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Jason I. Liounakos, Asham Khan, Karen Eliahu, Jennifer Z. Mao, Christopher R. Good, John Pollina, Colin M. Haines, Jeffrey L. Gum, Thomas C. Schuler, Ehsan Jazini, Richard V. Chua, Eiman Shafa, Avery L. Buchholz, Martin H. Pham, Kornelis A. Poelstra, and Michael Y. Wang

OBJECTIVE

Robotics is a major area for research and development in spine surgery. The high accuracy of robot-assisted placement of thoracolumbar pedicle screws is documented in the literature. The authors present the largest case series to date evaluating 90-day complication, revision, and readmission rates for robot-assisted spine surgery using the current generation of robotic guidance systems.

METHODS

An analysis of a retrospective, multicenter database of open and minimally invasive thoracolumbar instrumented fusion surgeries using the Mazor X or Mazor X Stealth Edition robotic guidance systems was performed. Patients 18 years of age or older and undergoing primary or revision surgery for degenerative spinal conditions were included. Descriptive statistics were used to calculate rates of malpositioned screws requiring revision, as well as overall complication, revision, and readmission rates within 90 days.

RESULTS

In total, 799 surgical cases (Mazor X: 48.81%; Mazor X Stealth Edition: 51.19%) were evaluated, involving robot-assisted placement of 4838 pedicle screws. The overall intraoperative complication rate was 3.13%. No intraoperative implant-related complications were encountered. Postoperatively, 129 patients suffered a total of 146 complications by 90 days, representing an incidence of 16.1%. The rate of an unrecognized malpositioned screw resulting in a new postoperative radiculopathy requiring revision surgery was 0.63% (5 cases). Medical and pain-related complications unrelated to hardware placement accounted for the bulk of postoperative complications within 90 days. The overall surgical revision rate at 90 days was 6.63% with 7 implant-related revisions, representing an implant-related revision rate of 0.88%. The 90-day readmission rate was 7.13% with 2 implant-related readmissions, representing an implant-related readmission rate of 0.25% of cases.

CONCLUSIONS

The results of this multicenter case series and literature review suggest current-generation robotic guidance systems are associated with low rates of intraoperative and postoperative implant-related complications, revisions, and readmissions at 90 days. Future outcomes-based studies are necessary to evaluate complication, revision, and readmission rates compared to conventional surgery.

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Gregory M. Mundis Jr., Jakub Godzik, Paul Park, Kai-Ming Fu, Stacie Tran, Juan S. Uribe, Michael Y. Wang, Khoi D. Than, David O. Okonkwo, Adam S. Kanter, Pierce D. Nunley, Neel Anand, Richard G. Fessler, Dean Chou, Renaud Lafage, Robert K. Eastlack, and on behalf of the International Spine Study Group

OBJECTIVE

Traditional surgery for adult spinal deformity (ASD) is effective but may result in exposure-related morbidity. Minimally invasive surgery (MIS) can potentially minimize this morbidity; however, high-level evidence is lacking. This study presents the first prospective multicenter investigation of MIS approaches for ASD.

METHODS

A prospective multicenter study was conducted. Inclusion criteria were age ≥ 18 years, with at least one of the following radiographic criteria: coronal Cobb (CC) angle ≥ 20°, sagittal vertical axis (SVA) > 5 cm, pelvic tilt (PT) > 25°, and thoracic kyphosis > 60°. Additional inclusion criteria were circumferential MIS, including interbody fusion (transforaminal lumbar interbody fusion [TLIF], lateral lumbar interbody fusion [LLIF], or anterior lumbar interbody fusion [ALIF]) with percutaneous posterior fixation on a minimum of 4 intervertebral levels. Radiographic and clinical outcomes (visual analog scale [VAS], Oswestry Disability Index [ODI], and Scoliosis Research Society–22 [SRS-22]) were collected preoperatively and at 12 months postoperatively; preoperative and postoperative values were compared using paired Student t-tests.

