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placement of pedicle screws, especially in patients with difficult anatomy, thereby increasing the feasibility, accuracy, and efficiency of the procedure. The robot functions as a semiactive surgical assistive device whose goal is not to substitute but to offer the surgeon a set of versatile tools that can broaden his or her ability to treat patients. Description: The robotic guidance system consists of a bed-mounted surgical arm and a workstation. We used the Mazor X Stealth Edition Robotic Guidance System by Medtronic for spine surgery, which has been previously described2-5. Unlike other systems that are navigation-based and require an optical tracking mechanism, this system relies on the preoperative plan to be referenced using the intraoperative registration. The workstation runs an interface software that facilitates preoperative planning, intraoperative image acquisition and registration, kinematic calculations, and real-time robot motion control. The robotic arm is mounted onto the bed as well as rigidly attached to the patient's spine. It can move in 6 degrees of freedom to provide the preplanned screw trajectory and entry point thereby allowing the surgeon to manually perform the drilling and screw insertion through either an open or percutaneous procedure by first seating a drill tube and then drilling and tapping the hole as needed. Alternatives: Other robotic systems include the ROSA robot by Medtech, the ExcelsiusGPS robot by Globus Medical, and the SurgiBot and ALF-X Surgical Robotic systems (both from TransEnterix). The Da Vinci Surgical System (Intuitive Surgical) has been utilized for laparoscopic anterior lumbar interbody fusion (ALIF), but it has not been approved by the U.S. Food and Drug Administration for actual spinal instrumentation. Alternative surgical techniques for pedicle screw placement include the freehand fluoroscopyguided technique and intraoperative image-assisted computer navigation techniques, including isocentric C-arm (Iso-C)3D(3-dimensional) navigation (Siemens), computed tomography (CT) navigation, O-arm navigation (Medtronic), CT-magnetic resonance imaging co-registration technology, and a 3D-visual guidance technique. Rationale: The robotic-guided pedicle screw placement offers the following benefits over conventional dorsal instrumentation techniques: improved accuracy and safety in pedicle screw insertion2-4,9-13; precision in screw size selection and planned screw positioning2; a reduction in exposure to radiation for the surgeon, the patient, and the operating-room staff9,11,12,14-19; simplicity and user-friendliness with a moderate learning curve10,11,20,21; ease of registration and reduction of operating time2; significant enhancement of the surgeon's ergonomics and dexterity for repetitive tasks in pedicle screw placement15,22-24; and a wider coverage in function to include utilization during minimally invasive surgery where applicable. Expected Outcomes: Accuracy rates between 94.5% and 99%, comparable with those in our study10, have been reported with the robotic-guided pedicle screw insertion technique, even in studies involving complex deformities and revision surgeries for congenital malformations, degenerative disorders, destructive tumors, and trauma2-4,9-13. The safety of this technique, in terms of reduced complications and intraoperative radiation exposure, has also been documented as higher than that for freehand fluoroscopic guidance or other navigation techniques9,11,12,14-19. The feasibility of this procedure has been further extended to minimally invasive procedures and to use in the cervical region, with replication of its advantages. It is associated with a reasonable learning curve, with consistent successful results after 25 to 30 patients. [ABSTRACT FROM AUTHOR]

Study Design: Prospective cohort study.Objective: The purpose of this study is to quantify the extent of change in sway associated with maintaining a balanced posture within the cone of economy (CoE), in a group of adult degenerative scoliosis (ADS) patients' pre and postsurgery and compare them to matched non-scoliotic controls.Summary Of Background Data: Patients with spinal deformities adopt a variety of postural changes in the spine, pelvis, and lower extremities in their effort to compensate for the anterior shift in the gravity line. ADS patients are known to exhibit an increased sway within their CoE. Greater sway expends more energy while standing when compared with healthy controls. Spinal alignment surgery has been shown to improve sagittal vertical axis and balance.Methods: Thirty-three ADS patients and performed a series of functional balance tests a week before and 3 months after surgery along with 20 non-scoliotic control.Results: ADS patients demonstrated more initial CoM (P = 0.001) and head (P = 0.011) displacements. Postoperatively ADS patients exhibited less CoM sway (P = 0.043) and head sway (P = 0.050), in comparison to their presurgery measures. Postsurgical ADS patients demonstrated more CoM (P = 0.002) and head (P = 0.012) displacements and increased muscle activity in comparison to non-scoliotic controls.Conclusion: Surgical alignment reduced the amount of sway, reduced the center of mass displacement, and reduced spine and lower extremity energy expenditure in ADS' patients. In symptomatic preoperative ADS patients, sagittal sway increased along with greater lumbar spine and lower extremity neuromuscular activity in comparison to a non-scoliotic control. Although surgical alignment improved ADS functional parameters during a dynamic balance test, these parameters approached but did not fully achieve non-scoliotic control parameters when measured 3 months after surgery.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Purpose: To study the effect of the number of previous operations on the outcome of revision adult spinal deformity (ASD) surgery.Methods: One hundred and thirty-seven consecutive patients who underwent revision ASD surgery were classified as follows: those who had one previous operation (group 1), had two previous operations (group 2) and had three or more previous operations (group 3). Perioperative complications and additional surgeries were reviewed. Back pain, leg pain, ODI scores and radiographic measurements were obtained.Results: Preoperatively, the patients in group 3 had worse ODI (60.0 vs. 48.1 and 47.9, p < 0.01) but not back pain or leg pain. Group 2 and group 3 had worse coronal plumb line (38.4 and 35.8 mm vs. 18.2 mm, p < 0.05) and SVA (99.7 and 153.9 mm vs. 67.8 mm, p < 0.05). Group 3 had worse PI-LL mismatch (40.1° vs. 25.3° and 26.2°, p = 0.08). Minor and major perioperative complication rates were 27.5% in group 1, 31.1% in group 2 and 39.0% in group 3 (p > 0.05). At mean 30-month follow-up, the additional surgery rates were 7.8, 17.8 and 22.0%, respectively (p = 0.07). The patients in all groups had improved back pain, leg pain and ODI scores. The net improvements on back pain, leg pain and ODI were not statistically different between the groups.Conclusions: Revision ASD patients who had two or more previous operations present with more coronal and sagittal imbalance and worse functional status. Patients who had three or more previous operations have relatively higher reoperation rate but similar perioperative complication rate and similar clinic improvements. These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

Study Design: A prospective cohort study.Objective: To examine the relationship of fear-avoidance beliefs and neuromuscular activity during gait in adult degenerative scoliosis (ADS) patients.Summary Of Background Data: Among patients with chronic spine pain, fear-avoidance beliefs are predictive of poor surgical outcomes. Fear-avoi occurs when patients perceive that movement will worsen underlying physical problems. This process leads them to restrict activity, which further heightens emotional distress. Patients with ADS have previously been shown to have an altered gait pattern. Electromyography is evolving into a useful tool to further our understanding of the pathologic manifestations of ADS during gait.Methods: Fifty ADS patients completed the Tampa Scale for Kinesiophobia (TSK) questionnaire and the Fear Avoidance Beliefs Questionnaire (FABQ). Surface electromyography electrodes were bilaterally placed on trunk and lower extremity muscles. Each patient performed a series of over-ground gait trials at a self-selected comfortable speed. Pearson Product Correlation analysis was used to determine the relationship between the self-reported fear of movement measures and the neuromuscular gait analysis biomechanical data.Results: The TSK total score and the FABQ physical were correlated with muscle onset of the External Oblique (P = 0.005), Gluteus Maximus (P = 0.018), Multifidi (P = 0.017), Erector Spinae (P = 0.014), Rectus Femoris (i = 0.008), Semitendinosus (P = 0.012), Tibilais Anterior (P = 0.012), and Medial Gastrocnemius (P = 0.010). Furthermore, the TSK total score, FABQ physical portion were correlated with muscle peak activity of Medial Gastrocnemius (P = 0.007), Multifidi (P = 0.014), and Tibilais Anterior (i = 0.050) and time to peak muscle activity of the Medial Gastrocnemius (P = 0.006) and Semitendinosus P = 0.038.Conclusion: This study demonstrates a strong correlation between neuromuscular gait parameters and fear-avoidance of movement which may reflect ADS patient experiences during ambulation. Further, it demonstrates that there are different aspects of fear-avoidance that may influence gait parameters. This study extends previous research on the role of fear-avoidance to include patients with spinal deformity.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Purpose: To examine the incidence of occult infection in revision spine surgeries and its correlation with preoperative inflammatory markers.Methods: We retrospectively reviewed all patients who underwent revision spine surgery and hardware removal between 2010 and 2016. Patients who had preoperative clinical signs of infection were excluded. The hardware and surrounding tissue culture results were obtained. The patients' diagnosis and preoperative inflammatory marker (ESR, CRP, and procalcitonin) levels were recorded.Results: A total of 162 consecutive patients were included in this study. The patients' mean age was 61 years (range 14-88). One hundred and three patients (63.6%) were female. Seventy-two patients (44.4%) had loose hardware and 88 patients (54.3%) had pseudarthrosis. Postoperatively, the hardware and/or surrounding tissue culture was positive in 15 patients (9.3%). The most commonly identified organisms were Propionibacterium acnes (7/15, 46.7%) and Staphylococcus (6/15, 40.0%). The other identified organisms were Pseudomonas aeruginosa (1/15, 6.7%) and Serratia marcescens (1/15, 6.7%). Only four patients with positive cultures had elevated preoperative ESR and CRP levels. Only two patients with positive cultures had elevated preoperative procalcitonin levels. There is no correlation between the patients' preoperative ESR, CRP, procalcitonin levels, and positive culture results (p > 0.05).Conclusions: Our study shows that occult infections are present in 9.3% of patients who underwent revision spine surgery and hardware removal although they did not have clinical signs of infection. Those commonly used preoperative inflammatory markers such as ESR, CRP, and procalcitonin may not be sensitive enough to detect occult infections in these patients. These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

