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Christopher I. Shaffrey and Justin S. Smith

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Michael Y. Wang

Object

The treatment of adult spinal deformity (ASD) remains a challenge for the spine surgeon. While minimally invasive surgery (MIS) has many favorable attributes that would be of great benefit for the ASD population, improvements in lordosis and sagittal balance have remained elusive in cases involving the MIS approach. This report describes the evolution of an MIS method for treating ASD with attention to sagittal correction.

Methods

Over an 18-month period 25 patients with thoracolumbar scoliosis were treated surgically. The mean patient age was 72 years, and 68% of the population was female. Patients were treated with multilevel facet osteotomies and interbody fusion in which expandable cages (mean 3.2 levels) were placed and percutaneous screw fixation (mean 5.3 levels) was performed. Seven patients underwent supplemental percutaneous iliac fixation.

Results

All patients underwent MIS without conversion to a traditional open procedure. The mean operative time was 273 mins and the mean blood loss was 416 ml. There were no intraoperative complications. The Cobb angle over the scoliotic deformity improved from a mean of 29.2° to that of 9.0° (p < 0.001). Lumbar lordosis between L-1 and S-1 improved from a mean of 27.8° to one of 42.6° (p < 0.001). Sagittal vertical axis improved from 7.4 cm to 4.3 cm (p = 0.001). Numeric pain scale scores improved as well, an average of 3.3 and 4.2 for the leg and back, respectively. A mean improvement of 20.8 points on the Oswestry Disability Index was seen at 12 months. Complications included: two cases requiring hardware repositioning, one case of screw pullout, one asymptomatic pedicle screw breach, prolonged hospitalization from constipation, and one acute coronary syndrome developing 3 days after surgery without myocardial damage.

Conclusions

An expanding body of evidence suggests that sagittal balance remains a keystone for good outcomes after ASD surgery. Minimally invasive surgery that involves a combination of osteotomies, interbody height restoration, and advanced fixation techniques may achieve this goal in patients with less severe deformities. While feasibility will have to be proven with larger series and improved surgical methods, the present technique holds promise as a means of reducing the significant morbidity associated with surgery in the ASD population.

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Alexander A. Khalessi, Gabriel Zada, Michael Y. Wang and James Forrest Calland

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Patrick C. Hsieh and Michael Y. Wang

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Michael Y. Wang and Michael Thambuswamy

Object

Ossification of the posterior longitudinal ligament (OPLL) is a disorder afflicting as many as 2% of East Asians. However, reports of OPLL in non-Asians have been sporadic in the medical literature. This study describes clinical and radiographic findings with OPLL in non-Asians at a tertiary care center treating a diverse multiethnic population.

Methods

Over a 6-year period, 43 patients not of East Asian descent presented to an urban tertiary medical center with OPLL. Patient data, including ethnicity, spinal cord function, Nurick grade, radiographic findings, OPLL subtype, and degree of cervical stenosis, were recorded.

Results

The average patient age was 59 years (range 32–92 years) with 18 women and 25 men. There were 22 Caucasian patients, 17 Hispanic patients, and 4 Black patients. With respect to the radiographic findings, OPLL morphology was continuous in 19, segmental in 17, mixed in 6, and other in 1. Average canal diameter was 7.6 mm (range 4.2–9.0 mm) at the most stenotic points. The mean Nurick grade was 2.95 at presentation, but 7 of the patients had OPLL identified incidentally and with early or minimal symptoms and signs of myelopathy.

Conclusions

Ossification of the posterior longitudinal ligament in non-Asians demonstrates similar demographic and radiographic characteristics as in East Asians. The representation of different ethnic groups mirrors the demographics of the medical center population in general, showing no specific predilection for particular ethnic groups. Surgical decompression in appropriately selected patients results in similar rates of improvement when compared with the Japanese literature.

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Michael Y. Wang and Praveen V. Mummaneni

Object

Adult degenerative scoliosis can be a cause of intractable pain, decreased mobility, and reduced quality of life. Surgical correction of this problem frequently leads to substantial clinical improvement, but advanced age, medical comorbidities, osteoporosis, and the rigidity of the spine result in high surgical complication rates. Minimally invasive surgery is being applied to this patient population in an effort to reduce the high complication rates associated with adult deformity surgery.

Methods

A retrospective study of 23 patients was undertaken to assess the clinical and radiographic results with minimally invasive surgery for adult thoracolumbar deformity surgery. All patients underwent a lateral interbody fusion followed by posterior percutaneous screw fixation and possible minimally invasive surgical transforaminal lumbar interbody fusion if fusion near the lumbosacral junction was necessary. A mean of 3.7 intersegmental levels were treated (range 2–7 levels). The mean follow-up was 13.4 months.

Results

The mean preoperative Cobb angle was 31.4°, and it was corrected to 11.5° at follow-up. The mean blood loss was 477 ml, and the operative time was 401 minutes. The mean visual analog scale score improvement for axial pain was 3.96. Clear evidence of fusion was seen on radiographs at 84 of 86 treated levels, with no interbody pseudarthroses. Complications included 2 returns to the operating room, one for CSF leakage and the other for hardware pullout. There were no wound infections, pneumonia, deep venous thrombosis, or new neurological deficits. However, of all patients, 30.4% experienced new thigh numbness, dysesthesias, pain, or weakness, and in one patient these new symptoms were persistent.

Conclusions

The minimally invasive surgical treatment of adult deformities is a promising method for reducing surgical morbidity. Numerous challenges exist, as the surgical technique does not yet allow for all correction maneuvers used in open surgery. However, as the techniques are advanced, the applicability of minimally invasive surgery for this population will likely be expanded and will afford the opportunity for reduced complications.

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David M. Benglis Jr., James D. Guest and Michael Y. Wang

Minimally invasive approaches to the cervical spine for lateral disc herniation or foraminal stenosis have recently been described. Lower rates of blood loss, decreased narcotic dependence, and less tissue destruction as well as shorter hospital stays are all advantages of utilizing these techniques. These observations can also be realized with a minimal access approach to cervical laminoplasty. Multiple levels of the cervical spine can be treated from a posterior approach with the potential to decrease the incidences of postoperative axial neck pain and kyphotic deformity. In this report the authors present a concise history of the open laminoplasty technique, provide data from previous cadaveric studies (6 cases) along with recent clinical experience for minimally invasive laminoplasty, and describe the advantages and challenges of this novel procedure.

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Michael Y. Wang, Steven C. Ludwig, D. Greg Anderson and Praveen V. Mummaneni

Minimally invasive spinal instrumentation techniques have evolved tremendously over the past decade. Although there have been numerous reports of lumbar instrumentation performed via a percutaneous or minimal incisional route, to date there have been no reports of minimally invasive iliac screw placement.

A method was developed for accurate placement of minimally invasive iliac screw placement based on a modification of currently available percutaneous lumbar instrumentation techniques. The method involves fluoroscopically guided insertion of a cannula-based screw system, and this technique was successful applied to treat an L-5 burst fracture with L-4 to iliac spinal stabilization via a minimally invasive approach.

This report demonstrates the feasibility of percutaneous iliac screw instrumentation. However, future studies will be needed to validate the safety and efficacy of this approach.

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Michael Y. Wang and Paul Khoueir