Human Disc Nucleotomy Alters Annulus Fibrosus Mechanics at Both Reference and Compressed Loads.

Nucleotomy is a common surgical procedure and is also performed in ex vivo mechanical testing to model decreased nucleus pulposus (NP) pressurization that occurs with degeneration. Here, we implement novel and noninvasive methods using magnetic resonance imaging (MRI) to study internal 3D annulus fibrosus (AF) deformations after partial nucleotomy and during axial compression by evaluating changes in internal AF deformation at reference loads (50 N) and physiological compressive loads (∼10% strain). One particular advantage of this methodology is that the full 3D disc deformation state, inclusive of both in-plane and out-of-plane deformations, can be quantified through the use of a high-resolution volumetric MR scan sequence and advanced image registration. Intact grade II L3-L4 cadaveric human discs before and after nucleotomy were subjected to identical mechanical testing and imaging protocols. Internal disc deformation fields were calculated by registering MR images captured in each loading state (reference and compressed) and each condition (intact and nucleotomy). Comparisons were drawn between the resulting three deformation states (intact at compressed load, nucleotomy at reference load, nucleotomy at compressed load) with regard to the magnitude of internal strain and direction of internal displacements. Under compressed load, internal AF axial strains averaged -18.5% when intact and -22.5% after nucleotomy. Deformation orientations were significantly altered by nucleotomy and load magnitude. For example, deformations of intact discs oriented in-plane, whereas deformations after nucleotomy oriented axially. For intact discs, in-plane components of displacements under compressive loads oriented radially outward and circumferentially. After nucleotomy, in-plane displacements were oriented radially inward under reference load and were not significantly different from the intact state at compressed loads. Re-establishment of outward displacements after nucleotomy indicates increased axial loading restores the characteristics of internal pressurization. Results may have implications for the recurrence of pain, design of novel therapeutics, or progression of disc degeneration.

Theory of MRI contrast in the annulus fibrosus of the intervertebral disc.

OBJECTIVE: Here we develop a three-dimensional analytic model for MR image contrast of collagen lamellae in the annulus fibrosus of the intervertebral disc of the spine, based on the dependence of the MRI signal on collagen fiber orientation. MATERIALS AND METHODS: High-resolution MRI scans were performed at 1.5 and 7 T on intact whole disc specimens from ovine, bovine, and human spines. An analytic model that approximates the three-dimensional curvature of the disc lamellae was developed to explain inter-lamellar contrast and intensity variations in the annulus. The model is based on the known anisotropic dipolar relaxation of water in tissues with ordered collagen. RESULTS: Simulated MRI data were generated that reproduced many features of the actual MRI data. The calculated inter-lamellar image contrast demonstrated a strong dependence on the collagen fiber angle and on the circumferential location within the annulus. CONCLUSION: This analytic model may be useful for interpreting MR images of the disc and for predicting experimental conditions that will optimize MR image contrast in the annulus fibrosus.

Internal three-dimensional strains in human intervertebral discs under axial compression quantified noninvasively by magnetic resonance imaging and image registration.

Study objectives were to develop, validate, and apply a method to measure three-dimensional (3D) internal strains in intact human discs under axial compression. A custom-built loading device applied compression and permitted load-relaxation outside of the magnet while also maintaining compression and hydration during imaging. Strain was measured through registration of 300 µm isotropic resolution images. Excellent registration accuracy was achieved, with 94% and 65% overlap of disc volume and lamellae compared to manual segmentation, and an average Hausdorff, a measure of distance error, of 0.03 and 0.12 mm for disc volume and lamellae boundaries, respectively. Strain maps enabled qualitative visualization and quantitative regional annulus fibrosus (AF) strain analysis. Axial and circumferential strains were highest in the lateral AF and lowest in the anterior and posterior AF. Radial strains were lowest in the lateral AF, but highly variable. Overall, this study provided new methods that will be valuable in the design and evaluation surgical procedures and therapeutic interventions.

Can axial loading restore in vivo disc geometry, opening pressure, and T2 relaxation time?

