Ventral Cervical Fusion Research Articles

485 Evaluating Surgical Arthrodesis With Novel MRI Grading Score

INTRODUCTION: Diagnostic imaging following cervical fusion often involves magnetic resonance imaging (MRI) to evaluate neural structures and computed tomography (CT) and/or dynamic radiographs to evaluate instrumentation and arthrodesis. CT and radiographs use ionizing radiation that increases risk for malignancy. Using MRI alone would protect patients and decrease healthcare utilization. METHODS: Single institution retrospective study evaluating patients who received postoperative CT and MRI following ventral cervical fusion procedures. Radiographic standards were used to evaluate for arthrodesis or pseudo-arthrosis. Blinded observers evaluated signal intensity using a region of interest (ROI) over the instrumented disc space, homogenous cerebral spinal fluid (CSF), and distal uninstrumented vertebral body (VB). A quotient (ROIinterspace/ROICSF and ROIinterspace/ROIVB) was used to create T1- and T2-interspace interbody scores (IIS). Additionally, T1 hypointense lines along endplates and facet joints were evaluated for degree of discontinuity. RESULTS: Study included 60 patients (50% female) with 110 instrumented levels and mean age 51.7 years-old. For T1-weighted MRI, median T1-IISCSF for arthrodesis was 176.2 compared to 130.9 for pseudo-arthrosis (p < 0.0001) while T1-IISVB for arthrodesis was 68.5 and pseudo-arthrosis was 52.7 (p < 0.0001). For T2-weighted MRI, median T2-IISCSF for arthrodesis was 27.7 and 14.2 for pseudo-arthrosis (p < 0.0001) while T2-IISVB for arthrodesis was 67.9 and 41.0 for pseudo-arthrosis (p < 0.0001). Median T1 hypointense discontinuity was graded at the endplates, left facet, and right facet as 1.5, 0.25, and 0.5 compared to pseudo-arthrosis as 1.0, 0.0, and 0.0, respectively (p < 0.0001, p = 0.002, and p = 0.001). The greatest area under the curve (AUC) after receiver operator characteristic (ROC) analysis was T1-IISVB (0.7743). CONCLUSIONS: We describe a novel scoring system that may help determine arthrodesis versus pseudo-arthrosis on MRI following ventral cervical fusion. Postoperative symptomatic patients may only require MRI for workup, which would protect patients from harm while decreasing healthcare utilization.

Outcome of Ventral Fusion of Two or Three Cervical Vertebrae with a Locking Compression Plate for the Treatment of Cervical Stenotic Myelopathy in Eight Horses.

It was recently shown that biomechanical stability achieved with a locking compression plate (LCP) for ventral cervical fusion in horses is similar to the commonly used Kerf cut cylinder. The advantages of the LCP system render it an interesting implant for this indication. The goal of this report was to describe surgical technique, complications and outcome of horses that underwent ventral fusion of two or three cervical vertebrae with an LCP. Medical records of eight horses were reviewed for patient data, history, preoperative grade of ataxia, diagnostic imaging, surgical technique and complications. Follow-up information was obtained including clinical re-examination and radiographs whenever possible. Two (n = 5) or 3 (n = 3) cervical vertebrae were fused in a mixed population with a median age of 9 months, median weight of 330 kg and median grade of ataxia of 3/5. A narrow 4.5/5.0 LCP (n = 6), a broad 4.5/5.0 LCP (n = 1) and a human femur 4.5/5.0 LCP (n = 1) were applied. Two horses were re-operated due to implant loosening. Six patients developed a seroma. Long-term complications included ventral screw migration in four, spinal cord injury in one and plate breakage in two horses at 720 to 1116 days after surgery. Outcome was excellent in three, good in four, poor in one patient. The use of an LCP for ventral cervical vertebral fusion is associated with good clinical results. However, a careful surgical technique is required to further reduce the complication rate.

