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Christopher I. Shaffrey and Justin S. Smith

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Michael J. Rauzzino, Christopher I. Shaffrey, James Wagner, Russ Nockels and Mark Abel

The indications for surgical intervention in patients with idiopathic scoliosis have been well defined. The goals of surgery are to achieve fusion and arrest progressive curvature while restoring normal coronal and sagittal balance. As first introduced by Harrington, posterior fusion, the gold standard of treatment, has a proven record of success. More recently, anterior techniques for performing fusion procedures via either a thoracotomy or a retroperitoneal approach have been popularized in attempts to achieve better correction of curvature, preserve motion segments, and avoid some of the complications of posterior fusion such as the development of the flat-back syndrome. Anterior instrumentation alone, although effective, can be kyphogenic and has been shown to be associated with complications such as pseudarthrosis and instrumentation failure. Performing a combined approach in patients with scoliosis and other deformities has become an increasingly popular procedure to achieve superior correction of deformity and to minimize later complications. Indications for a combined approach (usually consisting of anterior release, arthrodesis with or without use of instrumentation, and posterior segmental fusion) include: prevention of crankshaft phenomenon in juvenile or skeletally immature adolescents; correction of large curves (75°) or excessively rigid curves in skeletally mature or immature patients; correction of curves with large sagittal-plane deformities such as thoracic kyphosis (> 90°) or thoracic lordosis (> 20°); and correction of thoracolumbar curves that need to be fused to the sacrum. Surgery may be performed either in a staged proceedure or, more commonly, in a single sitting. The authors discuss techniques for combined surgery and complication avoidance.

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Adam S. Kanter, Christopher I. Shaffrey, Praveen Mummaneni, Michael Y. Wang and Juan S. Uribe

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Michael J. Rauzzino, Christopher I. Shaffrey, Russ P. Nockels, Gregory C. Wiggins, Jack Rock and James Wagner

The authors report their experience with 42 patients in whom anterior lumbar fusion was performed using titanium cages as a versatile adjunct to treat a wide variety of spinal deformity and pathological conditions. These conditions included congenital, degenerative, iatrogenic, infectious, traumatic, and malignant disorders of the thoracolumbar spine. Fusion rates and complications are compared with data previously reported in the literature.

Between July 1996 and July 1999 the senior authors (C.I.S., R.P.N., and M.J.R.) treated 42 patients by means of a transabdominal extraperitoneal (13 cases) or an anterolateral extraperitoneal approach (29 cases), 51 vertebral levels were fused using titanium cages packed with autologous bone. All vertebrectomies (27 cases) were reconstructed using a Miami Moss titanium mesh cage and Kaneda instrumentation. Interbody fusion (15 cases) was performed with either the BAK titanium threaded interbody cage (in 13 patients) or a Miami Moss titanium mesh cage (in two patients). The average follow-up period was 14.3 months. Seventeen patients had sustained a thoracolumbar burst fracture, 12 patients presented with degenerative spinal disorders, six with metastatic tumor, four with spinal deformity (one congenital and three iatrogenic), and three patients presented with spinal infections. In five patients anterior lumbar interbody fusion (ALIF) was supplemented with posterior segmental fixation at the time of the initial procedure. Of the 51 vertebral levels treated, solid arthrodesis was achieved in 49, a 96% fusion rate. One case of pseudarthrosis occurred in the group treated with BAK cages; the diagnosis was made based on the patient's continued mechanical back pain after undergoing L4–5 ALIF. The patient was treated with supplemental posterior fixation, and successful fusion occurred uneventfully with resolution of her back pain. In the group in which vertebrectomy was performed there was one case of fusion failure in a patient with metastatic breast cancer who had undergone an L-3 corpectomy with placement of a mesh cage. Although her back pain was immediately resolved, she died of systemic disease 3 months after surgery and before fusion could occur.

