Dimensions of the Subaxial Lateral Mass: A Systematic Review of Anatomic (Morphometric) Measurement Studies.

STUDY DESIGN: This was a systematic review. OBJECTIVE: To review and synthesize information on subaxial lateral mass dimensions in order to determine the ideal starting point, trajectory, and size of a lateral mass screw. SUMMARY OF BACKGROUND DATA: The use of lateral mass instrumentation for posterior cervical decompression and fusion has become routine as these constructs have increased rigidity and fusion rates. METHODS: A systematic search of Medline and EMBASE was conducted. Studies that provided subaxial cervical lateral mass measurements, distance to the facet, vertebral artery and neuroforamen and facet angle made either directly (eg, cadaver specimen) or from patient imaging were considered for inclusion. Pooled estimates of mean dimensions were reported with corresponding 95% confidence intervals. Stratified analysis based on level, sex, imaging plane, source (cadaver or imaging), and measurement method was done. RESULTS: Of the 194 citations identified, 12 cadaver and 10 imaging studies were included. Pooled estimates for C3-C6 were generally consistent for lateral mass height (12.1 mm), width (12.0 mm), depth (10.8 mm), distance to the transverse foramen (11.8 mm), and distance to the nerve. C7 dimensions were most variable. Small sex-based differences in dimensions were noted for height (1.2 mm), width (1.3 mm), depth (0.43 mm), transverse foramen distance (0.9 mm), and nerve distance (0.3-0.8 mm). No firm conclusions regarding differences between measurements made on cadavers and those based on patient computed tomographic images are possible; findings were not consistent across dimensions. The overall strength of evidence is considered very low for all findings. CONCLUSIONS: Although estimates of height, width, and depth were generally consistent for C3-C6, C7 dimensions were variable. Small sex differences in dimensions may suggest that surgeons should use a slightly smaller screw in female patients. Firm conclusions regarding facet angulation, source of measurement, and method of measurement were not possible.

Spinal Implant Density and Postoperative Lumbar Lordosis as Predictors for the Development of Proximal Junctional Kyphosis in Adult Spinal Deformity.

OBJECTIVE: To evaluate spinal implant density and proximal junctional kyphosis (PJK) in adult spinal deformity (ASD). METHODS: Consecutive patients with ASD receiving ≥5 level fusions were retrospectively analyzed between 2007 and 2010. INCLUSION CRITERIA: ASD, elective fusions, minimum 2-year follow-up. EXCLUSION CRITERIA: age <18 years, neuromuscular or congenital scoliosis, cervical or cervicothoracic fusions, nonelective conditions (infection, tumor, trauma). Instrumented fusions were classified by the Scoliosis Research Society-Schwab ASD classification. Statistical analysis consisted of descriptives (measures of central tendency, dispersion, frequencies), independent Student t tests, χ2, analysis of variance, and logistic regression to determine association of implant density [(number of screws + number of hooks)/surgical levels of fusion] and PJK. Mean and median follow-up was 2.8 and 2.7 years, respectively. RESULTS: Eighty-three patients (17 male, 66 female) with a mean age of 59.7 years (standard deviation, 10.3) were analyzed. Mean body mass index (BMI) was 29.5 kg/m2 (range, 18-56 kg/m2) with mean preoperative Oswestry Disability Index of 48.67 (range, 6-86) and mean preoperative sagittal vertical axis of 8.42. The mean levels fused were 9.95 where 54 surgeries had interbody fusion. PJK prevalence was 21.7%, and pseudoarthrosis was 19.3%. Mean postoperative Oswestry Disability Index was 27.4 (range, 0-74). Independent Student t tests showed that PJK was not significant for age, gender, BMI, rod type, mean postoperative sagittal vertical axis, or Scoliosis Research Society-Schwab ASD classification; but iliac fixation approached significance (P = 0.077). Implant density and postoperative lumbar lordosis (LL) were predictors for PJK (P = 0.018 and 0.045, respectively). Controlling for age, BMI, and gender, postoperative LL (not implant density) continued to show significance in multivariate logistic regression model. CONCLUSIONS: PJK, although influenced by a multitude of factors, may be statistically related to implant density and LL.

Time to Event Analysis for the Development of Venous Thromboembolism After Spinal Fusion ≥ 5 Levels.