Complications Related to Osteobiologics Use in Spine Surgery

Systematic review. The objectives of this systematic review were to identify the character and rates of complications in patients after the use of BMP in spine fusion surgery and to determine whether there is a dose-response relationship of BMP with complications. BMP is used on-label for ALIF with LT-CAGE and off-label for various spine fusion applications in the cervical, thoracic, and lumbar spines because of its effectiveness in promoting arthrodesis. Multiple studies published over the past several years have highlighted complications associated with BMP in a variety of clinical fusion scenarios. There are no systematic reviews on this topic, and thus, the complication profile of off-label use or physician directed use of BMP in spinal fusion surgery is not well characterized. Some of the reported complications are unique to BMP, which underscores the need for this thorough literature review. A systematic review of the English language literature was performed for articles published between 1990 and June 2009. Electronic databases and reference lists of key articles were searched to identify articles examining the use of BMP in spine surgery. Two independent reviewers assessed the level of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria and disagreements were resolved by consensus. Two hundred forty-' articles that assessed outcomes after BMP use in spinal surgery were identified from the literature; of these, 31 articles were selected for inclusion. We determined that multiple complications are associated after the use of rhBMP-2 in both cervical and lumbar spine fusion surgery. There is a mean incidence of 44%, 25%, and 27% of resorption, subsidence, and interbody cage migration reported for lumbar spine interbody fusion surgery although reoperation or long-term detrimental effect was rare. Cervical studies report a mean 5.8% of postoperative soft tissue problems, including dysphagia, when rhBMP-2 is used for ventral cervical fusion. It was determined that the strength of evidence of the peer-reviewed literature that report on types of complications is high for the lumbar and low for the cervical spine, respectively, and that the current strength of evidence on rates of complications with BMP is moderate and low, respectively. The complication profile of BMP-2 for ALIF with LT-CAGE is well characterized. Because of the lack of substantive data, the same is not true for other types of lumbar fusions, or for cervical or thoracic fusion applications. BMP has been associated with a variety of unique complications in the ventral cervical and lumbar spines. The published data on BMP fail to precisely profile this product's use in fusion surgery; hence, it should be used only after a careful consideration of the relevant data. Well-designed and executed studies are necessary to completely define the incidence of various complications relative to type of BMP, type and region of fusion, surgical technique, dose, and carrier, and importantly, to define the natural history and management of associated complications.

Comment to “Ventral cervical fusion at multiple levels using free vascularized double-islanded fibula - a technical report and review of the relevant literature” by K. G. Krishnan and A. Müller

Comment to “Ventral cervical fusion at multiple levels using free vascularized double-islanded fibula - a technical report and review of the relevant literature” by K. G. Krishnan and A. Müller

Intradiscal pressure recordings in the cervical spine.

Experimental investigations analyzing the biomechanics of the cervical spine are less common than similar studies of other regions of the spine. There are no reports on cervical intradiscal pressure (PID) measurements in vitro. We therefore wanted to establish normal values for PID under physiological conditions by simultaneous muscle force simulation. Moreover, the impact of ventral cervical fusion should be elucidated, because in clinical studies, it is a well-known phenomenon that the adjacent segments often show increased degenerative changes. We present a pilot study. Seven human cervical spine specimens were tested biomechanically in a specially developed spine tester. Only pure moments were used for flexion/extension, axial rotation, and lateral bending (maximal moment +/- 0.5 Nm). PID was measured simultaneously in C3-C4 and C5-C6. The specimens were tested as intact specimens and after discectomy and fusion in C4-C5. Both test situations were repeated with simulation of muscle forces. We found characteristic load-pressure curves for each of the three motion axes. In neutral position, PID correlated well with former published data from in vivo measurements. After fusion of C4-C5, there was a marked increase of PID in both adjacent segments (e.g., < or = 180% for axial rotation). With muscle force simulation, the increase was even higher (e.g., < or = 400% for axial rotation). For the first time, PID could be measured in the cervical spine in an experimental setting. The results obtained using normal specimens under physiological conditions confirmed those reported in two clinical studies. After cervical fusion, a marked increase in PID could be found in both adjacent segments. Presuming that an increase in PID had a negative effect on metabolism of the intervertebral disc, our results may help to explain why progressive degeneration occurs in these segments.

Intradiscal pressure forces on cervical intervertebral discs in physiologic and pathologic conditions. In vitro study

Clinical and experimental studies concerning intradiscal pressure have mainly been carried out using the lumbar spine. It has been shown that degenerative changes in the intervertebral disc and external loads can significantly influence intradiscal pressure. To see if these findings are also relevant for cervical discs, we carried out an in vitro study using human cervical spine specimens. The specimens were tested biomechanically under various conditions with simultaneous recording of intradiscal pressure in two cervical discs. We were able to confirm in vivo measurements of intradiscal pressure reported in the literature. Simulation of muscle force led to a marked increase in intradiscal pressure. Moreover, it was demonstrated that ventral cervical fusion has a significant influence on intradiscal pressure in both adjacent segments. In general, the results improve our understanding of the basic biomechanics of the cervical spine. The experiments with fused specimens could help to explain why degeneration is accelerated in adjacent motion segments after ventral cervical fusion.

Stress exertion on adjacent segments after ventral cervical fusion.

Special investigations of the adjacent segments are performed in patients with cervical fusion operations caused by different indications: Only a few of alteration was seen after operations caused by infectious disease, tumor or trauma. A different situation arises with degenerative lesions, where often progressive changes were seen in the adjacent segments. This phenomena may be dependent at first of the kind of lesion (degeneration) and only at second of the kind of operation.