disc-associated cervical spondylomyelopathy.

To investigate whether the presence of neurological signs and magnetic resonance imaging findings could predict the presence of a traction-responsive lesion in Dobermanns affected by disc-associated cervical spondylomyelopathy. Retrospective review of neurological signs and low-field pre- and post-traction magnetic resonance imaging abnormalities of the cervical spine (abnormal vertebral body shape and vertebral tipping, intervertebral disc degeneration, protrusion and ligamentum flavum hypertrophy) in Dobermanns with disc-associated cervical spondylomyelopathy. The main outcome of interest was response to linear traction (dynamic versus static) at C6-C7 intervertebral disc space. The association between investigated variables and response to linear traction was assessed. The study included 25 dogs. No association was identified between neurological status grading and the presence of a static or traction-responsive lesion. Of the investigated magnetic resonance findings, C7-T1 intervertebral disc degeneration was significantly (P = 0 · 03) associated with the presence of a traction-responsive lesion at C6-C7 intervertebral disc space. The presence of C7-T1 intervertebral disc degeneration might help in predicting the presence of traction-responsive C6-C7 intervertebral disc lesions.

Quantitation of circumferential syndesmophyte height along the vertebral rim in ankylosing spondylitis using computed tomography.

Using the 3-D imaging capability of computed tomography (CT), we developed an algorithm quantitating syndesmophyte height along the entire vertebral rim. We investigated its reliability and sensitivity to change, performed a 2-year longitudinal study, and compared it to CT measures of syndesmophyte volume. We performed thoracolumbar spine CT scans on 33 patients at baseline, Year 1, and Year 2, and computed syndesmophyte height in 4 intervertebral disc spaces (IDS). Height was computed every 5° (72 angular sectors) along the vertebral rim. These 72 measures were summed to form the circumferential height per IDS, and results from 4 IDS were summed to provide results per patient. To assess reliability, we compared results between 2 scans performed on the same day in 9 patients. Validity was assessed by associations with spinal flexibility. Coefficient of variation for circumferential syndesmophyte height was 0.893% per patient, indicating excellent reliability. Based on the Bland-Altman analysis, an increase in circumferential height of more than 3.44% per patient represented a change greater than measurement error. At years 1 and 2, mean (SD) circumferential syndesmophyte height increases were 10.2% (11.7%) and 16.1% (14.0%), respectively. Sensitivity to change was 0.72 and 0.87 at years 1 and 2, respectively. Circumferential syndesmophyte height correlated with the Schober test (r = -0.56, p = 0.0003) and lateral thoracolumbar flexion (r = -0.73, p < 0.0001). CT-based circumferential syndesmophyte height had excellent reliability and good sensitivity to change. It was more highly correlated with spine flexibility than syndesmophyte volume. The algorithm shows promise for longitudinal studies of syndesmophyte growth.

Spondylodiscitis Challenging Diagnosis in Immune Competent Child: A Case Report.

Spondylodiscitis, a combination of spondylitis and discitis, is an infection of the spine that involves the intervertebral disc and the vertebral body. Patients presented with little specific symptoms and suspicion for diagnosis is required. This report aimed to describe a female child patient with spondylodiscitis and to describe the diagnostic and therapeutic tools of such patient. This report recorded 2 year-old female child presented by fever, pain associated with standing and sitting, and 10 days history of refusal to walk in Prince Sultan Medical City, Riyadh, Saudi Arabia. Laboratory investigations as well as hip and knee ultrasound showed no abnormalities. However, and hip and lower back Magnetic Resonance Image (MRI) showed evidence of abnormal hyper intensity with enhancement of the bone marrow involving the vertebral bodies and adjacent endplates of 5th lumber (L5) and 1st sacral (S1) vertebrae with involvement of intervertebral disc space and paravertebral soft tissue component. Spondylodiscitis was suggested in the child, and conservative management by medical team of pediatrics and orthopedics consultant has immediately started. The treatment included antibiotics, non-steroidal analgesia and physical rehabilitation. The patient was completely evolved from condition within days. MRI taken 6 weeks later showed significant interval improvement of signs of spondylodiscitis, and the girl has been seen in the clinic after 4 months from discharge in good condition. Spondylodiscitis has to be considered in young children with acute ambulation changes. Prompt diagnosis and treatment involving the entire multidisciplinary team is emphasized in order to improve the prognosis of such patients.

