Peter G. Passias

Adult Scoliosis in Patients Over Sixty-five Years of Age: Outcomes of Operative versus Nonoperative Treatment at a Minimum Two-year Follow-up

Study Design. Retrospective case-control study. Objective. The purpose of this study was to compare the self-reported outcomes between operatively and nonoperatively treated patients over the age of 65 with adult scoliosis, using 4 distinct self-assessment questionnaires (SRS-22, SF-12, EQ5D, and Oswestry disability index [ODI]) and standard radiographic measurement parameters. Summary of Background Data. The current spine literature contains no studies that directly compare the self-reported and radiographic outcomes of operatively and nonoperatively treated patients over the age of 65 years with adult scoliosis. Methods. We retrospectively analyzed the self-reported outcomes of 83 adult scoliosis in patients over the age of 65 years. A total of 34 patients were treated operatively, whereas 49 patients were managed nonoperatively. For each of these patients, standard radiographic measurements were recorded both before and after treatment, and each patient received 4 questionnaires (SRS-22, SF-12, EQ5D, and ODI) that were completed with a minimum of 2-year follow-up from the time the treatment was initiated. The outcomes of both groups were then statistically compared. Results. As compared to the nonoperative group, the operative group reported significantly better self-assessment scores for the EQ5D index, EQ5D Visual Analogue Score, and SRS-22 questionnaires. However, no statistically significant difference between the groups was detected for the ODI, SF-12 Mental Health Component Summary, and SF-12 PCS. Furthermore, the operative group also had a significant improvement in radiographic measurements. Conclusion. Adult scoliosis patients over the age of 65 years treated operatively had significantly less pain, a better health-related quality of life, self image, mental health, and were more satisfied with their treatment than patients treated conservatively. However, we found no statistically significant differences in their degree of disability as measured by the ODI as well as physical and mental health by the SF-12 instrument. Preoperative radiographic deformity was not determined to be a significant factor for predicting whether an operative or nonoperative treatment course was chosen.

Measurement of Vertebral Kinematics Using Noninvasive Image Matching Method–validation and Application

Study Design. In vitro and in vivo laboratory study. Objective. To validate a dual fluoroscopic image matching technique for measurement of in vivo spine kinematics. Summary of Background Data. Accurate knowledge of the spinal structural functions is critical to understand the biomechanical factors that affect spinal pathology. Many studies have investigated vertebral motion both in vitro and in vivo. However, determination of in vivo motion of the vertebrae under physiologic loading conditions remains a challenge in biomedical engineering because of the limitations of current technology and the complicated anatomy of the spine. Methods. In in vitro validation, an ovine spine was moved to a known distance in a known speed by an MTS machine. The dual fluoroscopic system was used to capture the spine motion and reproduce the moving distance and speed. In in vivo validation, a living subject moved the spine in various positions under weightbearing. The fluoroscopes were used to reproduce the in vivo spine positions 5 times. The standard deviations in translation and orientation of the 5 measurements were used to evaluate the repeatability of technique. Results. The translation positions of the ovine spine could be determined with a mean accuracy less than 0.40 mm for the image matching technique using magnetic resonance image-based vertebral models. The spine speed could be reproduced within an accuracy of 0.2 mm/s. The repeatability of the method in reproducing in vivo human spine 6DOF kinematics was less than 0.3 mm in translation and less than 0.7° in orientation. Conclusion. The image matching technique was accurate and repeatable for noninvasive measurement of spine vertebral motion. The technique could be a useful tool for determination of vertebral positions and orientations before and after surgical treatment of spinal pathology to evaluate and improve the efficacy of the various surgical methods in restoring normal spine function.

Range of motion and orientation of the lumbar facet joints in vivo.