Study Design: A prospective cohort study.Objective: The current study utilized quantitative gait analysis to examine the relationship of fear-avoidance beliefs to gait patterns in patients with adult degenerative scoliosis (ADS).Summary Of Background Data: Among patients with chronic spine pain, fear-avoidance beliefs are predictive of behavioral deficiencies, poor work, and surgery outcomes. The impact of such beliefs on patients with major spinal deformity has yet to be investigated. Patients with ADS have previously been shown to have an altered gait pattern. Utilizing quantified gait analysis, this study aims to examine correlations between fear-avoidance and various aspects of gait in patients with ADS.Methods: Twenty-five ADS patients completed the Tampa Scale for Kinesiophobia (TSK) questionnaire and the Fear Avoidance Beliefs Questionnaire (FABQ). Each patient performed a series of overground gait trials at a self-selected comfortable speed. Pearson product correlation analysis was used to determine the relationship between the self-reported fear of movement measures and the objective gait analysis biomechanical data.Results: TSK score correlated strongly with gait speed, stride, step, double support times, and step length, and correlated moderately with cadence, and stride length. The FABQ physical portion strongly correlated with stride length and step length. The FABQ physical portion was moderately correlated with gait speed and single support time. The FABQ work portion was correlated with stride length and step length.Conclusion: This study demonstrates a strong correlation between biomechanical gait parameters, as measured with gait analysis, and fear-avoidance of movement, as measured with the TSK and FABQ. Further, it demonstrates that quantified gait analysis can be a useful tool to evaluate patients with spine deformity and to assess the outcomes of treatments in this group of patients. This study extends previous research on the role of fear-avoidance to include patients with spinal deformity.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: A non-randomized, prospective, concurrent control cohort study.Objective: The purpose of this study is to develop and evaluate a method to quantify the dimensions of the cone of economy (COE) and the energy expenditure associated with maintaining a balanced posture within the COE, scoliosis patients and compare them to matched non-scoliotic controls in a group of adult degenerative. Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. The cone of economy refers to the stable region of upright standing posture. The underlying assumption is that deviating outside one's individual cone challenges the balance mechanisms. Adult degenerative scoliosis (ADS) patients exhibit a variety of postural changes within their COE, involving the spine, pelvis and lower extremities, in their effort to compensate for the altered posture.Methods: Ten ADS patients and ten non-scoliotic volunteers performed a series of functional balance tests. The dimensions of the COE and the energy expenditure related to maintaining balance within the COE were measured using a human motion video capture system and dynamic surface electromyography.Results: ADS patients presented more COM sway in the sagittal (ADS: 1.59 cm vs. H: 0.61 cm; p = 0.049) and coronal (ADS: 2.84 cm vs. H: 1.72 cm; p = 0.046) directions in comparison to the non-scoliotic control. ADS patients presented with more COM (ADS: 33.30 cm vs. H: 19.13 cm; p = 0.039) and head (ADS: 31.06 cm vs. H: 19.13 cm; p = 0.013) displacements in comparison to the non-scoliotic controls. Scoliosis patients expended more muscle activity to maintain static standing, as manifest by increased muscle activity in their erector spinae (ADS: 37.16 mV vs. H: 20.31 mV; p = 0.050), and gluteus maximus (ADS: 33.12 mV vs. H: 12.09 mV; p = 0.001) muscles.Conclusions: We were able to develop and evaluate a method that quantifies the COE boundaries, COM displacement, and amount of sway within the COE along with the energy expenditure for a specific patient. This method of COE measurement will enable spine care practitioners to objectively evaluate their patients in an effort to determine the most appropriate treatment options, and in objectively documenting the effectiveness of their intervention. [ABSTRACT FROM AUTHOR]

Patient reported outcome measures (PROMs) are commonly used to indicate functional status however, there is a lack of published literature on their relation to objective functional outcome measures (FOMs) among adult spinal deformity (ASD) patients. The minimum clinically important difference (MCID) is often used among spine PROMs as the standard benchmark by which outcome success is gauged however there is no data currently available describing the relation of PROM MCIDs to concurrent changes in FOMs for ASD surgery patients. Additionally, it is currently unclear whether PROMs are suitable for serving as anchors for determining FOM MCIDs. To determine if achievement of PROMs MCID coincides with significant changes in objective walking and balance FOMs among ASD patients treated with realignment surgery at 3- and 12-month follow-ups. Nonrandomized, retrospective review of ASD patient PROM and FOM data before and after realignment surgery. A total of 80 patients treated with spinal fusion for ASD. Visual analog scales (VAS) for mid-back, low-back and leg pain, Oswestry Disability Index (ODI), Scoliosis Research Society SRS-22r, spatiotemporal and kinematic gait measures, and postural balance measures. ASD surgery patients who completed PROMs and functional evaluations one week before (P0) and at three (P3) and 12 (P12) months after surgery were included. Functional evaluations included walking and standing tests using three-dimensional motion tracking. FOMs which showed significant univariate P0-P3-P12 improvements were grouped and compared by achievement of MCID (aMCID=yes, nMCID=no) at P0-P3 and P0-P12 for each PROM using independent sample t-tests. All PROMs showed significant univariate improvements (P0, P3, P12 respectively): VAS middle-back (4.4±2.8, 1.9±2.4, 1.8±2.6, p<0.001), VAS low-back (5.6±2.9, 2.7±2.6, 2.3±2.9, p<0.001), VAS leg (4.7±3.6, 1.8±2.8, 1.7±2.6, p<0.001), ODI (40.4±15.5, 29.7±21.4, 22.9±22.3, p<0.001), SRS-22r (2.9±0.5, 3.4±0.8, 3.9±0.9, p<0.001). Three of 14 gait FOMs showed significant univariate improvements: walking speed (0.87±0.18m/s, 0.92±0.12m/s, 0.96±0.16m/s, p=0.024), single-support time (0.44±0.06s, 0.44±0.06s, 0.41±0.06s, p=0.031), and gait deviation index (75±11.2, 68.8±13.7, 80.6±16.3, p=0.003). MCID achievement was as follows: VAS middle-back (55% at P3, 67% @P12), VAS low-back (74% @P3, 76% @P12), VAS leg (55% @P3, 62% @P12), ODI (46% @P3, 51% @P12), SRS (43% @P3, 82% @P12). No significant pairwise differences were found for any FOMs when grouped by MCID achievement status for each PROM. Achievement of MCID for ASD PROMs commonly associated with function did not coincide with significant differences in FOMs that otherwise did show consistent improvements at P3 and P12 follow-ups. Improvements in FOMs with a lack of separation by PROM MCID suggests that PROMs and FOMs may be measuring different aspects of changes in functional status of ASD patients and may require different methods for determining clinical relevance. PROMs used for assessing ASD patient function may not be suitable anchors for determining clinical FOM benchmarks. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