The outcomes of arthroplasty in degenerative lesions in the lumbar spine

A retrospective study. To investigate the safety and effectiveness of total intervertebral disc replacement with a Maverick prosthesis in patients with discogenic pain in the lower lumbar spine. Lumbar disc arthroplasty has been developed as an alternative to rigid interbody fusion for patients with pathology in the lower lumbar discs. According to the developers, motion preservation in the operated segment should prevent secondary pathology of the adjacent segments. From November 2007 to date, 41 patients have been operated on and 42 disc prostheses have been placed. All patients underwent surgery in the same hospital by the same surgeon. The clinical and radiological results of treatment of 35 patients were studied. The patients were examined before surgery, immediately after surgery and then in the intervals of 3-6, 6-12, 12-24, and 36-48 months. The longest follow-up was 61 months. Mean follow-up was 30 months. Patients operated on using total intervertebral disc prosthesis demonstrated a significant improvement compared to their preoperative status. A significant reduction of back and leg pain intensity was observed. The quality of life significantly improved. The intervertebral disc space height, the sagittal balance and the balance in the adjacent levels were restored and preserved after correction. The motion in the implanted segment was preserved. Total lumbar disc replacement with a Maverick prosthesis has proved to be an effective and safe technique. The clinical and radiological methods showed the significant improvement of the patients' status.

The Microscopic Pictures of Degenerative Intervertebral Disc of Different Diseases with Additional Safranin-O Stain

Background: The lumbar spine and cervical spine are vulnerable with degeneration, which is related to idiosyncratic problem, aging or improper stress of the spine. Biochemical and structural changes of disc, narrowing of intervertebral disc space, acute or chronic disc protrusion related to disc degeneration with/without neural symptoms are well documented. We are interested in the morphologic changes of the excised herniated or degenerative discs from the spinal surgeries for herniated intervertebral disc (HIVD), spondylolisthesis or spinal stenosis. Methods: The specimens are collected under the permission of institutional review board (IRB), and are divided into three main groups, including 9 specimens (9 cases) of HIVD, 12 specimens (10 cases) of spondylolisthesis, and 10 specimens (10 cases) of spinal stenosis. Five disc specimens of 3 cadavers (3 from lumbar L4-5 disc and 2 from thoracic T9-10 disc) with no mentioned disc disease are obtained for control group. Histochemical stains of hematoxylin and eosin (H and E) stain and safranin-O-fast green stain are performed to evaluate the content of glycosaminoglycans and chondrocytic proliferation. The photos of disc lesions are taken with consistent LED light of Niko n Coolscope II to analyze the discoloration within the H and E and safranin-O stained sections. Kruskal-Wallis test (one-way ANOVA) was performed for significance check. Results: HIVD cases have younger age (p=0.036). The excised disc specimens of HIVD group show mild loss of glycosaminoglycans over nucleus pulposus, and even less eosinophilic change in the nucleus pulposus. The discs of spondylolisthesis and spinal stenosis groups may display uneven loss of glycosaminoglycans with occasionally massive loss, and more eosinophilic change than that of HIVD group (p=0.014). Clonal proliferation of chondrocytes over the areas other than endplate and outer rim of annulus fibrosus is a consistent phenomenon in all three groups of degenerative discs, and displaying lesser degree of chondrocytic proliferation among the HIVD cases without significant difference. Conclusion: We notice that focal eosinophilic change or even necrosis of extracellular matrix is probable an important pathologic picture of degenerative disc and clonal proliferation of chondrocytes is present in all 3 groups of degenerative intervertebral discs. The chondrocytic proliferation in the disc fibrocartilage might be similar to the chondrocytic proliferation within the articular cartilage of grade 3-4/6 knee osteoarthritis.