Background: Cadaveric intervertebral discs are often studied for a variety of research questions, and outcomes are interpreted in the in vivo context. Unfortunately, the cadaveric disc does not inherently represent the LIVE condition, such that the disc structure (geometry), composition (T2 relaxation time), and mechanical function (opening pressure, OP) measured in the cadaver do not necessarily represent the in vivo disc. Methods: We conducted serial evaluations in the Yucatan minipig of disc geometry, T2 relaxation time, and OP to quantify the changes that occur with progressive dissection and used axial loading to restore the in vivo condition. Results: We found no difference in any parameter from LIVE to TORSO; thus, within 2 h of sacrifice, the TORSO disc can represent the LIVE condition. With serial dissection and sample preparation the disc height increased (SEGMENT height 18% higher than TORSO), OP decreased (POTTED was 67% lower than TORSO), and T2 time was unchanged. With axial loading, an imposed stress of 0.20-0.33 MPa returned the disc to in vivo, LIVE disc geometry and OP, although T2 time was decreased. There was a linear correlation between applied stress and OP, and this was conserved across multiple studies and species. Conclusion: To restore the LIVE disc state in human studies or other animal models, we recommend measuring the OP/stress relationship and using this relationship to select the applied stress necessary to recover the in vivo condition.

Biaxial tension of fibrous tissue: using finite element methods to address experimental challenges arising from boundary conditions and anisotropy.

Planar biaxial tension remains a critical loading modality for fibrous soft tissue and is widely used to characterize tissue mechanical response, evaluate treatments, develop constitutive formulas, and obtain material properties for use in finite element studies. Although the application of tension on all edges of the test specimen represents the in situ environment, there remains a need to address the interpretation of experimental results. Unlike uniaxial tension, in biaxial tension the applied forces at the loading clamps do not transmit fully to the region of interest (ROI), which may lead to improper material characterization if not accounted for. In this study, we reviewed the tensile biaxial literature over the last ten years, noting experimental and analysis challenges. In response to these challenges, we used finite element simulations to quantify load transmission from the clamps to the ROI in biaxial tension and to formulate a correction factor that can be used to determine ROI stresses. Additionally, the impact of sample geometry, material anisotropy, and tissue orientation on the correction factor were determined. Large stress concentrations were evident in both square and cruciform geometries and for all levels of anisotropy. In general, stress concentrations were greater for the square geometry than the cruciform geometry. For both square and cruciform geometries, materials with fibers aligned parallel to the loading axes reduced stress concentrations compared to the isotropic tissue, resulting in more of the applied load being transferred to the ROI. In contrast, fiber-reinforced specimens oriented such that the fibers aligned at an angle to the loading axes produced very large stress concentrations across the clamps and shielding in the ROI. A correction factor technique was introduced that can be used to calculate the stresses in the ROI from the measured experimental loads at the clamps. Application of a correction factor to experimental biaxial results may lead to more accurate representation of the mechanical response of fibrous soft tissue.

Evaluation of intervertebral disc cartilaginous endplate structure using magnetic resonance imaging.

PURPOSE: The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage positioned between the vertebral endplate and nucleus pulposus (NP) that functions both as a mechanical barrier and as a gateway for nutrient transport into the disc. Despite its critical role in disc nutrition and degeneration, the morphology of the CEP has not been well characterized. The objective of this study was to visualize and report observations of the CEP three-dimensional morphology, and quantify CEP thickness using an MRI FLASH (fast low-angle shot) pulse sequence. METHODS: MR imaging of ex vivo human cadaveric lumbar spine segments (N = 17) was performed in a 7T MRI scanner with sequence parameters that were selected by utilizing high-resolution T1 mapping, and an analytical MRI signal model to optimize image contrast between CEP and NP. The CEP thickness at five locations along the mid-sagittal AP direction (center, 5 mm, 10 mm off-center towards anterior and posterior) was measured, and analyzed using two-way ANOVA and a post hoc Bonferonni test. For further investigation, six in vivo volunteers were imaged with a similar sequence in a 3T MRI scanner. In addition, decalcified and undecalcified histology was performed, which confirmed that the FLASH sequence successfully detected the CEP. RESULTS: CEP thickness determined by MRI in the mid-sagittal plane across all lumbar disc levels and locations was 0.77 ± 0.24 mm ex vivo. The CEP thickness was not different across disc levels, but was thinner toward the center of the disc. CONCLUSIONS: This study demonstrates the potential of MRI FLASH imaging for structural quantification of the CEP geometry, which may be developed as a technique to evaluate changes in the CEP with disc degeneration in future applications.

