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Eric B. Harris, Patrick Massey, James Lawrence, Jeffrey Rihn, Alex Vaccaro and D. Greg Anderson

Percutaneous pedicle screw fixation for lumbar posterolateral instrumented fusion is an attractive alternative to standard open techniques. The technical aspects of this procedure can be challenging and even frustrating when first learning the technique. However, once these techniques have been mastered, they offer a safe, less invasive, less traumatic, more aesthetic method for performing fusion. The authors have outlined a step-by-step method for performing this surgery, and include a case series that demonstrates excellent results in patients treated with this procedure.

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Tony Tannoury, Adam C. Crowl, Todd C. Battaglia, Donald P. K. Chan and D. Greg Anderson

Object. The authors sought to compare radiation exposure, surgical time, and accuracy of screw placement when using either standard fluoroscopy or virtual fluoroscopy for the placement of C1–2 transarticular screws.

Methods. Twenty-two C1–2 transarticular screws were placed in 11 cadavers in a randomized and alternating order by using either standard fluoroscopy or virtual fluoroscopy (fluoronavigation). The radiation time, procedure time, and accuracy of screw placement were recorded and statistically compared. A small but statistically significant reduction in fluoroscopy time was noted with the virtual fluoroscopy technique but the surgical times were similar between the two techniques. The incidence of noncritical and critical breaches (those at risk of causing a neurovascular injury) was not significantly different between the two groups. Careful analysis of the C1–2 anatomy in these specimens underscored the importance of placing the screw path in a maximally dorsal and medial portion of the C-2 isthmus to avoid injury to the vertebral artery and to maximize the bone purchase of the C-1 lateral mass.

Conclusions. Although virtual fluoroscopy may represent a useful tool for transarticular screw placement, it does not supplant traditional surgical techniques and does not appear to lower the incidence of bone breaches that can occur when performing this demanding procedure.

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Sergey Mlyavykh, Steven C. Ludwig, Jean-Pierre Mobasser, Christopher K. Kepler and D. Greg Anderson

Object

Lumbar spinal stenosis (LSS) is a common condition that leads to significant disability, particularly in the elderly. Current therapeutic modalities for LSS have certain drawbacks when applied to this patient population. The object of this study was to define the 12-month postoperative outcomes and complications of pedicle-lengthening osteotomies for symptomatic LSS.

Methods

A prospective, single-treatment clinical pilot study was conducted. A cohort of 19 patients (mean age 60.9 years) with symptomatic LSS was treated by pedicle-lengthening osteotomy procedures at 1 or 2 levels. All patients had symptoms of neurogenic claudication or radiculopathy secondary to LSS and had not improved after a minimum 6-month course of nonoperative treatment. Eleven patients had a Meyerding Grade I degenerative spondylolisthesis in addition to LSS. Clinical outcomes were measured using the Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ), 12-Item Short-Form Health Survey (SF-12), and a visual analog scale (VAS). Procedural variables, neurological outcomes, adverse events, and radiological imaging (plain radiographs and CT scans) were collected at the 1.5-, 3-, 6-, 9-, and 12-month time points.

Results

The pedicle-lengthening osteotomies were performed through percutaneous approaches with minimal blood loss in all cases. There were no operative complications. Four adverse events occurred during the follow-up period. Clinically, significant improvement was observed in the mean values of each of the outcome scales (comparing preoperative and 12-month values): ODI scores improved from 52.3 to 28.1 (p < 0.0001); the ZCQ physical function domain improved from 2.7 to 1.8 (p = 0.0021); the SF-12 physical component scale improved from 27.0 to 37.9 (p = 0.0024); and the VAS score for leg pain while standing improved from 7.2 to 2.7 (p < 0.0001). Imaging studies, reviewed by an independent radiologist, showed no evidence of device subsidence, migration, breakage, or heterotopic ossification. Thin-slice CT documented healing of the osteotomy site in all patients at the 6-month time point and an increase in the mean cross-sectional area of the spinal canal of 115%.

Conclusions

Treatment of patients with symptomatic LSS with a pedicle-lengthening osteotomy procedure provided substantial enlargement of the area of the spinal canal and favorable clinical results for both disease-specific and non–disease-specific outcome measures at the 12-month time point. Future studies are needed to compare this technique to alternative therapies for lumbar stenosis.

