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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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Michael Y. Wang

Adult spinal deformities (ASD) pose a challenge for the spinal surgeon. Because the spine is often rigid, mobilization of the segments is critical for effective correction, particularly in the sagittal plane. 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 problematic using MIS approaches, including MIS lateral methods. This video illustrates one method for achieving improvement of coronal and sagittal correction without the extensive exposure and soft tissue envelope disruption needed in open surgery, particularly for less severe deformities. By using multi-level TLIFs through a mini-open surgery, curves of less than 60° can be managed with minimal blood loss and within a reasonable surgical timeframe. While feasibility will have to be proven with larger series and improved surgical methods, this technique holds promise as a means of reducing the significant morbidity associated with surgery in the ASD population.

The video can be found here: http://youtu.be/I0rkDSAVas0.

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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 Jay Grossman

OBJECTIVE

One of the principal goals of minimally invasive surgery has been to speed postoperative recovery. In this case series, the authors used an endoscopic technique for interbody fusion combined with percutaneous screw fixation to obviate the need for general anesthesia.

METHODS

The first 10 consecutive patients treated with a minimum of 1 year's follow-up were included in this series. The patients were all treated using endoscopic access through Kambin's triangle to allow for neural decompression, discectomy, endplate preparation, and interbody fusion. This was followed by percutaneous pedicle screw and connecting rod placement using liposomal bupivacaine for long-acting analgesia. No narcotics or regional anesthetics were used during surgery.

RESULTS

All patients underwent the procedure successfully without conversion to open surgery. The patients' average age was 62.2 ± 9.0 years (range 52–78 years). All patients had severe disc height collapse, and 60% had a Grade I spondylolisthesis. The mean operative time was 113.5 ± 6.3 minutes (range 105–120 minutes), and blood loss was 65 ± 38 ml (range 30–190 ml). The mean length of hospital stay was 1.4 ± 1.3 nights. There were no intraoperative or postoperative complications. Comparison of preoperative and final clinical metrics demonstrated that the Oswestry Disability Index improved from 42 ± 11.8 to 13.3 ± 15.1; the 36-Item Short Form Health Survey (SF-36) Physical Component Summary improved from 47.6 ± 3.8 to 49.7 ± 5.4; the SF-36 Mental Component Summary decreased from 47 ± 3.9 to 46.7 ± 3.4; and the EQ-5D improved from 10.7 ± 9.5 to 14.2 ± 1.6. There were no cases of nonunion identified radiographically on follow-up imaging.

CONCLUSIONS

Endoscopic fusion under conscious sedation may represent a feasible alternative to traditional lumbar spine fusion in select patients. Larger clinical series are necessary to validate that clinical improvements are sustained and that arthrodesis rates are successful when compared with open surgery. This initial experience demonstrates the possible utility of this procedure.

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Michael Y. Wang and Gerd Bordon

OBJECTIVE

Pedicle subtraction osteotomy (PSO) is a powerful but high-risk surgical technique for destabilizing the spine for deformity correction in both the sagittal and coronal planes. Numerous reports have demonstrated the benefits of this technique for realigning the spine in a physiological posture; however, the open surgical technique is associated with a high complication rate. In this report the authors review data obtained in a series of patients who underwent PSO through a less invasive approach.

METHODS

Sixteen patients with severe coronal- and/or sagittal-plane deformities were treated in this series. Conservative measures had failed in all cases and patients had undergone a single-level PSO or extended PSO at L-2 or L-3. Fixation was accomplished using percutaneous instrumentation and interbody or facet joint fusions were used at the remaining levels. None of the procedures were aborted or converted to a traditional open procedure. Standard clinical and radiographic measures were used to assess patient outcomes.

RESULTS

Mean age was 68.8 years and mean follow-up duration was 17.7 months. An average of 7.6 levels were fused, and 50% of the patients had bilateral iliac screw fixation, with all constructs crossing both the thoracolumbar and lumbosacral junctions. Operative time averaged 356 ± 50 minutes and there was a mean blood loss of 843 ± 339 ml.

The leg visual analog scale score improved from a mean of 5.7 ± 2.7 to one of 1.3 ± 1.6, and the back visual analog scale score improved from a mean of 8.6 ± 1.3 to one of 2.4 ± 2.1. The Oswestry Disability Index score improved from a mean of 50.1 ± 14.4 to 16.4 ± 12.7, representing a mean reduction of 36.0 ± 16.9 points. The SF-36 physical component summary score changed from a mean of 43.4 ± 2.6 to one of 47.0 ± 4.3, and the SF-36 mental component summary score changed from a mean of 46.7 ± 3.6 to 46.30 ± 3.0.