While spine surgery can produce good outcomes in many patients, there are patients who do not benefit from the intervention and have conditions not thought not to be addressable by surgical intervention. These failed back surgery syndrome (FBSS) patients may be candidates for spinal cord stimulation (SCS) for pain management. While multiple studies have reported benefits of SCS related to pain reduction, improved quality of life, and reduced pain medication intake, there has been little investigation into measurable physical functional improvement in this population. The purpose of this study was to evaluate the effect of SCS on traditional self-reported pain and functional measures, the psychological parameter of kinesiphobia, as well as functional measures of balance and gait, in FBSS patients. Prospective repeated-measures design. A total of 15 symptomatic FBSS patients eligible for SCS. Outcome assessment was based on visual analog scales (VAS) for back and leg pain, Oswestry Disability index (ODI), Tampa Scale for Kinesiophobia (TSK) and functional testing components including balance, sway and gait. Patients completed patients reported outcomes and functional evaluations prior to the SCS trial procedure (Pre) and at 6 (Post6) and 12 (Post12) weeks after SCS implantation. Gait and balance were evaluated using 3D human motion capture and dynamic surface EMG. Balance effort and Cone of Economy (CoE) dimensions were as measured by total sway and range of sway (RoS), respectively. Repeated measurements and one-way analysis of variance (ANOVA) were used to analyze data. SCS implant significantly improved gait and balance in FBSS patients. The following gait parameters showerd significant improvement: Walking speed (Pre: 0.75, Post6: 0.86, Post12: 0.92 m/s, p<0.011), cadence (Pre: 85.42, Post6: 94.1, Post12: 95.94 steps/m, p<0.032), stride length (Pre: 0.98, Post6: 1.05, Post12: 1.07 m, p<0.049), and gait deviation index (GDI; Pre: 74.0, Post6: 83.2, Post12: 90.8, p<0.012). Additionally, significant improvements were seen in balance effort (head sway, Pre: 80.2, Post6: 52.2, Post12: 50.0 cm, p<0.049) sway dimensions as seen by reduced sagittal (p<0.047) and coronal (p<0.042) sway. For patient-reported outcomes, significant improvements were noted for VAS low back (Pre: 6.5, Post6: 3.6, Post12: 3.9, p<0.036), ODI (Pre: 57.6, Post6: 39.7, Post12: 38.3, p<0.006). Scores on the and TSK also improved significantly (p<0.044). The results of this study support prior literature reporting significant improvement in pain and self-reported function reflected in VAS and ODI scores. Additionally, significant improvements were found post-SCS in gait and balance. The results suggest that SCS is associated not only with significant improvement in patient self-reported outcome measures, but also with physical functional testing. The patients included in this study showed more efficient gait patterns and improves balanced. This may be reflective of an overall improvement in activities of daily living following SCS implantation. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

The spine community is continuously adding to its armamentarium of intraoperative techniques for visualization and instrumentation of the spine. Recently, three-dimensional printed spine models were introduced for use in preoperative planning, surgical simulation, and intraoperative guidance. We present a 14-year old African male with congenital kyphoscoliosis, small stature, an obvious gibbus deformity and coronal imbalance, who underwent a three-staged posterior surgical correction procedure, during which a 3D-printed spine biomodel was utilized for better appreciation of his complex spinal deformity patho-anatomy. During the first stage of the procedure, he developed diminished lower extremity motor strength bilaterally and bowel/bladder control, but, following his third stage procedure and with focused rehabilitation efforts, he has regained full control of his bowel and bladder function, and is able to ambulate and perform activities of daily living independently, albeit still requiring intermittent walking support with a single forearm crutch due to residual left leg weakness. The 3D spine biomodel functioned successfully as a valuable tool and surrogate anatomic blueprint for the surgeons, enabling adequate appreciation of the complex bony anatomy which could not be easily resolved on the conventionally available imaging modalities, intraoperative navigation or robotic platform. Theoretically, up to $2900 USD in savings, translated from the mean estimated time saved per procedure with the use 3D-printed spine models has been proposed in some studies. Therefore, 3D-printed spine models have utility in complex spinal deformity correction surgery. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. Sway is the movement of the COM in the horizontal plane when a person is standing in a static position. Cervical spondylotic myelopathy (CSM) patients have impaired body balance and proprioceptive loss. PURPOSE To quantify the amount of sway associated with maintaining a balanced posture within the cone of economy (COE) in a group of untreated CSM patients and compare them to matched healthy controls. STUDY DESIGN/SETTING A prospective cohort study. PATIENT SAMPLE Thirty-two CSM patients and sixteen healthy controls (HC). OUTCOME MEASURES Center of mass (COM) and head sway, spine and lower extremityIntegrated Electromyography (iEMG). METHODS Thirty-two CSM patients performed a series of functional balance tests a week before surgery. Sixteen healthy controls (HC) performed a similar balance test. The functional balance test was essentially a Romberg's test in which the patients are required to stand erect with feet together and eyes opened in their self-perceived balanced and natural position for a full minute. All test subjects were fitted to a full body reflective markers set and surface EMG. RESULTS CSM patients presented more center of mass (COM) sway in the anterior-posterior (CSM: 2.87 vs. C: 0.74cm; p=.023) and right-left (CSM: 5.16 vs. C: 2.51cm; p=.003) directions and head sway (anterior-posterior – CSM: 2.17 vs. C: 0.82cm; p=.010 and right-left – CSM: 3.66 vs. C: 1.69cm; p=.044) and more COM (CSM: 44.72cm vs. HC: 19.26cm, p=.001) and head (Pre: 37.87cm vs. C: 19.93cm, p=.001) total sway in comparison to the healthy controls. CSM patients expended statistically significantly more muscle activity to maintain static standing, as manifest by increased muscle activity in their Multifidus (CSM: 22.25mV vs. HC: 12.39mV, p=.038), Erector Spinae (CSM: 26.76mV vs. HC: 14.41mV, p=.044), Rectus Femoris (CSM: 29.05mV vs. HC: 16.07mV, p=.037), and Tibialis Anterior(CSM: 23.06mV vs. HC: 14.48mV, p=.048) muscles during one minute standing in comparison to healthy control. CONCLUSIONS In symptomatic CSM patients, COM and head total sway were significantly greater than controls. Individuals with CSM exhibit more trunk and lower extremity muscle activity, and thus expend more energy to maintain a balanced, static standing posture. While most of the balance research in patients with spinal disorders is done based on static x-rays and mostly focused on sagittal spinal alignment, this study is the first effort to evaluate global balance as a dynamic process. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT It has been reported that there is a significant correlation between the loss of thoracic kyphosis and the development of cervical kyphosis in Adolescent Idiopathic Scoliosis (AIS) patients. However, the clinical significance of cervical deformityin AIS patients is not clear. PURPOSE To evaluate the relationship between cervical deformity and neck pain in AIS patients. STUDY DESIGN/SETTING Retrospective comparative study. PATIENT SAMPLE A total of 99 consecutive AIS patients. OUTCOME MEASURES C2-C7 sagittal vertical axis (C2–C7SVA), C2-C7 lordosis, neck pain VAS score. METHODS We retrospectively analyzed a consecutive series of AIS patients from a single center. Radiographic measurements included Cobb angle, C2-C7SVA, and C2-C7 lordosis. Cervical deformity was defined as loss of lordotic or neutral cervical angle (CK) or C2-C7SVA more than 4 cm (CPSM). Patients were stratified by the presence of CK and/or CPSM. The Visual Analogue Scale(VAS) was used to assess the patients' neck pain. The patients' demographics were also recorded. RESULTS A total of 99 patients were included in this study. The patients' mean age was 14 years (range 10–18). Mean cervical lordosis and C2-C7SVA were 1.5° and 30.4mm respectively. CK and CPSM prevalence were 49% and 16%, respectively, and the prevalence of CK and/or CPSM was 59%. Twenty six percent of the patients had neck pain and their median pain scores were 2.3 points (range 0.5–8.2 points). There is no correlation between CK and neck pain (26.7% vs. 25.6%, p>.05), between CPSM and neck pain (42.9% vs. 23.0%, p>.05), and between CK and/or CPSM and neck pain (28.8% vs. 22.2%, p>.05). CONCLUSIONS In this series, cervical deformity is present in 59% and neck pain is present in 26% of AIS patients. However, there is no correlation between cervical deformity and neck pain. Our data suggests that the loss of cervical lordosis is a compensatory maneuver in AIS patients and it may not be clinically significant. [ABSTRACT FROM AUTHOR]

The term Cone of Economy (CoE) is commonly used when assessing balance in deformity patients. Recently a method that quantifies the CoE for a specific patient using 3D video kinematic and electromyography (EMG) data was developed. The present study further develops the method by evaluating what occurs inside the CoE using an analysis of balance control strategies. The postural control system uses distinct strategies such as the ankle, hip and suspensory strategies. Ankle strategy involves postural sway control from the ankles and feet. Hip strategy involves postural sway control from the pelvis and trunk. The suspensory strategy involves an adjustment of the center of mass (CoM) toward the base of support by bilateral lower-extremity flexion or a slight squatting motion. This study provides a method to quantify the CoE, neuromuscular energy expenditure, and balance control strategies associated with maintaining a balanced posture, in a group of adult degenerative scoliosis (ADS) patients. Nonrandomized, prospective, concurrent cohort study. Fifteen ADS patients and 15 nonscoliotic volunteers. Dimensions of CoE, overall sway inside the CoE, spine and lower extremity angles and neuromuscular activity at the minimum and maximum point of sway (sagittal and coronal). All patients were fitted with 51 external reflective markers. Surface EMG electrodes were placed on spine and lower extremity muscles. Patients performed a functional balance test that was similar to a Romberg's test, in which the patients were required to stand erect with their feet together and eyes open in their self-perceived balanced and natural position for a full minute. Data analyzed with repeated measurement ANOVA. ADS patients presented larger CoE dimensions (Head - Sagittal: ADS: 3.36 vs H: 1.39 cm; p=0.021; Coronal: ADS: 6.18 vs H: 3.31 cm; p=0.039; CoM - Sagittal: ADS: 2.16 vs H: 0.68 cm; p=0.023; Coronal: ADS: 3.46 vs H: 2.18 cm; p=0.010) along with more head (ADS: 56.19 vs 36.10 cm; p=0.003) and CoM (ADS: 36.37 vs 19.19 cm; p=0.002) overall sway inside the CoE in comparison to the nonscoliotic controls. At the peak sagittal sway for the head and CoM, ADS patients presented with more trunk and head flexion (p<0.005). At the peak coronal sway for the head and CoM, ADS patients presented with more knee and hip flexion (p<0.005). Scoliosis patients expended more muscle activity to maintain static standing, as manifest by increased muscle activity in their erector spinae (ADS: 39.21 mV vs H: 18.31 mV; p=0.010), and gluteus maximus (ADS: 31.89 mV vs H: 15.09 mV; p=0.029) muscles in comparison to the nonscoliotic controls. At the peak sagittal sway for the head and CoM, ADS patients presented with more erector spinae and gluteus maximus but less external oblique and tibialis anterior muscles activity (p<0.005). At the peak coronal sway for the head and CoM, ADS patients presented with more erector spinae and gluteus (p<0.005). ADS patients have larger CoE dimensions, increased sway and neuromuscular activity while using more hip and suspensory strategies in comparison to the nonscoliotic controls in their effort to maintain balance. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