MRI-based measurement of in vivo disc mechanics in a young population due to flexion, extension, and diurnal loading.

Background: Intervertebral disc degeneration is often implicated in low back pain; however, discs with structural degeneration often do not cause pain. It may be that disc mechanics can provide better diagnosis and identification of the pain source. In cadaveric testing, the degenerated disc has altered mechanics, but in vivo, disc mechanics remain unknown. To measure in vivo disc mechanics, noninvasive methods must be developed to apply and measure physiological deformations. Aim: Thus, this study aimed to develop methods to measure disc mechanical function via noninvasive MRI during flexion and extension and after diurnal loading in a young population. This data will serve as baseline disc mechanics to later compare across ages and in patients. Materials & Methods: To accomplish this, subjects were imaged in the morning in a reference supine position, in flexion, in extension, and at the end of the day in a supine position. Disc deformations and vertebral motions were used to quantify disc axial strain, changes in wedge angle, and anterior-posterior (A-P) shear displacement. T2 weighted MRI was also used to evaluate disc degeneration via Pfirrmann grading and T2 time. All measures were then tested for effect of sex and disc level. Results: We found that flexion and extension caused level-dependent strains in the anterior and posterior of the disc, changes in wedge angle, and A-P shear displacements. Flexion had higher magnitude changes overall. Diurnal loading did not cause level-dependent strains but did cause small level-dependent changes in wedge angle and A-P shear displacements. Discussion: Correlations between disc degeneration and mechanics were largest in flexion, likely due to the smaller contribution of the facet joints in this condition. Conclusion: In summary, this study established methods to measure in vivo disc mechanical function via noninvasive MRI and established a baseline in a young population that may be compared to older subjects and clinical disorders in the future.

Multiaxial validation of a finite element model of the intervertebral disc with multigenerational fibers to establish residual strain.

Finite element models of the intervertebral disc are used to address research questions that cannot be tested through typical experimentation. A disc model requires complex geometry and tissue properties to be accurately defined to mimic the physiological disc. The physiological disc possesses residual strain in the annulus fibrosus (AF) due to osmotic swelling and due to inherently pre-strained fibers. We developed a disc model with residual contributions due to swelling-only, and a multigeneration model with residual contributions due to both swelling and AF fiber pre-strain and validated it against organ-scale uniaxial, quasi-static and multiaxial, dynamic mechanical tests. In addition, we demonstrated the models' ability to mimic the opening angle observed following radial incision of bovine discs. Both models were validated against organ-scale experimental data. While the swelling only model responses were within the experimental 95% confidence interval, the multigeneration model offered outcomes closer to the experimental mean and had a bovine model opening angle within one SD of the experimental mean. The better outcomes for the multigeneration model, which allowed for the inclusion of inherently pre-strained fibers in AF, is likely due to its uniform fiber contribution throughout the AF. We conclude that the residual contribution of pre-strained fibers in the AF should be included to best simulate the physiological disc and its behaviors.

Impact of pulse sequence, analysis method, and signal to noise ratio on the accuracy of intervertebral disc T 2 measurement.

