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Mario J. Cardoso, Audra Mendelsohn and Michael K. Rosner

Object

Multilevel cervical arthroplasty achieved using the Prestige ST disc can be challenging and often unworkable. An alternative to this system is a hybrid technique composed of alternating total disc replacements (TDRs) and fusions. In the present study, the authors review the safety and radiological outcomes of cervical hybrid arthroplasty in which the Prestige ST disc is used in conjunction with 2 unique fusion techniques.

Methods

After obtaining institutional review board approval, the authors completed a retrospective review of all hybrid cervical constructs in which the Prestige ST disc was used between August 2007 and November 2009 at the Walter Reed Army Medical Center. A Prestige ST total disc replacement was performed in 119 patients. Thirty-one patients received a hybrid construct defined as a TDR and fusion (TDR–anterior cervical decompression and fusion [ACDF]) or as 2 TDRs separated by a fusion (TDR-ACDF-TDR). A resorbable plate and graft system (Mystique) or stand-alone interbody spacer (Prevail) was implanted at the fusion levels. Plain radiographs were compared and evaluated for cervical lordosis, range of motion, implant complications, development of adjacent-level disease, and pseudarthrosis. In addition, charts were reviewed for clinical complications related to the index surgery.

Results

Thirty-one patients (18 men and 13 women; mean age 50 years, range 32–74 years) received a hybrid construct. All patients were diagnosed with radiculopathy and/or myelopathy. Twenty-four patients received a 2-level and 7 a 3-level hybrid construct. In 2 patients in whom a 2-level hybrid construct was implanted, a noncontiguous TDR was also performed. The mean clinical and radiological follow-up duration was 18 months. There was no significant difference in preoperative (19.3° ± 13.3°) and postoperative (19.7° ± 10.5°) cervical lordosis (p = 0.48), but there was a significant decrease in range in motion (from 50.0° ± 11.8° to 38.9° ± 12.7°) (p = 0.003). There were no instances of screw backout, implant dislodgement, progressive kyphosis, formation of heterotopic bone, pseudarthrosis, or symptomatic adjacent-level disease. Seven patients had dysphasia and 1 patient had vocal cord paralysis at 6 weeks. By 3 months, both the dysphasia and the vocal cord paralysis were resolved in all patients.

Conclusions

Hybrid cervical arthroplasty involving the placement of a Prestige ST disc and either the Mystique resorbable plate or Prevail stand-alone interbody device is a safe and effective alternative to multilevel fusion for the management of cervical radiculopathy and myelopathy.

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Ross R. Moquin, Michael K. Rosner and Patrick B. Cooper

The authors report their preferred method for correcting Scheuermann disease via a combined anterior–posterior approach; their procedure is associated with a lower morbidity rate than the standard approach. Twenty-month follow-up examination demonstrated excellent maintenance of correction. The results satisfied the requirements to function without restriction in a vigorous military environment.

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Timothy R. Kuklo, Michael K. Rosner and David W. Polly Jr.

Object

Synthetic bioabsorbable implants have recently been introduced in spinal surgery; consequently, the indications, applications, and results are still evolving. The authors used absorbable interbody spacers (Medtronic Sofamor Danek, Memphis, TN) packed with recombinant bone morphogenetic protein (Infuse; Medtronic Sofamor Danek) for single- and multiple-level transforaminal lumbar interbody fusion (TLIF) procedures over a period of 18 months. This is a consecutive case series in which postoperative computerized tomography (CT) scanning was used to assess fusion status.

Methods

There were 22 patients (17 men, five women; 39 fusion levels) whose mean age was 41.6 years (range 23–70 years) and in whom the mean follow-up duration was 12.4 months (range 6–18 months). Bridging bone was noted as early as the 3-month postoperative CT scan when obtained; solid arthrodesis was routinely noted between 6 and 12 months in 38 (97.4%) of 39 fusion levels. In patients who underwent repeated CT scanning, the fusion mass appeared to increase with time, whereas the disc space height remained stable. Although the results are early (mean 12-month follow-up duration), there was only one noted asymptomatic delayed union/nonunion at L5–S1 in a two-level TLIF with associated screw breakage. There were no infections or complications related to the cages.

Conclusions

The bioabsorbable cages appear to be a viable alternative to metal interbody spacers, and may be ideally suited to spinal interbody applications because of their progressive load-bearing properties.

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Chris J. Neal and Michael K. Rosner

Object

Minimal-access transforaminal lumbar interbody fusion (TLIF) has gained popularity as a method of achieving interbody fusion via a posterior-only approach with the aim of minimizing injury to adjacent tissue. While many studies have reported successful outcomes, questions remain regarding the potential learning curve for successfully completing this procedure. The goal of this study, based on a single resident's experience at the only Accreditation Council for Graduate Medical Education–approved neurosurgical training center in the US military, was to determine if there is in fact a significant learning curve in performing a minimal-access TLIF.

Methods

The authors retrospectively reviewed all minimal-access TLIFs performed by a single neurosurgical resident between July 2006 and January 2008. Minimal-access TLIFs were performed using a tubular retractor inserted via a muscle-dilating exposure to limit approach-related morbidity. The accuracy of screw placement and operative times were assessed.

