Frank L. Acosta

Current Treatment Strategies and Outcomes in the Management of Symptomatic Vertebral Hemangiomas

OBJECTIVE: We analyzed the outcome of patients with symptomatic vertebral hemangiomas treated at University of California, San Francisco, over a 20 year period. Treatment included transarterial embolization, embolization followed by surgical decompression or vertebral reconstruction with arthrodesis, and percutaneous vertebroplasty alone. METHODS: All medical, surgical, and radiological records were reviewed retrospectively. All patients underwent follow-up neurological examination and evaluation of back pain. RESULTS: Sixteen patients diagnosed with symptomatic vertebral hemangiomas causing pain or neurological deficit were treated at University of California, San Francisco, between 1984 and 2004. Mean follow-up was 81 months. Seven of nine patients undergoing surgical decompression and tumor resection reported pain relief and demonstrated improvement in neurological deficit when present. Two patients had recurrent myelopathy: one was successfully treated with a second decompressive surgery, whereas the second underwent a staged vertebrectomy. All three patients undergoing vertebrectomy had cord compression from extraosseous tumor growth. Preoperative embolization reduced expected intraoperative blood loss in four patients. Three of four patients who underwent transarterial embolization alone experienced resolution of back pain. Two of four patients treated with vertebroplasty had long-term pain relief. CONCLUSION: Transarterial embolization followed by laminectomy is a safe and effective procedure for the treatment of cord compression by vertebral hemangioma causing stenosis without instability or deformity. Vertebrectomy preceded by embolization and followed by reconstruction can be used to treat cord compression from extraosseous tumor extension. Transarterial embolization without decompression is an effective treatment for painful intraosseous hemangiomas. Vertebroplasty is useful for improving pain symptoms, especially when vertebral body compression fracture has occurred in patients without neurological deficit, but is less effective in providing long-term pain relief.

Porcine Intervertebral Disc Repair Using Allogeneic Juvenile Articular Chondrocytes or Mesenchymal Stem Cells

Tissue engineering strategies for intervertebral disc repair have focused on the use of autologous disc-derived chondrocytes. Difficulties with graft procurement, harvest site morbidity, and functionality, however, may limit the utility of this cell source. We used an in vivo porcine model to investigate allogeneic non-disc-derived chondrocytes and allogeneic mesenchymal stem cells (MSCs) for disc repair. After denucleation, lumbar discs were injected with either fibrin carrier alone, allogeneic juvenile chondrocytes (JCs), or allogeneic MSCs. Discs were harvested at 3, 6, and 12 months, and cell viability and functionality were assessed qualitatively and quantitatively. JC-treated discs demonstrated abundant cartilage formation at 3 months, and to a lesser extent at 6 and 12 months. For the carrier and MSC-treated groups, however, there was little evidence of proteoglycan matrix or residual notochordal/chondrocyte cells, but rather a type I/II collagen-enriched scar tissue. By contrast, JCs produced a type II collagen-rich matrix that was largely absent of type I collagen. Viable JCs were observed at all time points, whereas no evidence of viable MSCs was found. These data support the premise that committed chondrocytes are more appropriate for use in disc repair, as they are uniquely suited for survival in the ischemic disc microenvironment.

Biomechanical Comparison of Posterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion Performed at 1 and 2 Levels

Study Design. Biomechanical laboratory study of human cadaveric spines. Objective. To determine the difference in acute stability between posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) performed at 1 and 2 levels with and without posterior fixation. Summary of Background Data. Circumferential spinal fusion with both an interbody graft and posterior pedicle screw-rod construct has been advocated to decrease pseudarthrosis rates. Both PLIF and TLIF theoretically allow for 3-column fixation and fusion. Methods. Specimens underwent either PLIF or TLIF at L2–L3 (single-level) and L3–L4 (2-level), both with and without pedicle screw instrumentation. During TLIF, an interbody allograft was placed in the anterior or middle column. Nondestructive, nonconstraining pure moment loading was applied to each specimen. Results. There were no significant differences in the range of motion after either PLIF or TLIF at 1 level. The addition of pedicle screws tended more strongly to increase rigidity after 1-level PLIF compared to TLIF. Position of the TLIF graft did not affect stability. The addition of pedicle screws to a 2-level construct significantly reduced all motions tested. Conclusions. Based on our findings, posterior fixation with a pedicle screw-rod construct is suggested for 1-level PLIF and TLIF, and is necessary to achieve stability after interbody fusion across 2 levels using either technique.