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Michael Y. Wang, Steven C. Ludwig, D. Greg Anderson and Praveen V. Mummaneni

Minimally invasive spinal instrumentation techniques have evolved tremendously over the past decade. Although there have been numerous reports of lumbar instrumentation performed via a percutaneous or minimal incisional route, to date there have been no reports of minimally invasive iliac screw placement.

A method was developed for accurate placement of minimally invasive iliac screw placement based on a modification of currently available percutaneous lumbar instrumentation techniques. The method involves fluoroscopically guided insertion of a cannula-based screw system, and this technique was successful applied to treat an L-5 burst fracture with L-4 to iliac spinal stabilization via a minimally invasive approach.

This report demonstrates the feasibility of percutaneous iliac screw instrumentation. However, future studies will be needed to validate the safety and efficacy of this approach.

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Ali Kiapour, D. Greg Anderson, David B. Spenciner, Lisa Ferrara and Vijay K. Goel

Object

Lumbar spinal stenosis (LSS) may lead to disabling neurogenic symptoms and has traditionally been treated using open laminectomy. A new technique for correcting LSS involves lengthening the lumbar pedicles through bilateral percutaneous pedicle osteotomies. In this paper, the authors' goal was to evaluate the changes in spinal canal dimensions and kinematic behavior after pedicle-lengthening osteotomies.

Methods

The kinematic behavior of 8 cadaveric lumbar segments was evaluated intact and after bilateral pedicle-lengthening osteotomies at the L-4, L-5, and L-4 and L-5 levels. Testing was conducted with and without a compressive preload using a custom kinematic apparatus that allowed for 3D tracking of each vertebra during flexion-extension, right-left bending, and right-left rotation. A validated finite element (FE) spine model was used to measure the changes in the cross-sectional area of the spinal canal and neural foramen after 2-, 3-, and 4.5-mm simulated pedicle-lengthening osteotomy procedures.

Results

The overall and segmental kinematics were not significantly altered after the pedicle-lengthening osteotomy procedure at the L-4 and/or L-5 pedicles. The kinematic signatures of the intact and lengthened states were similar for all motion pairs. The FE spine model yielded kinematics predictions within or close to the 95% confidence interval for the cadaveric data. The FE spine demonstrated substantial, pedicle length–dependent enlargement of the cross-sectional areas of the spinal canal and neural foramen after simulated pedicle lengthening.

Conclusions

Bilateral pedicle-lengthening osteotomies produced substantial increases in the cross-sectional areas of the spinal canal and neural foramen without significantly altering normal spinal kinematics. This technique deserves further study as a less invasive treatment option for LSS.

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Sergey Mlyavykh, Steven C. Ludwig, Christopher K. Kepler and D. Greg Anderson

OBJECTIVE

Lumbar spinal stenosis (LSS) is a common condition that leads to significant disability, particularly in the elderly. Current therapeutic options have certain drawbacks. This study evaluates the 5-year clinical and radiographic results of a minimally invasive pedicle-lengthening osteotomy (PLO) for symptomatic LSS.

METHODS

A prospective, single-arm, clinical pilot study was conducted involving 20 patients (mean age 61.7 years) with symptomatic LSS treated by a PLO procedure at 1 or 2 lumbar levels. All patients had symptoms of neurogenic claudication or radiculopathy secondary to LSS, and had not improved after a minimum 6-month course of nonoperative treatment. Eleven patients had a Meyerding grade I degenerative spondylolisthesis in addition to LSS. Clinical outcomes were measured using the Oswestry Disability Index, Zürich Claudication Questionnaire, 12-Item Short Form Health Survey, and a visual analog scale for back and leg pain. Procedural variables, neurological outcomes, adverse events, and radiological imaging (plain radiographs and CT scans) were collected at the 1.5-, 3-, 6-, 9-, 12-, 24-, and 60-month time points.

