Adult spinal deformity correction surgery using age-adjusted alignment thresholds: clinical outcomes and mechanical complication rates. A systematic review of the literature.

PURPOSE: Adult spinal deformity (ASD) surgery gives good clinical outcomes but has a high rate of mechanical complications (MC). In 2016, Lafage described the age-adjusted alignment thresholds (AAAT) to adapt the correction in relation to patient's age proposing less aggressive corrections for the elderly population. The aim of this review was to clarify the effectiveness of AAAT to achieve good health-related quality of life (HRQoL) and their relationship with post-operative MC. MATERIALS AND METHODS: We performed a review of the literature, including articles reporting data on post-operative HRQoL and MC rates in relation to the AAAT. Data were stratified according to whether they matched the AAAT, dividing the population in undercorrected (U), matched (M) and overcorrected (O). The quality of the included studies was assessed using the GRADE and MINORS systems. RESULTS: Six articles reporting data from 1,825 patients were included. The different categories (U, M and O) had homogeneous pre-operative sagittal parameters (p > 0.05) that became statistically different after surgeries (p < 0.05). Proximal junctional kyphosis (PJK) was more frequent in the O group compared to U (p = 0.05). Post-operative HRQoL parameters were similar in the 3 groups (p > 0.05). The quality of the included studies was generally low with a high bias risk. CONCLUSION: The results extrapolated from this review are interesting, as for the same HRQoL the U group had a lower MC rate. Unfortunately, the results are inconsistent, mainly because of the low quality of the included studies and the lack of reporting of some important patient- and surgery-related factors.

Factors influencing complications after 3-columns spinal osteotomies for fixed sagittal imbalance from multiple etiologies: a multicentric cohort study about 286 cases in 273 patients.

PURPOSE: Spinal osteotomies performed to treat fixed spinal deformities are technically demanding and associated with a high complications rate. The main purpose of this study was to analyze complications and their risk factors in spinal osteotomies performed for fixed sagittal imbalance from multiple etiologies. METHODS: The study consisted of a blinded retrospective analysis of prospectively collected data from a large multicenter cohort of patients who underwent 3-columns (3C) spinal osteotomy, between January 2010 and January 2017. Clinical and radiological data were compared pre- and post-operatively. Complications and their risk factors were analyzed. RESULTS: Two hundred eighty-six 3C osteotomies were performed in 273 patients. At 1 year follow-up, both clinical (VAS pain, ODI and SRS-22 scores) and radiological (SVA, SSA, loss of lordosis and pelvic version) parameters were significantly improved (p < 0.001). A total of 164 patients (59.2%) experienced at least 1 complication (277 complications). Complications-free survival rates were only 30% at 5 years. Most of those were mechanical (35.2%), followed by general (17.6%), surgical site infection (17.2%) and neurological (10.9%). Pre-operative neurological status [RR = 2.3 (1.32-4.00)], operative time (+ 19% of risk each additional hour) and combined surgery [RR = 1.76 (1.08-2.04)] were assessed as risk factors for overall complication (p < 0.05). The use of patient-specific rods appeared to be significantly associated with less overall complications [RR = 0.5 (0.29-0.89)] (p = 0.02). CONCLUSION: Spinal 3C osteotomies were efficient to improve both clinical and radiological parameters despite high rates of complication. Efforts should be made to reduce operative time which appears to be the strongest predictive risk factor for complication.

GAP score potential in predicting post-operative spinal mechanical complications: a systematic review of the literature.

PURPOSE: In 2017, the GAP score was proposed as a tool to reduce mechanical complications (MC) in adult spinal deformity (ASD) surgery: the reported MC rate for the GAP proportioned category was only 6%, which is clearly lower to the MC rate reported in the literature. The aim of this study is to analyse if the most recent literature confirms the promising results of the original article. MATERIALS AND METHODS: Using the PRISMA flow chart, we reviewed the literature to analyse GAP score capacity in predicting MC occurrence. We included articles clearly reporting ASD surgery MC stratified by GAP categories and the score's overall capacity to predict MC using the area under the curve (AUC). The quality of the included studies was evaluated using GRADE and MINORS systems. RESULTS: Eleven retrospective articles (1,517 patients in total) were included. The MC distribution per GAP category was as follows: GAP-P, 32.8%; GAP-MD, 42.3%; GAP-SD, 55.4%. No statistically significant difference was observed between the different categories using the Kruskal-Wallis test (p = 0.08) and the two-by-two Pearson-Chi square test (P Vs MD, p = 0.300; P Vs SD, p = 0.275; MD Vs SD, p = 0.137). The global AUC was 0.68 ± 0.2 (moderate accuracy). The included studies were of poor quality according to the GRADE system and had a high risk of bias based on the MINORS criteria. CONCLUSION: The actual literature does not corroborate the excellent results reported by the original GAP score article. Further prospective studies, possibly stratified by type of MC and type of surgery, are necessary to validate this score.

