Langston T. Holly

Minimally invasive transforaminal lumbar interbody fusion (TLIF): technical feasibility and initial results.

Forty-nine patients underwent minimally invasive transforaminal lumbar interbody fusion (TLIF) from October 2001 to August 2002 (minimum 18-month follow-up). The diagnosis was degenerative disc disease with herniated nucleus pulposus (HNP) in 26, spondylolisthesis in 22, and a Chance-type seatbelt fracture in 1. The majority of cases (n = 45) were at L4-L5 or L5-S1. A paramedian, muscle-sparing approach was performed through a tubular retractor docked unilaterally on the facet joint. A total facetectomy was then conducted, exposing the disc space. Discectomy and endplate preparation were completed through the tube using customized surgical instruments. Structural support was achieved with allograft bone or interbody cages. Bone grafting was done with local autologous or allograft bone, augmented with recombinant human bone morphogenetic protein-2 in some cases. Bilateral percutaneous pedicle screw-rod placement was accomplished with the Sextant system. There were no conversions to open surgery. Operative time averaged 240 minutes. Estimated blood loss averaged 140 mL. Mean length of hospital stay was 1.9 days. All patients presenting with preoperative radiculopathy (n = 45) had resolution of symptoms postoperatively. Complications included two instances of screw malposition requiring screw repositioning and two cases of new radiculopathy postoperatively (one from graft dislodgement, the other from contralateral neuroforaminal stenosis). Narcotic use was discontinued 2-4 weeks postoperatively. Improvements in average Visual Analogue Pain Scale and Oswestry Disability Index (preoperative to last follow-up) scores were 7.2-2.1 and 46-14, respectively. At last follow-up, all patients had solid fusions by radiographic criteria. Results of this study indicate that minimally invasive TLIF is feasible and offers several potential advantages over traditional open techniques.

Minimally Invasive Lumbar Fusion

Study Design. Review article. Objectives. To provide an overview of current techniques for minimally invasive lumbar fusion. Summary of Background Data. Minimally invasive techniques have revolutionized the management of pathologic conditions in various surgical disciplines. Although these same principles have been used in the treatment of lumbar disc disease for many years, minimally invasive lumbar fusion procedures have only recently been developed. The goals of these procedures are to reduce the approach-related morbidity associated with traditional lumbar fusion, yet allow the surgery to be performed in an effective and safe manner. Methods. The authors’ clinical experience with minimally invasive lumbar fusion was reviewed, and the pertinent literature was surveyed. Results. Minimally invasive approaches have been developed for common lumbar procedures such as anterior and posterior interbody fusion, posterolateral onlay fusion, and internal fixation. As with all new surgical techniques, minimally invasive lumbar fusion has a learning curve. As well, there are benefits and disadvantages associated with each technique. However, because these techniques are new and evolving, evidence to support their potential benefits is largely anecdotal. Additionally, there are few long-term studies to document clinical outcomes. Conclusions. Preliminary clinical results suggest that minimally invasive lumbar fusion will have a beneficial impact on the care of patients with spinal disorders. Outcome studies with long-term follow-up will be necessary to validate its success and allow minimally invasive lumbar fusion to become more widely accepted.

Intraoperative spinal navigation.