OBJECTIVE: Venous thromboembolism (VTE) is an important complication after spine surgery with an incidence of 31%. To our knowledge, no study has reported a time-dependent examination of factors influencing VTE. We report factors influencing first and multiple VTE events and perform a time-dependent analysis. METHODS: A retrospective analysis was performed of consecutive, "high-risk" patients receiving multilevel spinal fusion and an inferior vena cava (IVC) filter during the period 2000-2008. Descriptive statistics and frequencies were examined. Student t tests and logistic regression analysis identified confounders influencing development of acute VTE. Kaplan-Meier survival and Cox proportional hazard model evaluated time-dependent risk factors. Multivariate linear regression model analyzed multiple acute VTE events. RESULTS: There were 218 patients (149 women and 69 men) with an average age of 59.2 years (range, 18-86 years) who had 252 hospitalizations with an average stay of 20.3 days (SD = 15.6). There were 72 VTE events, with mean time to VTE of 15 days (SD = 18.1). Logistic regression identified factors influencing development of acute VTE, including sex (P = 0.04, OR = 0.243), VTE history (P = 0.001, OR = 8.0), IVC filter type (P = 0.050, OR = 15.6), chemoprophylaxis (P = 0.013, OR = 0.82), and hospital stay (P < 0.001, OR = 0.16). Kaplan-Meier curve revealed VTE history increased the rate of VTE development (P = 0.003). Cox proportional hazard model demonstrated IVC filter type (P = 0.003, hazard ratio = 5.042) and VTE history (P = 0.001, hazard ratio = 4.187) were significant for first VTE events. Linear regression analysis identified factors influencing development of multiple VTE events during a hospitalization, including VTE history (P < 0.01), chemoprophylaxis (P = 0.003), IVC filter type (P = 0.015), and hospital stay (P < 0.001). Mean and median follow-up were 3.3 years and 2.8 years, respectively. CONCLUSIONS: Sex, VTE history, IVC filter type, chemoprophylaxis, and hospital stay influenced development of VTE. Time to VTE correlated with DVT history and IVC filter type, whereas VTE history and hospital stay influenced multiple VTE events.

Predicting Kyphosis Correction During Posterior-Only Vertebral Column Resection by the Amount of Spinal Column Shortening.

STUDY DESIGN: Retrospective. OBJECTIVE: To investigate the relationship between the amount of correction achieved (K°) and extent of vertebral column shortening (mm) with posterior vertebral column resection (PVCR). SUMMARY OF BACKGROUND DATA: There is no scientific reference to the correlation between K° and column shortening (mm) with PVCR. METHODS: Based on simple geometry, we tested the hypothesis that we could predict the amount of actual kyphosis correction (K°) by calculation on 26 kyphotic PVCR patients. Using multiple linear measurements (mm), two angular approximations (°) were calculated: the geometric approximation (G°) using the geometric calculation (G-cal), and the rough approximation (R°) by more simplistic calculation (R-cal). Both G° and R° were compared against K° as measured on the pre- and postoperative radiographs. If calculated G° and R° is close to measured K°, we can use the calculations (G-cal and R-cal) in the clinical situation. RESULTS: The mean correction of K° was 38°. K°-G° and K°-R° were not significantly greater than 3° and 6°, respectively. As K° was very close to G° and R°, K° can replace G° and R°. Therefore, we can use G-cal and R-cal in the clinical setting and we can determine how much posterior shortening and what cage size is required to obtain a certain amount of K°. CONCLUSIONS: With two calculations (G-cal & R-cal), we can determine how much vertebral column shortening (mm) we need during PVCR to obtain the amount of kyphosis correction desired (K°). In order to obtain K°, using the formula deduced from G-cal and R-cal, we can determine the shortening between the upper and lower pedicle screws and cage size.

Renin-angiotensin system inhibitors and troponin elevation in spinal surgery.