Hemostats in Spine Surgery: Literature Review and Expert Panel Recommendations.

Bleeding in spine surgery is a common occurrence but when bleeding is uncontrolled the consequences can be severe due to the potential for spinal cord compression and damage to the central nervous system. There are many factors that influence bleeding during spine surgery including patient factors and those related to the type of surgery and the surgical approach to bleeding. There are a range of methods that can be employed to both reduce the risk of bleeding and achieve hemostasis, one of which is the adjunct use of hemostatic agents. Hemostatic agents are available in a variety of forms and materials and with considerable variation in cost, but specific evidence to support their use in spine surgery is sparse. A literature review was conducted to identify the pre-, peri-, and postsurgical considerations around bleeding in spine surgery. The review generated a set of recommendations that were discussed and ratified by a wider expert group of spine surgeons. The results are intended to provide a practical guide to the selection of hemostats for specific bleeding situations that may be encountered in spine surgery.

Percutaneous Transpedicular Fixation by PEEK Polymer Implants Combined with Cementoplasty for Vertebral Compression Fractures: A Pilot Study.

PURPOSE: To evaluate the feasibility and safety of percutaneous transpedicular fixation by PEEK polymer implants and cementoplasty for vertebral compression fracture (VCF). MATERIALS AND METHODS: From February 2019 to December 2019, 6 consecutive patients (3 men and 3 women; mean age 55 ± 8 years; range 40-64 years) who had percutaneous transpedicular fixation with cementoplasty for the treatment of VCF (5 tumor lesions, 1 traumatic) were included. The procedure duration, length of hospital stay, and complications were reported. Visual analog scale (VAS) and the Oswestry disability index (ODI) for pain and disability were assessed before and 2 months after the procedure. RESULTS: The mean procedure duration was 74 ± 47 min (range 20-140 min). The median length of hospital stay was 3 days (range 2-63) after the procedure. Only minor adverse events were reported (4 asymptomatic cement leakages) but no severe complications. No cases of procedural site fracture during follow-up were noted (median 198 days; range 78-238 days). The mean VAS score decreased from 6.2 ± 1.8 mm (median 6 mm; range 4-9 mm) before the procedure to 1.7 ± 2.1 mm (median 1; range 0-5 mm) after the procedure. The ODI decreased from 36 ± 14% (range 18-54%) before the procedure to 23 ± 10% (range 11-30%) at 2-months follow-up. CONCLUSIONS: Percutaneous transpedicular fixation of VCF by PEEK implants with cementoplasty appears feasible and safe.

Postoperative spino-pelvic stereoradiography to predict adjacent segment disease.

PURPOSE: The purpose of this study was to identify sagittal spinopelvic parameters predictive of adjacent segment disease (ASD) on postoperative whole spine weight-bearing stereoradiography. MATERIALS AND METHODS: A total of 84 patients with previous spinal fusion surgery and documented radiological follow-up with early weight-bearing postoperative whole spine stereoradiography (EOS® Imaging System) were retrospectively included. A pathological group of 42 patients (9 men, 33 women; mean age, 63.1±11.5 [SD] years) who developed documented ASD (mean follow-up, 76.75 months; range: 31.5-158.5 months) was compared with a control group of 42 asymptomatic patients (7 men, 35 women; mean age, 60.9±11.8 [SD] years) (mean follow-up, 115 months; range: 60-197 months) based on sagittal balance evaluation and routinely used spino-pelvic parameters. Comparisons were made using uni- and multivariate analyses. RESULTS: At univariate analysis, patients with ASD had an anteriorly displaced sagittal vertical axis (CAM plumb line) and an inadequate lumbar lordosis (LL) in reference to pelvic incidence (PI) compared to controls. They also had higher C7 slope and C2-C7 offset. At multivariate analysis, C2-C7 offset (OR=1.152; 95% CI: 1.056-1.256; P=0.001) and a lack of LL (OR=5.063; 95% CI: 1.139-22.498; P=0.033) were significantly associated with ASD. CONCLUSION: Anterior cervical imbalance, reflected by an increase in C2-C7 offset and insufficient restoration of LL are postoperative predictive factors of ASD on stereoradiography.