Study Design. Controlled laboratory study. Objective. To measure the range of motion of lumbar facet (zygapophyseal) joints in vivo during various functional weight-bearing positions of the upper body. Summary of Background Data. Determination of normal in vivo motion of the lumbar facet joints remains elusive despite numerous in vitro studies, animal models, and finite element simulations. Alterations in motion of the facet joints have been thought to be associated with various types of lumbar spine pathology including disc degeneration, facet degeneration, and neural impingement. Methods. Eleven healthy subjects underwent magnetic resonance imaging (MRI) to obtain three-dimensional models of the lumbar vertebrae from L2–L5. Each patient was then scanned using a dual-fluoroscopic imaging system while positioning the body in different postures: maximal forward-backward bend, side-to-side bending, and maximal left-right torsion. This fluoroscopic set-up was then recreated in solid modeling software where positions of the vertebrae were reproduced at each studied posture by matching the MRI-based models to the fluoroscopic images. The kinematics was measured using a Cartesian coordinate system placed in the center of each facet. The facet orientation in the sagittal and transverse plane was also determined. Results. During flexion-extension movements of the trunk, the facet joints rotated primarily along the mediolateral axis (average: 2°–6°) and were translated in the cephalad caudad direction (average: 2–4 mm). However, during lateral bending and twisting, the facet joints did not rotate or translate in 1 dominant direction. Instead, the resulting motion represented a coupling of rotation and translation in different directions (average: <5° and 3 mm). Further, the kinematic behavior of the facets of the upper lumbar spine (L2–L3 and L3–L4) were similar but different from that of the lower lumbar spine (L4–L5). Conclusion. These findings provide baseline information to enable the study of kinematic changes that occur in pathologic conditions of the spine and to determine how these might be affected following surgical intervention.

Segmental Lumbar Rotation in Patients with Discogenic Low Back Pain During Functional Weight-Bearing Activities

BACKGROUND Little information is available on vertebral motion in patients with discogenic low back pain under physiological conditions. We previously validated a combined dual fluoroscopic and magnetic resonance imaging system to investigate in vivo lumbar kinematics. The purpose of the present study was to characterize mechanical dysfunction among patients with confirmed discogenic low back pain, relative to asymptomatic controls without degenerative disc disease, by quantifying abnormal vertebral motion. METHODS Ten subjects were recruited for the present study. All patients had discogenic low back pain confirmed clinically and radiographically at L4-L5 and L5-S1. Motions were reproduced with use of the combined imaging technique during flexion-extension, left-to-right bending, and left-to-right twisting movements. From local coordinate systems at the end plates, relative motions of the cephalad vertebrae with respect to caudad vertebrae were calculated at each of the segments from L2 to S1. Range of motion of the primary rotations and coupled translations and rotations were determined. RESULTS During all three movements, the greatest range of motion was observed at L3-L4. L3-L4 had significantly greater motion than L2-L3 with left-right bending and left-right twisting movements (p < 0.05). The least motion occurred at L5-S1 for all movements; the motion at this level was significantly smaller than that at L3-L4 (p < 0.05). Range of motion during left-right bending and left-right twisting at L3-L4 was significantly larger in the degenerative disc disease group than in the normal group. The range of motion at L4-L5 was significantly larger in the degenerative group than in the normal group during flexion; however, the ranges of motion in both groups were similar during left-to-right bending and left-to-right twisting. CONCLUSIONS The greatest range of motion in patients with discogenic back pain was observed at L3-L4; this motion was greater than that in normal subjects, suggesting that superior adjacent levels developed segmental hypermobility prior to undergoing fusion. L5-S1 had the least motion, suggesting that segmental hypomobility ensues at this level in patients with discogenic low back pain.

In-vivo motion characteristics of lumbar vertebrae in sagittal and transverse planes