It has been shown that pedicle screw instrumentation in the cervical spine has superior biomechanical pullout strength and stability. However, due to the complex and variable anatomy of the cervical pedicles and the risk of catastrophic complications, cervical pedicle screw placement is not widely utilized. The purpose of this study is to review and report our experience with robotic guided cervical pedicle screw placement. We retrospectively reviewed consecutive patients who underwent cervical pedicle screw fixation with robotic guidance using pre- and postoperative CT scans by the investigator. Medical charts were reviewed for technical issues and intraoperative complications. A total of 62 cervical pedicle screws were reviewed in eight consecutive patients. Screw placement and deviation (mm) from the preoperative plan were assessed.We also reviewed the Medical charts for technical issues and intra-operative complications. Screw placement and deviation from the preoperative plan were assessed using the robotic system's planning software by fusing the preoperative CT (with the planned cervical pedicle screws) to the postoperative CT. This process was carried out by manually aligning the anatomical landmarks on the two CTs. Once a satisfactory fusion was achieved, the software's measurement tool was used manually to compare the planned vs actual screw placements in both axial and sagittal planes, at the midpoint of the pedicle in a resolution of 0.1 millimeters. Medical charts were reviewed for technical issues and intraoperative complications. A total of 62 cervical pedicle screws were reviewed in eight patients. The patients' mean age was 65 years, M:F ratio was 1:1, and the mean BMI was 25.17. No intraoperative complications that related to the placement of cervical pedicle screws were reported and robotic-guidance was successful in all 62 screws. The number of screws placed were 8 at C2, 12 at both C3 and C4, 10 at C5, 11 at C6, and 9 at C7. Postoperative CT scans showed that there were ten pedicle screw breaches (16.1%), all were medial, all less than 1 mm, with no clinical consequences. No pedicle screw breached the foramen transversarium. In the axial plane, the left side screws deviated from the pre-operative plan by 1.2±0.76 mm and the right-side screws deviated from the preoperative plan by 1.4±1.16 mm. In the sagittal plane, the left side screw deviated from the pre-operative plan by 1.2±1.16 mm and the right-side screw deviated from the preoperative plan by 1.4±0.94 mm. This study indicates that robotic-guided cervical pedicle screw placement is feasible with clinically acceptable results. The medial breaches did not result in any clinical consequences akin to passing a sublaminar wire or placing a hook into the epidural space. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Background Context: Surgical correction strategies for adult spinal deformity (ASD) relies heavily on radiographic alignment goals, however, there is often debate regarding degree of correction and how static alignment translates to physical ability in daily life. Kinematic analysis has the potential to improve the concept of ideal spinal alignment by providing clinically meaningful estimates of dynamic changes in spinal alignment during activities of daily life.Purpose: Estimate representative dynamic ranges of spinal alignment during gait among ASD patients using 3D motion tracking; compare dynamic alignment between mild and severe deformity patients and to healthy adults.Study Design/setting: Retrospective review at a single institution.Patient Sample: Fifty-two ASD patients and 46 healthy adults.Outcome Measures: Radiographic alignment, kinematic spine motion, spatiotemporal gait measures, patient reported outcomes (VAS pain, ODI, SRS-22r).Methods: Spinal alignment was assessed radiographically and during standing and overground walking tests. Dynamic alignment was initialized by linking radiographic alignment to kinematic alignment during standing and at initial heel contact during gait. Dynamic changes in maximums and minimums during gait were made relative to initial heel contact for each gait cycle. Total range-of-motion (RoM) was measured for both ASD and healthy subjects. Dynamic alignment measures included coronal and sagittal vertical axes (CVA, SVA), T1 pelvic angle (TPA), lumbar lordosis (LL), and pelvic tilt (PT). ASD patient's deformities were classified as either Mild or Severe based on the SRS-Schwab ASD classification.Results: Severe ASD patients had significantly larger dynamic maximum and minimums for SVA, TPA, LL, and PT (all p<.05) compared with Mild ASD patients. ASD patients exhibited little difference in dynamic alignment compared with healthy subjects. Only PT had a significant difference in dynamic RoM compared with healthy (p<.001).Conclusions: Mild and Severe ASD patients exhibited similar global dynamic alignment measures during gait and had comparable RoM to healthy subjects except with greater PT and reduced spatiotemporal performance which may be key compensatory mechanisms for dynamic stabilization. [ABSTRACT FROM AUTHOR]

Unfortunately, in the abstract at the results section units have been published incorrectly. [ABSTRACT FROM AUTHOR]

• Finite element (FE) method is used to study three different types of screw–bone connections. • Both the spinal implants and the bone are subjected to higher stress right after the pedicle-screw-instrumented surgery. • Holding capability is smaller and the bone and implants are subjected to larger von Mises stress in the contact connection than those in the bonded connection. • Considerable differences were observed between simplified and non-simplified screw FE models in the von Mises stress. Finite element (FE) method has been widely used to study the screw–bone connections. Screw threads are often excluded from the FE spine model to reduce computational cost. However, no study has been conducted to compare the effect of such simplification in the screw models on the predicting accuracy of the model. The effects of different screw–bone connection types on the overall spine biomechanics are also unknown. In this study, three different types of screw–bone connections were compared using FE simulations in this study: (1) screw and bone are not fully bonded (contact connection); (2) screw is rigidly bonded with the bone (bonded connection); and (3) simplified-geometry-rigid (SGR) connection. Screw pullout test and physiological spinal loading test were simulated for the screws in this study: (1) pullout test where the pedicle screws were inserted in polyurethane foam; and (2) physiological spinal loading test (flexion, extension, lateral bending, and axial rotation) where the screws were fused into previously-validated FE lumbar spine model. The FE spine model used in this study included L 1 –L 5 spine levels and simulated major ligaments and resultant muscle forces. This study indicated that the holding capability in the screw–bone interaction is smaller and the bone and implants are subjected to larger von Mises stress (up to 44.88%) in the contact connection than those in the bonded connection. Among the four spinal loading cases tested in this study, flexion produced the highest von Mises stress in both the bone and the implants. Considerable differences were observed between simplified and non-simplified screw FE models in the von Mises stress at screw–bone contact region within spinal loading environment and the ultimate screw pullout strength in pullout test. This study concluded that both the spinal implants and the bone are subjected to higher stress immediately after the pedicle-screw-instrumented surgery and before the screw and bone are fully bonded. The screw–bone interface is less likely to fail after the screw and bone are fully bonded. SGR screw model is able to predict screw force and rod stress that are consistent with those predicted by non-simplified screw models. [ABSTRACT FROM AUTHOR]