Revision after spinal stenosis surgery.

PURPOSE: To make a literature review on spinal stenosis recurrence after a first surgery and edit rules to avoid this complication. METHODS: We conducted two separate PUBMED searches to evaluate the revision post-stenosis and degenerative scoliosis surgery using the terms: lumbar vertebrae/surgery, spinal stenosis, spine, scoliosis and reoperation. The resulting papers were categorized into three groups: (1) those that evaluated reoperation post-simple decompression; (2) those that evaluated spinal decompression and fusion for short (3 levels or less) or long (more than 3 levels) segment spinal fusion; and (3) those diagnosing the stenosis during the surgery. RESULTS: (1) We found 11 relevant papers that only looked at revision spine surgery post-laminectomy for spinal stenosis. (2) We found 20 papers looked at reoperation post-laminectomy and fusion amongst which there were two papers specifically comparing long-segment (> 3 level) and short-segment (3 or less levels) fusions. (3) In the unspecified group, we found only one article. Fifteen articles were excluded as they were not specifically looking at our objective criteria for revision surgery. In regard to revision post-adult deformity surgery, we found 18 relevant articles. CONCLUSIONS: After this literature review and analysis of post-operative stenosis, it seems important to provide some advice to avoid revision surgeries more or less induced by the surgery. It looks interesting when performing simple decompression without fusion in the lumbar spine to analyse the risk of instability induced by the decompression and facet resection but also by a global balance analysis. Regarding pre-operative stenosis in a previously operated area, different causes may be evocated, like screw or cage malpositionning but also insufficient decompression which is a common cause. Intraoperatively, the use of neuromonitoring and intraoperative CT scan with navigation are useful tool in complex cases to avoid persisting stenosis. Pre-op analysis and planning are key parameters to decrease post-op problems. These slides can be retrieved under Electronic Supplementary Material.

Sagittal balance of the spine.

The static sagittal balance of the normal spine is a physiological alignment of the spine in the most efficient manner by the muscular forces. During gait, this balance is constantly thwarted by single-foot support. This analysis involves the study of parameters which are now well defined. The pelvic incidence is constant, and the sacral slope and the pelvic tilt are positional. The cervical parameters are the upper (O-C2) and lower cervical curvatures (C2-C7), the C7 slope, the spino-cranial angle and the vertical cervical offset. At the thoracic and lumbar level, they are, respectively, kyphosis and lordosis. The OD-HA (odontoid hip axis) angle is the most efficient parameter to analyse the global balance. The average values of these parameters are reported with the new 3D measurements by Le Huec et al. The relationship between these different parameters was analysed, and Roussouly proposed his classification of the different spine shape. Ageing makes it possible to show compensation mechanisms at three levels: spinal, pelvic and lower limbs. Understanding these different data allows for better planning of the surgical management of the patients. Global evaluation of the entire spine and the measurement of the aforementioned parameters allow to determine the extent of the correction to be performed during surgery. Taking these parameters into account also enables us to understand the complications involved in this type of surgery: transitional syndromes or junctional syndromes. Integration of these parameters into the study of gait is an area still under investigation. These slides can be retrieved under Electronic Supplementary Material .

Thoracic osteotomy for Gorham-Stout disease of the spine: a case report and literature review.

