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Grégoire P. Chatain and Michael Finn

Reconstruction of the spinopelvic continuity after sacral resection for primary sacral tumors remains challenging. Complex anatomical and biomechanical factors of this transition zone may be addressed with the advancement of 3D-printed implants. Here, the authors report on a 67-year-old patient with a sacral chordoma who initially underwent total en bloc sacrectomy followed by standard spinopelvic reconstruction. Pseudarthrosis and instrumentation failure of the lumbosacral junction construct subsequently developed. A custom 3D-printed sacral prosthesis was created using high-resolution CT images. Emergency Food and Drug Administration approval was obtained, and the custom device was implanted as a salvage reconstruction surgery. Made of porous titanium mesh, the custom artificial sacrum was placed in the defect based on the anticipated osteotomic planes and was fixed with a screw-rod system along with a fibular bone strut graft. At the 18-month follow-up, the patient was disease free and walking short distances with assistance. CT revealed excellent bony incorporation into the graft.

The use of a custom 3D-printed prosthesis in spinal reconstruction has been rarely reported, and its application in sacral reconstruction and long-term outcome are novel. While the implant was believed to be critical in endowing the region with enough biomechanical stability to promote healing, the procedure was difficult and several key learning points were discovered along the way.

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Michael A. Finn and Marion L. Walker

✓Spinal lipomas, particularly lipomas of the conus medullaris and terminal filum, are the most common form of occult spinal dysraphism and represent a wide spectrum of disease with regard to anatomy, clinical presentation, and treatment options. These lesions, however, are united by a similar embryology and pathological mechanism by which symptoms arise.

Recently, the treatment of these lesions has generated much controversy, with some physicians advocating surgical treatment for all patients regardless of symptoms and others proposing that surgery be withheld until symptoms develop. The authors discuss lumbosacral spinal lipomas, with particular attention to the theories of their origin, anatomical and pathological features, and treatment options, including a review of current controversies.

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Michael A. Finn and Meic H. Schmidt

✓ Castleman disease is a rare lymphoproliferative disease of unknown cause. In most cases, afflicted patients present with a mediastinal mass although the disease may manifest in numerous other sites, including intracranially and rarely intraspinally. The authors report on the case of a 19-year-old woman who presented with a large paraspinal mass emanating from the T7–8 neural foramen. The morphological and signal characteristics revealed on magnetic resonance imaging were similar to those of nerve sheath tumors. The patient underwent open biopsy sampling of the lesion, and results of a pathological evaluation revealed hyaline-vascular type Castleman disease. She underwent radiotherapy and remains symptom-free with a radiographically stable lesion 1 year later. Although the disease has been reported to mimic a meningioma when encountered in intracranial locations, to the authors' knowledge, this is the first case of the disorder mimicking a nerve sheath tumor. When the diagnosis of Castleman disease is made, good results can be obtained with partial resection and radiotherapy.

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Michael A. Finn, Todd D. McCall and Meic H. Schmidt

✓Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovium with a predisposition for the appendicular skeleton. Rarely PVNS can arise from the spine, where this disorder usually presents with localized or radicular pain secondary to involvement of the posterior elements. The authors report the case of an 82-year-old woman who presented with long-standing neck pain and acute upper-extremity numbness and weakness. Computed tomography imaging revealed a mixed sclerotic and lucent lesion affecting the dens and right lateral mass of C-2. There was also a pathological fracture at the base of the dens with 8 mm of anterior dens displacement. Magnetic resonance imaging demonstrated a diffusely infiltrative process that was nonenhancing. Because of instability, the patient underwent transarticular screw fixation, and a biopsy of the lesion was also performed at this time. Histopathological analysis was consistent with a diagnosis of PVNS. To the authors' knowledge, this is the first report of PVNS involving the C-2 vertebra or causing a pathological fracture.

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Michael Finn, Paul Klimo Jr. and William T. Couldwell

✓Dural arteriovenous fistulas (dAVFs) are acquired direct arteriovenous shunts that often drain into the dural venous sinus. Treatment options generally involve disrupting the abnormal vascular conduits by using a combination of modalities, including surgical disconnection, radiosurgery, and transarterial and transvenous embolization. Often these modalities provide only partial treatment of fistulous lesions, and thus the fistula recurs and symptoms result. The authors report on a novel surgical technique in which the involved venous sinuses are skeletonized and an interpositional dural substitute is placed between the disconnected sinus and native dura mater and over the pial surface adjacent to the sinus. The technique, which is demonstrated in an illustrative case, is intended to preserve native venous drainage and to prevent recruitment of new vascularization to the venous sinus postoperatively. The authors have not observed reconstitution of fistulas over areas treated with this technique, which offers the advantage of inhibiting vascular ingrowth (refistulization) while maintaining venous sinus patency.

