Biomedical subjects

Frank L Acosta

Publications and source records attributed to Frank L Acosta.

At least 19 recordsLinked to original sources

PubMed2007

Corpectomy followed by the placement of instrumentation with titanium cages and recombinant human bone morphogenetic protein-2 for vertebral osteomyelitis.

OBJECT: The treatment of vertebral osteomyelitis includes antibiotics with or without surgical intervention. The decision to place instrumentation into an infected spinal column remains controversial. The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in patients with osteomyelitis is also extremely controversial. The authors review their experience in performing corpectomy and fusion with titanium cages and rhBMP-2 in patients with vertebral instability and/or neurological compromise due to vertebral osteomyelitis. METHODS: Data obtained in 15 patients treated between 2001 and 2005 were included in this analysis. Nine patients presented primarily with axial pain and six with radiculopathy or myelopathy. Seven patients had an associated epidural abscess. The cervical spine was affected in six patients, the thoracic spine in five, and the lumbar spine in four. All patients underwent corpectomy of the involved vertebral bodies; the authors then performed spinal reconstruction, placing a titanium cage-plate system with morcellized allograft/autograft and rhBMP-2. In 10 patients, supplemental posterolateral screw-rod fixation was conducted. A one-level corpectomy was performed in one patient, a two-level corpectomy in 13, and a six-level corpectomy in one. A morcellized allograft and rhBMP-2-filled titanium cage was used in 10 patients, and an autograft and rhBMP-2-filled cage in five patients. The most common pathogen was Staphylococcus aureus. All patients received intravenous antibiotics for at least 6 weeks postoperatively, and life-long antibiotic therapy was required in three patients with coccidiomycoses, candida, and tuberculosis osteomyelitis, respectively. There were no recurrent infections. Radiography demonstrated evidence of fusion in all patients at the last follow-up examination. The mean follow-up period was 20 months. CONCLUSIONS: Corpectomy followed by titanium cage-plate reconstruction and the placement of rhBMP-2 may be a safe and effective treatment for selected patients with vertebral osteomyelitis. This surgical therapy does not appear, at least based on preliminary results, to lead to recurrent hardware infections. Based on the results obtained in this limited series, the authors found that rhBMP-2 can be used in the setting of active infection with excellent fusion rates and without complication. The morbidity associated with the autograft donor site is avoided when using cages. Antibiotic therapy tailored to the specific organism should be continued for at least 6 weeks after surgery, and life-long therapy is required in cases of fungal or tuberculosis infections.

Adult↗

PubMed2006

Successful outcome of six-level cervicothoracic corpectomy and circumferential reconstruction: case report and review of literature on multilevel cervicothoracic corpectomy.

UNLABELLED: The authors report the successful outcome of a six-level corpectomy across the cervico-thoracic spine with circumferential reconstruction in a patient with extensive osteomyelitis of the cervical and upper thoracic spine. To the authors' knowledge, this is the first report of a corpectomy extending across six levels of the cervico-thoracic spine. CLINICAL RELEVANCE: the authors recommend anterior cage and plate-assisted reconstruction and additional posterior instrumentation using modern spinal surgical techniques and implants.

Anti-Bacterial Agents↗

PubMed2006

Coblation of spinal endplates in preparation for interbody spinal fusion.

Posterior lumbar interbody fusion (PLIF) and anterior lumbar interbody fusion (ALIF) have become routine alternatives to intertransverse process fusion. The use of Coblation (ArthroCare Corporation, Sunnyvale, CA) allows for routine and reproducible removal of cartilaginous endplate down to the bony endplate. Our experience with this new technology is reviewed. The authors used Coblation to prepare endplates of 10 consecutive patients undergoing interbody fusion. The results were compared to the following 10 consecutive patients undergoing interbody fusion with endplates prepared in the standard fashion with curettes and rongeurs. The same interbody grafts and instrumentation were used in all patients. Follow-up X-rays were done at 1 week, 6 weeks, 6 months, 1 year, and then each year thereafter. The 20 patients were reviewed along with their films. In each patient the disk spaces and the ALIF/PLIF cages appeared to be fused by 6 months. There was one superficial wound infection in each group. In each of the cases in which PLIF was performed, the cages were augmented by posterior lateral graft and pedicle screw fixation. All patients in both groups reported improvement in pain and/or neurologic symptoms by 6 months. The patients were followed for 4.6 years in the Coblation group and 4.1 years in the standard group. Disk space height was measured in all patients at 6 months. In the Coblation group, average disk space height was 9.0 mm compared to 8.2 mm in the standard group (p<0.1). We feel that the maintenance of normal structures within the lumbar spine with anterior/posterior lumbar interbody fusions and non-mechanical means of preparing the endplates are advantageous. Clearly, the number of patients involved and the length of follow-up limit this study, but it serves as an early indicator that endplate preparation may play a role in graft subsidence and fusion rates. Additional study is warranted.

