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Sandi Lam and Larry T. Khoo

Object

Vertebroplasty and kyphoplasty are minimally invasive procedures used to treat persistently symptomatic vertebral compression fractures (VCFs). Both interventions usually involve injection of polymethyl methacrylate (PMMA). The purpose of this technical note was to review the theory and surgical technique for a novel percutaneous system for fracture reduction and stabilization of VCFs by using bone graft.

Methods

This technical note highlights the Optimesh system as an alternative method of minimally invasive VCF reduction and stabilization with the delivery of a bone graft containment device. Instead of using PMMA as in vertebroplasty or kyphoplasty, this system allows the delivery of allograft and/or autograft bone, with its osteoinductive, osteoconductive, and osteogenic properties.

Conclusions

This system allows for restoration of sagittal alignment of the spine with direct control of bone graft delivery by using a mesh graft containment device that allows for ingrowth of new bone and vascular tissue.

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Nouzhan Sehati, Larry T. Khoo and Langston T. Holly

Object

Lumbar synovial cysts are a potential cause of radiculopathy and back pain, and the definitive treatment is the complete excision of the cyst. This report summarizes the authors' preliminary clinical experience with the minimally invasive resection of lumbar synovial cysts.

Methods

Nineteen patients (nine men and 10 women) with symptomatic synovial cysts underwent minimally invasive resection. The mean patient age was 64 years of age (range 43–80 years). The presenting symptom was radiculopathy in 16 patients, low-back pain in two, and lower-extremity weakness in one. There were 16 cases of a cyst located at the L4–5 level, two at L3–4, and one at L5–S1. The mean cyst diameter was 13.7 mm (range 3–30 mm).

The mean follow-up time was 16 months (range 4–29 months). Clinical outcomes were graded, based on the Macnab modified criteria, as excellent, good, fair, or poor. Eighteen patients (95% of cases) reported either excellent (10 patients) or good (eight patients) results, and a fair result was reported by one patient (5% of cases). The mean operative time was 158 minutes (range 75–270 minutes), and the average intraoperative blood loss was 31 ml (range 10–100 ml). Two patients had intraoperative dural tears that resulted in cerebrospinal fluid leaks that resolved following primary closure.

Conclusions

Synovial cysts can be safely and effectively treated using minimally invasive surgical techniques. Long-term follow up is required to determine whether this approach results in less need for fusion than conventional surgical approaches.

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Sean S. Armin, Langston T. Holly and Larry T. Khoo

For decades, lumbar disc herniation and lumbar stenosis have been treated surgically via traditional open techniques. With recent emphasis on minimally invasive approaches in spine surgery, a number of new techniques has been introduced that are aimed at treating these 2 common pathological conditions. Currently the most widely used and efficacious minimally invasive technique for treating these disorders is direct decompression with minimally invasive surgery. Due to the scarcity of large randomized studies, however, it is difficult to compare the effectiveness and possible superiority of this technique with traditional decompression. Further studies are needed to evaluate this issue.

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Editorial

Ectopic bone

Vincent C. Traynelis

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Srinath Samudrala, Larry T. Khoo, Seung C. Rhim and Richard G. Fessler

Procedures involving anterior surgical decompression and fusion are being performed with increasing frequency for the treatment of a variety of pathological processes of the spine including trauma, deformity, infection, degenerative disease, failed-back syndrome, discogenic pain, metastases, and primary spinal neoplasms. Because these operations involve anatomy that is often unfamiliar to many neurological and orthopedic surgeons, a significant proportion of the associated complications are not related to the actual decompressive or fusion procedure but instead to the actual exposure itself. To understand the nature of these injuries, a detailed anatomical study and dissection was undertaken in six cadaveric specimens. Critical structures at risk in the abdomen and retroperitoneum were identified, and their anatomical relationships were categorized and photographed. These structures included the psoas muscle, kidneys, ureters, diaphragm and crura, esophageal hiatus, thoracic duct, greater splanchnic nerves, phrenic nerves, sympathetic chains, medial arcuate ligament, superior and inferior hypogastric plexus, segmental and radicular vertebral vessels, aorta, vena cava, median sacral artery, common iliac vessels, iliolumbar veins, lumbosacral plexus, and presacral hypogastric plexus. Based on these dissections and an extensive review of the literature, the authors provide a detailed anatomically based discussion of the complications associated with anterior lumbar surgery.

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Nicola Marotta, Murat Cosar, Luiz Pimenta and Larry T. Khoo

Object

The authors describe a new paracoccygeal approach to the L5–S1 junction for interbody fusion with transsacral instrumentation. The purpose of this technical note is to demonstrate a novel surgical approach, technique, and instrumentation system for the treatment of L5–S1 instability in degenerative disc disease and spondylolisthesis.

Methods

This technical note highlights the AxiaLif (TranS1) transsacral system as an alternative method to transforaminal lumbar interbody fusion or posterior lumbar interbody fusion. Via a novel presacral approach corridor, a truly percutaneous L5–S1 discectomy, interbody distraction, and fixation are achieved, and retroperitoneal viscera and dorsal neural elements are avoided. Percutaneous pedicle screw fixation is then used to provide additional stabilization at the treated level.

Conclusions

This novel technique of interbody distraction and fusion via a truly percutaneous approach corridor allows for circumferential treatment of the lower lumbar segments with minimal risk to the anterior organs and dorsal neural elements.