Lumbar vertebrae are complicated in structure and function. The purpose of this study was to investigate the in-vivo motion characteristics of different portions of the lumbar vertebrae during functional activities. Motion of L2, L3 and L4 was reproduced using a combined dual fluoroscopic and MR imaging technique during flexion-extension and left-right twisting of the trunk. The ranges of motion (ROM) of the proximal vertebra with respect to the distal one at 3 representative locations: the center of the vertebral body, the center of the spinal canal and the tip of the spinous process were measured. Centers of rotation (COR) of the vertebrae were then determined by calculation of the points of zero motion in 2D sagittal and transverse planes. During flexion-extension, the center of the vertebral body moved less than 0.6mm, while the tip of the spinous process moved less than 7.5mm in the sagittal plane. The CORs of both L23 (L2 with respect to L3) and L34 were located inside the vertebral body, at a distance about one-third the length of the vertebral body from the posterior edge. During left-right twisting, the center of the vertebral body moved less than 1.0mm, while the tip of the spinous process moved less than 1.6mm in the transverse plane. The CORs of both L23 and L34 were located approximately 30mm anterior to the front edge of the vertebral body. The results of this study may be used to define the ideal locations for surgical placement of the disc prosthesis, thus help improve the prosthesis design and surgical treatment of various pathological conditions.

Measurement of geometric deformation of lumbar intervertebral discs under in-vivo weightbearing condition

Quantitative data of spinal intervertebral disc deformation is instrumental for investigation of spinal disc pathology. In this study, we employed a combined dual fluoroscopic imaging system and the MR imaging technique to determine the lumbar disc deformation in living human subjects. Discs at L2-3, L3-4 and L4-5 levels were investigated in 8 normal subjects. The geometric deformation of the discs under full body weight loading condition (upright standing) was determined using the supine, non-weightbearing condition as a reference. The average maximum tensile deformation was -21% in compression and 24% in tension, and maximum shear deformation on the disc surface reached 26%. The data indicated that different portions of the disc are under different tensile and shear deformation. Further, discs of L2-3, L3-4 and L4-5 have different deformation behavior under the physiological weightbearing condition. In general, the higher level discs have higher deformation values. The technique used in this study can be used to investigate the deformation behaviors of diseased discs as well as the efficacy of different surgical modalities at restoring normal disc deformation patterns.

Lumbar Facet Joint Motion in Patients with Degenerative Disc Disease at Affected and Adjacent Levels: An In Vivo Biomechanical Study

Study Design. Controlled laboratory study. Objective. To evaluate the effect of lumbar degenerative disc diseases (DDDs) on motion of the facet joints during functional weight-bearing activities. Summary of Background Data. It has been suggested that DDD adversely affects the biomechanical behavior of the facet joints. Altered facet joint motion, in turn, has been thought to associate with various types of lumbar spine pathology including facet degeneration, neural impingement, and DDD progression. However, to date, no data have been reported on the motion patterns of the lumbar facet joint in DDD patients. Methods. Ten symptomatic patients of DDD at L4–S1 were studied. Each participant underwent magnetic resonance images to obtain three-dimensional models of the lumbar vertebrae (L2–S1) and dual fluoroscopic imaging during three characteristic trunk motions: left-right torsion, left-right bending, and flexion-extension. In vivo positions of the vertebrae were reproduced by matching the three-dimensional models of the vertebrae to their outlines on the fluoroscopic images. The kinematics of the facet joints and the ranges of motion (ROMs) were compared with a group of healthy participants reported in a previous study. Results. In facet joints of the DDD patients, there was no predominant axis of rotation and no difference in ROMs was found between the different levels. During left-right torsion, the ROMs were similar between the DDD patients and the healthy participants. During left-right bending, the rotation around mediolateral axis at L4–L5, in the DDD patients, was significantly larger than that of the healthy participants. During flexion-extension, the rotations around anterioposterior axis at L4–L5 and around craniocaudal axis at the adjacent level (L3–L4), in the DDD patients, were also significantly larger, whereas the rotation around mediolateral axis at both L2–L3 and L3–L4 levels in the DDD patients were significantly smaller than those of the healthy participants. Conclusion. DDD alters the ROMs of the facet joints. The rotations can increase significantly not only at the DDD levels but also at their adjacent levels when compared to those of the healthy participants. The increase in rotations did not occur around the primary rotation axis of the torso motion but around the coupled axes. This hypermobility in coupled rotations might imply a biomechanical mechanism related to DDD.

Primary Versus Revision Surgery in the Setting of Adult Spinal Deformity: A Nationwide Study on 10,912 Patients.