There has been growing interest in functional outcomes following surgical treatments for degenerative spinal pathologies (DSP). Objective functional measures provide unbiased metrics for assessing both patient's individual baseline functional deficits and postoperative recovery. Balance is a key component to assessment of spine treatment outcomes and has been objectively shown to improve postoperatively among many common DSP. There has, however, been a fundamental lack of understanding of exactly how DSP affects standing postural control and whether it is also impacted by surgical treatments. A novel technique was recently developed using a single force plate which provides direct assessment of balance control and quantifies balance strategy reliance but has yet to be applied to DSP. To provide preliminary data on balance strategy reliance among DSP using a novel force plate analysis and to compare to health (H) controls. Retrospective review at a single institution. DSP patients 122 adult spinal deformity (ASD, 85F/36M, 61yr, 1.6m, 77kg), 81 degenerative lumbar spondylolisthesis (DLS, 51F/31M, 60yr, 1.7m, 81kg), 140 lumbar spinal stenosis (LSS, 40F/100M, 54yr, 1.7m, 92kg), 106 cervical spondylotic myelopathy (CSM, 58F/48M, 62yr, 1.7m, 82kg), and 61 H (37F/24M, 40yr, 1.7m, 72kg). PROMs VAS pain, ODI/NDI; balance strategy reliance data. Subjects completed 60-second quiescent standing tests with eyes open and arms at their sides while on a force plate. Center of pressure (COP) range of sway (ROS) was used to assess baseline balance deficits. Balance strategy reliance was assessed using force intersection point (FIP) analysis which quantifies degree of balance activation by sway frequency ∼1.75Hz relates to knee and hip involvement at smaller amplitudes. FIP amplitude is reported as % height of the center of mass. PROMs indicated DSP patients had severe VAS pain (Neck (CSM) 4.8, Back >6.0, Leg >4.0) and disability (ODI/NDI >40). DSP patients all exhibited significantly elevated ROS (mean coronal=31mm, mean sagittal=45mm) compared to H (18mm and 32mm respectively). ASD had significantly lower FIP at 3.5Hz (23%, p=0.003) and 4.0Hz (17%, p=0.029) compared to H (32% and 24%). DLS had significantly lower FIP at 3.0Hz (33%, p=0.036) than H (38%). LSS had significantly lower FIP in 3.5Hz (25%, 0.018), 4.0Hz (18%, p=0.030), and 4.5Hz (14%, p=0.005) than H (32%, 24%, 22% respectively). CSM had significantly lower FIP at 2.5Hz (49%, p=0.027), 3.0Hz (33%, p=0.011), and 4.5Hz (14%, p=0.003) than H (53%, 38%, and 22% respectively). Averages in low frequency FIPs tended to be greater than H and averages in high frequency FIPs tended to be less than H. FIP provides novel insight into balance deficits among DSP patients which no method has previously quantified and negates issues associated with voluntary shifts in sway by providing simulatenous data across a range of relevant frequencies. Symptomatic DSP patients exhibited differences in balance strategy reliance compared to H with a general increase in low frequency, ankle-based reliance and a decrease in higher frequency, knee- and hip-based reliance. FIP analysis data is simple to implement clinically with a single force plate and may serve as a future screening tool for DSP screenings. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Purpose: To review our experience with robotic guided S2-alar iliac (S2AI) screw placement.Methods: We retrospectively reviewed patients who underwent S2AI fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed by fusing preoperative CT (with the planned S2AI screws) to postoperative CT. The software's measurement tool was used to compare the planned vs. actual screw placements in axial and lateral views, at entry point to the S2 pedicle and at a 30 mm depth at the screws' mid-shaft, in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications.Results: 35 S2AI screws were reviewed in 18 patients. The patients' mean age was 60 years. No intra-operative complications that related to the placement of S2AI screws were reported and robotic guidance was successful in all 35 screws. Post-operative CT scans showed that all trajectories were accurate. No violations of the iliac cortex or breaches of the anterior sacrum were noted. At the entry point, the screw deviated from the pre-operative plan by 3.0 ± 2.2 mm in the axial plane and 1.8 ± 1.6 mm in the lateral plane. At 30 mm depth, the screw deviated from the pre-operative plan by 2.1 ± 1.3 mm in the axial plane and 1.2 ± 1.1 mm in the lateral plane.Conclusions: Robotic guided S2AI screw placement is feasible and accurate. No screw malpositions or complications that related to the placement of S2AI screws occurred in this series. Larger studies are needed to assess the long-term clinical outcomes of robotic guided sacral-pelvic fixation. [ABSTRACT FROM AUTHOR]

Finite element (FE) method is a proven powerful and efficient tool to study the biomechanics of the human lumbar spine. However, due to the large inter-subject variability of geometries and material properties in human lumbar spines, concerns existed on the accuracy and predictive power of one single deterministic FE model with one set of spinal geometry and material properties. It was confirmed that the combined predictions (median or mean value) of several distinct FE models can be used as an improved prediction of behavior of human lumbar spine under identical loading and boundary conditions. In light of this improved prediction, five FE models (L1-L5 spinal levels) of the human lumbar spine were developed based on five healthy living subjects with identical modeling method. The five models were extensively validated through experimental and computational results in the literature. Mesh convergence and material sensitivity analysis were also conducted. We have shown that the results from the five FE models developed in this paper were consistent with the experimental data and simulation results from the existing literature. The validated modeling method introduced in this study can be used in modeling dysfunctional lumber spines such as disc degeneration and scoliosis in future work. [ABSTRACT FROM PUBLISHER]

Abstract: Over 700,000 osteoporotic compression fractures occur each year in the United States, twice the number of hip fractures. These vertebral fractures, most of which occur in the elderly, represent significant personal and societal burdens. Percutaneous vertebroplasty (PVP) is a minimally invasive method that involves the percutaneous injection of polymethylmethacrylate (PMMA) into a collapsed vertebral body to stabilize the vertebra. Kyphoplasty is an advanced minimally invasive technique with a number of potential advantages over PVP, including lower risk of cement extravasation and better restoration of vertebral body height and spinal biomechanics. The filling materials used for both these techniques require good biocompatibility, good biomechanical strength and stiffness, and good radiopacity for the fluoroscopy guided procedures. New filler materials (synthetic bone substitutes, e.g., composite resin materials, calcium phosphate or calcium sulfate cements) in addition to new PMMA formulations are now available for clinical use. In this review paper, we will focus on the issues and characteristics of these filler materials as they pertain to vertebral augmentation procedures. [Copyright &y& Elsevier]

Patient reported outcome measures (PROMs) benchmarked by the minimum clinically important difference (MCID) are often used to indicate patient functional status before and after surgery for degenerative lumbar pathology (DLP). Prior research has shown that not all spine PROMs directly relate to objective functional improvements in activities like walking and standing. Currently it is unclear whether achieving PROMs MCID should be considered outrightly indicative of improved functional outcomes measures (FOMs). Determine if achievement of PROMs MCID relates to significant changes in objective gait and balance FOMs among surgical DLP patients. Non-randomized, retrospective review of DLP patient pre- and postoperative PROM and FOM data. There were 99 patients treated with decompression or single-level fusion for DLP. Visual analog scales (VAS) for low-back and leg pain, Oswestry Disability Index (ODI), spatiotemporal and kinematic gait measures, and postural balance measures (range-of-sway: ROS, total-sway distance: TSD). Surgical DLP patients completed PROMs and functional evaluations one week before surgery (P0) and at three- and 12-month postoperative follow-ups (P3 and P12). Functional evaluations included walking and balance tests using three-dimensional motion tracking. FOMs showing significant P0-P3-P12 univariate improvements were compared between achieved MCID (aMCID) and not achieved MCID (nMCID) for each PROM at P0-P3 and P0-P12. All PROMs showed significant univariate improvements (P0, P3, P12 respectively): VAS low-back (4.2±3.7, 1.7±1.7, 2.5±2.9, p=0.002), VAS-leg (5.8±3, 1.4±1.9, 1.6±2.6, p<0.001), ODI (43.4±13.6, 23.9±15.8,22.9±17.1, p<0.001). Two of 14 gait FOMs showed significant univariate improvements: increased step length (0.54±0.05m, 0.56±0.04m, 0.57±0.04m, p=0.043) and reduced single-support time (0.45±0.07s,0.44±0.06s, 0.42±0.04s, p=0.040). Three of six balance FOMs showed significant univariate improvements: reduced coronal ROS (2.95±2.19cm, 1.88±0.9cm, 1.9±0.73cm, p=0.025), reduced sagittal ROS (6.58±2.58cm, 5.5±1.72cm, 5.16±1.56cm, p=0.025), and reduced TSD (71±45.4cm, 50.3±19cm, 48±14.2cm, p=0.014) for the head. MCID achievement was as follows: VAS low-back: 67%@P3, 46%@P12; VAS leg: 73%@P3, 75% @P12; ODI: 58%@P3, 72%@P12. aMCID yielded significantly greater improvements in the following FOMs (aMCID/nMCID respectively): @P3: longer step length for VAS leg (0.03±0.03m/-0.01±0.05m, p=0.021), less coronal head ROS for VAS low-back (-1.59±3.19cm/-0.09±1.67cm, p=0.016) and VAS leg (-1.54±3.07cm/0.07±1.75cm, p<0.001), less sagittal head ROS for VAS leg (-1.94±4.1cm/-0.9±3.43cm, p=0.003), and less head TSD for VAS leg (-26.17±53.17cm/-8.54±32.57cm, p=0.002); @P12: less sagittal head ROS for ODI (-1.63±4.44cm/-0.71±2.38cm, p=0.046). Although significant, relative numeric improvements were minimal for head ROS. Select statistically significant differences in FOMs were found however, numerical differences were low and widespread improvements across all FOMs were not found, even with significant univariate improvements. Achieving MCID for VAS leg pain may be related to improved step length and dynamic balance, but there is little evidence to suggest that it should be considered indicative of overall functional improvement of DLP surgery patients. PROMs and FOMs may be measuring different yet equally important aspects of DLP patient function. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Minimally invasive spine surgery reduces tissue dissection and retraction, decreasing the morbidity associated with traditional open spine surgery by decreasing blood loss, blood transfusion, complications, and pain. One of the key challenges with a minimally invasive approach is achieving consistent posterior fusion. Although advantageous in all fusion surgeries, solid posterior fusion is particularly important in spinal deformity, revisions, and fusions without anterior column support. A minimally invasive surgical approach accomplished without sacrificing the quality of the posterior fusion has the potential to decrease both short- and long-term complications compared to the traditional open techniques. Innovations in navigated and robotic-assisted spine surgery continue to address this need. In this article, we will outline the feasibility of achieving posterior facet fusion using the Mazor X Stealth Edition Robotic Guidance System. [ABSTRACT FROM AUTHOR]