Noninvasive assessments of intervertebral disc health and degeneration are critical for addressing disc degeneration and low back pain. Magnetic resonance imaging (MRI) is exceptionally sensitive to tissue with high water content, and measurement of the MR transverse relaxation time, T 2, has been applied as a quantitative, continuous, and objective measure of disc degeneration that is linked to the water and matrix composition of the disc. However, T 2 measurement is susceptible to inaccuracies due to Rician noise, T 1 contamination, and stimulated echo effects. These error generators can all be controlled for with proper data collection and fitting methods. The objective of this study was to identify sequence parameters to appropriately acquire MR data and to establish curve fitting methods to accurately calculate disc T 2 in the presence of noise by correcting for Rician noise. To do so, we compared T 2 calculated from the typical monoexponential (MONO) fits and noise corrected exponential (NCEXP) fits. We examined how the selected sequence parameters altered the calculated T 2 in silico and in vivo. Typical MONO fits were frequently poor due to Rician noise, and NCEXP fits were more likely to provide accurate T 2 calculations. NCEXP is particularly less biased and less uncertain at low SNR. This study showed that the NCEXP using sequences with data from 20 echoes out to echo times of ~300 ms is the best method for calculating T 2 of discs. By acquiring signal data out to longer echo times and accounting for Rician noise, the curve fitting is more robust in calculating T 2 despite the noise in the data. This is particularly important when considering degenerate discs or AF tissue because the SNR of these regions is lower.

Introduction and methodology: guidelines for the surgical management of cervical degenerative disease.

In March 2006, the Joint Section on Disorders of the Spine and Peripheral Nerves of the American Association of Neurological Surgeons and Congress of Neurological Surgeons compiled an expert group to perform an evidence-based review of the clinical literature on management of cervical degenerative spine disease. This process culminated in the formation of the Guidelines for the Surgical Management of Cervical Degenerative Disease. The purpose of the Guidelines was to address questions regarding the therapy, diagnosis, and prognosis of cervical degenerative disease using an evidence-based approach. Development of an evidence-based review and recommendations is a multitiered process. Typical guideline development consists of 5 processes: 1) collection and selection of the evidence; 2) assessment of the quality and strength of the evidence; 3) analysis of the evidentiary data; 4) formulation of recommendations; and 5) guideline validation. This manuscript details the methodology in compiling the Guidelines for the Surgical Management of Cervical Degenerative Disease.

The natural history of cervical spondylotic myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to delineate the natural history of cervical spondylotic myelopathy (CSM) and identify factors associated with clinical deterioration. METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to the natural history of CSM. Abstracts were reviewed and studies meeting the inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons. RESULTS: The natural history of CSM is mixed: it may manifest as a slow, stepwise decline or there may be a long period of quiescence (Class III). Long periods of severe stenosis are associated with demyelination and may result in necrosis of both gray and white matter. With severe and/or long lasting CSM symptoms, the likelihood of improvement with nonoperative measures is low. Objectively measurable deterioration is rarely seen acutely in patients younger than 75 years of age with mild CSM (modified Japanese Orthopaedic Association scale score > 12; Class I). In patients with cervical stenosis without myelopathy, the presence of abnormal electromyography findings or the presence of clinical radiculopathy is associated with the development of symptomatic CSM in this patient population (Class I). CONCLUSIONS: The natural history of CSM is variable, which may affect treatment decisions.

Clinical prognostic indicators of surgical outcome in cervical spondylotic myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to assess whether clinical factors predict surgical outcomes in patients undergoing cervical surgery. METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to clinical preoperative factors. Abstracts were reviewed, and studies that met the inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Preoperative sensory-evoked potentials may aid in providing prognostic information in selected patients in whom clinical factors do not provide clear guidance (Class II). Age, duration of symptoms, and preoperative neurological function may commonly affect outcome (Class III). CONCLUSIONS: Age, duration of symptoms, and preoperative neurological function should be discussed with patients when surgical intervention for cervical spondylotic myelopathy is considered. Preoperative sensory-evoked potentials may be considered for patients in whom clinical factors do not provide clear guidance if such information would potentially change therapeutic decisions.