RESULTS

Seventy-five patients with a minimum 1-year follow-up were identified (75 of 111; 67.6%). The mean ± SD age was 68.8 ± 9.0 years, and 48 patients (64%) were female. Patients underwent a mean of 6.7 ± 2.9 levels of fusion with LLIF (85%), ALIF (55%), and TLIF (9%); the mean estimated blood loss was 547.6 ± 567.2 mL, and the mean length of stay was 7.0 ± 3.7 days. Significant improvements were observed in ODI (−19 ± 12.9, p < 0.001), SRS-22 (0.8 ± 0.66, p < 0.001), VAS back (−4.3 ± 2.8, p < 0.001), and VAS leg (−3.0 ± 3.2, p < 0.001) scores. Significant decreases in SVA (−26.4 ± 53.6 mm; p < 0.001), pelvic incidence–lumbar lordosis (−11.3° ± 14.9°, p < 0.001), and CC angle (−12.1° ± 11.8°, p < 0.001) were also observed. Complications occurred in 39 patients (52%); 11 patients (15%) experienced major complications, and 16 patients (21%) required reoperation.

CONCLUSIONS

MIS approaches for ASD resulted in meaningful symptomatic improvement. The complication rates were similar to historic norms, with a fairly high reoperation rate at 1 year. Longer follow-up will be necessary to evaluate the durability of this approach in the treatment of ASD.

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Roberto J. Perez-Roman, Wendy Gaztanaga, Victor M. Lu, and Michael Y. Wang

OBJECTIVE

Lumbar stenosis treatment has evolved with the introduction of minimally invasive surgery (MIS) techniques. Endoscopic methods take the concepts applied to MIS a step further, with multiple studies showing that endoscopic techniques have outcomes that are similar to those of more traditional approaches. The aim of this study was to perform an updated meta-analysis and systematic review of studies comparing the outcomes between endoscopic (uni- and biportal) and microscopic techniques for the treatment of lumbar stenosis.

METHODS

Following PRISMA guidelines, a systematic search was performed using the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Ovid Embase, and PubMed databases from their dates of inception to December 14, 2020. All identified articles were then systematically screened against the following inclusion criteria: 1) studies comparing endoscopic (either uniportal or biportal) with minimally invasive approaches, 2) patient age ≥ 18 years, and 3) diagnosis of lumbar spinal stenosis. Bias was assessed using quality assessment criteria and funnel plots. Meta-analysis using a random-effects model was used to synthesize the metadata.

RESULTS

From a total of 470 studies, 14 underwent full-text assessment. Of these 14 studies, 13 comparative studies were included for quantitative analysis, totaling 1406 procedures satisfying all criteria for selection. Regarding postoperative back pain, 9 studies showed that endoscopic methods resulted in significantly lower pain scores compared with MIS (mean difference [MD] −1.0, 95% CI −1.6 to −0.4, p < 0.01). The length of stay data were reported by 7 studies, with endoscopic methods associated with a significantly shorter length of stay versus the MIS technique (MD −2.1 days, 95% CI −2.7 to −1.4, p < 0.01). There was no significant difference with respect to leg visual analog scale scores, Oswestry Disability Index scores, blood loss, surgical time, and complications, and there were not any significant quality or bias concerns.

CONCLUSIONS

Both endoscopic and MIS techniques are safe and effective methods for treating patients with symptomatic lumbar stenosis. Patients who undergo endoscopic surgery seem to report less postoperative low-back pain and significantly reduced hospital stay with a trend toward less perioperative blood loss. Future large prospective randomized trials are needed to confirm the findings in this study.