RESULTS

The PLOs were performed through percutaneous incisions, with minimal blood loss in all cases. There were no operative complications. Four adverse events occurred during the follow-up period. Statistically significant improvement was observed in each of the outcome instruments and maintained over the 5-year follow-up period. Imaging studies, reviewed by an independent radiologist, showed no evidence of device subsidence, migration, breakage, or heterotopic ossification. Thin-slice CT scans documented healing of the osteotomy site in all patients at the 6-month time point and an increase of 115% in the mean cross-sectional area of the spinal canal.

CONCLUSIONS

Treatment of patients with symptomatic LSS with a PLO procedure provided substantial enlargement of the area of the spinal canal and favorable clinical results for both disease-specific and non–disease-specific outcome measures at all follow-up time points out to 5 years. Future research is needed to compare this technique to alternative therapies for LSS.

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Joseph C. Noggle, Daniel M. Sciubba, Amer F. Samdani, D. Greg Anderson, Randal R. Betz and Jahangir Asghar

Object

Lumbar spondylolysis occurs in approximately 6% of the population and presents with localized mechanical back pain, often in young athletes. Surgical treatment may involve decompression, lumbar intersegmental fusion, or direct repair of pars defects. Although such open procedures may effectively resolve symptoms, minimal-access approaches may additionally decrease collateral damage to soft tissues, allowing young, active patients to resume athletic activities sooner. In this study, the authors review their experience repairing bilateral lumbar spondylolyses with screw and hook constructs placed via a minimal-access approach.

Methods

Five consecutive pediatric patients with bilateral L-5 spondylolysis were treated. Bilateral incisions (2.5 cm) were made over L-5. Exposure was maintained with bilateral expandable tubular retractor systems. Pedicle screws were placed in the L-5 pedicles and attached to hooks under the L-5 laminae. A direct repair was performed at the pars defect. Clinical characteristics, operative variables, and postoperative outcomes were collected.

Results

All 5 patients underwent surgery; 4 were male (80%) and 1 was female (20%), and the mean age was 15.8 years (range 15–17 years). The mean estimated blood loss and duration of surgery were 37 ml (range 15–75 ml) and 1.94 hours (range 1–3 hours), respectively. Postoperative hospital stays ranged from 1 to 3 days (mean 1.8 days). The only complication occurred in 1 patient who experienced minor superficial wound breakdown. All patients have experienced resolution of symptoms at this preliminary stage, which has continued over an 8-month follow-up period.

Conclusions

Lumbar spondylolysis can be adequately and safely treated via minimal-access surgical repair of the pars interarticularis by using pedicle screws and rod-hook constructs. This approach may decrease the collateral soft tissue damage common to open dissections, and may be ideal for young, active surgical candidates.

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Anuj V. Peddada, D. James Sceats, Gerald A. White, Gyongyver Bulz, Greg L. Gibbs, Barry Switzer, Susan Anderson and Alan T. Monroe

This case report of 74-year-old man with trigeminal neuralgia is presented to underscore the importance of evaluating the entire treatment plan, especially when delivering large doses where even a low percentage of the prescription dose can contribute a substantial dose to an unintended target. The patient was treated using the CyberKnife stereotactic radiosurgery system utilizing a nonisocentric beam treatment plan with a 5-mm fixed collimator generating 111 beams to deliver 6000 cGy to the 79% isodose line with a maximum dose of 7594 cGy to the target. Two weeks after treatment the patient's trigeminal neuralgia symptoms resolved; however, the patient developed oral mucositis due to the treatment. This case report reviews the cause of mucositis and makes recommendations on how to prevent unintended targets from receiving treatment.

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Christopher K. Kepler, Christopher Kong, Gregory D. Schroeder, Nikolaus Hjelm, Amir Sayadipour, Alexander R. Vaccaro and D. Greg Anderson

OBJECT

The purpose of this study was to characterize changes in American Spinal Injury Association motor score (AMS) in the 1st week after traumatic central cord syndrome (CCS) to identify predictors of improved early outcome in patients treated with early versus delayed surgical intervention.