Adult↗

PubMed2006

Recent advances: infections of the spine.

The global increase of spinal infections is concomitant with the rise of its risk factors, including HIV/AIDS, diabetes mellitus, intravenous drug use, advanced age, and gunshot wounds to the spine. Because spinal infections have a wide span of presentation, early detection and differentiation are notoriously challenging. Current advances in laboratory and imaging techniques, such as polymerase chain reaction, fluorodeoxyglucose positron emission tomography, and 99mTc-ciprofloxacin scintigraphy, allow for better diagnostic rendering of the infection and its degree of spinal involvement. Less invasive surgical procedures and preventive surgical management have helped reduce spinal infection morbidities such as deformity and neurologic deficit. Although proper antibiotic regimen and correct surgical management are of vital importance to successful patient outcome, early detection remains the most critical factor.

Journal Article↗

PubMed2006

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.

Adult↗

PubMed2006

Expandable cylindrical cages in the cervical spine: a review of 22 cases.

OBJECT: Expandable cylindrical cages (ECCs) have been utilized successfully to reconstruct the thoracic and lumbar spine. Their advantages include ease of insertion, reduced endplate trauma, direct application/maintenance of interbody distraction force, and one-step kyphosis correction. The authors present their experience with ECCs in the reconstruction of the cervical spine in patients with various pathological conditions. METHODS: Data obtained in 22 patients were reviewed retrospectively. A standard anterior cervical corpectomy was performed in all cases. Local vertebral body bone was harvested for use as graft material. Patients underwent pre- and postoperative assessment involving the visual analog scale (VAS), Nurick grading system for determining myelopathy disability, and radiographic studies to determine cervical kyphosis/lordosis and cage subsidence. Fusion was defined as the absence of motion on flexion-extension x-ray films. Sixteen patients presented with spondylotic myelopathy, two with osteomyelitis, two with fracture, one with tumor metastasis, and one with severe stenosis. Fourteen patients underwent supplemental posterior spinal fusion, seven underwent single-level corpectomy, and 15 patients underwent multilevel corpectomy. No perioperative complications occurred. The mean follow-up period was 22 months. In 11 patients with preexisting kyphosis (mean deformity +19 degrees), the mean correction was 22 degrees. There was no statistically significant difference in subsidence between single- and multilevel corpectomy or between 360 degrees fusion and anterior fusion alone. The VAS scores improved by 35%, and the Nurick grade improved by 31%. The fusion rate was 100%. CONCLUSIONS: The preliminary results support the use of ECCs in the cervical spine in the treatment of patients with various disease processes. No significant subsidence was noted, and pain and functional scores improved in all cases. Expandable cylindrical cages appear to be well suited for cervical reconstruction and for correcting sagittal malalignment.

Adult↗

PubMed2005

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.

Biomechanical Phenomena↗

PubMed2005

The potential role of mesenchymal stem cell therapy for intervertebral disc degeneration: a critical overview.