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David T. Asuzu, Jonathan J. Yun, Mohammed Ali Alvi, Andrew K. Chan, Cheerag D. Upadhyaya, Domagoj Coric, Eric A. Potts, Erica F. Bisson, Jay D. Turner, Jack J. Knightly, Kai-Ming Fu, Kevin T. Foley, Luis Tumialan, Mark Shaffrey, Mohamad Bydon, Praveen V. Mummaneni, Paul Park, Scott Meyer, Anthony L. Asher, Oren N. Gottfried, Khoi D. Than, Michael Y. Wang, and Avery L. Buchholz

OBJECTIVE

Degenerative cervical myelopathy (DCM) results in significant morbidity. The duration of symptoms prior to surgical intervention may be associated with postoperative surgical outcomes and functional recovery. The authors’ objective was to investigate whether delayed surgical treatment for DCM is associated with worsened postoperative outcomes.

METHODS

Data from 1036 patients across 14 surgical centers in the Quality Outcomes Database were analyzed. Baseline demographic characteristics and findings of preoperative and postoperative symptom evaluations, including duration of symptoms, were assessed. Postoperative functional outcomes were measured using the Neck Disability Index (NDI) and modified Japanese Orthopaedic Association (mJOA) scale. Symptom duration was classified as either less than 12 months or 12 months or greater. Univariable and multivariable regression were used to evaluate for the associations between symptom duration and postoperative outcomes.

RESULTS

In this study, 513 patients (49.5%) presented with symptom duration < 12 months, and 523 (50.5%) had symptoms for 12 months or longer. Patients with longer symptom duration had higher BMI and higher prevalence of anxiety and diabetes (all p < 0.05). Symptom duration ≥ 12 months was associated with higher average baseline NDI score (41 vs 36, p < 0.01). However, improvements in NDI scores from baseline were not significantly different between groups at 3 months (p = 0.77) or 12 months (p = 0.51). Likewise, the authors found no significant differences between groups in changes in mJOA scores from baseline to 3 months or 12 months (both p > 0.05).

CONCLUSIONS

Surgical intervention resulted in improved mJOA and NDI scores at 3 months, and this improvement was sustained in both patients with short and longer initial symptom duration. Patients with DCM can still undergo successful surgical management despite delayed presentation.

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Andrew K. Chan, Robert K. Eastlack, Richard G. Fessler, Khoi D. Than, Dean Chou, Kai-Ming Fu, Paul Park, Michael Y. Wang, Adam S. Kanter, David O. Okonkwo, Pierce D. Nunley, Neel Anand, Juan S. Uribe, Gregory M. Mundis Jr., Shay Bess, Christopher I. Shaffrey, Vivian P. Le, Praveen V. Mummaneni, and the International Spine Study Group

OBJECTIVE

Previous studies have demonstrated the short-term radiographic and clinical benefits of circumferential minimally invasive surgery (cMIS) and hybrid (i.e., minimally invasive anterior or lateral interbody fusion with an open posterior approach) techniques to correct adult spinal deformity (ASD). However, it is not known if these benefits are maintained over longer periods of time. This study evaluated the 2- and 3-year outcomes of cMIS and hybrid correction of ASD.

METHODS

A multicenter database was retrospectively reviewed for patients undergoing cMIS or hybrid surgery for ASD. Patients were ≥ 18 years of age and had one of the following: maximum coronal Cobb angle (CC) ≥ 20°, sagittal vertical axis (SVA) > 5 cm, pelvic incidence–lumbar lordosis mismatch (PI-LL) ≥ 10°, or pelvic tilt (PT) > 20°. Radiographic parameters were evaluated at the latest follow-up. Clinical outcomes were compared at 2- and 3-year time points and adjusted for age, preoperative CC, levels operated, levels with interbody fusion, presence of L5–S1 anterior lumbar interbody fusion, and upper and lower instrumented vertebral level.