Complications related to the anterior approach included two vascular injuries (two left common iliac vein lacerations); one injury to the sympathetic plexus; one case of superficial phlebitis; two cases of prolonged ileus (greater than 48 hours postoperatively); one anterior femoral cutaneous nerve palsy; and one superficial wound infection. No deaths were directly related to the surgical procedure. There were no cases of dural laceration and no nerve root injury. There were no cases of deep venous thrombosis, pulmonary embolus, retrograde ejaculation, abdominal hernia, bowel or ureteral injury, or deep wound infection. Fusion-related complications included an iliac crest hematoma and prolonged donor-site pain in one patient. There were no complications related to placement or migration of the cages, but there was one case of screw fracture of the Kaneda device that did not require revision.

The authors conclude that anterior lumbar fusion performed using titanium interbody or mesh cages, packed with autologous bone, is an effective, safe method to achieve fusion in a wide variety of pathological conditions of the thoracolumbar spine. The fusion rate of 96% compares favorably with results reported in the literature. The complication rate mirrors the low morbidity rate associated with the anterior approach. A detailed study of clinical outcomes is in progress. Patient selection and strategies for avoiding complication are discussed.

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Gregory C. Wiggins, Michael J. Rauzzino, Christopher I. Shaffrey, Russ P. Nockels, Richard Whitehill, Mark E. Shaffrey, James Wagner and Tord D. Alden

This study was conducted to determine the safety, efficacy, and complication rate associated with the anterior approach in the use of a new titanium mesh interbody fusion cage for the treatment of unstable thoracolumbar burst fractures. The experience with this technique is compared with the senior authors' (C.S., R.W., and M.S.) previously published results in the management of patients with unstable thoracolumbar burst fractures.

Between 1996 and 1999, 21 patients with unstable thoracolumbar (T12-L3) burst fractures underwent an anterolateral decompressive procedure in which a titanium cage and Kaneda device were used. Eleven of the 21 patients had sustained a neurological deficit, and all patients improved at least one Frankel grade (average 1.2 grades). There was improvement in outcome in terms of blood loss, correction of kyphosis, and pain, as measured on the Denis Pain and Work Scale, in our current group of patients treated via an anterior approach when compared with the results in those who underwent a posterior approach.

In our current study the anterior approach was demonstrated to be a safe and effective technique for the management of unstable thoracolumbar burst fractures. It offers superior results compared with the posterior approach. The addition of the new titanium mesh interbody cage to our previous anterior technique allows the patient's own bone to be harvested from the corpectomy site and used as a substrate for fusion, thereby obviating the need for iliac crest harvest. The use of the cage in association with the Kaneda device allows for improved correction of kyphosis and restoration of normal sagittal alignment in addition to improved functional outcomes.

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Michael P. Kelly, Lawrence G. Lenke, Christopher I. Shaffrey, Christopher P. Ames, Leah Y. Carreon, Virginie Lafage, Justin S. Smith and Adam L. Shimer

Object

The goal in this study was to evaluate the risk factors for complications, including new neurological deficits, in the largest cohort of patients with adult spinal deformity to date.

Methods

The Scoli-RISK-1 inclusion criteria were used to identify eligible patients from 5 centers who were treated between June 1, 2009, and June 1, 2011. Records were reviewed for patient demographic information, surgical data, and reports of perioperative complications. Neurological deficits were recorded as preexisting or as new deficits. Patients who underwent 3-column osteotomies (3COs) were compared with those who did not (posterior spinal fusion [PSF]). Between-group comparisons were performed using independent samples t-tests and chi-square analyses.

Results

Two hundred seven patients were identified—75 who underwent PSF and 132 treated with 3CO. In the latter group, patients were older (58.9 vs 49.4 years, p < 0.001), had a higher body mass index (29.0 vs 25.8, p = 0.029), smaller preoperative coronal Cobb measurements (33.8° vs 56.4°, p < 0.001), more preoperative sagittal malalignment (11.7 cm vs 5.4 cm, p < 0.001), and similar sagittal Cobb measurements (45.8° vs 57.7°, p = 0.113). Operating times were similar (393 vs 423 minutes, p = 0.130), although patients in the 3CO group sustained higher estimated blood loss (2120 vs 1700 ml, p = 0.066). Rates of new neurological deficits were similar (PSF: 6.7% vs 3CO: 9.9%, p = 0.389), and rates of any perioperative medical complication were similar (PSF: 46.7% vs 3CO: 50.8%, p = 0.571). Patients who underwent vertebral column resection (VCR) were more likely to sustain medical complications than those treated with pedicle subtraction osteotomy (73.7% vs 46.9%, p = 0.031), although new neurological deficits were similar (15.8% vs 8.8%, p = 0.348). Regression analysis did not reveal significant predictors of neurological injury or complication from collected data.