Study Design. Retrospective review of a prospectively collected database. Objective. This study compares patient demographics, incidence of comorbidities, procedure-related complications, and mortality following primary versus revision adult spinal deformity surgery Summary of Background Data. Although adult spinal deformity (ASD) surgery has been extensively investigated, no previous study has provided nationwide estimates of patient characteristics and procedure-related complications for primary versus revision spinal deformity surgery comparatively. Methods. Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for anterior and/or posterior thoracic and/or lumbar spinal fusion and refusion were included for patients aged 25+ and 4+ levels fused with any diagnoses specific for scoliosis. Patient demographics, comorbidity, and procedure-related complications incidence were determined for primary versus revision cohorts. Multivariate analysis reported as (OR [95% CI]). Results. Discharges for 9133 primary and 850 revision cases were identified. Patients differed on the basis of demographic and hospital data. Average comorbidity indices for the cohorts were similar (P = 0.580), as was in-hospital mortality (P = 0.163). The incidence of procedure-related complications was higher for the revision cohort (46.96 % vs. 71.97%, P = 0.001). The mean hospital course for the revision cohort was longer (6.37 vs. 7.13 days, P < 0.0001). Revisions had an increased risk of complications involving the nervous system (1.34[1.10–1.6]), hematoma/seroma formation (2.31[1.92–2.78]), accidental vessel or nerve puncture (1.44[1.29–1.61]), wound dehiscence (2.18[1.48–3.21]), postop infection (3.10[2.50–3.85]), and ARDS complications (1.43[1.28–1.60]). The primary cohort had a decreased risk for GI (0.65[0.55–0.76]) and GU complications (0.71[0.51–0.99]). Conclusion. Relative to primary cases, those undergoing revision correction of spinal deformity have a higher risk of many procedure-related complications with a longer hospital course despite similar baseline comorbidity burden and the in-hospital mortality rate. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality and direct future research to improve outcomes.

A Review of the Diagnosis and Treatment of Atlantoaxial Dislocations

Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning “atlantoaxial dislocation” or “atlantoaxial subluxation” on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.

Prospective Multicenter Assessment of Early Complication Rates Associated With Adult Cervical Deformity Surgery in 78 Patients

BACKGROUND Few reports have focused on treatment of adult cervical deformity (ACD). OBJECTIVE To present early complication rates associated with ACD surgery. METHODS A prospective multicenter database of consecutive operative ACD patients was reviewed for early (≤30 days from surgery) complications. Enrollment required at least 1 of the following: cervical kyphosis >10 degrees, cervical scoliosis >10 degrees, C2-7 sagittal vertical axis >4 cm, or chin-brow vertical angle >25 degrees. RESULTS Seventy-eight patients underwent surgical treatment for ACD (mean age, 60.8 years). Surgical approaches included anterior-only (14%), posterior-only (49%), anterior-posterior (35%), and posterior-anterior-posterior (3%). Mean numbers of fused anterior and posterior vertebral levels were 4.7 and 9.4, respectively. A total of 52 early complications were reported, including 26 minor and 26 major. Twenty-two (28.2%) patients had at least 1 minor complication, and 19 (24.4%) had at least 1 major complication. Overall, 34 (43.6%) patients had at least 1 complication. The most common complications included dysphagia (11.5%), deep wound infection (6.4%), new C5 motor deficit (6.4%), and respiratory failure (5.1%). One (1.3%) mortality occurred. Early complication rates differed significantly by surgical approach: anterior-only (27.3%), posterior-only (68.4%), and anterior-posterior/posterior-anterior-posterior (79.3%) (P = .007). CONCLUSION This report provides benchmark rates for overall and specific ACD surgery complications. Although the surgical approach(es) used were likely driven by the type and complexity of deformity, there were significantly higher complication rates associated with combined and posterior-only approaches compared with anterior-only approaches. These findings may prove useful in treatment planning, patient counseling, and ongoing efforts to improve safety of care. ABBREVIATIONS 3CO, 3-column osteotomiesACD, adult cervical deformityEBL, estimated blood lossISSG, International Spine Study groupSVA, sagittal vertical axis.