Cervical surgical techniques for the treatment of cervical spondylotic myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to compare the efficacy of different surgical techniques for the treatment of cervical spondylotic myelopathy (CSM). METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to anterior and posterior cervical spine surgery and CSM. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: A variety of techniques have improved functional outcome after surgical treatment for CSM, including anterior cervical discectomy with fusion (ACDF), anterior cervical corpectomy with fusion (ACCF), laminoplasty, laminectomy, and laminectomy with fusion (Class III). Anterior cervical discectomy with fusion and ACCF appear to yield similar results in multilevel spine decompression for lesions at the disc level. The use of anterior plating allows for equivalent fusion rates between these techniques (Class III). If anterior fixation is not used, ACCF may provide a higher fusion rate than multilevel ACDF but also a higher graft failure rate than multilevel ACDF (Class III). Anterior cervical discectomy with fusion, ACCF, laminectomy, laminoplasty, and laminectomy with arthrodesis all provide near-term functional improvement for CSM. However, laminectomy is associated with late deterioration compared with the other types of anterior and posterior surgeries (Class III). CONCLUSIONS: Multiple approaches exist with similar near-term improvements; however, laminectomy appears to have a late deterioration rate that may need to be considered when appropriate.

Cervical laminectomy for the treatment of cervical degenerative myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to examine the efficacy of cervical laminectomy for the treatment of cervical spondylotic myelopathy (CSM). METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to cervical laminectomy and CSM. Abstracts were reviewed after which studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Laminectomy has improved functional outcome for symptomatic cervical myelopathy (Class III). The limitations of the technique are an increased risk of postoperative kyphosis compared to anterior techniques or laminoplasty or laminectomy with fusion (Class III). However, the development of kyphosis may not necessarily to diminish the clinical outcome (Class III). CONCLUSIONS: Laminectomy is an acceptable therapy for near-term functional improvement of CSM (Class III). It is associated with development of kyphosis, however.

Laminectomy and fusion for the treatment of cervical degenerative myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to examine the efficacy of cervical laminectomy and fusion for the treatment of cervical spondylotic myelopathy (CSM). METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to cervical laminectomy, fusion, and CSM. Abstracts were reviewed, after which studies that met the inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Class I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations which contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer-review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Cervical laminectomy with fusion (arthrodesis) improves functional outcome in patients with CSM and ossification of the posterior longitudinal ligament (OPLL). Functional improvement is similar to laminectomy or laminoplasty for patients with CSM and OPLL. In contrast to laminectomy, cervical laminectomy with fusion it is not associated with late deformity (Class III). CONCLUSIONS: Laminectomy with fusion (arthrodesis) is an effective strategy to improve functional outcome in CSM and OPLL.

Cervical laminoplasty for the treatment of cervical degenerative myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to examine the efficacy of cervical laminoplasty in the treatment of cervical spondylotic myelopathy (CSM). METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to cervical laminoplasty and CSM. Abstracts were reviewed and studies meeting the inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons and Congress of Neurological Surgeons. RESULTS: Cervical laminoplasty has improved functional outcome in the setting of CSM or ossification of the posterior longitudinal ligament. Using the Japanese Orthopaedic Association scale score, approximately 55-60% average recovery rate has been observed (Class III). The functional improvement observed after laminoplasty may be limited by duration of symptoms, severity of stenosis, severity of myelopathy, and poorly controlled diabetes as negative risk factors (Class II). There is conflicting evidence regarding age, with 1 study citing it as a negative risk factor, and another not demonstrating this result. CONCLUSIONS: Cervical laminoplasty is recommended for the treatment of CSM or ossification of the posterior longitudinal ligament (Class III).

Anterior cervical surgery for the treatment of cervical degenerative myelopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to examine the efficacy of anterior cervical surgery for the treatment of cervical spondylotic myelopathy (CSM). METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and key words relevant to anterior cervical surgery and CSM. Abstracts were reviewed, and studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Mild CSM (modified Japanese Orthopaedic Association [mJOA] scale scores > 12) responds in the short term (3 years) to either surgical decompression or nonoperative therapy (prolonged immobilization in a stiff cervical collar, "low-risk" activity modification or bed rest, and antiinflammatory medications) (Class II). More severe CSM responds to surgical decompression with benefits being maintained a minimum of 5 years and as long as 15 years postoperatively (Class III). CONCLUSIONS: Treatment of mild CSM may involve surgical decompression or nonoperative therapy for the first 3 years after diagnosis. More severe CSM (mJOA scale score