INTRODUCTION: Gorham-Stout syndrome is an aggressive, non-heritable skeletal disease characterized by osteolysis following minor trauma. The primary involvement of the spine is less common (10 %) and has been described in only about 20 cases; there is no consensus about the best way to treat this condition. PURPOSE OF THE STUDY: To report a case of Gorham-Stout syndrome involving the thoracic spine and to review the literature to suggest a post-operative treatment to prevent osteolysis. CASE REPORT: A thirty-year-old female patient was admitted to the unit in March 2013 for a pathologic T4 fracture. X-rays and CT scan revealed the onset of T4 osteolysis and an increase in thoracic kyphosis (the local kyphosis was up to 100°). We performed surgery by posterior approach, combining posterior fixation with screws and rods from T3 to T9, decompression and vertebral osteotomy of 65°. The immediate outcome of surgery was good and the patient returned home after 24 days. At 6 and 12 months of follow-up, the patient was walking normally with no neurological sequelae. CONCLUSION: We report a case of Gorham-Stout syndrome involving the thoracic spine that was successfully treated by interpedicular osteotomy associated with a 6 month follow-up. We suggest that this strategy can provide good results, because after fusion, the disease process remains stable. Because of the lack of cases reported, surgeons must be careful when using multiple treatments, because these treatments have many side effects. LEVEL OF EVIDENCE: Level IV case report.

Vaccine development to prevent Staphylococcus aureus surgical-site infections.

BACKGROUND: Staphylococcus aureus surgical-site infections (SSIs) are a major cause of poor health outcomes, including mortality, across surgical specialties. Despite current advances as a result of preventive interventions, the disease burden of S. aureus SSI remains high, and increasing antibiotic resistance continues to be a concern. Prophylactic S. aureus vaccines may represent an opportunity to prevent SSI. METHODS: A review of SSI pathophysiology was undertaken in the context of evaluating new approaches to developing a prophylactic vaccine to prevent S. aureus SSI. RESULTS: A prophylactic vaccine ideally would provide protective immunity at the time of the surgical incision to prevent initiation and progression of infection. Although the pathogenicity of S. aureus is attributed to many virulence factors, previous attempts to develop S. aureus vaccines targeted only a single virulence mechanism. The field has now moved towards multiple-antigen vaccine strategies, and promising results have been observed in early-phase clinical studies that supported the recent initiation of an efficacy trial to prevent SSI. CONCLUSION: There is an unmet medical need for novel S. aureus SSI prevention measures. Advances in understanding of S. aureus SSI pathophysiology could lead to the development of effective and safe prophylactic multiple-antigen vaccines to prevent S. aureus SSI.

Normative 3D acetabular orientation measurements by the low-dose EOS imaging system in 102 asymptomatic subjects in standing position: Analyses by side, gender, pelvic incidence and reproducibility.

BACKGROUND: Three-dimensional (3D) acetabular orientation is a fundamental topic in orthopedic surgery. Computed tomography (CT) allows 3D measurement of native acetabular orientation, but with a substantial radiation dose. The EOS imaging system was developed to perform this kind of evaluation, but has not been validated in this indication with specific attention to the acetabulum. We therefore performed a prospective study using EOS to assess: (1) the reproducibility of the 3D acetabulum orientation measures; (2) normative asymptomatic acetabular morphology in standing position, according to side and gender; and (3) the relationship between acetabular anteversion and pelvic incidence. HYPOTHESIS: The low-dose EOS imaging system is a reproducible method for measuring 3D acetabular orientation in standing position. PATIENTS AND METHODS: In a previous prospective study of spine sagittal balance, 165 asymptomatic volunteers were examined on whole-body EOS biplanar X-ray; 102 had appropriate images for pelvic and acetabular analysis, with an equal sex-ratio (53 female, 49 male). These EOS images were reviewed using sterEOS 3D software, allowing automatic measurement of acetabular parameters (anteversion and inclination) and pelvic parameters (pelvic incidence, pelvic tilt and sacral slope) in an anatomical (anterior pelvic plane: APP) and a functional reference plane (patient vertical plane: PVP). RESULTS: Both intra- and inter-observer analysis showed good agreement (ICC>0.90); Bland-Altman plot distributions were good. Acetabular anatomical anteversion and inclination relative to APP (AAAPP and AIAPP, respectively) were significantly greater in women than in men, with no effect of side (right AAA: women 21.3°±3.4° vs. men 16.1°±3.3° (P<0001); right AIAPP: women 55.3°±3.7° vs. men 52.5°±3.0° (P<0001); left AAAPP: women 20.9°±3.5° vs. men 15.6°±4.0° (P<0001); left AIAPP: women 54.6°±3.5° vs. men 52.7°±2.8° (P=0003)). The same differences between men and women were observed when measurements were related to PVP. Pelvic incidence subgroup (<44°; 44-62°; >62°) correlated significantly with functional acetabular orientation in standing position: PVP functional anteversion decreased by 5° relative to APP anteversion with incidence <44°, was equal to APP with incidence 44-62°, and or was greater by 4° relative to APP with incidence >62°. DISCUSSION: The use of a 3D sterEOS software prototype version for 3D reconstruction of the native acetabulum from standard EOS X-ray was shown to be a reliable and reproducible method. This innovative method enabled the reference values of 3D acetabular orientation in standing position to be measured for the first time. The results reinforced the concept of hip-spine relationships, and involved very low radiation dose. LEVEL OF EVIDENCE: IV prospective study without control group.