Renin-angiotensin system (RAS) inhibition by angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) has been shown to reduce cardiovascular mortality and non-fatal myocardial infarction (MI) in high-risk surgical patients. However, their effect in spinal surgery has not been explored. Our objective was to determine the effect of RAS inhibitors on postoperative troponin elevation in spinal fusions, and to examine their correlation with hospital stay. We retrospectively analyzed 208 consecutive patients receiving spinal fusions ⩾5 levels between 2007-2010 with a mean follow-up of 1.7 years. Inclusion criteria were age ⩾18 years, elective fusions for kyphoscoliosis, and semi-elective fusions for tumor or infection. Exclusion criteria were trauma and follow-up <1 year. Descriptives, frequencies, and logistic and linear regression were used to analyze troponin elevation (⩾0.04 ng/mL), peak troponin level, and hospital stay. The results featured 208 patients with a mean body mass index (BMI) 28.5 kg/m(2) who underwent 345 spinal fusions. ACEI/ARB were withheld the day prior to surgery in 121 patients with 11 patients noteworthy for intra-operative electrocardiogram changes, 126 patients with troponin elevation, and 14 MI identified prior to discharge. Multivariate logistic regression identified BMI (p=0.04), estimated blood loss (p=0.015), and preoperative ACEI/ARB (p=0.015, odds ratio=2.7) as significant independent predictors for postoperative troponin elevation. Multivariate linear regression showed preoperative Oswestry Disability Index (p=0.002), unplanned return to operating room (p=0.007), pneumonia prior to hospital discharge (p<0.01), and preoperative ACEI/ARB to be associated with hospital stay. In patients with spinal fusions ⩾5 levels, ACEI/ARB are independently associated with postoperative troponin elevation and increased hospital stay.

Metastatic gastrointestinal stromal tumor to the thoracic and lumbar spine: first reported case and surgical treatment.

BACKGROUND CONTEXT: Metastatic epidural spinal cord compression from gastrointestinal stromal tumors (GISTs) is a rarely reported phenomenon. PURPOSE: To describe the surgical management of metastatic GIST to two noncontiguous regions of the spinal column. STUDY DESIGN: Case report. METHODS: Review of the medical chart, radiographic studies, and relevant literature. RESULTS: The patient underwent direct surgical decompression and stabilization of the cervicothoracic junction and the lumbar region during treatment of two distinct sites of metastatic pathology. CONCLUSIONS: Treatment of epidural compression from metastatic GIST with direct decompression and stabilization is safe and feasible.

Techniques for operative correction of proximal junctional kyphosis of the upper thoracic spine.

STUDY DESIGN: Retrospective study of a consecutive series of patients treated for proximal junctional kyphosis (PJK) of the upper thoracic and cervicothoracic spine. OBJECTIVE: To discuss corrective techniques for the management of symptomatic kyphosis at the junction of fused and mobile segments of the upper thoracic and cervicothoracic spine in patients who complain of pain, neurological deficit, ambulatory difficulty, and/or social isolation. SUMMARY OF BACKGROUND DATA: PJK is an unfortunately common, but important, complication seen in long instrumented fusions to the upper thoracic and cervicothoracic spine. Although often asymptomatic, its incidence and prevalence warrant a discussion on treatment options for symptomatic patients. METHODS: After the institutional review board confirmed approval, we retrospectively analyzed patients who received treatment of PJK from 2003 to 2009. Segmental instrumentation and intraoperative neurophysiological monitoring were used in all patients. Data acquisition was performed by reviewing electronic medical records and radiographs. Inclusion criteria were patients who underwent surgical correction of PJK of the cervicothoracic and upper thoracic spine and had more than 2-year follow-up. Preoperative lumbar lordosis, preoperative thoracic kyphosis, pre- and postoperative sagittal balance, and sagittal proximal junctional Cobb angle were obtained. All corrective procedures were performed in 2 stages, each patient receiving cervical traction between cases. RESULTS: Inclusion criteria were met in 7 patients (5 women and 2 men), with mean age of 55 years (range, 18-80 years). Six patients received multilevel Smith-Petersen osteotomies, with 2 patients receiving rib osteotomies, and 1 patient received a vertebral column resection. The mean preoperative and postoperative proximal junctional Cobb angles were 45° (range, 14°-89.7°) and 14° (range, 3.0°-38.0°), respectively. The mean degree of correction was 31° (range, 11°-79.2°). All patients had maintained or improved sagittal balance. No patient sustained a temporary or permanent neurological deficit after correction related to surgery. All patients had 2-year follow-up, and there were no mortalities. CONCLUSION: For a selected cohort of patients who develop PJK of the upper thoracic and cervicothoracic spine, osteotomies, cervical traction, and intraoperative manual reduction provide a significant improvement of proximal junctional Cobb angles. To our knowledge, this is the first study to address treatment for symptomatic patients with this condition.

Morbidity and mortality after spinal deformity surgery in patients 75 years and older: complications and predictive factors.