Study Design. Review article. Objectives. To provide a detailed overview of current methods for intraoperative spinal navigation using image-guided surgical technology. Summary of Background Data. The development of novel intraoperative navigational techniques has been an important advancement in the field of spine surgery. These techniques, commonly referred to as image-guided surgery (IGS), provide simultaneous, multiplanar views of spinal anatomy. They can be used for detailed preoperative planning and allow the spinal surgeon to track the position of surgical instruments in real time. IGS technology can increase the accuracy of spinal instrumentation procedures and improve patient safety. Methods. The relevant medical literature was reviewed, as was the authors’ clinical and laboratory experience with intraoperative spinal navigation. Results. Image-guided spinal instrumentation procedures in the cervical, thoracic, and lumbar spine have lower rates of screw misplacement than do those performed without image guidance. In a typical IGS spinal procedure, surgical instruments are tracked in the operating room, and their positions are superimposed onto preoperatively acquired computed tomography scans (CT-based image guidance) or intraoperatively acquired fluoroscopic images (virtual fluoroscopy). A new development, the combination of isocentric C-arm fluoroscopy with computer-assisted image guidance, allows the C-arm to create intraoperative CT images that can be used for image-guided navigation without the need for a surgeon-dependent registration step. Each of these technologies has distinct advantages and limitations. Conclusions. Intraoperative spinal navigation has advanced rapidly in recent years, beneficially affecting a variety of surgical procedures. Future technological developments will widen its clinical application and minimize its shortcomings.

Percutaneous placement of posterior cervical screws using three-dimensional fluoroscopy.

Study Design. The placement of percutaneous posterior cervical screws using three-dimensional fluoroscopic guidance was performed in intact human cadaver specimens. Objectives. To determine the accuracy and feasibility of placing entirely percutaneous posterior cervical screws using a novel form of spinal image guidance. Summary of Background Data. Conventional image guidance has been shown to increase the accuracy of many open cervical instrumentation procedures. There are presently no published studies reporting this novel method for guiding the percutaneous placement of posterior cervical screws. Methods. An isocentric C-arm was used to obtain CT images of three intact cadaver specimens. A percutaneous dynamic reference array was attached to the C2 spinous process of each specimen. Light-emitting diodes attached to the C-arm were tracked with an electro-optical camera. The image data set was then transferred to the image-guided workstation, which performed an automated registration. Using the workstation, trajectories were planned for bilateral C1–C2 transarticular, C3–C6 lateral mass, and C7 pedicle screw placement. Through 1.5-cm incisions, a drill guide fitted with light-emitting diodes was used for sequential, image-guided drilling, tapping, and placement of cannulated 4.0 mm screws at each level. Postprocedure, thin-cut CT scanning was used to determine the accuracy of screw placement. Results. A total of 41 of 42 percutaneous screws (97.6%) were accurately placed. All of the transarticular atlantoaxial and subaxial lateral mass screws showed no evidence of foramen transversarium, neural foramen, or facet joint violation. One of the C7 pedicle screws had a minor cortical wall violation. Conclusion. This study demonstrates the feasibility of placing percutaneous posterior cervical screws. Three-dimensional fluoroscopy appears to enable highly accurate, percutaneous three-dimensional cervical spine navigation.

ACR Appropriateness Criteria® on Metastatic Bone Disease

Appropriate imaging modalities for screening, staging, and surveillance of patients with suspected and documented metastatic disease to bone include (99m)Tc bone scanning, MRI, CT, radiography, and 2-[(18)F]fluoro-2-deoxyglucose-PET. Clinical scenarios reviewed include asymptomatic stage 1 breast carcinoma, symptomatic stage 2 breast carcinoma, abnormal bone scan results with breast carcinoma, pathologic fracture with known metastatic breast carcinoma, asymptomatic well-differentiated and poorly differentiated prostate carcinoma, vertebral fracture with history of malignancy, non-small-cell lung carcinoma staging, symptomatic multiple myeloma, osteosarcoma staging and surveillance, and suspected bone metastasis in a pregnant patient. No single imaging modality is consistently best for the assessment of metastatic bone disease across all tumor types and clinical situations. In some cases, no imaging is indicated. The recommendations contained herein are the result of evidence-based consensus by the ACR Appropriateness Criteria((R)) Expert Panel on Musculoskeletal Radiology.

ACR Appropriateness Criteria Low Back Pain.