Techniques for anterior cervical decompression for radiculopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to identify the best techniques for anterior cervical nerve root decompression. METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and keywords relevant to techniques for the surgical management of cervical radiculopathy. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer-review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Both anterior cervical discectomy (ACD) and anterior cervical discectomy with fusion (ACDF) are equivalent treatment strategies for 1-level disease with regard to functional outcome (Class II). Anterior cervical discectomy with fusion may achieve a more rapid reduction of neck and arm pain compared to ACD with a reduced risk of kyphosis, although functional outcomes may be similar. Anterior cervical discectomy with fusion is not a lasting means of increasing foraminal or disc height compared to ACD. Anterior cervical plating (ACDF with instrumentation) improves arm pain (but not other clinical parameters) better than ACDF in the treatment of 2-level disease (Class II). With respect to 1-level disease, plating may reduce the risk of pseudarthrosis and graft problems (Class III) but does not necessarily improve clinical outcome alone (Class II). Cervical arthroplasty is recommended as an alternative to ACDF in selected patients for control of neck and arm pain (Class II). CONCLUSIONS: Anterior cervical discectomy, ACDF, and arthroplasty are effective techniques for addressing surgical cervical radiculopathy.

Cervical laminoforaminotomy for the treatment of cervical degenerative radiculopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to examine the efficacy of posterior laminoforaminotomy in the treatment of cervical radiculopathy. METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and key words relevant to posterior laminoforaminotomy and cervical radiculopathy. Abstracts were reviewed, and studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations which contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Posterior laminoforaminotomy improves clinical outcome in the treatment of cervical radiculopathy resulting from soft lateral cervical disc displacement or cervical spondylosis with resulting narrowing of the lateral recess. All studies were Class III. The most frequent design flaw involved the lack of utilization of validated outcomes measures. In addition, few historical studies included a detailed preoperative analysis of the patients. As such, the vast majority of studies that included both pre- and postoperative assessments with legitimate outcomes measures have been performed since 1990. CONCLUSIONS: Posterior laminoforaminotomy is an effective treatment for cervical radiculopathy.

Indications for anterior cervical decompression for the treatment of cervical degenerative radiculopathy.

OBJECT: The objective of this systematic review was to use evidence-based medicine to identify the indications and utility of anterior cervical nerve root decompression. METHODS: The National Library of Medicine and Cochrane Database were queried using MeSH headings and key words relevant to surgical management of cervical radiculopathy. Abstracts were reviewed after which studies meeting inclusion criteria were selected. The guidelines group assembled an evidentiary table summarizing the quality of evidence (Classes I-III). Disagreements regarding the level of evidence were resolved through an expert consensus conference. The group formulated recommendations that contained the degree of strength based on the Scottish Intercollegiate Guidelines network. Validation was done through peer review by the Joint Guidelines Committee of the American Association of Neurological Surgeons/Congress of Neurological Surgeons. RESULTS: Anterior nerve root decompression via anterior cervical discectomy (ACD) with or without fusion for radiculopathy is associated with rapid relief (3-4 months) of arm/neck pain, weakness, and/or sensory loss compared with physical therapy (PT) or cervical collar immobilization. Anterior cervical discectomy and ACD with fusion (ACDF) are associated with longer term (12 months) improvement in certain motor functions compared to PT. Other rapid gains observed after anterior decompression (diminished pain, improved sensation, and improved strength in certain muscle groups) are also maintained over the course of 12 months. However, comparable clinical improvements with PT or cervical immobilization therapy are also present in these clinical modalities (Class I). Conflicting evidence exists as to the efficacy of anterior cervical foraminotomy with reported success rates of 52-99% but recurrent symptoms as high as 30% (Class III). CONCLUSIONS: Anterior cervical discectomy, ACDF, and anterior cervical foraminotomy may improve cervical radicular symptoms. With regard to ACD and ACDF compared to PT or cervical immobilization, more rapid relief (within 3-4 months) may be seen with ACD or ACDF with maintenance of gains over the course of 12 months (Class I). Anterior cervical foraminotomy is associated with improvement in clinical function but the quality of data are weaker (Class III), and there is a wide range of efficacy (52-99%).