Treatment of intracranial glioma with in situ interferon-gamma and tumor necrosis factor-alpha gene transfer

Interferon-gamma (IFNγ) and tumor necrosis factor-alpha (TNFα) are potent immunostimulatory cytokines with demonstrated tumoricidal effects in a variety of cancers. With the aim of investigating their ability to generate antitumor immune responses in malignant brain tumors, we describe the use of in situ adenoviral-mediated IFNγ and TNFα gene transfer in glioma-bearing rodents. Survival was prolonged in mice treated with AdmIFNγ or AdTNFα compared to AdLacZ- and saline-inoculated controls, and AdmIFNγ- or AdTNFα-treated animals revealed significantly smaller tumors. These effects were accompanied by significant up-regulation of tumor MHC-I expression in AdmIFNγ-inoculated animals, and of MHC-II in AdTNFα-treated tumors. Significantly enhanced intratumoral infiltration with CD4+ and CD8+ T cells was visible in animals treated with AdmIFNγ, AdTNFα, or a combination of AdmIFNγ and AdTNFα. In addition, AdTNFα therapy down-regulated the expression of endothelial Fas ligand, a cell membrane protein implicated as a contributor to immune privilege in cancer. These findings demonstrate the effectiveness of local IFNγ and TNFα gene transfer as a treatment strategy for glioma and illustrate possible physiological pathways responsible for the therapeutic benefit observed.

Human Disc Nucleus Properties and Vertebral Endplate Permeability

Study Design. Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan (GAG) content, and degeneration in samples harvested from human cadaveric spines. Objective. To test the hypothesis that variation in endplate permeability and porosity contributes to changes in intervertebral disc cell density and overall degeneration. Summary of Background Data. Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density, and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors and patient features that may impede efforts at disc tissue engineering. Methods. Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32–85 years) and classified for degeneration using the magnetic resonance imaging-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method, while the nuclear GAG content was quantified using the dimethylmethylene blue technique. Specimens were imaged at 8&mgr;m resolution using microCT; bony porosity was calculated. Analysis of variance, linear regression, and multiple comparison tests were used to analyze the data. Results. Nucleus cell density increased as the disc height decreased (R2 = 0.13; P = 0.01) but was not related to subchondral bone porosity (P > 0.5), total mobility (P > 0.4), or age (P > 0.2). When controlling for disc height, however, a significant, negative effect of age on cell density was observed (P = 0.03). In addition to this, GAG content decreased with age nonlinearly (R2 = 0.83, P < 0.0001) and a cell function measurement, GAGs/cell, decreased with degeneration (R2 = 0.24; P < 0.0001). Total mobility (R2 = 0.14; P < 0.01) and porosity (R2 = 0.1, P < 0.01) had a positive correlation with age. Conclusion. Although cell density increased with degeneration, cell function indicated that GAGs/cell decreased. Because permeability and porosity increase with age and degeneration, this implies that cell dysfunction, rather than physical barriers to transport, accelerates disc disease.