OBJECT: As the population continues to age, relatively older geriatric patients will present more frequently with complex spinal deformities that may require surgical intervention. To the authors' knowledge, no study has analyzed factors predictive of complications after major spinal deformity surgery in the very elderly (75 years and older). The authors' objective was to determine the rate of minor and major complications and predictive factors in patients 75 years of age and older who underwent major spinal deformity surgery requiring a minimum 5-level arthrodesis procedure. METHODS: Twenty-one patients who were 75 years of age or older and underwent thoracic and/or lumbar fixation and arthrodesis across 5 or more levels for spinal deformity were analyzed retrospectively. The medical and surgical records were reviewed in detail. Age, diagnosis, comorbidities, operative data, hospital data, major and minor complications, and deaths were recorded. Factors predictive of perioperative complications were identified by logistic regression analysis. RESULTS: The mean patient age was 77 years old (range 75-83 years). There were 14 women and 7 men. The mean follow-up was 41.2 months (range 24-81 months). Fifteen patients (71%) had at least 1 comorbidity. A mean of 10.5 levels were fused (range 5-15 levels). Thirteen patients (62%) had at least 1 perioperative complication, and 8 (38%) had at least one major complication for a total of 17 complications. There were no perioperative deaths. Increasing age was predictive of any perioperative complication (p = 0.03). However, major complications were not predicted by age or comorbidities as a whole. In a subset analysis of comorbidities, only hypertension was predictive of a major complication (OR 10, 95% CI 1.3-78; p = 0.02). Long-term postoperative complications occurred in 11 patients (52%), and revision fusion surgery was necessary in 3 (14%). CONCLUSIONS: Patients 75 years and older undergoing major spinal deformity surgery have an overall perioperative complication rate of 62%, with older age increasing the likelihood of a complication, and a long-term postoperative complication rate of 52%. Patients in this age group with a history of hypertension are 10 times more likely to incur a major perioperative complication. However, the mortality risk for these patients is not increased.

Predicting the outcome of selective thoracic fusion in false double major lumbar "C" cases with five- to twenty-four-year follow-up.

STUDY DESIGN: Retrospective radiographic and clinical study. OBJECTIVE: To examine the long-term outcome of selective thoracic fusion (STF) performed for lumbar "C" modifier curves in adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The efficacy of STF in lumbar "C" false double major curves is controversial. We examined the 5- to 24-year outcomes of patients with "C" lumbar curves who underwent STF at a single institution to determine which factors help predict successful outcome. METHODS: Thirty-two patients (age, 14.8 ± 2.0 years) with a lumbar "C" modifier underwent primary STF and had minimum 5-year follow-up (mean, 6.8 years). All patients were fused distally to either T12 or L1. At latest follow-up, 18 were considered successful (group S), 2 required reoperation to accommodate worsening deformity (group R), and 12 were considered marginal outcomes (group M), as defined by >3 cm coronal imbalance (n = 5), >5 mm worsening of lumbar apical vertebra translation compared with preoperative (n = 4), >1 Nash-Moe grade worsening of lumbar apical vertebra rotation (n = 1), >10° thoracolumbar junction kyphosis which was at least 5° worse than preoperative (n = 5), and lumbar Cobb angle >5° worse than preoperative (n = 2). Clinical outcomes were determined by Scoliosis Research Society (SRS)-30 at final follow-up. RESULTS: Of the multiple factors considered, 2-month postoperative standing lumbar sagittal alignment was most predictive for long-term outcome (P < 0.019 by Kruskal-Wallis ANOVA). Satisfactory outcomes had statistically significantly greater T12-S1 lordosis than those that were marginal (64.8° (group S) vs. 52.0° (group M); P = 0.014) or required reoperation (64.8° [group S] vs. 38.0° [group R]; P < 0.001). Traditionally considered variables such as apical vertebra rotation, apical vertebra translation, Cobb angle magnitudes, coronal and sagittal balance, and their respective thoracic-to-lumbar ratios were not independently significant. CONCLUSION: Selective thoracic fusions performed for lumbar "C" modifier scoliotic deformities generally have excellent long-term radiographic and SRS-30 outcomes at 5- to 24-year follow-up. Care should be taken to ensure that overcorrection of the thoracic curve is not performed beyond the ability of the lumbar curve to compensate. Furthermore, consideration of selective thoracic fusion should not be ruled out simply because the patient may have a somewhat stiff lumbar curve based on side-bending radiographs.