Conclusions

Despite higher estimated blood loss, rates of all complications (49.3%) and new neurological deficits (8.7%) did not vary for patients who underwent complex reconstruction, whether or not a 3CO was performed. Patients who underwent VCR sustained more medical complications without an increase in new neurological deficits. Prospective studies of patient factors, provider factors, and refined surgical data are needed to define and optimize risk factors for complication and neurological deficits.

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Aaron J. Clark, Roxanna M. Garcia, Malla K. Keefe, Tyler R. Koski, Michael K. Rosner, Justin S. Smith, Joseph S. Cheng, Christopher I. Shaffrey, Paul C. McCormick and Christopher P. Ames

Object

Adult spinal deformity (ASD) surgery is increasing in the spinal neurosurgeon's practice.

Methods

A survey of neurosurgeon AANS membership assessed the deformity knowledge base and impact of current training, education, and practice experience to identify opportunities for improved education. Eleven questions developed and agreed upon by experienced spinal deformity surgeons tested ASD knowledge and were subgrouped into 5 categories: 1) radiology/spinopelvic alignment, 2) health-related quality of life, 3) surgical indications, 4) operative technique, and 5) clinical evaluation. Chi-square analysis was used to compare differences based on participant demographic characteristics (years of practice, spinal surgery fellowship training, percentage of practice comprising spinal surgery).

Results

Responses were received from 1456 neurosurgeons. Of these respondents, 57% had practiced less than 10 years, 20% had completed a spine fellowship, and 32% devoted more than 75% of their practice to spine. The overall correct answer percentage was 42%. Radiology/spinal pelvic alignment questions had the lowest percentage of correct answers (38%), while clinical evaluation and surgical indications questions had the highest percentage (44%). More than 10 years in practice, completion of a spine fellowship, and more than 75% spine practice were associated with greater overall percentage correct (p < 0.001). More than 10 years in practice was significantly associated with increased percentage of correct answers in 4 of 5 categories. Spine fellowship and more than 75% spine practice were significantly associated with increased percentage correct in all categories. Interestingly, the highest error was seen in risk for postoperative coronal imbalance, with a very low rate of correct responses (15%) and not significantly improved with fellowship (18%, p = 0.08).

Conclusions

The results of this survey suggest that ASD knowledge could be improved in neurosurgery. Knowledge may be augmented with neurosurgical experience, spinal surgery fellowships, and spinal specialization. Neurosurgical education should particularly focus on radiology/spinal pelvic alignment, especially pelvic obliquity and coronal imbalance and operative techniques for ASD.

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Michael P. Kelly, Lawrence G. Lenke, Jakub Godzik, Ferran Pellise, Christopher I. Shaffrey, Justin S. Smith, Stephen J. Lewis, Christopher P. Ames, Leah Y. Carreon, Michael G. Fehlings, Frank Schwab and Adam L. Shimer

OBJECTIVE

The authors conducted a study to compare neurological deficit rates associated with complex adult spinal deformity (ASD) surgery when recorded in retrospective and prospective studies. Retrospective studies may underreport neurological deficits due to selection, detection, and recall biases. Prospective studies are expensive and more difficult to perform, but they likely provide more accurate estimates of new neurological deficit rates.

METHODS

New neurological deficits were recorded in a prospective study of complex ASD surgeries (pSR1) with a defined outcomes measure (decrement in American Spinal Injury Association lower-extremity motor score) for neurological deficits. Using identical inclusion criteria and a subset of participating surgeons, a retrospective study was created (rSR1) and neurological deficit rates were collected. Continuous variables were compared with the Student t-test, with correction for multiple comparisons. Neurological deficit rates were compared using the Mantel-Haenszel method for standardized risks. Statistical significance for the primary outcome measure was p < 0.05.