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Virany Huynh Hillard, Daniel R. Fassett, Michael A. Finn and Ronald I. Apfelbaum

Object

An iliac crest autograft is the gold standard for bone grafting in posterior atlantoaxial arthrodesis but can be associated with significant donor-site morbidity. Conversely, an allograft has historically performed suboptimally for atlantoaxial arthrodesis as an onlay graft. The authors have modified a bone grafting technique to allow placement of a bicortical iliac crest allograft in an interpositional manner, and they evaluated it as an alternative to an autograft in posterior atlantoaxial arthrodesis.

Methods

The records of 89 consecutive patients in whom C1–2 arthrodesis was performed between 2001 and 2005 were reviewed.

Results

Forty-seven patients underwent 48 atlantoaxial arthrodeses with an allograft (mean follow-up 16.1 months, range 0–49 months), and 42 patients underwent autograft bone grafting (mean follow-up 17.6 months, range 0–61.0 months). The operative time was 50 minutes shorter in the allograft (mean 184 minutes, range 106–328 minutes) than in the autograft procedure (mean 234 minutes, range 154–358 minutes), and the estimated blood loss was 50% lower in the allograft group than in the autograft group (mean 103 ml [range 30–200 ml] vs mean 206 ml [range 50–400 ml], respectively). Bone incorporation was initially slower in the allograft than in the autograft group but equalized by 12 months postprocedure. The respective fusion rates after 24 months were 96.7 and 88.9% for autografts and allografts. Complications at the donor site occurred in 16.7% of the autograft patients, including 1 pelvic fracture, 1 retained sponge, 1 infection, 2 hernias requiring repair, 2 hematomas, and persistent pain.

Conclusions

The authors describe a technique for interpositional bone grafting between C-1 and C-2 that allows for the use of an allograft with excellent fusion results. This technique reduced the operative time and blood loss and eliminated donor-site morbidity.

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Michael A. Finn, Nathan D. Faulkner, Scott J. Hetzel and Paul A. Anderson

Object

Dural tears are a frequent complication of spinal surgery and contribute to significant morbidity. Occasionally, dural tears cannot be closed primarily and dural patch grafts must be utilized. No data exist on the comparative immediate hydrostatic strength of various patch materials used alone or with a biological adhesive in a spinal dural tear model. Thus, the authors conducted this study to determine the comparative effectiveness of various patch materials used with and without biological adhesive.

Methods

Twenty-four thoracic spines from calves were prepared with laminectomies and spinal cord evacuation, leaving the dura intact. Foley catheters were inflated on either side of a planned dural defect, and baseline hydrostasis was measured using a fluid column at 30, 60, and 90 cm of H2O. A standard dural defect (1 × 2 cm) was created, and 8 patches of each material (human fascia lata, Duragen, and Preclude) were sutured in place using 5-0 Prolene hemo-seal running sutures. Hydrostasis was again tested at the same pressures. Finally, a hydrogel sealant (Duraseal) was placed over the defect and hydrostasis was again tested. Results were analyzed with repeated measures ANOVA.

Results

The leakage rate increased significantly at each pressure tested for all conditions. There was no difference in leakage among the 3 patch materials at any of the pressures or for either condition (with or without sealant). All patch materials allowed significantly greater leakage than the intact condition at all pressures. The use of sealant reduced leakage significantly at the 30 and 60 mm Hg pressures to levels similar to the intact condition. At 90 mm Hg, leakage of the sealed construct was greater than at the intact condition but significantly less than without the use of sealant.

Conclusions

All 3 dural patch materials were of similar hydrostatic strength and allowed greater leakage than at the intact condition. The use of sealant reduced the amount of leakage at all pressures compared with patching alone but allowed more leakage than the intact state at a high hydrostatic pressure (90 mm Hg).

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Frank S. Bishop, Michael A. Finn, Mical Samuelson and Richard H. Schmidt

In severe cases, posttraumatic cerebral sinus thrombosis can result in venous congestion and persistent intracranial hypertension refractory to both conventional medical therapy and surgical decompression. The authors report a unique case of a patient successfully treated with endovascular mechanical thrombolysis using balloon angioplasty for clinically significant posttraumatic venous sinus thrombosis and review the reported treatments for cerebral venous sinus occlusive disease.