Lumbar scoliosis associated with spinal stenosis in idiopathic and degenerative cases.

UNLABELLED: Degenerative de novo scoliosis is commonly present in older adult patients. The degenerative process including disc bulging, facet arthritis, and ligamentum flavum hypertrophy contributes to the appearance of symptoms of spinal stenosis. Idiopathic scoliosis has also degenerative changes that can lead to spinal stenosis. PURPOSE: The aetiology, prevalence, biomechanics, classification, symptomatology, and treatment of idiopathic and degenerative lumbar scoliosis in association with spinal stenosis are reviewed. STUDY DESIGN: Review study is based on a review of pertinent but non-exhaustive literature of the last 20 years in PubMed in English language. METHODS: Retrospective analysis of studies focused on all parameters concerning scoliosis associated with stenosis. RESULTS: Very few publications have focused specifically on idiopathic scoliosis and stenosis, and this was before the advent of modern segmental instrumentation. On the other hand, many papers were found for degenerative scoliosis and stenosis with treatment methods based on aetiology of spinal canal stenosis and analysis of global sagittal and frontal parameters. Satisfactory clinical results after operative treatment range from 83 to 96 % but with increased percentage of complications. Recent literature analysed the importance of stabilizing or not the spine after decompression in such situation knowing the increasing risk of instability after facet resection. No prospective randomized studies were found to support short instrumentation. Long instrumentation and fusion to prevent distabilization after decompression were always associated with higher complication rates. Imbalance patients with unsatisfactory compensation capacities were at risk of complications. CONCLUSIONS: Operative treatment using newly proposed classification system of lumbar scoliosis with associated canal stenosis is useful. Sagittal balance and rotatory dislocation are the main parameters to analyse to determine the length of fusion.

Clinical and radiological outcomes of lumbar posterior subtraction osteotomies are correlated to pelvic incidence and FBI index : Prospective series of 63 cases.

PURPOSE: Pedicle subtraction osteotomy (PSO) is one of the surgical options for treating alignment disorders of the fused spine (due to post-surgical fusion or related to arthritis). It enables satisfactory sagittal realignment and improved function due to economic sagittal balance. The aim of this study was to analyze clinical and radiological results of PSO after a minimum follow-up of 2 years and demonstrate the benefit of sub-group analysis as a function of pelvic incidence (PI). METHODS: A descriptive prospective single center study of 63 patients presenting with spinal global malalignment who underwent correction by PSO. Function was assessed by the Oswestry disability index (ODI), a visual analog scale of lumbar pain (VAS) and a SF-36 questionnaire. Radiographic analyses of pre- and post-operative pelvic-spinal parameters were performed on X-rays obtained by EOS(®) imaging after 3D modeling. Global analysis and analysis of sub-groups as a function of pelvic incidence were performed and the full balance integrated index (FBI) was calculated. RESULTS: this series showed a marked clinical improvement and significant progress of functional scores. Global post-operative radiological analysis showed a significant improvement in all pelvic and spinal parameters. The mean correction obtained after PSO was 31.7° ± 8.4°, hence global improvement of lumbar lordosis of 22°. The sagittal vertical angle (SVA) decreased from +9 cm before surgery to +4.3 cm after surgery. Sub-group analysis demonstrated greater improvement in pelvic tilt, sacral slope and spinal parameters of patients with a small or moderate pelvic incidence; all had an FBI index <10°. Most of the pelvic and spinal parameters of patients with a large pelvic incidence were insufficiently corrected and they had an FBI index >10° CONCLUSION: PSO is a surgical procedure enabling correction of multiplane rigid spinal deformities that require major sagittal correction. It was seen to be highly effective in patients with a small or moderate pelvic incidence (PI <60°) but was sometimes less effective in patients with large pelvic incidence due to insufficient lordosis correction. Clinical results were highly correlated with the value of the FBI index.