Low-back pain is the most common health problem for men and women between 20 and 50 years of age, resulting in 13 million doctor visits in the US annually, with significant costs to society in terms of lost time from work and direct and indirect medical expenses. Although the exact origin of most cases of low-back pain remains unknown, it is understood that degenerative damage to the intervertebral disc (IVD) plays a central role in the pathogenic mechanism leading to this disorder. Current treatment modalities for disc-related back pain (selective nerve root blocks, surgical discectomy and fusion) are costly procedures aimed only at alleviating symptoms. Consequently, there is growing interest in the development of novel technologies to repair or regenerate the degenerated IVD. Recently, mesenchymal stem cells (MSCs) have been found to possess the capacity to differentiate into nucleus pulposus-like cells capable of synthesizing a physiological, proteoglycan-rich extracellular matrix characteristic of healthy IVDs. In this article, the authors review the use of MSCs for repopulation of the degenerating IVD. Although important obstacles to the survival and proliferation of stem cells within the degenerating disc need to be overcome, the potential for MSC therapy to slow or reverse the degenerative process remains substantial.

Animals↗

PubMed2005

Biomechanics of stabilization after cervicothoracic compression-flexion injury.

STUDY DESIGN: Biomechanical laboratory research. OBJECTIVE: To determine whether anterior, posterior, or combined instrumentation provides the best stability for treating a cervicothoracic compression-flexion injury. SUMMARY OF BACKGROUND DATA: As the junction between the mobile cervical spine and rigid thoracic spine, the cervicothoracic junction poses unique challenges to the success of any fixation system spanning this region. Although posterior instrumentation is the preferred method of fixation in the unstable cervical spine, it is unknown whether this is the case across the unstable cervicothoracic junction. METHODS: Flexion, extension, lateral bending, and axial rotation of cadaveric specimens were studied during application of nondestructive pure moments in a sequence of conditions: (1) intact, (2) after destabilization, (3) with posterior instrumentation from C6-T1 or T2, and (4) with corpectomy/graft and anterior alone or combined anterior/posterior instrumentation. RESULTS: Compared to anterior instrumentation, posterior instrumentation allowed an 89% smaller range of motion (ROM) during lateral bending (P = 0.01) and 64% smaller ROM during axial rotation (P = 0.04). In most loading modes, combined instrumentation outperformed either anterior or posterior instrumentation alone. Most biomechanical measurements of stability improved when posterior instrumentation was extended from T1 to T2. Small and usually insignificant reductions in ROM averaging 15% were observed with C7 included in the posterior construct versus C7 excluded. CONCLUSIONS: Combined instrumentation provides a significant improvement in stability over either anterior or posterior instrumentation alone. Extension of the posterior instrumentation to include T2 improves stability at T1-T2 as well as rostral levels. Inclusion of C7 in the construct is largely inconsequential biomechanically.

Adult↗

PubMed2005

Kyphoplasty-augmented short-segment pedicle screw fixation of traumatic lumbar burst fractures: initial clinical experience and literature review.

OBJECT: Surgical intervention for thoracolumbar burst fractures is indicated for patients with neurological deficits and/or evidence of severe spinal instability. The goals of surgery are decompression, deformity correction, and stabilization. Nevertheless, the optimal surgical strategy to achieve these goals remains a subject of debate. Short-segment pedicle screw fixation is associated with a 20 to 50% incidence of pedicle screw failure and progressive spinal deformity. Initial biomechanical and clinical studies have shown that reinforcement of short-segment pedicle screw fixation with vertebroplasty improves spinal stability and decreases instrument failure rates. In this study, the authors describe their initial clinical experience with kyphoplasty used to augment short-segment pedicle screw fixation of traumatic lumbar burst fractures. METHODS: Five patients with traumatic burst fractures of the lumbar spine were included in this retrospective review of patients treated for this disorder at the University of California, San Diego and the University of California, San Francisco between 2002 and 2004. All patients underwent transpedicular kyphoplasty and short-segment pedicle screw fixation. The mean follow-up period was 10.6 months (range 6-18 months). All patients underwent short-segment pedicle screw fixation reinforced with polymethyl methacrylate kyphoplasty. The preoperative, postoperative, and follow-up plain x-ray films were evaluated. Radiographic analysis included measurements of kyphotic angulation, anterior vertebral body height, and evidence of bone fusion. Clinical evaluation was performed postoperatively and at follow-up review. CONCLUSIONS: Based on the authors' initial experience, kyphoplasty supplementation may improve the long-term integrity of short-segment pedicle screw constructs and allow for improved rates of fusion and better clinical outcomes in patients with traumatic lumbar burst fractures.