Extension of prior idiopathic scoliosis fusions to the sacrum: a matched cohort analysis of sixty patients with minimum two-year follow-up.

STUDY DESIGN: Comparative study. OBJECTIVE: To compare the radiographic and clinical outcomes of patients undergoing extension of a previous idiopathic scoliosis fusion to the sacrum using either autogenous bone graft or recombinant human bone morphogenetic protein-2 (rhBMP-2). SUMMARY OF BACKGROUND DATA: Extension of an existing idiopathic scoliosis fusion to the sacrum for distal degeneration or sagittal imbalance has been associated with a high rate of pseudarthrosis. We hypothesized that rhBMP-2 could be successfully used as a substitute for distant autograft in this challenging population. METHODS: Consecutive patients were identified from a single institution prospective database. The control group (autogenous harvesting without rhBMP-2, 1998-2002) included 24 of 25 patients with minimum 2-year follow-up while the study group (rhBMP-2 without distant autograft, 2002-2006) included 36 of 39 patients with minimum 2-year follow-up. Radiographs were measured using standard adult deformity criteria. Fusions were evaluated by independent observers using a published 4-point scale. Clinical outcomes were evaluated using Scoliosis Research Society and Oswestry Disability Index Questionnaires. RESULTS: Groups were well matched with respect to demographic, radiographic, and surgical data with the following exceptions: the control group (autogenous graft, no BMP) was younger (43.5 vs. 49.8 years; P = 0.04), had more anterior levels fused (3.3 vs. 1.7; P = 0.01), more thoracoabdominal approaches (25% vs. 2.7%; P = 0.01), and greater estimated blood loss (1938 vs. 1221 mL; P = 0.01). There was 1 wound complication (deep infection) in each group. Rates of radiographic pseudarthrosis (11.1% vs. 20.8%) and revision for pseudarthrosis (5.6% vs. 12.5%) were lower in the rhBMP-2 group, although this did not reach statistical significance. Preoperative, postoperative, and improvements in Scoliosis Research Society and Oswestry Disability Index scores were similar between groups. We did not observe any increase in adverse events with the use of rhBMP-2. CONCLUSION: BMP-2 is a safe and effective alternative to iliac or rib harvesting when extending an existing idiopathic scoliosis fusion to the sacrum.

Thoracic pedicle subtraction osteotomy for fixed sagittal spinal deformity.

STUDY DESIGN.: A retrospective clinical study. OBJECTIVE.: To find the corrective capacity of a thoracic pedicle subtraction osteotomy (PSO), determine if segmental correction is dependent on level, and to compute the impact of thoracic PSO on regional and global spinal balance. SUMMARY OF BACKGROUND DATA.: PSO is a technique popularized in the lumbar spine primarily for the correction of fixed sagittal imbalance. Despite several studies describing the clinical and radiographic outcome of lumbar PSO, there is no study in literature reporting its application in the thoracic spine. METHODS.: We retrospectively analyzed patients with fixed thoracic kyphosis who underwent thoracic PSOs for sagittal realignment. Segmental pedicle screw instrumentation and intraoperative neurophysiologic monitoring was used in all patients. Data acquisition was performed by reviewing medical charts and radiographs to determine sagittal correction (segmental/regional/global) and complications. Clinical outcome using the Scoliosis Research Society-22 (SRS-22) instrument was determined by interview. RESULTS.: A total of 25 thoracic PSOs were performed (mean: 1.7 PSOs/patient, range: 1-3) in 15 patients (9 M/6 F). The study population had an average age of 56 years (range, 36-81 years) and was followed up after surgery for a mean of 3.5 years (range, 24-75 months). The osteotomies were carried out in the proximal thoracic spine (T2-T4, n = 6), midthoracic spine (T5-T8, n = 12), and distal thoracic spine (T9-T12, n = 7). Mean correction at the PSO for all 25 levels was 16.3 degrees +/- 9.6 degrees . Stratified by region of the spine, thoracic PSO correction was as follows: T2-T4 = 10.7 degrees +/- 15.8 degrees , T5-T8 = 14.7 degrees +/- 4.6 degrees , and T9-T12 = 23.9 degrees +/- 4.1 degrees . Mean thoracic kyphosis (T2-T12 Cobb angle) was improved from 75.7 degrees +/- 30.9 degrees to 54.3 degrees +/- 21.4 degrees resulting in a significant regional sagittal correction of 21.4 degrees +/- 13.7 degrees (P < 0.005). Global sagittal balance was improved from 106.1 +/- 56.6 to 38.8 +/- 37.0 mm yielding a mean correction of 67.3 +/- 54.7 mm (P < 0.005). One patient, in whom there was segmental translation during osteotomy closure, had a decline in intraoperative somatosensory-evoked potentials. No patient sustained a temporary or permanent neurologic deficit after surgery. The mean SRS-22 Questionnaire score at final follow-up was 82.4 +/- 10.2. CONCLUSION.: Thoracic PSO can be performed safely. Segmental sagittal correction appears to vary based on the region of the thoracic spine the PSO is performed. The distal thoracic segments, which more closely resemble lumbar segments in morphology, rendered the greatest sagittal correction after PSO, approximately 24 degrees . There was no case of neurologic injury associated with thoracic PSO, and clinical outcomes according to the SRS-22 instrument were generally favorable.

