Stephen L. Ondra

Standing Balance and Sagittal Plane Spinal Deformity: Analysis of Spinopelvic and Gravity Line Parameters

Study Design. Prospective study of 131 patients and volunteers recruited for an analysis of spinal alignment and gravity line (GL) assessment by force plate analysis. Objective. To determine relationships between GL, foot position, and spinopelvic landmarks in subjects with varying sagittal alignment. Additionally, the study sought to analyze the role of the pelvis in the maintenance of GL position. Summary of Background Data. Force plate technology permits analysis of foot position and GL in relation to radiographically obtained landmarks. Previous investigation noted fixed GL-heel relationship across a wide age range despite changes in thoracic kyphosis. The pelvis as balance regulator has not been studied in the setting of sagittal spinal deformity. Methods. The 131 subjects were grouped by sagittal vertical axis (SVA) offset from the sacrum: sagittal forward (>2.5 cm), neutral (−2.5 cm ≤ SVA ≤ 2.5 cm), and sagittal backward (SVA <−2.5 cm). Simultaneous spinopelvic radiographs and GL measure were obtained. Offsets between spinopelvic landmarks, heel position, and GL were calculated. Group comparisons were made for all offsets to determine significance. Results. Aside from the offset T9-GL and GL-heels, all other offsets between spinopelvic landmarks and GL revealed significant differences (P < 0.001) across the 3 subject groups. However, with increasing SVA, the GL kept a rather fixed location relative to the feet. A correlation between posterior pelvic shift in relation to the heels with increasing SVA in this study population was confirmed (r = 0.6, P < 0.001). Conclusion. Increasing SVA in standing subjects leads to a posterior pelvic shift in relation to the feet. However, no significant difference in GL-heel offset is noted with increasing SVA. It thus appears that pelvic shift (in relation to the feet) is an important component in maintaining a rather fixed GL-Heels offset even in the setting of variable SVA and trunk inclination.

Surgical excision of a cavernous hemangioma of the rostral brain stem: case report.

A 23-year-old pregnant woman presented with sudden diplopia, ataxia, hemiparesis, and headache secondary to a brain stem hemorrhage. Magnetic resonance imaging (MRI) revealed a hematoma associated with a probable cavernous hemangioma of the rostral brain stem. In this report, we discuss the MRI findings leading to the preoperative diagnosis, as well as the surgical techniques involved in the successful resection.

Cervical spondylotic myelopathy: treatment with posterior decompression and Luque rectangle bone fusion

Cervical spondylotic myelopathy appears to result from a combination of factors. The two major components are 1) compressive forces resulting from narrowing of the spinal canal, and 2) dynamic forces owing to mobility of the cervical spine. There is substantial evidence to suggest that the repetitive trauma to the spinal cord that is sustained with movement in a spondylotic canal may be a major cause of progressive myelopathy. Utilization of extensive anterior procedures that remove the diseased ventral features as well as eliminate the dynamic forces owing to the accompanying fusion have grown in popularity. Cervical laminectomy enlarges the spinal canal, but does not reduce the dynamic forces affecting the spinal cord, and may actually increase cervical mobility, leading to a perpetuation of the myelopathy. The authors propose the combination of posterior decompression and Luque rectangle bone fusion to deal with both the compressive and the dynamic factors that lead to cervical spondylotic myelopathy. Ten patients who had advanced myelopathy underwent the combined procedures. Nine of the 10 experienced significant neurological improvement, and the 10th has had no progression. The combination of posterior decompression and Luque rectangle bone fusion may offer a simple, safe, and effective alternative treatment for cervical spondylotic myelopathy.

Cryptococcal skull infection: a case report with review of the literature.

A case of cryptococcal osteomyelitis of the skull is presented. The patient was an immunocompetent host with skull and skin involvement without central nervous system or pulmonary extension. The radiographic findings are reviewed to include skull films, bone scan, and computed tomographic and magnetic resonance imaging scans. The patient underwent surgical debridement of the lesion as well as systemic medical therapy with amphotericin B and flucytosine. The medical and surgical therapy for such lesions is reviewed. Surgical intervention is emphasized for the removal of bony sequestrum and nonviable bone while maintaining an intact dura.