Retroperitoneal oblique corridor to the L2–S1 intervertebral discs in the lateral position: an anatomic study

OBJECT Access to the intervertebral discs from L2-S1 in one surgical position can be challenging. The transpsoas minimally invasive surgical (MIS) approach is preferred by many surgeons, but this approach poses potential risk to neural structures of the lumbar plexus as they course through the psoas. The lumbar plexus and iliac crest often restrict the L4-5 disc access, and the L5-S1 level has not been a viable option from a direct lateral approach. The purpose of the present study was to investigate an MIS oblique corridor to the L2-S1 intervertebral disc space in cadaveric specimens while keeping the specimens in a lateral decubitus position with minimal disruption of the psoas and lumbar plexus. METHODS Twenty fresh-frozen full-torso cadaveric specimens were dissected, and an oblique anatomical corridor to access the L2-S1 discs was examined. Measurements were taken in a static state and with mild retraction of the psoas. The access corridor was defined at L2-5 as the left lateral border of the aorta (or iliac artery) and the anterior medial border of the psoas. The L5-S1 corridor of access was defined transversely from the midsagittal line of the inferior endplate of L-5 to the medial border of the left common iliac vessel and vertically to the first vascular structure that crosses midline. RESULTS The mean access corridor diameters in the static state and with mild psoas retraction, respectively, were as follows: at L2-3, 18.60 mm and 25.50 mm; at L3-4, 19.25 mm and 27.05 mm; and at L4-5, 15.00 mm and 24.45 mm. The L5-S1 corridor mean values were 14.75 mm transversely, from midline to the left common iliac vessel and 23.85 mm from the inferior endplate of L-5 cephalad to the first midline vessel. CONCLUSIONS The oblique corridor allows access to the L2-S1 discs while keeping the patient in a lateral decubitus position without a break in the table. Minimal psoas retraction without significant tendon disruption allowed for a generous corridor to the disc space. The L5-S1 disc space can be accessed from an oblique angle consistently with gentle retraction of the iliac vessels. This study supports the potential of an MIS oblique retroperitoneal approach to the L2-S1 discs.

Complications and Outcomes of Lumbar Spine Surgery in Elderly People: A Review of the Literature

As the number of elderly persons in the United States continues to increase, there will be an associated increase in age‐related diseases, such as degenerative conditions of the lumbar spine. Elderly patients frequently present to their geriatrician or primary care provider with low back and leg pain. Spine surgery is one of several options the geriatric patient may consider for symptomatic relief, but the literature describing the safety and efficacy of spine surgery in older patients is inconclusive and at times confusing. The purpose of this article is to describe common degenerative conditions of the lumbar spine and to review the complications and outcomes of spine surgery in elderly patients, with particular attention to how they compare with those of younger patients. A better understanding of the risks and prognosis associated with these types of surgeries will enable more‐informed decision‐making by patients and physicians.

Long-term investigation of nonsurgical treatment for thoracolumbar and lumbar burst fractures: an outcome analysis in sight of spinopelvic balance

The nonsurgical treatment of thoracolumbar (TLB) and lumbar burst (LB) fractures remains to be of interest, though it is not costly and avoids surgical risks. However, a subset of distinct burst fracture patterns tend to go with a suboptimal radiographic and clinical long-term outcome. Detailed fracture pattern and treatment-related results in terms of validated outcome measures are still lacking. In addition, there are controversial data on the impact of local posttraumatic kyphosis that is associated, in particular, with nonsurgical treatment. The assessment of global spinal balance following burst fractures has not been assesed, yet. Therefore, the current study intended to investigate the radiographical and clinical long-term outcome in neurologically intact patients with special focus on the impact of regional posttraumatic kyphosis, adjacent-level compensatoric mechanisms, and global spine balance on the clinical outcome. For the purpose of a homogenous sample, strong in- and exclusion criteria were applied that resulted in a final study sample of 21 patients with a mean follow-up of 9.5 years. Overall, clinical outcome evaluated by validated measures was diminished, with 62% showing a good or excellent outcome and 38% a moderate or poor outcome in terms of the Greenough Low Back Outcome Scale. Notably, vertebral comminution in terms of the load-sharing classification, posttraumatic kyphosis, and an overall decreased lumbopelvic lordosis showed a significant effect on clinical outcome. A global and segmental curve analysis of the spine T9 to S1 revealed significant alterations as compared to normals. But, the interdependence of spinopelvic parameters was not disrupted. The patients’ spinal adaptability to compensate for the posttraumatic kyphotic deformity varied in the ranges dictated by pelvic geometry, in particular the pelvic incidence. The study substantiates the concept that surgical reconstruction and maintenance of a physiologically shaped spinal curve might be the appropriate treatment in the more severely crushed TLB and LB fractures.