Insufficient restoration of lumbar lordosis and FBI index following pedicle subtraction osteotomy is an indicator of likely mechanical complication.

PURPOSE: Pedicle subtraction osteotomies (PSO) enable correction of spinal deformities but remain difficult and are associated with high complication rates. This study aimed to prospectively review different post-operative complications and mechanical problems in patients who underwent PSO as treatment for sagittal imbalance as sequelae of degenerative disc disease or previous spinal fusion. METHOD: This was a descriptive prospective single center study of 63 patients who underwent sagittal imbalance correction by PSO. Radiographic analysis of pre- and post-operative pelvic and spinal parameters was completed based on EOS images following 3D modeling. Global and sub-group analyses were completed based on the Roussouly classification. A systematic analysis of post-operative complications was conducted during hospital stay and at follow-up visits. RESULTS: Complications included 15 cases (20.2%) of bilateral leg pain, with transient neurological deficit in 6 cases (9.5%), and 9 cases (12.5%) of early surgical site infections. Intra-operative complications included five tears of the dura mater and two cases of excessive blood loss (>5,000 mL). Two mortalities occurred from major intracerebral bleeds in the early post-operative period. Mechanical complications were principally non-union (9 cases) and junctional kyphosis (3 cases). All 19 post-operative complications (28.1%) were revised at an average of 2 years following surgery. All mechanical complications were found in the patients who had insufficient imbalance correction and this was mainly associated with high PI (>60°) or a moderate PI (45-60º) combined with excess FBI pre-operatively that remained >10° post-operatively. CONCLUSION: Infection and neurologic complications following PSO are relatively common, and frequently reported in the literature. The principal cause of mechanical complications, such as non-union or junctional kyphosis, was insufficient sagittal correction, characterized by post-operative FBI >10°. The risks of insufficient correction are greater in patients with higher pelvic incidence and those patients who required very high correction.

Sagittal balance parameters influence indications for lumbar disc arthroplasty or ALIF.

UNLABELLED: Chronic lower back pain is a potentially incapacitating condition associated with disc degeneration. Although therapy is primarily pharmaceutical, surgery comprising arthrodesis constitutes an alternative. Anterior intersomatic lumbar arthrodesis (ALIF, anterior interbody lumbar fusion) is the reference approach, although total disc arthroplasty may also be undertaken. Analysis of pelvic and spinal parameters provides the best indication of sagittal balance. MATERIALS AND METHODS: This was a prospective study in a continuous series of 99 patients presenting chronic lower back pain due to disc disease. Pelvic incidence, sacral slope, pelvic tilt, spino-sacral angle (SSA) and the four back types in the Roussouly classification were studied in radiographs of the whole spine under load using an EOS imaging system. RESULTS: The pre-operative SSA value for the study population was 126.09° ± 8.45° and the mean spine tilt angle was 90° compared with 95° in healthy subjects. Following surgery, the SSA was considerably increased in the discal arthroplasty, resulting in a significantly more balanced spinal position. In the group of patients undergoing arthrodesis using the ALIF technique, no such significant improvement was found despite the use of a lordosis cage. We showed that in cases of low pelvic incidence, it was necessary to maintain a Roussouly type 1 or 2 back without increasing lordosis. The results demonstrated the value of L4-L5 disc prostheses in these subjects. L5-S1 arthrodesis seemed a more suitable approach for treating patients with elevated sacral slope (back type 3 or 4). This new type of analysis of sagittal parameters should be performed prior to all surgical procedures involving lumbar prostheses.

Correlation of clinical outcome and spinopelvic sagittal alignment after surgical treatment of low-grade isthmic spondylolisthesis.