Study Design: Systematic review.Objective: The aim of this review is to present an overview of robotic spine surgery (RSS) including its history, applications, limitations, and future directions.Summary Of Background Data: The first RSS platform received United States Food and Drug Administration approval in 2004. Since then, robotic-assisted placement of thoracolumbar pedicle screws has been extensively studied. More recently, expanded applications of RSS have been introduced and evaluated.Methods: A systematic search of the Cochrane, OVID-MEDLINE, and PubMed databases was performed for articles relevant to robotic spine surgery. Institutional review board approval was not needed.Results: The placement of thoracolumbar pedicle screws using RSS is safe and accurate and results in reduced radiation exposure for the surgeon and surgical team. Barriers to utilization exist including learning curve and large capital costs. Additional applications involving minimally invasive techniques, cervical pedicle screws, and deformity correction have emerged.Conclusion: Interest in RSS continues to grow as the applications advance in parallel with image guidance systems and minimally invasive techniques.Irb Approval: N/A. [ABSTRACT FROM AUTHOR]

Introduction: The ultrasonic BoneScalpel is a tissue-specific device that allows the surgeon to make precise osteotomies while protecting collateral or adjacent soft tissue structures. The device is comprised of a blunt ultrasonic blade that oscillates at over 22,500 cycles/s with an imperceptible microscopic amplitude. The recurring impacts pulverize the noncompliant crystalline structure resulting in a precise cut. The more compliant adjacent soft tissue is not affected by the ultrasonic oscillation. The purpose of this study is to report the experience and safety of using this ultrasonic osteotome device in a variety of spine surgeries. Methods: Data were retrospectively collected from medical charts and surgical reports for each surgery in which the ultrasonic scalpel was used to perform any type of osteotomy (facetectomy, laminotomy, laminectomy, en bloc resection, Smith Petersen osteotomy, pedicle subtraction osteotomy, etc.). The majority of patients had spinal stenosis, degenerative or adolescent scoliosis, pseudoarthrosis, adjacent segment degeneration, and spondylolisthesis et al. Intra-operative complications were also recorded. Results: A total of 128 consecutive patients (73 female, 55 male) beginning with our first case experience were included in this study. The mean age of the patients was 58 years (range 12–85 years). Eighty patients (62.5 %) had previous spine surgery and/or spinal deformity. The ultrasonic scalpel was used at all levels of the spine and the average levels operated on each patient were 5. The mean operation time (skin to skin) was 4.3 h and the mean blood loss was 425.4 ml. In all cases, the ultrasonic scalpel was used to create the needed osteotomies to facilitate the surgical procedure without any percussion on the spinal column or injury to the underlying nerves. There was a noticeable absence of bleeding from the cut end of the bone consistent with the ultrasonic application. There were 11 instances of dural injuries (8.6 %) and two of which were directly associated with the use of ultrasonic device. In no procedure was the use of the ultrasonic scalpel abandoned for use of another instrument due to difficulty in using the device or failure to achieve the desired osteotomy. Conclusions: Overall, the ultrasonic scalpel was safe and performed as desired when used as a bone cutting device to facilitate osteotomies in a variety of spine surgeries. However, caution should be taken to avoid potential thermal injury and dural tear. If used properly, this device may decrease the risk of soft tissue injury associated with the use of high speed burrs and oscillating saws during spine surgery. [ABSTRACT FROM AUTHOR]

Introduction: It has been shown that pedicle screw instrumentation in the cervical spine has superior biomechanical pullout strength and stability. However, due to the complex and variable anatomy of the cervical pedicles and the risk of catastrophic complications, cervical pedicle screw placement is not widely utilized. Study design: A retrospective, consecutive patient review. Objective: To review and report our experience with robotic guided cervical pedicle screw placement. Methods: We retrospectively reviewed preoperative and postoperative CT scans of 12 consecutive patients who underwent cervical pedicle screw fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed using the robotic system's planning software by fusing the preoperative CT (with the planned cervical pedicle screws) to the post-op CT. This process was carried out by manually aligning the anatomical landmarks on the two CTs. Once a satisfactory fusion was achieved, the software's measurement tool was used manually to compare the planned vs. actual screw placements in the axial, sagittal and coronal planes within the instrumented pedicle in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications. Results: Eighty-eight cervical pedicle screws were reviewed in 12 patients; mean age = 65 years, M:F = 2:1, and mean BMI = 27.99. No intra-operative complications related to the cervical pedicle screw placement were reported. Robotic guidance was successful in all 88 screws: eight in C2, 14 in C3, 16 in each of C4 and C5, 19 in C6, and 15 at C7. There were 14 pedicle screw breaches (15.9%); all were medial, less than 1 mm, and with no clinical consequences. In the axial plane, the screws deviated from the preoperative plan by 1.32 ± 1.17 mm and in the sagittal plane by 1.27 ± 1.00 mm. In the trajectory view, the overall deviation was 2.20 ± 1.17 mm. Although differences were observed in screw deviation from the pre-op plan between the right and left sides, they were not statistically significant (p > 0.05). Conclusion: This study indicates that robotic-guided cervical pedicle screw placement is feasible and safe. The medial breaches did not result in any clinical consequences. [ABSTRACT FROM AUTHOR]

Abstract: Background context: Allograft bone is commonly used in various spinal surgeries. The large amount of recalled allograft tissue, particularly in recent years, has increased concerns regarding the safety of allograft bone for spinal surgery. An analysis of allograft recall and its safety in spinal surgery has not been reported previously. Purpose: To determine 1) the number and types of allograft recall and the reasons for recall, 2) the types of disease transmission to spine patients, and 3) assess the safety of allograft bone in spinal surgery. Study design/setting: Retrospective review. Methods: A retrospective review of all Food and Drug Administration (FDA) data from 1994 to June 2007 was reviewed to determine the amount and types of recalled allograft tissue. The literature and data from the Center for Disease Control were reviewed to determine the number and types of disease transmissions from allograft bone that have occurred to spine surgery patients during the study period. Results: There were 59,476 musculoskeletal allograft tissue specimens recalled by FDA during the study period, which accounts for 96.5% of all allograft tissue recalled in the United States. Improper donor evaluation, contamination, and recipient infections are the main reasons for allograft recall. There has been one case of human immunodeficiency virus infection transmission to a spine surgery patient in 1988. This is the only reported case of viral transmission. There are no reports of bacterial disease transmission from the use of allograft bone to spine surgery patients. Conclusions: The precise number of allografts used in spine surgery annually and the precise incidence of disease transmission to spine surgery patients linked to the use of allograft tissue is unknown. Musculoskeletal allograft tissue accounts for the majority of recalled tissue by FDA. Despite the large number of allograft recalls in this country, there is only one documented case in the literature of disease transmission to a spine surgery patient. There appears to be no overt risk associated with the use of allograft bone in spine surgery. However, as discussed in this article, there are certain aspects regarding the use of allograft bone that should be considered. [Copyright &y& Elsevier]

Abstract: Background context: Allograft bone is commonly used in various spinal surgeries. The large amount of recalled allograft tissue, particularly in recent years, has increased concerns regarding the safety of allograft bone for spinal surgery. An analysis of allograft recall and its safety in spinal surgery has not been reported previously. Purpose: To determine 1) the number and types of allograft recall and the reasons for recall, 2) the types of disease transmission to spine patients, and 3) assess the safety of allograft bone in spinal surgery. Study design/setting: Retrospective review. Methods: A retrospective review of all Food and Drug Administration (FDA) data from 1994 to June 2007 was reviewed to determine the amount and types of recalled allograft tissue. The literature and data from the Center for Disease Control were reviewed to determine the number and types of disease transmissions from allograft bone that have occurred to spine surgery patients during the study period. Results: There were 59,476 musculoskeletal allograft tissue specimens recalled by FDA during the study period, which accounts for 96.5% of all allograft tissue recalled in the United States. Improper donor evaluation, contamination, and recipient infections are the main reasons for allograft recall. There has been one case of human immunodeficiency virus infection transmission to a spine surgery patient in 1988. This is the only reported case of viral transmission. There are no reports of bacterial disease transmission from the use of allograft bone to spine surgery patients. Conclusions: The precise number of allografts used in spine surgery annually and the precise incidence of disease transmission to spine surgery patients linked to the use of allograft tissue is unknown. Musculoskeletal allograft tissue accounts for the majority of recalled tissue by FDA. Despite the large number of allograft recalls in this country, there is only one documented case in the literature of disease transmission to a spine surgery patient. There appears to be no overt risk associated with the use of allograft bone in spine surgery. However, as discussed in this article, there are certain aspects regarding the use of allograft bone that should be considered. [Copyright &y& Elsevier]