Posterior vertebral column subtraction osteotomy: a novel surgical approach for the treatment of multiple recurrences of tethered cord syndrome.

Recurrent tethered cord syndrome (TCS) has been reported to develop in 5-50% of patients following initial spinal cord detethering operations. Surgery for multiple recurrences of TCS can be difficult and is associated with significant complications. Using a cadaveric tethered spinal cord model, Grande and colleagues demonstrated that shortening of the vertebral column by performing a 15-25-mm thoracolumbar osteotomy significantly reduced spinal cord, lumbosacral nerve root, and terminal filum tension. Based on this cadaveric study, spinal column shortening by a thoracolumbar subtraction osteotomy may be a viable alternative treatment to traditional surgical detethering for multiple recurrences of TCS. In this article, the authors describe the use of posterior vertebral column subtraction osteotomy (PVCSO) for the treatment of 2 patients with multiple recurrences of TCS. Vertebral column resection osteotomy has been widely used in the surgical correction of fixed spinal deformity. The PVCSO is a novel surgical treatment for multiple recurrences of TCS. In such cases, PVCSO may allow surgeons to avoid neural injury by obviating the need for dissection through previously operated sites and may reduce complications related to CSF leakage. The novel use of PVCSO for recurrent TCS is discussed in this report, including surgical considerations and techniques in performing PVCSO.

Abdominal complications following kyphosis correction in ankylosing spondylitis.

Spinal deformity surgery is associated with high rates of morbidity and a wide range of complications. The most significant abdominal complications following kyphosis correction, while uncommon, can certainly pose significant infectious and hemodynamic risks to the patient. Abdominal compartment syndrome is the most severe of the sequelae. It is the end result of elevated abdominal compartment pressure with physiological compromise and end organ system dysfunction. Although most commonly associated with trauma, abdominal compartment syndrome has also been witnessed following massive fluid shifts, which can occur during adult spinal deformity surgery. In this manuscript, we report on 2 patients with ankylosing spondylitis who developed significant abdominal pathology requiring exploratory laparotomy following kyphosis correction. In addition to describing the details of each case, we propose explanations of the relevant pathophysiology and review diagnostic and treatment strategies for such events. The key to effectively treating such a debilitating complication is to recognize it quickly and intervene rapidly and aggressively.

Maximizing the potential of minimally invasive spine surgery in complex spinal disorders.

Minimally invasive surgery (MIS) in the spine was primarily developed to reduce approach-related morbidity and to improve clinical outcomes compared with those following conventional open spine surgery. Over the past several years, minimally invasive spinal procedures have gained recognition and their utilization has increased. In particular, MIS is now routinely used in the treatment of degenerative spine disorders and has been shown to be as effective as conventional open spine surgeries. Although the procedures are not yet widely recognized in the context of complex spine surgery, the true potential in minimizing approach-related morbidity is far greater in the treatment of complex spinal diseases such as spinal trauma, spinal deformities, and spinal oncology. Conventional open spine surgeries for complex spinal disorders are often associated with significant soft tissue disruption, blood loss, prolonged recovery time, and postsurgical pain. In this article the authors review numerous cases of complex spine disorders managed with MIS techniques and discuss the current and future implications of these approaches for complex spinal pathologies.