Long-term biomechanical stability and clinical improvement after extended multilevel corpectomy and circumferential reconstruction of the cervical spine using titanium mesh cages.

Study Design Retrospective review of clinical case series. Objective We present our experience with extended (≥3 levels) anterior cervical corpectomy (EACC) and reconstruction. Summary of Background Data Multilevel cervical corpectomy has traditionally been associated with increased graft-related complications and worse clinical outcomes compared with single-level procedures. Data specifically regarding corpectomies across 3 or more levels remains limited. Methods Retrospective review of data on 20 patients who underwent anterior cervical corpectomies with titanium mesh cage reconstruction and supplemental posterolateral fixation across 3 or more levels of the cervical spine. Anteroposterior/lateral plain films were used to determine sagittal balance and cage subsidence. Fusion was defined as the lack of motion on flexion-extension radiographs. Patients underwent preoperative and postoperative clinical assessment using visual analog scores and Nurick grading. Results Surgery was performed for spondylotic myelopathy in 15 patients, osteomyelitis in 4, and fracture in 1. Corpectomies were performed across an average of 3.4 levels. Average follow-up was 33 months. Local autograft was used in all cases except osteomyelitis, where allograft was used instead. Sagittal balance was improved or maintained in all patients and was not related to number of corpectomy levels. An average of 30.2 degrees of kyphosis correction was achieved in 9 patients. All patients demonstrated radiographic evidence of fusion without significant cage subsidence and no cases of instrumentation failure. Improvement in pain and functional scores occurred in all cases. Conclusions Circumferential reconstruction using titanium mesh cages after EACC can provide appropriate, biomechanically stable fixation and allows for significant correction of preexisting kyphosis. Supplemental posterior instrumentation may limit delayed cage subsidence and loss of sagittal balance after this procedure. EACC and circumferential reconstruction seems to be an effective treatment for symptomatic degenerative, traumatic, or infectious pathology involving 3 or more levels of the anterior cervical spine.

En bloc resection for primary and metastatic tumors of the spine: a systematic review of the literature.

BACKGROUNDThe efficacy of en bloc resection for spinal tumors is unknown because most of the current evidence is provided by small, single-institution clinical series or case reports. OBJECTIVETo combine all previously published reports of en bloc resection for primary and metastatic spinal tumors, to describe the overall pattern of disease-free survival, and to investigate potentially prognostic factors for recurrence. METHODSA complete MEDLINE search for all articles reporting survival data for en bloc resection of spinal tumors was undertaken; 44 articles met inclusion criteria from which 306 eligible patients were identified. RESULTSThere were 229 cases of primary tumors with a mean follow-up of 65.0 months and 77 cases of solitary metastatic tumors with a mean follow-up of 26.5 months. Median time to recurrence was 113 months for the primary group and 24 months for the metastatic group. Disease-free survival rates at 1, 5, and 10 years were 92.6%, 63.2%, and 43.9%, respectively, for the primary group and 61.8%, 37.5%, and 0%, respectively, for the metastatic group; 5-year disease-free survival rates were 58.4% for chordoma and 62.9% for chondrosarcoma. After adjusting for covariates, age, male sex, metastatic tumors, and osteosarcomas were significantly associated with a tumor recurrence. CONCLUSIONThis study provides the largest published series of patients undergoing en bloc resection for spinal tumors. Median time to recurrence reached almost 10 years in patients with primary tumors; however, it was only 2 years in those with isolated metastatic tumors.