Symptomatic Pineal Cyst: Case Report

Pineal cysts are being described with increasing frequency since the advent of magnetic resonance imaging. Although pineal cysts are incidental findings in as many as 4% of magnetic resonance imaging studies, symptomatic pineal cysts are quite rare. We present a case of pineal cyst causing aqueductal obstruction with symptomatic hydrocephalus and resultant headache and syncope, which was treated by surgical resection. A review of the relevant literature and discussion follow.

Combined transmandibular-zygomatic approach and infratemporal craniotomy for intracranial skull base tumors

Large intracranial skull base tumors remain surgically treacherous lesions. The preauricular transzygomatic infratemporal approach to this area has rapidly gained popularity. This article presents modifications to this approach which improved visualization and access to the infratemporal fossa. The procedure increases visualization, minimizes brain retraction, and results in improved resection and outcome. Reconstruction is rapid and there are minimal functional and cosmetic deficits.

Salvage technique of posterior iliac bolt placement in long-segment spinal constructs with a previous posterior iliac crest harvest: technical note.

OBJECTIVE AND IMPORTANCE: Fusion between the lumbar spine and sacrum has been used to treat deformity, degenerative disease, trauma, and tumor. These constructs have a higher failure rate when a long construct is designed, in patients with poor bone quality, and in patients with previous irradiation or with significant osteoporosis. CLINICAL PRESENTATION: Extending the construct to the pelvis has been shown to increase the fusion rate of these patients and to reduce the risk of hardware failure before fusion has occurred. INTERVENTION: We extend the constructs with the use of iliac bolts placed within the posterior iliac crests. Placement of these bolts can be challenging after the posterior iliac crest has been harvested for autologous bone in a previous operation. CONCLUSION: The purpose of this technical note is to describe our salvage technique of iliac bolt placement as an adjunct to lumbar-sacral fusions in a previously harvested iliac crest.

A DIRECT COMPARISON OF RHOP-1 AND RHBMP-2 IN A RHESUS MONKEY POSTEROLATERAL ENVIRONMENT

Background: Clinical trials investigating spinal applications of rhOP-1 and rhBMP-2 have been performed, but little evidence exists to guide informed decision-making between the two options. The purpose is to compare the boneforming capabilities of various rhBMP-2 and rhOP-1 formulations in a challenging nonhuman primate model. Material and Methods: Nine rhesus monkeys were used in a side-by-side comparison in the L4-L5 posterolateral fusion environment, rhOP-1 (right) and rhBMP-2 (left). 50% human graft volume is used in this model. Formulations were grouped as: 1) Clinical IDE: rhOP-1 0.875mg/cc, 2.25cc/side (50% clinical volume) rhBMP-2 2.0mg/cc, 5cc/side (50% clinical volume) 2) Volume matching: rhOP-1 0.875mg/cc, 2.25cc/side (50% clinical volume) rhBMP-2 2.0 mg/cc, 2.25cc/side (22.5% clinical volume) 3) Current clinical use: rhOP-1 0.875mg/cc, 1.125 cc/side increased to 5cc/side with TCP (50% clinical volume) rhBMP-2 1.5mg/cc, 2cc/side with increased to 5cc/side with â-TCP/HA (50% clinical volume) CTs were performed 2, 4, and 6 months. At 6 months, CT scans were examined for bridging bone and quantitative radiography was performed measuring cross-sectional area along each fusion mass. Results: 5/9 rhBMP-2 sides demonstrated bridging bone, 2/9 lacked bridging bone, and 2/9 were indeterminate. All rhOP-1 sides (0/9) lacked bridging bone. Early graft migration away from the posterolateral bed was observed in 3/3 rhOP-1 TCP. Quantitative radiography exhibited 5x larger rhBMP-2 fusion mass areas in Groups 1 and 3 (p 0.05) and 3.5x larger in Group 2 (p 0.072) compared to rhOP-1. Discussion: Clear differences were observed in the efficacy of rhBMP-2 and rhOP-1, with rhBMP-2 having higher rates of bridging bone and larger fusion masses. The uniform lack of bone formation on the rhOP-1 side of this model may lead to instability and limit model effectiveness in predicting clinical fusion outcomes. Migration of rhOP-1 was seen when combined with TCP. These results suggest rhBMP-2 is a more effective recombinant protein for posterolateral fusion. I N T E R N A T I O N A L S O C I E T Y F O R T H E S T U D Y O F L U M B A R S P I N E