Most patients presenting with uncomplicated acute low back pain (LBP) and/or radiculopathy do not require imaging. Imaging is considered in those patients who have had up to 6 weeks of medical management and physical therapy that resulted in little or no improvement in their back pain. It is also considered for those patients presenting with red flags raising suspicion for serious underlying conditions, such as cauda equina syndrome, malignancy, fracture, and infection. Many imaging modalities are available to clinicians and radiologists for evaluating LBP. Application of these modalities depends largely on the working diagnosis, the urgency of the clinical problem, and comorbidities of the patient. When there is concern for fracture of the lumbar spine, multidetector CT is recommended. Those deemed to be interventional candidates, with LBP lasting for > 6 weeks having completed conservative management with persistent radiculopathic symptoms, may seek MRI. Patients with severe or progressive neurologic deficit on presentation and red flags should be evaluated with MRI. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (the RAND/UCLA Appropriateness Method and the Grading of Recommendations Assessment, Development, and Evaluation) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diffusion tensor imaging predicts functional impairment in mild-to-moderate cervical spondylotic myelopathy

BACKGROUND CONTEXT Magnetic resonance imaging (MRI) is the standard imaging modality for the assessment of cervical spinal cord; however, MRI assessment of the spinal cord in cervical spondylotic myelopathy patients has not demonstrated a consistent association with neurologic function or outcome after surgical or medical intervention. Thus, there is a need for sensitive imaging biomarkers that can predict functional impairment in patients with advanced cervical spondylosis. PURPOSE To implement diffusion tensor imaging (DTI) as an imaging biomarker for microstructural integrity and functional impairment in patients with cervical spondylosis. STUDY DESIGN Nonrandomized, single institution study. PATIENT SAMPLE Forty-eight cervical spondylosis patients with or without spinal cord signal change underwent DTI of the spinal cord along with functional assessment. OUTCOME MEASURES Functional measures of neurologic function via modified Japanese Orthopedic Association (mJOA) score. METHODS A zoomed-echoplanar imaging technique and two-dimensional spatially selective radiofrequency excitation pulse were used for DTI measurement. Fractional anisotropy (FA), mean diffusivity (MD), radial and axial diffusion (AD) coefficient, AD anisotropy, ψ, defined as AD-MD, and the standard deviation (SD) of primary eigenvector orientation were evaluated at the site of compression. RESULTS Results suggest average FA, transverse apparent diffusion coefficient, ψ, and SD of primary eigenvector orientation at the spinal level of highest compression were linearly correlated with mJOA score. Receiver-operator characteristic analysis suggested FA and ψ could identify stenosis patients with mild-to-moderate symptoms with a relatively high sensitivity and specificity. CONCLUSIONS The results of this study support the potential use of DTI as a biomarker for predicting functional impairment in patients with cervical spondylosis.

Advances in MR imaging for cervical spondylotic myelopathy

PurposeTo outline the pathogenesis of cervical spondylotic myelopathy (CSM), the correlative abnormalities observed on standard magnetic resonance imaging (MRI), the biological implications and current status of diffusion tensor imaging (DTI), and MR spectroscopy (MRS) as clinical tools, and future directions of MR technology in the management of CSM patients.MethodsA systematic review of the pathogenesis and current state-of-the-art in MR imaging technology for CSM was performed.ResultsCSM is caused by progressive, degenerative, vertebral column abnormalities that result in spinal cord damage related to both primary mechanical and secondary biological injuries. The T2 signal change on conventional MRI is most commonly associated with neurological deficits, but tends not to be a sensitive predictor of recovery of function. DTI and MRS show altered microstructure and biochemistry that reflect patient-specific pathogenesis.ConclusionAdvanced imaging techniques, including DTI and MRS, show higher sensitivity to microstructural and biochemical changes within the cord, and may aid in management of CSM patients.