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Zachary A. Smith, Colin C. Buchanan, Dan Raphael and Larry T. Khoo

Ossification of the posterior longitudinal ligament (OPLL) is an important cause of cervical myelopathy that results from bony ossification of the cervical or thoracic posterior longitudinal ligament (PLL). It has been estimated that nearly 25% of patients with cervical myelopathy will have features of OPLL. Patients commonly present in their mid-40s or 50s with clinical evidence of myelopathy. On MR and CT imaging, this can be seen as areas of ossification that commonly coalesce behind the cervical vertebral bodies, leading to direct ventral compression of the cord. While MR imaging will commonly demonstrate associated changes in the soft tissue, CT scanning will better define areas of ossification. This can also provide the clinician with evidence of possible dural ossification. The surgical management of OPLL remains a challenge to spine surgeons. Surgical alternatives include anterior, posterior, or circumferential decompression and/or stabilization. Anterior cervical stabilization options include cervical corpectomy or multilevel anterior cervical corpectomy and fusion, while posterior stabilization approaches include instrumented or noninstrumented fusion or laminoplasty. Each of these approaches has distinct advantages and disadvantages. While anterior approaches may provide more direct decompression and best improve myelopathy scores, there is soft-tissue morbidity associated with the anterior approach. Posterior approaches, including laminectomy and fusion and laminoplasty, may be well tolerated in older patients. However, there often is associated axial neck pain and less improvement in myelopathy scores. In this review, the authors discuss the epidemiology, imaging findings, and clinical presentation of OPLL. The authors additionally discuss the merits of the different surgical techniques in the management of this challenging disease.

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Zachary A. Smith, Zhenzhou Li, Nan-Fu Chen, Dan Raphael and Larry T. Khoo

Object

In this paper, the authors' goal was to demonstrate the clinical and technical nuances of a minimally invasive lateral extracavitary approach (MI-LECA) for thoracic corpectomy and anterior column reconstruction.

Methods

A cadaveric feasibility study and the subsequent application of this approach in 3 clinical cases are reported. Six procedures were completed in 3 human cadavers. Minimally invasive, extrapleural thoracic corpectomies were performed with the aid of a 24-mm tubular retraction system, using a posterolateral incision and an oblique approach angle. Fluoroscopy and postprocedural CT scanning, using 3D volumetric averaging software, was used to evaluate the degree of bone removal and decompression. Three clinical cases, including a T-11 burst fracture, a T-7 plasmacytoma, and a T4–5 vertebral body (VB) tuberculosis lesion, were treated using the approach.

Results

At 6 cadaveric levels, the mean circumferential volumetric decompression was 48% ± 16%, and the mean resection of the VB was 72% ± 13%. The mean change in anterior and posterior vertebral height with expansion of the corpectomy cage was 47 and 61 mm, respectively. There were no violations of the pleura or dura. Pedicle screw reliability was 95.8% (23 of 24 screws) with a single lateral breach. All 3 patients in the clinical cohort had excellent clinical outcomes. There was a single pleural tear requiring chest tube drainage. Operative images and a video clip are provided to illustrate the approach.

Conclusions

A minimally invasive lateral extracavitary thoracic corpectomy has the ability to provided excellent spinal cord decompression and VB resection. The procedure can be completed safely and successfully with minimal blood loss and little associated morbidity. This approach has the potential to improve upon established traditional open corridors for posterolateral thoracic corpectomy.

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Michael L. Levy, Larry T. Khoo, J. Diaz Day, Mark Liker and J. Gordon McComb

Complete extirpation of tumor remains the primary goal of neurosurgeons in treating intracranial craniopharyngiomas. The intimate relationship of these lesions with the structures of the skull base and the difficulties of obtaining adequate operative visualization often make total removal an elusive goal. The authors describe the use of a combined fronto-orbitozygomatic temporopolar craniotomy to maximize the operative corridor and thereby increase the probability of maximum tumor resection without morbidity and mortality. They applied this approach in four children with craniopharyngiomas that involved the sellar and parasellar, third ventricle, cavernous sinus, and interpeduncular fossa regions. The surgical results are summarized with a presentation of pre- and postoperative imaging from two illustrative cases. A detailed description of the operative procedure is provided with a comparison to other previously described surgical approaches.

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Nan-Fu Chen, Zachary A. Smith, Eric Stiner, Sean Armin, Hormoz Sheikh and Larry T. Khoo

Object

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been approved for use in the lumbar spine in conjunction with the lumbar tapered cage. However, off-label use of this osteoinductive agent is observed with anterior fusion applications as well as with both posterior lumbar interbody fusion and transforaminal lumbar interbody fusion (TLIF). Complications using rhBMP-2 in the cervical spine have been reported. Although radiographic evidence of ectopic bone in the lumbar spine has been described following rhBMP-2 use, this finding was not previously believed to be of clinical relevance.

Methods

This study was a retrospective review of 4 patients who underwent minimally invasive spinal TLIF (MIS-TLIF) in which bone fusion was augmented with rhBMP-2 applied to an absorbable collagen sponge. Case presentations, operative findings, imaging data, and follow-up findings were reviewed.

Results

Four cases with delayed symptomatic neural compression following the off-label use of rhBMP-2 with MIS-TLIF were identified.

Conclusions

Although previously believed to be only a radiographic finding, the development of ectopic bone following rhBMP-2 use in lumbar fusion can be clinically significant. This paper describes 4 cases of delayed neural compression following MIS-TLIF. The reader should be aware of this potential complication following the off-label use of rhBMP-2 in the lumbar spine.