RESULTS

Overall, 197 (108 cMIS, 89 hybrid) patients were included with 187 (99 cMIS, 88 hybrid) and 111 (60 cMIS, 51 hybrid) patients evaluated at 2 and 3 years, respectively. The mean (± SD) follow-up duration for cMIS (39.0 ± 13.3 months, range 22–74 months) and hybrid correction (39.9 ± 16.8 months, range 22–94 months) were similar for both cohorts. Hybrid procedures corrected the CC greater than the cMIS technique (adjusted p = 0.022). There were no significant differences in postoperative SVA, PI-LL, PT, and sacral slope (SS). At 2 years, cMIS had lower Oswestry Disability Index (ODI) scores (adjusted p < 0.001), greater ODI change as a percentage of baseline (adjusted p = 0.006), less visual analog scale (VAS) back pain (adjusted p = 0.006), and greater VAS back pain change as a percentage of baseline (adjusted p = 0.001) compared to hybrid techniques. These differences were no longer significant at 3 years. At 3 years, but not 2 years, VAS leg pain was lower for cMIS compared to hybrid techniques (adjusted p = 0.032). Those undergoing cMIS had fewer overall complications compared to hybrid techniques (adjusted p = 0.006), but a higher odds of pseudarthrosis (adjusted p = 0.039).

CONCLUSIONS

In this review of a multicenter database for patients undergoing cMIS and hybrid surgery for ASD, hybrid procedures were associated with a greater CC improvement compared to cMIS techniques. cMIS was associated with superior ODI and back pain at 2 years, but this difference was no longer evident at 3 years. However, cMIS was associated with superior leg pain at 3 years. There were fewer complications following cMIS, with the exception of pseudarthrosis.

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Jacob K. Greenberg, Stephen Shelby Burks, Christopher F. Dibble, Saad Javeed, Vivek P. Gupta, Alexander T. Yahanda, Roberto J. Perez-Roman, Vaidya Govindarajan, Andrew T. Dailey, Sanjay Dhall, Daniel J. Hoh, Daniel E. Gelb, Adam S. Kanter, Eric O. Klineberg, Michael J. Lee, Praveen V. Mummaneni, Paul Park, Charles A. Sansur, Khoi D. Than, Jon J. W. Yoon, Michael Y. Wang, and Wilson Z. Ray

OBJECTIVE

Minimally invasive surgery (MIS) techniques can effectively stabilize and decompress many thoracolumbar injuries with decreased morbidity and tissue destruction compared with open approaches. Nonetheless, there is limited direction regarding the breadth and limitations of MIS techniques for thoracolumbar injuries. Consequently, the objectives of this study were to 1) identify the range of current practice patterns for thoracolumbar trauma and 2) integrate expert opinion and literature review to develop an updated treatment algorithm.

METHODS

A survey describing 10 clinical cases with a range of thoracolumbar injuries was sent to 12 surgeons with expertise in spine trauma. The survey results were summarized using descriptive statistics, along with the Fleiss kappa statistic of interrater agreement. To develop an updated treatment algorithm, the authors used a modified Delphi technique that incorporated a literature review, the survey results, and iterative feedback from a group of 14 spine trauma experts. The final algorithm represented the consensus opinion of that expert group.

RESULTS

Eleven of 12 surgeons contacted completed the case survey, including 8 (73%) neurosurgeons and 3 (27%) orthopedic surgeons. For the 4 cases involving patients with neurological deficits, nearly all respondents recommended decompression and fusion, and the proportion recommending open surgery ranged from 55% to 100% by case. Recommendations for the remaining cases were heterogeneous. Among the neurologically intact patients, MIS techniques were typically recommended more often than open techniques. The overall interrater agreement in recommendations was 0.23, indicating fair agreement. Considering both literature review and expert opinion, the updated algorithm indicated that MIS techniques could be used to treat most thoracolumbar injuries. Among neurologically intact patients, percutaneous instrumentation without arthrodesis was recommended for those with AO Spine Thoracolumbar Classification System subtype A3/A4 (Thoracolumbar Injury Classification and Severity Score [TLICS] 4) injuries, but MIS posterior arthrodesis was recommended for most patients with AO Spine subtype B2/B3 (TLICS > 4) injuries. Depending on vertebral body integrity, anterolateral corpectomy or mini-open decompression could be used for patients with neurological deficits.