Adult↗

PubMed2005

Cervical disc arthroplasty: general introduction.

Cervical disc arthroplasty is a relatively new motion-preserving technique for the treatment of symptomatic degenerative disc disease of the cervical spine. Unlike anterior discectomy and fusion, cervical disc replacement restores normal motion and a physiologic biomechanical environment to adjacent disc levels, thereby decreasing the incidence of adjacent segment disease. To date, cervical disc arthroplasty has been at least as effective as cervical fusion in providing symptomatic relief while reducing perioperative morbidity, eliminating the need for postoperative external immobilization, and allowing for earlier return to normal function. No significant complications have been associated with this procedure so far. Further study in the form of large, randomized, prospective studies is needed to make conclusions about the long-term efficacy of this procedure as well as to determine the patient populations that may benefit most from cervical disc arthroplasty.

Arthroplasty, Replacement↗

PubMed2005

The Charité Artificial Disc: insertion technique.

The Charité Artificial Disc is the first commercially available motion-preserving technology for the lumbar spine. The Charité is the first US Food and Drug Administration-approved artificial disc for the treatment of single-level lumbar degenerative disc disease from L4 to S1. With thousands of implantations worldwide since 1987, it has the longest clinical experience of any artificial disc. No other artificial disc has the substantial preclinical and clinical history that validates its use.

Arthroplasty, Replacement↗

PubMed2005

Emerging directions in motion preservation spinal surgery.

In this review, we focus on novel surgical techniques and spinal arthroplasty systems inactive development. First, we discuss systems that allow for minimally invasive approaches to the lumbar disc space: (1) lateral approaches, (2) posterior approaches,and (3) oblique approaches. These techniques offer the potential for a minimally invasive lumbar arthroplasty system. Second, we discuss novel facet replacement technology. The facet joints, with the intervertebral disc, comprise the three-joint complex of the spinal unit. Facet joint health is thus crucial to proper disc biomechanics and function. Finally,we discuss dynamic neutralization of the lumbar spine with an artificial posterior tension band device. This allows for a certain degree of immobilization without fusion. Minimally invasive surgical approaches, facet arthroplasty, and posterior tension band devices may be the future of motion preservation spinal surgery.

Arthroplasty↗

PubMed2005

The ProDisc artificial disc: insertion technique.

The ProDisc artificial lumbar disc was designed for use in treatment of degenerative lumbar disease. The disc is implanted using an anterior approach to the lumbar spine with the assistance of intraoperative fluoroscopy. A variety of insertion instruments guide the surgeon through this process. The disc is implanted via an anterior approach, generally retroperitoneally but on occasion transperitoneally. The different approaches and insertion technique are described in this article.

Arthroplasty, Replacement↗

PubMed2005

Frameless stereotactic image-guided C1-C2 transarticular screw fixation for atlantoaxial instability: review of 20 patients.

OBJECTIVE: We retrospectively studied 20 adults who underwent C1-C2 transarticular screw (TAS) fixation utilizing frameless stereotaxy. METHODS: The study group comprised 13 men and 7 women, with a mean age of 63 years (range 12-87 years). All patients demonstrated clinical and radiographic evidence of C1-C2 instability. The cause of the instability was trauma in 11 patients, rheumatoid arthritis in 6 patients, failed prior surgery in 2 patients, and congenital malformation in 1 patient. All patients underwent stabilization with C1-C2 TASs using image-guided frameless stereotaxy. RESULTS: There were no new or worsening neurologic symptoms reported at 18-month follow-up. Motor weakness improved in seven of nine patients, myelopathy in seven of seven, and gait in three of six patients in whom these deficits were present preoperatively. Postoperative complications included one surgical site abscess, one cutaneous pressure ulcer, and one iliac crest donor site infection. Of 36 screws placed, 33 (92%) were well positioned. Normal C1-C2 alignment was achieved in 17 of 20 (85%) patients. In 4 of 20 cases, screw implant, which was thought to be anatomically difficult, if not impossible, on the basis of routine magnetic resonance or computed tomography imaging, was actually accomplished successfully using surgical navigation. CONCLUSIONS: C1-C2 TAS placement is a safe and accurate surgical technique that may improve neurologic function. Use of intraoperative navigation can facilitate achieving difficult surgical trajectories that match the patient's anatomy, thus allowing TAS implant in patients who otherwise would not be candidates for this type of internal fixation.