RESULTS

Overall, 272 patients were enrolled in pSR1 and 207 patients were enrolled in rSR1. Inclusion criteria, defining complex spinal deformities, and exclusion criteria were identical. Sagittal Cobb measurements were higher in pSR1, although sagittal alignment was similar. Preoperative neurological deficit rates were similar in the groups. Three-column osteotomies were more common in pSR1, particularly vertebral column resection. New neurological deficits were more common in pSR1 (pSR1 17.3% [95% CI 12.6–22.2] and rSR1 9.0% [95% CI 5.0–13.0]; p = 0.01). The majority of deficits in both studies were at the nerve root level, and the distribution of level of injury was similar.

CONCLUSIONS

New neurological deficit rates were nearly twice as high in the prospective study than the retrospective study with identical inclusion criteria. These findings validate concerns regarding retrospective cohort studies and confirm the need for and value of carefully designed prospective, observational cohort studies in ASD.

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Dominic Maggio, Tamir T. Ailon, Justin S. Smith, Christopher I. Shaffrey, Virginie Lafage, Frank Schwab, Regis W. Haid Jr., Themistocles Protopsaltis, Eric Klineberg, Justin K. Scheer, Shay Bess, Paul M. Arnold, Jens Chapman, Michael G. Fehlings, Christopher Ames, AOSpine North America and International Spine Study Group

OBJECT

The associations among global spinal alignment, patient-reported disability, and surgical outcomes have increasingly gained attention. The assessment of global spinal alignment requires standing long-cassette anteroposterior and lateral radiographs; however, spine surgeons routinely rely only on short-segment imaging when evaluating seemingly isolated lumbar pathology. This may prohibit adequate surgical planning and may predispose surgeons to not recognize associated pathology in the thoracic spine and sagittal spinopelvic malalignment. The authors used a case-based survey questionnaire to evaluate if including long-cassette radiographs led to changes to respondents' operative plans as compared with their chosen plan when cases contained standard imaging of the involved lumbar spine only.

METHODS

A case-based survey was distributed to AOSpine International members that consisted of 15 cases of lumbar spine pathology and lumbar imaging only. The same 15 cases were then shuffled and presented a second time with additional long-cassette radiographs. Each case required participants to select a single operative plan with 5 choices ranging from least to most extensive. The cases included 5 “control” cases with normal global spinal alignment and 10 “test” cases with significant sagittal and/or coronal malalignment. Mean scores were determined for each question with higher scores representing more invasive and/or extensive operative plans.

RESULTS

Of 712 spine surgeons who started the survey, 316 (44%) completed the entire series, including 68% of surgeons with spine fellowship training and representation from more than 40 countries. For test cases, but not for control cases, there were significantly higher average surgical invasiveness scores for cases presented with long-cassette radiographs (4.2) as compared with those cases with lumbar imaging only (3.4; p = 0.002). The addition of long-cassette radiographs resulted in 82.1% of respondents recommending instrumentation up to the thoracic spine, a 23.2% increase as compared with the same cases presented with lumbar imaging only (p = 0.008).

CONCLUSIONS

This study demonstrates the importance of maintaining a low threshold for performing standing long-cassette imaging when assessing seemingly isolated lumbar pathology. Such imaging is necessary for the assessment of spinopelvic and global spinal alignment, which can be important in operative planning. Deformity, particularly positive sagittal malalignment, may go undetected unless one maintains a high index of suspicion and obtains long-cassette radiographs. It is recommended that spine surgeons recognize the prevalence and importance of such deformity when contemplating operative intervention.

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Shian Liu, Renaud Lafage, Justin S. Smith, Themistocles S. Protopsaltis, Virginie C. Lafage, Vincent Challier, Christopher I. Shaffrey, Kris Radcliff, Paul M. Arnold, Jens R. Chapman, Frank J. Schwab, Eric M. Massicotte, S. Tim Yoon, Michael G. Fehlings and Christopher P. Ames

OBJECT

Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM.

METHODS

A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures.

RESULTS

At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2–7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = −0.377, p = 0.003; mJOA score, Extension R = −0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade.

CONCLUSIONS

Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.