Results

A single resident/attending team performed 28 minimal-access TLIF procedures. In total, 65 screws were placed at L-2 (1 screw), L-3 (2 screws), L-4 (18 screws), L-5 (27 screws), and S-1 (17 screws) from the resident's perspective. Postoperative CTs were reviewed to determine the accuracy of screw placement. An accuracy of 95.4% (62 of 65) properly placed screws was noted on postoperative imaging. Two screws (at L-5 in the patient in Case 17 and at S-1 in the patient in Case 9) were lateral, and no revision was needed. One screw (at L-4 in Case 24) was 1 mm medial without symptoms or the need for revision. In evaluating the operative times, 2 deformity cases (Grade III spondylolisthesis) were excluded. The average operating time per level in the remaining 26 cases was 113.25 minutes. The average time per level for the first 13 cases was 121.2 minutes; the amount of time decreased to 105.3 minutes for the second group of 13 cases (p = 0.25).

Conclusions

In summary, minimal-access TLIF can be safely performed in a training environment without a significant complication rate due to the expected learning curve.

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Chris J. Neal, Michael K. Rosner and Timothy R. Kuklo

Object. Disc arthroplasty in the lumbar spine is an alternative to fusion when treating discogenic pain. Its theoretical benefits include preservation of the motion segment and the potential prevention of adjacent-segment degeneration. Despite the need to evaluate the benefit of preserving the adjacent segments after disc replacement, no study has been conducted to assess the ability of magnetic resonance (MR) imaging to depict the adjacent segments in patients who have undergone disc replacement surgery.

Methods. Postoperative lumbar MR images were obtained in the first 10 patients in whom a metal-on-metal disc arthroplasty system was used to treat the L4–5 or L5—S1 levels. At the superior adjacent level, the superior endplate and disc space were demonstrated on 90% of the images on both T1-weighted fluid-attenuated inversion-recovery (FLAIR) and T2-weighted sequences despite the presence of artifacts. The inferior endplate at this level was documented on 70% of both T1-weighted FLAIR and T2-weighted sequences. At the level below the disc replacement in patients who underwent L4–5 surgery, the superior endplate was demonstrated on 66.7% of the T1-weighted FLAIR sequences but only 33.3% of the T2-weighted images. The disc space and inferior endplate were depicted on 66.7% of both T1-weighted FLAIR and T2-weighted sequences. Axial images revealed an artifact in every adjacent space except at the L5—S1 level.

Conclusions. Based on the results of this pilot study, it appears that sagittal MR imaging can be undertaken to evaluate the adjacent motion segment for degenerative changes following total disc arthroplasty in most patients. This imaging modality will provide an additional measure to assess the long-term efficacy of this intervention compared with other treatment modalities and the natural history of lumbar disc degeneration.

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Michael K. Rosner, Timothy R. Kuklo, Rabih Tawk, Ross Moquin and Stephen L. Ondra

Object

The purpose of this study was to evaluate the safety and efficacy of prophylactic inferior vena cava (IVC) filter placement in high-risk patients who undergo major spine reconstruction.

Methods

In the pilot study, 22 patients undergoing major spine reconstruction received prophylactic IVC filters. These patients were prospectively followed to evaluate complications related to the filter, the rate of deep venous thrombosis (DVT) formation, and the rate of pulmonary embolism (PE). These data were compared with those obtained in a retrospective review for PE in a matched cohort treated at the same institution. At a second institution the treatment guidelines were implemented in 17 patients undergoing complex spine surgery with the same follow-up criteria.

In the pilot study, no patient experienced PE (0%), whereas two had DVT (9%). Bilateral DVT developed postoperatively in one patient (associated morbidity rate 4.5%), who required thrombolytic therapy. One patient died of unrelated surgical complications. The PE rate in the matched cohort at the same institution was 12%. At the second institution, no patient had PE, and no complications were noted.

Conclusions

In this patient population, prophylactic IVC filter placement appears to decrease the PE rate substantially, from 12 to 0%. The placement of IVC filters appears to be a safe and efficacious intervention for prevention of PE in high-risk patients.

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Randy S. Bell, Alexander H. Vo, Patrick B. Cooper, Carrie L. Schmitt and Michael K. Rosner

✓ Eosinophilic meningitis has been defined as meningitis in which a total cerebrospinal fluid (CSF) sample is found to have more than 10 eosinophils per millimeter or is composed of greater than 10% eosinophils. The differential diagnosis is broad and the clinical presentation, lacking an internalized CSF diversion system, is often nonspecific. With respect to patients with shunt systems, a positive correlation exists between CSF eosinophilia and eventual shunt failure requiring revision. In this paper the authors present the highest reported level of CSF eosinophilia in conjunction with a rifampin and minocycline–impregnated ventriculostomy catheter recently approved by the Food and Drug Administration.

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Mario J. Cardoso and Michael K. Rosner

Object

Minimally invasive lumbar spine surgery has dramatically evolved over the last decade. Minimally invasive techniques and transforaminal lumbar interbody fusion (TLIF) often require a steep learning curve. Surgical techniques require pre-positioning the patient in maximal kyphosis to optimize visualization of the disc space and prevent unnecessary retraction of neural structures. The authors describe their experience in validating the surgical technique recommendation of Wilson frame–induced kyphosis.