Abstract: Background context: Osteoporotic compression fractures are an important public health concern, leading to significant morbidity, mortality and economic burden. Cement augmentation procedures used to treat these fractures alter the biomechanics of the fractured segment, which could promote adjacent failure. However, if alignment is improved or restored, there will be less risk of adjacent failure. Purpose: To determine the effects of load (compression/flexion), adjacent vertebral location (superior/inferior) and augmentation on vertebral segment stiffness and adjacent vertebral strain in the upper and lower thoracic spine. Study design: Human cadaveric thoracic spine segments were tested under load control before and after the creation of experimentally augmented vertebral compression fractures. Methods: Six T1–T5 and six T8–T12 segments were obtained from eight thoracic spines with known bone mineral density (BMD). Rosette strain gauges were applied to T2, T4, T9 and T11 to measure strain adjacent to the experimental fracture sites T3 and T10. Two compression fractures were created in succession, the first in flexion preceded by a weakening defect in T3 and T10 and the second created in an adjacent vertebra in compression without prior weakening. The first fracture was reduced with the inflatable bone tamp (IBT) and augmented with cement. Compression and flexion tests were performed before and after the first fracture while measuring vertebral cortical shear strain on T2, T4, T9 and T11 and stiffness of the entire segment. Strain and stiffness were compared by using a repeated measures analysis using adjacent vertebral location (superior/inferior), augmentation and load (compression/flexion) as factors. Results: The mean BMD was 0.61±0.11 g/cm2 (T1–T5) and 0.78±0.07 g/cm2 (T8–T12). Stiffness in compression and flexion increased with load (p<.05, and p>.27, respectively). Augmentation reduced compressive and bending stiffness (p=.23, and p=.19, respectively), whereas the adjacent vertebral strain increased (p>.11). The adjacent strain in flexion was much greater than in compression (p<.03). Cement augmentation caused greater amounts of inferior than superior adjacent strain (p>.19). The applied moment at first fracture was 2.98±1.28 Nm (T1–T5) and 8.44±1.02 Nm (T8–T12). The compressive load at second fracture was 1122±993 N (T1–T5) and 2906±1008 N (T8–T12). Adjacent vertebral strain during the second compression and flexion tests exceeded that during the first compression and flexion tests (p=.11). Adjacent vertebral strain at second fracture exceeded that at first fracture (p=.007) and was greater on the superior adjacent vertebra than the inferior (p=.47). Conclusion: With axial compressive loads, the addition of flexion increases fracture risk. Cement augmentation of a fractured vertebral segment reduces stiffness while increasing both the superior and inferior adjacent cortical strain. This increment in strain that is greatest on the inferior adjacent vertebra effectively redistributes loads from the superior adjacent vertebra to the inferior adjacent vertebra, sparing the superior adjacent vertebra from failure. [Copyright &y& Elsevier]

: Background contextVertebral compression fractures (VCFs) are a common clinical problem and may follow trauma or be pathological. Osteoporosis increases susceptibility to fracture by reducing bone mass and weakening bone architecture. Approximately 2.5 million osteoporotic fractures occur worldwide annually, usually involving the vertebrae, wrist and hip. In the United States 700,000 VCFs occur annually, causing significant morbidity, mortality and economic burden. An initial VCF often leads to subsequent VCFs. The strain distribution along the anterior cortex, the major load-bearing pathway in flexion, may be predictive of impending VCF. Regions of high strain distribution are likely to experience secondary fracture.: PurposeTo investigate the distribution of anterior cortical strain at, above and below an experimentally created index VCF to determine the vertebral body at risk of secondary fracture.: Study designIn vitro experimental study using cadaveric thoracic spinal segments.: MethodsSeventeen thoracic spines underwent dual-energy X-ray absorptiometry (DEXA) to assess bone mineral density and were divided into T1–T3 (Subsegment 1), T4–T6 (Subsegment 2), T7–T9 (Subsegment 3) and T10–T12 (Subsegment 4). Rectangular rosette strain gauges were applied to the anterior cortices of the vertebrae of each subsegment (vertebrae in each specimen were denoted V1-superior, V2-intermediate and V3-inferior). V1 and V3 were partially embedded into polyester resin blocks, which were used to mount the specimens in a materials testing machine. Nondestructive predefect testing was performed in compression at 125 N and 250 N, followed by flexion at 1.25 Nm and 2.5 Nm. To ensure fracture reproducibility, V2 of each specimen had a trabecular defect created to a volume of 21.3±4.4% of the V2 centrum. Postdefect nondestructive compression and flexion were then performed in a manner similar to the predefect tests, followed by destructive testing in flexion. Anterior cortical shear strain on V1, V2 and V3, applied moments and applied flexion angle were all measured and analyzed.: ResultsA VCF occurred in 55 of the 59 subsegments. Fifty-one VCF (93%) were seen in V2 and 4 VCF (7%) were seen in V1. After the creation of the trabecular defect, the shear strain on V2 increased, but a comparison of the postdefect with the predefect nondestructive tests showed no significant differences. The pre- and postdefect shear strain distribution in compression and flexion was V1strain > V3strain > V2strain. Shear strain at failure was highest on V2, and in all subsegments there were significant differences between V2 and V3 (p<.05). In all subsegments there were no significant differences between V2 and V1 (p > .05) at failure with the exception of Subsegment 1 where V2 and V1 were significantly different (p<.05). The predominant strain pattern at failure was V2strain > V1strain > V3strain (V2strain≫V3strain). Using shear strain as the codeterminant of peak moment with bending stiffness and applied angle at failure, the strain on V1 was the greatest predictor (p = .0084; R2 = 0.78). These findings suggest that the events leading to a secondary fracture probably start before the index VCF occurs and continue with loading beyond the index VCF.: ConclusionAnterior cortical strain is concentrated at the apex of a thoracic kyphotic curve. The vertebral body immediately above the index VCF has the next highest amount of strain and therefore the highest risk of secondary fracture. [Copyright &y& Elsevier]

Background: Although interbody cages are widely used, there is little histological documentation of the tissue within cages in the human spine. The purpose of this study was to describe the contents of retrieved, clinically failed, interbody cages from human patients, with special reference to the influence of graft type on the viability of bone in the cages.Methods: Seventy-eight cages that had been retrieved from forty-eight patients were analyzed. There were eight carbon-fiber cages and seventy threaded metal cages. Of the sixty-seven cages for which information about grafting was available, fifty-six had been packed with autograft only, six had local autograft mixed with demineralized bone matrix, four had allograft, and one had demineralized bone matrix only. The indications for cage retrieval included a failed fusion, malposition or migration of the cage, trauma (a compression fracture at the fusion site), low-back pain, progressive spondylosis, nerve-root impingement, and/or infection. The cages had been in situ for an average of twenty-two months. Undecalcified sections through the center of each plastic embedded cage were reviewed, and the approximate areas occupied by viable bone, necrotic bone, fibrocartilage, hyaline cartilage, fibrous tissue, and graft substitute were visually estimated. Debris particles were estimated by a semiquantitative scoring system.Results: Seventy-one of the seventy-eight cages showed evidence of vascular ingrowth and areas of histologically viable bone, representing incorporating bone graft. The average area occupied by viable bone was 44% (range, 0% to 80%). In some cages, relatively large fragments of cortical bone graft were associated with only minimal new-bone formation. Fibrocartilage occupied up to 50% of the available area in these failed cages. Some cages also contained small fibrocartilage seams connecting segments of bone in a pattern that suggested motion in vivo. In thirty-one of the seventy-eight cages, > or = 5% of the available area was occupied by hyaline cartilage, probably from vertebral end plates or facet joints.Conclusions: While this study was not designed to test the efficacy of cages or of bone graft, the prevalence of hyaline and fibrocartilage in these failed cages illustrates the importance of graft and graft-site preparation to maximize bone-graft incorporation.Level Of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: Navigation and robotic-guided systems are being used more often to facilitate efficient and accurate placement of hardware during spinal surgeries. Preoperative surgical planning is a key step in the safe use of these tools. No studies have yet investigated the predictive accuracy of surgical planning using a robotic guidance system. Methods: Data were prospectively collected from patients in whom Mazor X-Align ™ [Medtronic Inc., Minneapolis, MN., USA] robotic guidance system software was used to plan their spinal instrumentation in order to achieve the best possible correction and the plans executed intraoperatively under robotic guidance. Results: A total of 33 patients (26 females, 7 males) were included. Their mean age was 51 years (12–79), and their mean BMI was 23.90 (15.55–35.91). Their primary diagnoses were scoliosis (20), kyphosis (5), spondylolisthesis (4), adjacent segment degeneration (3), and metastatic tumor (1). Preoperatively, the patients' mean coronal Cobb Angle (CA) was 36.5 ± 14.4°, and their mean sagittal CA was 27.7 ± 20.0°. The mean planned correction coronal CA was 0.2 ± 1.2°, and the mean planned correction sagittal CA was 28.4 ± 16.7°. Postoperatively, the patients' mean coronal CA that was achieved was 5.8 ± 7.4°, and their mean sagittal CA was 31.0 ± 18.3°. The mean difference between the planned and achieved angles was 5.5 ± 7.4° for the coronal, and 9.03 ± 9.01° for the sagittal CA. For the thoracic kyphosis and lumbar lordosis, the mean difference between the planned and postoperatively measured values was 15.3 ± 10.8 and 12.8 ± 9.6, respectively. Conclusion: This study indicates that the predictive accuracy of the use of preoperative planning software and robotic guidance to facilitate the surgical plan is within 6° and 9° in the coronal and sagittal planes, respectively. [ABSTRACT FROM AUTHOR]