CONCLUSIONS

Spine trauma experts endorsed a range of strategies for treating thoracolumbar injuries but felt that MIS techniques were an option for most patients. The updated treatment algorithm may provide a foundation for surgeons interested in safe approaches for using MIS techniques to treat thoracolumbar trauma.

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Doniel Drazin, J. Patrick Johnson, Tiffany Perry, Michael Y. Wang, Jens R. Chapman, and Bernhard Meyer

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Vaidya Govindarajan, Jean-Paul Bryant, Roberto J. Perez-Roman, and Michael Y. Wang

OBJECTIVE

Cervical fractures in patients with ankylosing spondylitis can have devastating neurological consequences. Currently, several surgical approaches are commonly used to treat these fractures: anterior, posterior, and anterior-posterior. The relative rarity of these fractures has limited the ability of surgeons to objectively determine the merits of each. The authors present an updated systematic review and meta-analysis investigating the utility of anterior surgical approaches relative to posterior and anterior-posterior approaches.

METHODS

After a comprehensive literature search of the PubMed, Cochrane, and Embase databases, 7 clinical studies were included in the final qualitative and 6 in the final quantitative analyses. Of these studies, 6 compared anterior approaches with anterior-posterior and posterior approaches, while 1 investigated only an anterior approach. Odds ratios and 95% confidence intervals were calculated where appropriate.

RESULTS

A meta-analysis of postoperative neurological improvement revealed no statistically significant differences in gross rates of neurological improvement between anterior and posterior approaches (OR 0.40, 95% CI 0.10–1.59; p = 0.19). However, when analyzing the mean change in neurological function, patients who underwent anterior approaches had a significantly lower mean change in postoperative neurological function relative to patients who underwent posterior approaches (mean difference [MD] −0.60, 95% CI −0.76 to −0.45; p < 0.00001). An identical trend was seen between anterior and anterior-posterior approaches; there were no statistically significant differences in gross rates of neurological improvement (OR 3.05, 95% CI 0.84–11.15; p = 0.09). However, patients who underwent anterior approaches experienced a lower mean change in neurological function relative to anterior-posterior approaches (MD −0.46, 95% CI −0.60 to −0.32; p < 0.00001). There were no significant differences in complication rates between anterior approaches, posterior approaches, or anterior-posterior approaches, although complication rates trended lower in patients who underwent anterior approaches.

CONCLUSIONS

The results of this review and meta-analysis demonstrated the varying benefits of anterior approaches relative to posterior and anterior-posterior approaches in treatment of cervical fractures associated with ankylosing spondylitis. While reports demonstrated lower degrees of neurological improvement in anterior approaches, they may benefit patients with less-severe injuries if lower complication rates are desired.

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Andrew K. Chan, Praveen V. Mummaneni, John F. Burke, Rory R. Mayer, Erica F. Bisson, Joshua Rivera, Brenton Pennicooke, Kai-Ming Fu, Paul Park, Mohamad Bydon, Steven D. Glassman, Kevin T. Foley, Christopher I. Shaffrey, Eric A. Potts, Mark E. Shaffrey, Domagoj Coric, John J. Knightly, Michael Y. Wang, Jonathan R. Slotkin, Anthony L. Asher, Michael S. Virk, Panagiotis Kerezoudis, Mohammed A. Alvi, Jian Guan, Regis W. Haid, and Dean Chou

OBJECTIVE

Reduction of Meyerding grade is often performed during fusion for spondylolisthesis. Although radiographic appearance may improve, correlation with patient-reported outcomes (PROs) is rarely reported. In this study, the authors’ aim was to assess the impact of spondylolisthesis reduction on 24-month PRO measures after decompression and fusion surgery for Meyerding grade I degenerative lumbar spondylolisthesis.