Avoidance of Wrong Level Surgery in the Lumbar Spine: A Technical Report

Study Background: Wrong level surgery remains one of the detrimental technical mistakes that can occur during a surgeon’s career. There is a higher frequency of wrong site surgery in the lumbar spine compared to the cervical spine. The authors aim to present a localization technique designed to aid in the prevention of wrong level surgery with the use of preoperative and intraoperative localization. Methods: We prospectively followed 240 patients who underwent less exposure surgery for the lumbar spine. We identified the correct operative level using a combination of a 22-guage spinal needle placed under fluoroscopy in the lamina of the vertebra of the target intervertebral disc space prior to incision and then placing a hooked dilator between the spinous processes of the intervertebral space to provide actual confirmation within the operative space. Results: Data showed that all 240 patients had surgery performed on the correct level using the described technique and the placement of the percutaneous needle assisted in minimizing the incision size to less than 5 cm for a single level fusion in all cases. Conclusion: The described technique allows for localization prior to incision, smaller incision size, consistent and accurate localization when performing lumbar spinal surgery.

Radiographical and clinical evaluation of extreme lateral interbody fusion: effects of cage size and instrumentation type with a minimum of 1-year follow-up.

Prospective single-cohort observational study. To compare cage settling rates after extreme lateral interbody fusion (XLIF) across various implant sizes and fixation types. Secondary objectives were to detect factors associated with cage settling and correlation with clinical and radiographical improvement. Intervertebral cage settling can occur postoperatively after interbody fusion, limiting the long-term correction achieved with surgery. Clinical and radiographical data were collected on 140 consecutive patients treated with extreme lateral interbody fusion at 223 levels (range, 1-5). All patients received supplemental pedicle screw fixation or lateral plating. Average follow-up was 15.5 months (range, 12-36 mo). At 12 months, disability improved by 44%, low back pain improved by 49%, leg pain improved by 48%, and quality of life improved by 50% (P < 0.001). Foraminal height improved from 15.7 mm to 21.2 mm, disc height improved from 4.6 mm to 9.4 mm, discal lordosis improved from 4.0 to 8.1, and segmental lordosis improved from 10.7 to 13.7 (P < 0.001). Cage settling 1 mm or more occurred in 20% of cages immediately postoperatively and in 62% at 12 months. Settling more than 4 mm occurred in 5% of cages immediately postoperatively and in 24% at 12 months postoperatively. Pedicle screw fixation was associated with a higher rate of cage settling 1 mm or more compared with lateral plating, though magnitude of settling at the anterior inferior endplate was higher for lateral plating (4.9 mm vs. 3.5 mm). Taller cage height, narrower cage width, and shorter cage length were significantly associated with increased risk of cage settling more than 4 mm at 12 months postoperatively. In patients with no cage settling immediately postoperatively, risk of settling more than 4 mm at 12 months was 6.8 times greater with narrower cages. Risk of cage settling after extreme lateral interbody fusion may be reduced with the use of wider cages to engage more central endplate bone, longer cages to span the ring apophysis and osteophytes, and avoid overdistraction of the intervertebral disc space with shorter cages. 3.

Dynamics of syndesmophyte growth in AS as measured by quantitative CT: heterogeneity within and among vertebral disc spaces.

Syndesmophytes in AS typically grow slowly, but it is not known whether growth is uniform among syndesmophytes in the same intervertebral disc space (IDS) or among different IDSs in the same patient or if growth is heterogeneous. We examined the dynamics of syndesmophyte growth over 24 months using CT, with the main aim of determining if syndesmophytes in the same IDS or the same patient grow at similar rates. We performed lumbar spine CT scans on 33 patients and measured syndesmophytes in four IDSs using a validated computer algorithm. Scans were done at baseline and 12 and 24 months. We compared absolute and percentage changes in volume from baseline to 12 months and to 24 months among syndesmophytes in the same IDS and among four IDSs of each patient. We also examined whether growth among all IDSs differed between study years. Among 60 IDSs with at least two syndesmophytes at baseline (range 2-6), there was substantial heterogeneity in both absolute (P < 0.0001) and percentage (P = 0.0002) volume increases among syndesmophytes in the same IDS. Several IDSs had both syndesmophytes with no growth and syndesmophytes that increased by >100 mm(3). Similarly there was significant heterogeneity in syndesmophyte growth among IDSs of individual patients. Increases in total syndesmophyte volume for each patient also tended to differ between study years (P = 0.07). Syndesmophytes in AS do not all grow continuously. Rates of growth over 24 months commonly differ between syndesmophytes in the same IDS and between different IDSs in the same patient, suggesting that local factors regulate syndesmophyte growth.