Background: Changes in balance are common in individuals with spinal disorders and may cause falls. Balance efficiency, is the ability of a person to maintain their center of gravity with minimal neuromuscular energy expenditure, oftentimes referred to as Cone of Economy (CoE). CoE balance is defined by two sets of measures taken from the center of mass (CoM) and head: 1) the range-of-sway (RoS) in the coronal and sagittal planes, and 2) the overall sway distance. This allows spine caregivers to assess the severity of a patient's balance, balance pattern, and dynamic posture and record the changes following surgical intervention. Maintenance of balance requires coordination between the central nervous and musculoskeletal systems.Research Question: To discern differences in balance effort values between common degenerative spinal pathologies and a healthy control group.Methods: Three-hundred and forty patients with degenerative spinal pathologies: cervical spondylotic myelopathy (CSM), adult degenerative scoliosis (ADS), sacroiliac dysfunction (SIJD), degenerative lumbar spondylolisthesis (DLS), single-level lumbar degeneration (LD), and failed back syndrome (FBS), and 40 healthy controls were recruited. A functional balance test was performed approximately one week before surgery recorded by 3D video motion capture.Results: Balance effort and compensatory mechanisms were found to be significantly greater in degenerative spinal pathologies patients compared to controls. Head and Center of Mass (CoM) overall sway ranged from 65.22 to 92.78 cm (p < 0.004) and 35.77-53.31 cm (p < 0.001), respectively in degenerative spinal pathologies patients and in comparison to controls (Head: 44.52 cm, CoM: 22.24 cm). Patients with degenerative spinal pathologies presented with greater trunk (1.61-2.98°, p < 0.038), hip (4.25-5.87°, p < 0.049), and knee (4.55-6.09°, p < 0.036) excursion when compared to controls (trunk: 0.95°, hip: 2.97°, and knee: 2.43°).Significance: The results of this study indicate that patients from a wide variety of degenerative spinal pathologies similarly exhibit markedly diminished balance (and compensatory mechanisms) as indicated by increased sway on a Romberg test and a larger Cone of Economy (CoE) as compared to healthy controls. Balance effort, as measured by overall sway, was found to be approximately double in patients with degenerative spinal pathologies compared to healthy matched controls. Clinicians can compare CoE parameters among symptomatic patients from the different cohorts using the Haddas' CoE classification system to guide their postoperative prognosis. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT Gait and balance analyses can provide an objective measure of function. Patients with adult degenerative scoliosis (ADS) demonstrate an altered gait and balance patterns. Spinopelvic parameters are commonly used by clinicians to evaluate patients with ADS. However, few studies have examined the correlation between patients' spinopelvic parametersoutcome and objective biomechanical gait and balance analyses. PURPOSE To determine the correlation between spinopelvic parameters with objective biomechanical measures of function. STUDY DESIGN/SETTING A prospective cohort study. PATIENT SAMPLE Thirty-nine patients with symptomatic ADS who have been deemed appropriate surgical candidates. OUTCOME MEASURES CVA, SVA, Cobb angle, PI-LL and T1PAalong with gait spatiotemporal parameters and COM and head sway during functional balance test. METHODS Gait and functional balance analyses were performed the week before surgery. Spatiotemporal parameters (ie gait speed, cadence, stride length, width and time etc.) were calculated during the gait evaluation. The functional balance test was similar to a Romberg's test. COM and head displacements in the sagittal and coronal planes and total sway amount along with spine and lower extremity neuromuscular activity were calculated. Furthermore, spinopelvic parameters were obtained on the same day of testing. Correlations were determined between the spinopelvic parameters and objective gait and balance analyses biomechanical data using Pearson's Product Correlation in SPSS. RESULTS The CVA was correlated with walking speed (r=0.343, p=.050), single support time (r=0.336, p=.050) during gait and external oblique (r=0.551, p=.008) muscle activity during the balance test. The SVA was correlated with horizontal COM (r=0.55, p=.004) and head (r=0.716, p=.001) sway in the coronal plane and gluteus maximus (r=0.450, p=.031) muscle activity during the balance test. The Cobb angle was correlated with COM total sway (r=-0.381, p=.050) and multifidus (r=−0.432, p=.035) muscle activity during the balance test. The PI-LL was correlated with single support time (r=0.493, p=.004) during gait and multifidus (r=0.406, p=.050) and semitendinosus (r=0.472, p=.023) muscle activity during the balance test. The T1PA was correlated with head sway in the coronal plane (r=0.403, p=.046) and external oblique (r=−0.484, p=.022) and gluteus maximus (r=0.387, p=.050) muscle activity during the balance test. CONCLUSIONS This study demonstrated a strong correlation between biomechanical parameters as measured with objective gait and balance analyses and spinopelvic parametersas measured with CVA, SVA, Cobb angle, PI-LL and T1PA. With higher values of the spinopelvic parameters, single support time, COM and head sway and neuromuscular activity were increased. Quantified gait and balance analyses can be a useful tool to evaluate patient outcomes. Objective functional performance measures can help to improve the evaluation and understanding of the biomechanical effects of spinal disorders on locomotion. [ABSTRACT FROM AUTHOR]

Accurate assessment of pain and function are crucial to the effective management of patients with spinal disorders. The most frequently-utilized measure of function is the Oswestry Disability Index (ODI), a self-report measure designed for low back pain patients, which assesses potential deficiencies in 10 different domains. The ODI has several limitations. Due to its subjective nature, ODI is inherently limited by factors such as recall error, social desirability, misinterpretation of terminology, and failure to quantify the totality of physical activity dimensions and contexts. Thus, the relationship between patients' self-reported ODI scores and their actual functional limitations is likely quite suspect. Gait analysis is an alternative objective tool that can both provide a clearer picture of the impact of pain on patients' functional ability and can allow for more accurate assessment of the effectiveness of spinal interventions. To investigate the relationship of self-reported function to objectively-measured gait pattern alterations in patients with spinal disorder. A prospective cohort study. A total of 235 spinal disorder patients (85 adult degenerative scoliosis, 66 cervical spondylotic myelopathy, 64 spondylolisthesis, and 20 sacroiliac). The main measures were ODI scores along with gait spatiotemporal parameters: cadence, walking speed, stride time, step time, opposite foot off, opposite foot contact, foot off, single support, double support, stride length, step length, and gait width. Patients completed the ODI questionnaire one week before their surgery. Each patient also performed a series of over-ground gait trials at a self-selected comfortable speed. Correlation analysis was used to determine the relationship between the self-reported function measures and the objective gait biomechanical data. The ODI overall score was not correlated with any of the spatiotemporal variables (p>0.050). Detailed analysis shows correlation between the ODI walking question score to stride length (r=-0.132, p=0.048) and gait width (r=0.133, p=0.046). For patients with spinal disorders, the ODI may not adequately reflect functional deficits due to its subjectivity. Function is objective and quantifiable, whereas pain in and of itself is subjective and unquantifiable. There was a minimal correlation between the ODI walking domain score and objective gait parameters. The multidimensional, complex, and subjective nature of pain makes it very challenging to assess both in terms of intensity and in terms of relief as a response to treatment. It is important for pain and function assessments to have scientifically valid tools in order to determine quality and intensity of pain and function, aid diagnosis, direct treatment, and evaluate effectiveness after discrete interventions. The data presented from this preoperative patient population validates that gait parameters provide an objectively accurate analysis of gait. Objective gait analysis could significantly affect surgical decision-making and allow for better understanding of the effects of spinal surgery on patients' function, and, ultimately, quality of life. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]