Surgical treatment of fixed cervical kyphosis with myelopathy.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: To investigate clinical and radiographic outcomes following the surgical treatment of fixed cervical kyphosis with myelopathy. SUMMARY OF BACKGROUND DATA: To our knowledge, a study specifically addressing the surgical treatment of fixed cervical sagittal deformity has never before been published. METHODS: Sixteen patients treated surgically for fixed cervical kyphosis and myelopathy were followed for a mean of 4.5 years (range, 25-112 months). The study group consisted of 9 males and 7 females, with an average age of 52 years (range, 31-78 years). The principal etiologies of cervical deformity were prior laminectomy (63%), advanced spondylosis (19%), infection (6%), neuromuscular disease (6%), and metabolic disease (renal osteodystrophy) (6%). All patients were clinically evaluated by the Nurick classification and Odom criteria both before surgery and at the time of most recent follow-up. Radiographic analysis was performed using thin-cut CT scans, dynamic radiographs, and 14 x 36-inch scoliosis films. RESULTS: The mean preoperative cervical Cobb angle as measured from the C2-C7 was +38 degrees and improved to -10 degrees at final follow-up, yielding an average correction of 48 degrees . The mean number of anterior and posterior segments fused was 4.8 (range, 2-6) and 7.2 (range, 3-14), respectively. The mean Nurick score improved from 2.4 before surgery to 1.5 at the time of follow-up. According to Odom criteria, outcomes were as follows: excellent (38%), good (50%), fair (6%), and poor (6%). At the time of most recent follow-up, solid bony arthrodesis and maintenance of correction occurred in all patients; however, revision was required in one patient. CONCLUSION: The treatment of fixed cervical kyphosis with myelopathy using circumferential spinal osteotomies and instrumented reconstruction is technically demanding; however, restoration and maintenance of a neutral or lordotic cervical profile and excellent clinical outcomes are achievable.

Surgical treatment of vertebral osteomyelitis with recombinant human bone morphogenetic protein-2.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: To evaluate the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) as the primary graft material for the surgical treatment of vertebral osteomyelitis. SUMMARY OF BACKGROUND DATA: The clinical and radiographic results using allograft, autograft, and vascularized bone flaps for the surgical treatment of osteomyelitis have been previously reported. Despite an expanding body of literature documenting the value of rhBMP-2 in spinal fusion, its application to the management of spinal infection has never before been analyzed. METHODS: Twenty patients underwent surgical treatment of vertebral osteomyelitis using rhBMP-2 and were analyzed with a mean follow-up of 40 months (range, 24-53 months). All patients were treated with anterior column debridement and instrumented reconstruction. Four (20%) patients were treated with an anterior approach alone while the remaining 16 (80%) patients underwent circumferential spinal reconstruction. Clinical outcomes were assessed by Frankel grade and Odom criteria. Radiographic fusion was characterized based on thin-section computerized tomography (CT) analysis. RESULTS: Pathogens responsible for infection included Staphylococcus aureus (11; 55%), S. epidermidis (6; 30%), Bacteroides (1; 5%), and polymicrobial species (1; 5%). Infected segments of the spinal column based on region were found to be: thoracic (1; 5%), thoracolumbar (5; 25%), lumbar (11; 55%), and lumbosacral (3; 15%). The mean number of anterior and posterior segments fused was 3.3 (range, 2-5) and 6.5 (range 2-16), respectively. Forty-five percent of the subjects underwent multilevel corpectomies and fusion. All patients demonstrated clinical and radiographic evidence of spinal fusion at the time of follow-up. Patients had stable (14 patients) or improved (6 patients) Frankel grades after surgery. Odom criteria at final follow-up were: excellent (3; 15%), good (12; 60%), fair (4; 20%), and poor (1; 5%). There was no case of persistent or recurrent infection requiring revision surgery. CONCLUSION: rhBMP-2 is a valuable graft option for the surgical treatment of vertebral osteomyelitis. When dosed in the manner reported, very high rates of fusion are achievable as is eradication of infection.

Reversal of neurologic deterioration after vertebral column resection by spinal cord untethering and duraplasty.