Minimally Invasive Atlantoaxial Fusion

BACKGROUND C1-C2 fusion has significantly advanced from predominantly wiring/cable modalities to more biomechanically stable screw-rod techniques. Minimally invasive surgical techniques represents the most recent modification of atlantoaxial fixation. The indications, rationale, and surgical technique of this novel procedure are described. METHODS Six patients requiring C1-C2 fusion (5 type II odontoid fractures and 1 os odontoideum) underwent minimally invasive C1-C2 fusion over a 2-year period. The cohort consisted of 5 men and 1 woman with a mean age of 51 years (age range, 39-64 y). All 6 patients underwent bilateral segmental atlantoaxial fixation using an expandable tubular retractor. RESULTS The mean follow-up time was 32 months (age range, 24-46 mo) There were no intraoperative complications, and the mean estimated blood loss was 100 mL. Solid fusion was achieved in all 6 patients, without pathological motion on dynamic studies. Postoperative computed tomographic images showed no hardware malposition in the scanned patients (4 of the 6 patients). CONCLUSIONS Placement of C1 and C2 instrumentation using minimally invasive techniques is technically feasible. Because the instrumentation and the means of obtaining arthrodesis do not differ substantively from the standard approach, we would not anticipate long-term results to be different from those of an open procedure, apart from the approach-related morbidity.BACKGROUNDC1–C2 fusion has significantly advanced from predominantly wiring/cable modalities to more biomechanically stable screw-rod techniques. Minimally invasive surgical techniques represents the most recent modification of atlantoaxial fixation. The indications, rationale, and surgical technique of this novel procedure are described. METHODSSix patients requiring C1–C2 fusion (5 type II odontoid fractures and 1 os odontoideum) underwent minimally invasive C1–C2 fusion over a 2-year period. The cohort consisted of 5 men and 1 woman with a mean age of 51 years (age range, 39–64 y). All 6 patients underwent bilateral segmental atlantoaxial fixation using an expandable tubular retractor. RESULTSThe mean follow-up time was 32 months (age range, 24–46 mo) There were no intraoperative complications, and the mean estimated blood loss was 100 mL. Solid fusion was achieved in all 6 patients, without pathological motion on dynamic studies. Postoperative computed tomographic images showed no hardware malposition in the scanned patients (4 of the 6 patients). CONCLUSIONSPlacement of C1 and C2 instrumentation using minimally invasive techniques is technically feasible. Because the instrumentation and the means of obtaining arthrodesis do not differ substantively from the standard approach, we would not anticipate long-term results to be different from those of an open procedure, apart from the approach-related morbidity.

The Effect of an Anterior Cervical Operation for Cervical Radiculopathy or Myelopathy on Associated Headaches

BACKGROUND Headaches related to the cervical spine have been reported by various authors, and modalities of treatment are as varied as their speculated causes. The purpose of this study was to determine if anterior cervical reconstructive surgery (cervical arthrodesis and disc arthroplasty) for the treatment of radiculopathy or myelopathy also helps to alleviate associated headaches. METHODS We conducted a post hoc analysis of study cohorts combined from prospective studies comparing the results of Prestige and Bryan cervical arthroplasty devices and those of anterior cervical arthrodesis with allograft and anterior instrumentation. A total of 1004 patients (51.6% were male) were evaluated with use of the Neck Disability Index questionnaire preoperatively and at five points postoperatively, with the latest evaluation at twenty-four months, resulting in a follow-up of 803 patients. RESULTS At the twenty-four-month follow-up, the improvement from baseline with regard to headache was significant in both groups (p < 0.0001), with patients who underwent arthroplasty reporting numerically better pain scores. Most arthroplasty and arthrodesis patients (64% and 58.5%, respectively) had improvement in the pain score of at least one grade. Conversely, the pain scores for 8.4% of those who had an arthroplasty and 13.7% of those who had arthrodesis worsened by at least one grade. For the remainder, the score was unchanged. Overall, the patients who had an arthroplasty had significant improvement more frequently than did the patients who had arthrodesis (p = 0.011). CONCLUSIONS At two years postoperatively, patients undergoing anterior cervical operations, both those who have an arthroplasty and those who have an arthrodesis, for cervical radiculopathy and myelopathy can be expected to have significant improvement from baseline with regard to headache symptoms.