METHODS

The Quality Outcomes Database (QOD) was queried for patients undergoing posterior lumbar fusion for spondylolisthesis with a minimum 24-month follow-up, and quantitative correlation between Meyerding slippage reduction and PROs was performed. Baseline and 24-month PROs, including the Oswestry Disability Index (ODI), EQ-5D, Numeric Rating Scale (NRS)–back pain (NRS-BP), NRS-leg pain (NRS-LP), and satisfaction (North American Spine Society patient satisfaction questionnaire) scores were noted. Multivariable regression models were fitted for 24-month PROs and complications after adjusting for an array of preoperative and surgical variables. Data were analyzed for magnitude of slippage reduction and correlated with PROs. Patients were divided into two groups: < 3 mm reduction and ≥ 3 mm reduction.

RESULTS

Of 608 patients from 12 participating sites, 206 patients with complete data were identified in the QOD and included in this study. Baseline patient demographics, comorbidities, and clinical characteristics were similarly distributed between the cohorts except for depression, listhesis magnitude, and the proportion with dynamic listhesis (which were accounted for in the multivariable analysis). One hundred four (50.5%) patients underwent lumbar decompression and fusion with slippage reduction ≥ 3 mm (mean 5.19, range 3 to 11), and 102 (49.5%) patients underwent lumbar decompression and fusion with slippage reduction < 3 mm (mean 0.41, range 2 to −2). Patients in both groups (slippage reduction ≥ 3 mm, and slippage reduction < 3 mm) reported significant improvement in all primary patient reported outcomes (all p < 0.001). There was no significant difference with regard to the PROs between patients with or without intraoperative reduction of listhesis on univariate and multivariable analyses (ODI, EQ-5D, NRS-BP, NRS-LP, or satisfaction). There was no significant difference in complications between cohorts.

CONCLUSIONS

Significant improvement was found in terms of all PROs in patients undergoing decompression and fusion for lumbar spondylolisthesis. There was no correlation with clinical outcomes and magnitude of Meyerding slippage reduction.

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Jean-Paul Bryant, Roberto J. Perez-Roman, S. Shelby Burks, and Michael Y. Wang

OBJECTIVE

Osteoporosis represents the most common metabolic disease of the bone, with an estimated 10% of adults aged 50 years or older affected in the United States. This patient population is at increased risk for spine fracture and instrumentation-related complications after spine surgery. Surgeon knowledge of the available treatments for patients with low bone mineral density (BMD) and how they impact biology of fusion may help mitigate negative effects in the postoperative period. Recombinant parathyroid hormone, which is sold under the name teriparatide, is the most extensively studied bone-protecting agent in humans. Additionally, the success of the monoclonal antibody denosumab has led to further clinical investigations of human patients undergoing spine surgery. Another monoclonal antibody, romosozumab, was recently approved by the US FDA for human use in patients with osteoporosis. Although studies of romosozumab in patients undergoing spine surgery have not been conducted, this is a promising potential therapeutic agent based on its early success in preclinical and clinical trials. Here, the authors aimed to review the mechanisms of action and evidence of use of antiresorptive and anabolic agents in patients with osteoporosis undergoing spine surgery.

METHODS

In accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic review was conducted to explore the antiresorptive and anabolic agents used in the perioperative period in patients with osteoporosis undergoing spinal surgery. The search was performed by using the PubMed, Embase, and Cochrane Library databases. Titles and abstracts were screened and subsequently selected for full review.

RESULTS

The initial search returned 330 articles. Of these articles, 23 final articles were included and reviewed. Many of these articles reported that use of adjuvant agents in the perioperative period improved radiographic evidence of bony fusion and bone fusion rates. These agents tended to improve BMD postoperatively.

CONCLUSIONS

Although antiosteoporosis agents are effective to varying degrees as treatments of patients with low BMD, teriparatide and bisphosphonates have been the most extensively studied with respect to spinal instrumentation. The advent of newer agents represents an area for further exploration, especially due to the current paucity of controlled investigations. It is imperative for spine surgeons to understand the mechanisms of action of these drugs and their effects on biology of fusion.