Methods

Over the past 6 months, data obtained in 20 consecutive patients (40 total levels) undergoing minimally invasive TLIF were reviewed. In each patient, preincision intraoperative radiographs were reviewed at L4–5 and L5–S1 with the patient on a Wilson frame in maximal lordosis and then in maximal kyphosis. The change in disc space angle at L4–5 and L5–S1 after changing from maximal lordosis to maximal kyphosis was reviewed. Descriptive statistics were calculated for sagittal plane angular measures at L4–5 and L5–S1 in lordosis and kyphosis, including absolute differences and percentage of change between positions. Inferential statistics were calculated using paired t-tests with α= 0.05.

Results

Twenty patients underwent single- or multilevel minimally invasive TLIF. Inducing kyphosis with the Wilson frame aided in optimizing exposure and decreasing the need for neural structure retraction. Both L4–5 and L5–S1 showed statistically significant (p < 0.001) and clinically meaningful changes with increased segmental flexion in the kyphotic position. At L4–5 the mean increase in flexion was 4.5° (95% CI 2.9–6.0°), representing an average 47% change. The mean increase in flexion at L5–S1 was 3.2° (95% CI 2.3–4.2°), representing an average 20.8% change. In lordosis the mean angle at L4–5 was 10.6 ± 4.4° and at L5–S1 was 17 ± 7.0°. In kyphosis the mean angle at L4–5 was 6.1 ± 4.5° and at L5–S1 was 13.8 ± 6.5°. Additionally, there was a statistically significant difference (p < 0.05) in percentage of change between the 2 levels, with L4–5 showing a greater change (27% more flexion) between positions, but the absolute mean difference between the levels was small (1.3°).

Conclusions

Minimally invasive TLIF is challenging and requires a significant learning curve. The recommended surgical technique of inducing kyphosis with the Wilson frame prior to incision significantly optimizes exposure. The authors' experience demonstrates that this technique is essential when performing minimally invasive lumbar spinal fusions.

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Mario J. Cardoso and Michael K. Rosner

Object

In this study, the authors review the technique for inserting the Prestige ST in a contiguous multilevel cervical disc arthroplasty in patients with radiculopathy and myelopathy. They describe the preoperative planning, surgical technique, and their experience with 10 patients receiving a contiguous Prestige ST implant. They present contiguous multilevel cervical arthroplasty as an alternative to multilevel arthrodesis.

Methods

After institutional board review approval was obtained, the authors performed a retrospective review of all contiguous multilevel cervical disc arthroplasties with the Prestige ST artificial disc between August 2007 and November 2009 at a single institution by a single surgeon. Clinical criteria included patients who had undergone a multilevel cervical disc arthroplasty performed for radiculopathy and myelopathy without the presence of a previous cervical fusion. Between August 2007 and November 2009, 119 patients underwent cervical arthroplasty. Of the 119 patients, 31 received a Hybrid construct (total disc resection [TDR]–anterior cervical decompression and fusion [ACDF] or TDR-ACDF-TDR) and 24 received a multilevel cervical arthroplasty. The multilevel cervical arthroplasty group consisted of 14 noncontiguous and 10 contiguous implants. This paper examines patients who received contiguous Prestige ST implants.

Results

Ten men with an average age of 45 years (range 25–61 years) were treated. Five patients presented with myelopathy, 3 presented with radiculopathy, and 2 presented with myeloradiculopathy. Twenty-two 6 × 16–mm Prestige ST TDRs were implanted. Six patients received 2-level Prestige ST implants. Five patients received TDRs at C5–6 and C6–7, and 1 patient received TDRs at C3–4 and C4–5. One patient received a TDR at C3–4, C5–6, and C6–7 where C4–5 was a congenital block vertebra. Three patients (2 with 3-level disease and 1 with 4-level disease) received contiguous Prestige ST implants as well as a Prevail ACDF as part of their constructs. The mean clinical and radiographic follow-up was 12 months. There has been no case of screw backout, implant dislodgment, progressive kyphosis, formation of heterotopic bone, evidence of pseudarthrosis at the Prevail levels, or development of symptomatic adjacent level disease.

Conclusions

Multilevel cervical arthroplasty with the Prestige ST is a safe and effective alternative to fusion for the management of cervical radiculopathy and myelopathy.

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Steven K. Gudeman, Humbert G. Sullivan, Michael J. Rosner and Donald P. Becker

✓ The authors report a patient with bilateral papillomas of the choroid plexus of the lateral ventricles with documentation of cerebrospinal fluid (CSF) hypersecretion causing hydrocephalus. Special attention is given to the large volume of CSF produced by these tumors (removal of one tumor reduced CSF outflow by one-half) and to the fact that CSF diversion was not required after both tumors were removed. Since tumor removal alone was sufficient to stop the progression of hydrocephalus, we feel that this case supports the concept that elevated CSF production by itself is sufficient to cause hydrocephalus in patients with papillomas of the choroid plexus.