METHODS

All patients presenting to a regional spinal cord injury center between January 2004 and June 2009 were queried for those with a diagnosis of CCS. Patients treated conservatively were excluded. A prospectively maintained spinal cord injury database was used to track AMS throughout each patient’s hospitalization. Hospital records provided information regarding demographics, presenting neurological examination, imaging findings, comorbidities, timing and nature of surgical procedures, and length of stay (LOS) in the hospital and intensive care unit (ICU). Patients were separated into those who underwent early surgery, within 1 day of presentation (early group), and those who underwent surgery on a delayed basis (delayed group). Differences between groups were analyzed using the Student t-test and chi-square test. Predictors of outcome were identified using correlation analysis and multiple linear regression.

RESULTS

Of 426 patients in the database, 80 (18.8%) were diagnosed as having CCS, and 68 of them ultimately underwent surgical decompression. Nineteen (28%) of 68 patients underwent surgery within 1 day of presentation (early group) while the remaining 49 patients (72%) underwent surgery on a delayed basis (delayed group). The mean age in the early group was significantly younger than that of the delayed group (52 vs 59 years, p = 0.049). Other characteristics were similar between groups including sex, proportion of patients with cord edema on MRI (44% early vs 55% delayed, p = 0.47), and proportion of patients with cervical fracture (26% early vs 28% delayed, p = 0.98). Patients in the early group presented with an AMS of 62.5 versus 70.0 for the delayed group (p = 0.36). No difference in the change in AMS was seen at 7 days between the early group (-2.9 points) and the delayed group (-4.2 points) (p = 0.34). Additionally, the number of patients who had early improvement was similar between the early and delayed groups (50% vs 48%, respectively, p = 0.94). Neither time in the ICU (3.4 vs 3.4 days, p = 0.84) nor the overall LOS (10.5 vs 12.5 days, p = 0.59) was different in the early versus delayed groups, respectively. Correlation analysis and multiple linear regression demonstrated early surgery was not associated with change in AMS or AMS at Day 7. Age was identified as the only significant predictor of change in AMS and had a negative effect (coefficient = -0.34, p = 0.025).

CONCLUSIONS

Early treatment of patients with CCS remains controversial. Although some long-term neurological recovery is expected in patients with a CCS, surgeons and patients should not expect early neurological improvement with or without early operative intervention.

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Zeeshan Sardar, David Alexander, William Oxner, Stephan du Plessis, Albert Yee, Eugene K. Wai, D. Greg Anderson and Peter Jarzem

OBJECT

Failure of fusion after a transforaminal lumbar interbody fusion (TLIF) procedure is a challenging problem that can lead to ongoing low-back pain, dependence on pain medication, and inability to return to work. B2A is a synthetic peptide that has proven efficacy in achieving fusion in animal models and may have a better safety profile than bone morphogenetic protein. The authors undertook this study to evaluate the safety and efficacy of B2A peptide–enhanced ceramic granules (Prefix) in comparison with autogenous iliac crest bone graft (ICBG, control) in patients undergoing single-level TLIF.

METHODS

Twenty-four patients with single-level degenerative disorders of the lumbar spine at L2–S1 requiring TLIF were enrolled between 2009 and 2010. They were randomly assigned to 3 groups: a control group (treated with ICBG, n = 9), a Prefix 150 group (treated with Prefix 150 μg/cm3 granules, n = 8), and a Prefix 750 group (treated with Prefix 750 μg/cm3 granules, n = 7). Outcome measures included the Oswestry Disability Index (ODI), visual analog pain scale, and radiographic fusion as assessed by CT and dynamic flexion/extension lumbar plain radiographs.

RESULTS

At 12 months after surgery, the radiographic fusion rate was 100% in the Prefix 750 group, 78% in the control group, and 50% in the Prefix 150 group, although the difference was not statistically significant (p = 0.08). At 6 weeks the mean ODI score was 41.0 for the control group, 27.7 for the Prefix 750 group, and 32.2 for the Prefix 150 group, whereas at 12 months the mean ODI was 24.4 for control, 31.1 for Prefix 750, and 29.7 for Prefix 150 groups. Complications were evenly distributed among the groups.

CONCLUSIONS

Prefix appears to provide a safe alternative to autogenous ICBG. Prefix 750 appears to show superior radiographic fusion when compared with autograft at 12 months after TLIF, although no statistically significant difference was demonstrated in this small study. Prefix and control groups both appeared to demonstrate comparable improvements to ODI at 12 months.