Coronal alignment improved from a mean of 27.9 ± 43.6 mm to 16.0 ± 17.2 mm. The lumbar Cobb angle improved from a mean of 41.2° ± 18.4° to 15.4° ± 9.6°, and lumbar lordosis improved from 23.1° ± 15.9° to 48.6° ± 11.7°. Pelvic tilt improved from a mean of 33.7° ± 8.6° to 24.4° ± 6.5°, and the sagittal vertical axis improved from 102.4 ± 73.4 mm to 42.2 ± 39.9 mm. The final lumbar lordosis–pelvic incidence difference averaged 8.4° ± 12.1°. There were 4 patients who failed to achieve less than or equal to a 10° mismatch on this parameter. Ten of the 16 patients underwent delayed postoperative CT, and 8 of these had developed a solid arthrodesis at all levels treated. A total of 6 complications occurred in this series. There were no cases of symptomatic proximal junction kyphosis.

CONCLUSIONS

Advancements in minimally invasive technique have resulted in the ability to manage increasingly complex deformities with hybrid approaches. In this limited series, the authors describe the results of utilizing a tissue-sparing mini-open PSO to correct severe spinal deformities. This method was technically feasible in all cases with acceptable radiographic outcomes similar to open surgery. However, high complication rates associated with these deformity corrections remain problematic.

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Joanna E. Gernsback and Michael Y. Wang

Vertebral augmentation with cement has become a common procedure for the treatment of compression fractures, leading to a growing population who have had this procedure and are now in need of another spinal surgery. This technical note reports an undescribed method for placing pedicle screws through a previously cemented level.

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Jeremiah N. Johnson and Michael Y. Wang

Bilateral pedicle fractures in the spine are uncommon in the absence of bony abnormality, previous surgery, or trauma. The authors report a case of spontaneous bilateral lumbar pedicle fracture in a 50-year-old sedentary woman, which caused intractable pain and did not respond to months of conservative management. The fractures were surgically treated using a percutaneous, minimally invasive technique with screws placed directly through the fractures into the vertebral body. The pedicles were strategically tapped to achieve the lag effect and reapproximate the posterior fragment with the anterior elements. The patient tolerated the procedure well and experienced early improvement of her symptoms, and follow-up imaging showed evidence of fracture healing. Transpedicular fixation and the use of the lag effect could be a useful strategy in the treatment of future cases involving poorly healing pedicle fractures causing persistent symptoms.

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The evolution of minimally invasive spine surgery

JNSPG 75th Anniversary Invited Review Article

Jang W. Yoon and Michael Y. Wang

The field of minimally invasive spine surgery (MISS) has rapidly evolved over the past 3 decades. This review follows the evolution of techniques and principles that have led to significant advances in the field. While still representing only a subset of spine surgeries, MISS’s goals of reducing soft-tissue trauma and mitigating the morbidity of surgery are being realized, translating into more rapid recovery, lower infection rates, and higher cost savings. Future advances in technology and techniques can be anticipated.

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George M. Ghobrial and Michael Y. Wang

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Michael Y. Wang and Barth A. Green

Object

Cervical stenotic myelopathy can be treated via anterior or posterior approaches. In anterior cervical decompression and fusion (ACDF), because the risks and likelihood of pseudarthrosis increase with the number of treated segments, attempts are typically made to limit the number of treated levels. Thus, postoperative recurrence of myelopathy following ACDF may occur because stenotic levels were not treated or because adjacent segments have degenerated. Revision decompressive surgery via an anterior approach is one solution; however, if the stenosis involves multiple levels a posterior decompressive laminoplasty can be performed as an alternative.

Methods

Twenty-four cases treated over an 8-year period were identified and data were retrospectively reviewed. In 15 cases posterior decompressive surgery was necessary because of progressive spinal degeneration and stenosis (five cases following initial treatment for radiculopathy, seven after initial treatment for spondylotic myelopathy, and three due to spreading of an ossified posterior longitudinal ligament). In nine cases revision surgery was undertaken because the initial decompression was inadequate.

The mean follow-up period after the second surgery was 16 months. Improvements in myelopathy were seen in 83% of patients (mean improvement of 1.25 points on the Nurick Scale). Preoperative severe gait disorders were associated with poor recovery. Complications included two cases of transient C-5 nerve root palsy and two cases of new persistent axial neck pain.

Conclusions

Laminoplasty is a straightforward and effective treatment for failed ACDF due to inadequate decompression or progressive degeneration of the spinal column, avoiding reentry through scar tissue. In terms of myeolpathic pain, the recovery rate is comparable with that related to revision ACDF.