INTRODUCTION: The aim of this prospective study was to assess the sagittal alignment of the spine and pelvis before and after surgical treatment of isthmic spondylolisthesis with flat sacrum. At the same time, the functional outcome was analyzed and correlation examined. MATERIALS AND METHODS: This study comprises analysis of 30 subjects (mean age 43 years) with isthmic spondylolisthesis and an average follow-up of 2.5 years after posterior spinal fusion. Radiological spinopelvic parameters were measured and functional evaluation was made using the Oswestry Disability Index. RESULTS: Significant improvement toward more normal values for PT and SS in relation to PI was observed after surgery. Pelvic incidence was unaffected by surgery. Correction of the spinosacral angle shows that the anterior tilt with anterior sagittal imbalance due to spondylolisthesis may be corrected by reduction and fusion of the slipped level. Functional outcome was satisfactory with a statistically significant difference between preoperative values and final follow-up values. The sub-group of patients with insufficient restoration of sagittal balance parameters had less good outcomes than the others. DISCUSSION AND CONCLUSION: Surgical management of low- and mid-grade isthmic spondylolisthesis showed good clinical outcome with restoration of correct values for the pelvic position-dependent parameters, i.e., pelvis tilt, sacral slope, C7 plumb line position and SSA.

Sagittal imbalance cascade for simple degenerative spine and consequences: algorithm of decision for appropriate treatment.

INTRODUCTION: The main objective of all the sagittal compensating mechanisms is to allow a subject to stand and keep an erect position. MATERIALS AND METHODS: The cascade of compensating mechanisms appears progressively with the increasing amount of imbalance of the spine until compensation is no longer possible. The loss of lumbar lordosis can be considered as the initiating event of sagittal imbalance. This loss of the normal lordosis pushes the C7 plumb line forward. RESULTS: The assessment of sagittal balance has to include to be complete: a parameter measuring the global balance of the trunk, either C7 plumb line and sacral plateau, the position of the pelvis rotation by the pelvic tilt, and a description of the position of the lower limbs. Those three parameters have been taken into account by the newly described method called full balance integrated (FBI). This evaluation is easily done on a sagittal full spine standing X-ray from C2 to the pelvis, including the first 10 cm of the femur. CONCLUSION: Three questions to answer: What is the value of the pelvis incidence? Is the patient balanced? Are there compensatory mechanisms?

Electrical conductivity measurement: a new technique to detect iatrogenic initial pedicle perforation.

Pedicle screw fixation has achieved significant popularity amongst spinal surgeons for both single and multi-level spinal fusion. Misplacement and pedicle cortical violation occurs in over 20% of screw placement and can result in potential complications such as dysthesia, paraparesis or paraplegia. There have been many advances in techniques available for navigating through the pedicle; however, these techniques are not without drawbacks. A new electrical conductivity-measuring device, previously evaluated on the porcine model to detect the pedicle violation, was evaluated amongst nine European Hospitals to be used in conjunction with the methods currently used in that centre. This new device is based on two original principles; the device is integrated in the drilling or screwing tool. The technology allows real-time detection of perforation through two independent parameters, impedance variation and evoked muscle contractions. Data was collected twofold. Initially, the surgeon was given the device and a comparison was made between the devices ability to detect a breech and the surgeon's ability to detect one using his traditional methods of pedicle preparation. In the second module of the study, the surgeon was limited to using the electrical conductivity detection device as their sole guide to detect pedicle breaches. A comparison was made between the detection ability of the device and the other detection possibilities. Post-operative fine cut CT scanning was used to detect the pedicle breaches. Overall, the 11 trial surgeons performed a total of 521 pedicle drillings on 97 patients. Initially there were 147 drillings with 23 breaches detected. The detection rate of these breaches were 22/23 for the device compared to 10/23 by the surgeon. Over both parts of the study 64 breaches (12.3%) were confirmed on post-operative CT imaging. The electrical conductivity detection device detected 63 of the 64 breaches (98.4%). There was one false negative and four false positives. This gives the device an overall sensitivity of 98% and specificity of 99% for detecting a pedicle breach. The negative predictive value was 99.8%, with a positive predictive value of 94%. No adverse event was noted with the use of the electrical conductivity device. Electrical conductivity monitoring may provide a simple, safe and sensitive method of detecting pedicle breech during routine perforation of the pedicle, in the course of pedicle screw placement.