Adolescent↗

PubMed2005

Artificial pedicle screw reconstruction of the cervical spine after lateral paramedian transpedicular approach for lesions of the ventral cervical spinal canal.

OBJECTIVE: We describe in detail the anatomic and surgical principles of a lateral cervical paramedian transpedicular approach, a novel technique that provides access to the ventral cervical spinal canal. We also describe single-stage posterior column reconstruction of the cervical spine in which traditional cervical lateral mass screws are used simultaneously to reconstruct the cervical pedicle and to allow for three-column stabilization in a continuous posterior screw-rod construct after this approach. METHODS: This technique is a modification of traditional thoracic posterolateral extracavitary approaches and has been used by our group for the resection of intradural and extradural spinal lesions, as we illustrate. RESULTS: This approach is particularly useful in cases where significant pathological characteristics of the trachea or esophagus preclude an anterior approach to the cervical spine and in cases in which multiple levels are involved. CONCLUSION: Cervical spinal stability is enhanced, because all cervical levels are incorporated into the final screw-rod construct.

Adult↗

PubMed2005

Neurocutaneous melanosis presenting with hydrocephalus. Case report and review of the literature.

Neurocutaneous melanosis (NCM) is a rare congenital neurocutaneous syndrome characterized by large or multiple congenital melanocytic nevi and benign or malignant melanocytic tumors of the leptomeninges. The authors report the case of a 5-month-old girl with congenital giant melanocytic nevi who presented with symptomatic hydrocephalus. A right frontal ventriculostomy was performed in the patient. Magnetic resonance imaging demonstrated melanocyte accumulation within the hippocampi, medulla, and cerebellum. Cerebrospinal fluid cytology revealed no presence of melanocytes. A ventriculoperitoneal shunt was placed; the patient's neurological condition improved and she was discharged home in good condition. The diagnosis of neurocutaneous melanosis should be considered in a case in which an infant or child presents with hydrocephalus and either large or multiple (> or = 3) congenital melanocytic nevi. Although our patient's neurological status improved following treatment for hydrocephalus, there is no definitive therapy for NCM and symptomatic patients have a poor prognosis. Our case illustrates to the neurosurgeon the importance of recognizing the likelihood of underlying pathological conditions of the central nervous system in a child with cutaneous melanocytic nevi.

Female↗

PubMed2005

Biomechanical analysis of a newly designed bioabsorbable anterior cervical plate. Invited submission from the joint section meeting on disorders of the spine and peripheral nerves, March 2005.

OBJECT: The authors present a biomechanical analysis of a newly designed bioabsorbable anterior cervical plate (ACP) for the treatment of one-level cervical degenerative disc disease. They studied anterior cervical discectomy and fusion (ACDF) in a human cadaveric model, comparing the stability of the cervical spine after placement of the bioabsorbable fusion plate, a bioabsorbable mesh, and a more traditional metallic ACP. METHODS: Seven human cadaveric specimens underwent a C6-7 fibular graft-assisted ACDF placement. A one-level resorbable ACP was then placed and secured with bioabsorbable screws. Flexibility testing was performed on both intact and instrumented specimens using a servohydraulic system to create flexion-extension, lateral bending, and axial rotation motions. After data analysis, three parameters were calculated: angular range of motion, lax zone, and stiff zone. The results were compared with those obtained in a previous study of a resorbable fusion mesh and with those acquired using metallic fusion ACPs. For all parameters studied, the resorbable plate consistently conferred greater stability than the resorbable mesh. Moreover, it offered comparable stability with that of metallic fusion ACPs. CONCLUSIONS: Bioabsorbable plates provide better stability than resorbable mesh. Although the results of this study do not necessarily indicate that a resorbable plate confers equivalent stability to a metal plate, the resorbable ACP certainly yielded better results than the resorbable mesh. Bioabsorbable fusion ACPs should therefore be considered as alternatives to metal plates when a graft containment device is required.

Absorbable Implants↗