STUDY DESIGN: Case report. OBJECTIVE: To describe a novel surgical approach for the treatment of a patient who developed neurologic deterioration after vertebral column resection (VCR). SUMMARY OF BACKGROUND DATA: VCR is a valuable osteotomy technique for the treatment of fixed spinal deformity. Despite an evolving compendium of information about this procedure, little has been described regarding the management of neurologic complications after VCR. METHODS: A 58-year-old woman underwent a T12 VCR for the treatment of fixed sagittal post-traumatic deformity. The patient was monitored intraoperatively with SSEPs and TcMEPs, both of which revealed no changes at any point during the operation. She awoke with normal motor function; however, her strength and sensory modalities deteriorated in a gradual progressive pattern over the first several postoperative days. She was then taken back to the operating room and intradural exploration was performed at the osteotomy site. RESULTS: The patient was found to have dense arachnoid adhesions that tethered the spinal cord to the dura at the level of the osteotomy. With spinal column shortening during osteotomy closure, tension was placed on the spinal cord, which was bound by the adhesions. Spinal cord untethering and duraplasty proved to be successful in reversing her neurologic deterioration. Moreover, kyphosis correction was maintained. CONCLUSION: In patients with neurologic deterioration after VCR and no clear evidence of epidural neural compression, intradural exploration should be considered.

Pedicled omental flaps as an adjunct in the closure of complex spinal wounds.

STUDY DESIGN: A retrospective clinical study. OBJECTIVE: To evaluate the safety and efficacy of using an omental flap in complex spine reconstruction in patients at high-risk for wound dehiscence. SUMMARY OF BACKGROUND DATA: Postoperative wound dehiscence represents a major cause of morbidity in patients undergoing instrumented spinal reconstruction. A variety of approaches for the prevention and treatment of this problem have been previously described in the literature; however, the use of omental flaps has received little attention. METHODS: In this retrospective analysis, 5 patients were studied both clinically and radiographically. The study population included 4 women and 1 man, with a mean age of 49 years (range, 31-67 years). All patients underwent an omental flap procedure at the time of spinal reconstruction because of significant soft tissue defects or active spinal infection. Mean clinicoradiographic follow-up was 53 months (range, 36-115 months). RESULTS: At the time of follow-up, all patients had well-healed surgical wounds with an acceptable structural and esthetic result. One patient in the study group experienced minor supra-fascial wound dehiscence. In terms of spinal outcome, all patients achieved successful bony arthrodesis; 1 patient, however, developed symptomatic adjacent segment degeneration and was treated by extension of the fusion construct. CONCLUSION: In patients undergoing thoracolumbar surgery who are at high risk of spinal wound dehiscence, closure using a pedicled omental flap is a viable procedure that may limit the risk of dehiscence and improve outcome.

Anterior lumbar interbody fusion in comparison with transforaminal lumbar interbody fusion: implications for the restoration of foraminal height, local disc angle, lumbar lordosis, and sagittal balance.

OBJECT: A primary consideration of all spinal fusion procedures is restoration of normal anatomy, including disc height, lumbar lordosis, foraminal decompression, and sagittal balance. To the authors' knowledge, there has been no direct comparison of anterior lumbar interbody fusion (ALIF) with transforaminal lumbar interbody fusion (TLIF) concerning their capacity to alter those parameters. The authors conducted a retrospective radiographic analysis directly comparing ALIF with TLIF in their capacity to alter foraminal height, local disc angle, and lumbar lordosis. METHODS: The medical records and radiographs of 32 patients undergoing ALIF and 25 patients undergoing TLIF from between 2000 and 2004 were retrospectively reviewed. Clinical data and radiographic measurements, including preoperative and postoperative foraminal height, local disc angle, and lumbar lordosis, were obtained. Statistical analyses included mean values, 95% confidence intervals, and intraobserver/interobserver reliability for the measurements that were performed. RESULTS: Our results indicate that ALIF is superior to TLIF in its capacity to restore foraminal height, local disc angle, and lumbar lordosis. The ALIF procedure increased foraminal height by 18.5%, whereas TLIF decreased it by 0.4%. In addition, ALIF increased the local disc angle by 8.3 degrees and lumbar lordosis by 6.2 degrees, whereas TLIF decreased the local disc angle by 0.1 degree and lumbar lordosis by 2.1 degrees. CONCLUSIONS: The ALIF procedure is superior to TLIF in its capacity to restore foraminal height, local disc angle, and lumbar lordosis. The improved radiographic outcomes may be an indication of improved sagittal balance correction, which may lead to better long-term outcomes as shown by other studies. Our data, however, demonstrated no difference in clinical outcome between the two groups at the 2-year follow-up.