This 18-year-old man suffered severe closed head injury from a fall while skateboarding. A head CT scan demonstrated basilar skull fractures involving the left jugular foramen. A CT angiogram revealed thrombosis of the left transverse sinus and occlusion of the sigmoid sinus and internal jugular vein. Despite treatment with anticoagulation therapy and decompressive hemi- and suboccipital craniectomies, intracranial hypertension remained refractory. Serial angiography demonstrated progressive sinus occlusion. Endovascular balloon thrombolysis of the left transverse and sigmoid sinuses resulted in immediate reduction of intracranial pressures and improved sinus patency. Intracranial pressure measurements remained low after the procedure. The patient eventually improved neurologically, was able to follow commands and walk, and was discharged to a rehabilitation facility for further recovery.

Anticoagulation therapy, surgical decompression, and endovascular thrombolysis have been reported as treatment modalities for clinically significant posttraumatic venous sinus thrombosis. In this case, endovascular mechanical thrombolysis with balloon angioplasty resulted in resolution of thrombus and successful immediate reduction of intracranial pressure. This treatment may be considered in patients with critically elevated intracranial pressure from posttraumatic venous sinus occlusion refractory to other treatment measures.

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Andrew T. Dailey, David Hart, Michael A. Finn, Meic H. Schmidt and Ronald I. Apfelbaum

Object

Fractures of the odontoid process are the most common fractures of the cervical spine in patients over the age of 70 years. The incidence of fracture nonunion in this population has been estimated to be 20-fold greater than that in patients under the age of 50 years if surgical stabilization is not used. Anterior and posterior approaches have both been advocated, with excellent results reported, but surgeons should understand the drawbacks of the various techniques before employing them in clinical practice.

Methods

A retrospective review was undertaken to identify patients who had direct fixation of an odontoid fracture at a single institution from 1991 to 2006. Patients were followed up using flexion-extension radiographs, and stability was evaluated as bone union, fibrous union, or nonunion. Patients with bone or fibrous union were classified as stable. In addition, the incidence of procedure- and nonprocedure-related complications was extracted from the medical record.

Results

Of the 57 patients over age 70 who underwent placement of an odontoid screw, 42 underwent follow-up from 3 to 62 months (mean 15 months). Stability was confirmed in 81% of these patients. In patients with fixation using 2 screws, 96% demonstrated stability on radiographs at final follow-up. Only 56% of patients with fixation using a single screw demonstrated stability on radiographs. In the immediate postoperative period, 25% of patients required a feeding tube and 19% had aspiration pneumonia that required antibiotic treatment.

Conclusions

Direct fixation of Type II odontoid fractures showed stability rates > 80% in this challenging population. Significantly higher stabilization rates were achieved when 2 screws were placed. The anterior approach was associated with a relatively high dysphagia rate, and patients must be counseled about this risk before surgery.

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Frank S. Bishop, Mical M. Samuelson, Michael A. Finn, Kent N. Bachus, Darrel S. Brodke and Meic H. Schmidt

Object

Thoracolumbar corpectomy is a procedure commonly required for the treatment of various pathologies involving the vertebral body. Although the biomechanical stability of anterior reconstruction with plating has been studied, the biomechanical contribution of posterior instrumentation to anterior constructs remains unknown. The purpose of this study was to evaluate biomechanical stability after anterior thoracolumbar corpectomy and reconstruction with varying posterior constructs by measuring bending stiffness for the axes of flexion/extension, lateral bending, and axial rotation.

Methods

Seven fresh human cadaveric thoracolumbar spine specimens were tested intact and after L-1 corpectomy and strut grafting with 4 different fixation techniques: anterior plating with bilateral, ipsilateral, contralateral, or no posterior pedicle screw fixation. Bending stiffness was measured under pure moments of ± 5 Nm in flexion/extension, lateral bending, and axial rotation, while maintaining an axial preload of 100 N with a follower load. Results for each configuration were normalized to the intact condition and were compared using ANOVA.

Results

Spinal constructs with anterior-posterior spinal reconstruction and bilateral posterior pedicle screws were significantly stiffer in flexion/extension than intact spines or spines with anterior plating alone. Anterior plating without pedicle screw fixation was no different from the intact spine in flexion/extension and lateral bending. All constructs had reduced stiffness in axial rotation compared with intact spines.

Conclusions

The addition of bilateral posterior instrumentation provided significantly greater stability at the thoracolumbar junction after total corpectomy than anterior plating and should be considered in cases in which anterior column reconstruction alone may be insufficient. In cases precluding bilateral posterior fixation, unilateral posterior instrumentation may provide some additional stability.