How is spinal range of motion affected by disc- and facet degeneration and spinopelvic anatomy

Background: We aimed to investigate how disc- and facet joint degeneration relate to ROM and spinopelvic alignment parameters. Their interrelation, however, is not yet understood, although eminent in patient specific modeling approaches and surgical decision making. Further is not yet sufficiently understood whether spinal alignment parameters relate to the degenerative states. Methods: The ROM of lumbar spinal segments was quantified using flexion/extension radiographs of 90 patients. The grades of degeneration of discs (IDD, Pfirrmann grades, n=440) and facet joints (FJD, Weishaupt classification, n=406) were assessed in CT and MRI scans. Results: The grade of IDD was significantly related to changes in ROM (p<0.01) whereas no association was observed with the amount of FJD. Grade V IDD was associated with a significant decrease in motion (p<0.01) compared to all other IDD grades (II-IV), which did not differ significantly among each other. The combined occurrence of IDD and FJD revealed the largest angular segmental ROM in segments with the lowest IDD (II) and lowest FJD (0). The lowermost ROM was present in fused segments (control), followed by those with severe IDD (V). In combination with FJD, the destabilizing effect of initial IDD was only observed if FJD was already in an advanced state. Conclusions: While the degree of facet joint degeneration seems not significantly associated with limitations in spinal motion, severe lumbar disc degeneration limits segmental motion, nearly equal to spinal fusion. This should affect counseling patients undergoing spinal fusion with questions on the probability of adjacent segment degeneration compared to the natural course. Keywords: Degenerative Disease; Facet Joint Degeneration; Facet Joint Osteoarthritis; Intervertebral Disc Degeneration; Kinematics; Sagittal Alignment

Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy

PURPOSE: High tibial osteotomy (HTO) is an effective treatment option in early osteoarthritis. However, preoperative planning and surgical execution can be challenging. Computer assisted three-dimensional (3D) planning and patient-specific instruments (PSI) might be helpful tools in achieving successful outcomes. Goal of this study was to assess the accuracy of HTO using PSI. METHODS: All medial open wedge PSI-HTO between 2014 and 2016 were reviewed. Using pre- and postoperative radiographs, hip-knee-ankle angle (HKA) and posterior tibial slope (PTS) were determined two-dimensionally (2D) to calculate 2D accuracy. Using postoperative CT-data, 3D surface models of the tibias were reconstructed and superimposed with the planning to calculate 3D accuracy. RESULTS: Twenty-three patients could be included. A mean correction of HKA of 9.7° ± 2.6° was planned. Postoperative assessment of HKA correction showed a mean correction of 8.9° ± 3.2°, resulting in a 2D accuracy for HKA correction of 0.8° ± 1.5°. The postoperative PTS changed by 1.7° ± 2.2°. 3D accuracy showed average 3D rotational differences of - 0.1° ± 2.3° in coronal plane, - 0.2° ± 2.3° in transversal plane, and 1.3° ± 2.1° in sagittal plane, whereby 3D translational differences were calculated as 0.1 mm ± 1.3 mm in coronal plane, - 0.1 ± 0.6 mm in transversal plane, and - 0.1 ± 0.6 mm in sagittal plane. CONCLUSION: The use of PSI in HTO results in accurate correction of mechanical leg axis. In contrast to the known problem of unintended PTS changes in conventional HTO, just slight changes of PTS could be observed using PSI. The use of PSI in HTO might be preferable to obtain desired correction of HKA and to maintain PTS

Risk factors for perioperative morbidity in spine surgeries of different complexities: a multivariate analysis of 1009 consecutive patients

BACKGROUND CONTEXT There is a broad spectrum of complications during or after surgical procedures, with differing incidences reported in the published literature. Heterogeneity can be explained by the lack of an established evidence-based classification system for documentation and classification of complications in a standardized manner. PURPOSE To identify predictive risk factors for peri- and early post-operative morbidities in spine surgeries of different complexities in a large cohort of consecutive patients. STUDY DESIGN Retrospective case series. OUTCOME MEASURES Occurrence of peri- and early post-operative morbidities. METHODS A classification of surgical complexity (grade I-III) was created and applied to 1009 patients who consecutively underwent spine surgery at a single university hospital. The incidence and type of peri- and early post-operative morbidities were documented. Multivariate binary logistic regression analyzed risk factors for (a) hospital stay≥10 days, (b) intermediate care unit (IMC) stay≥24 hours, (c) blood loss>500mL, and occurrence of a (d) surgical or (e) medical morbidity. RESULTS A deviation from the regular postoperative course (defined as "morbidity") included surgical reasons such as relapse of symptoms of any kind (3.3%), wound healing problems (2.4%), implant-associated complications (1.6%), post-operative neurological deficits (1.5%), infection (1.5%), fracture (0.8%), and dural tear in need of revision (0.6%). Medical reasons included anemia (1.8%), symptomatic electrolyte derailment (1.0%), and cardiac complications (0.7%), among others. An independent risk factor associated with a surgical reason for an irregular post-operative course was male gender. For a medical reason high creatinine levels preoperatively, higher blood loss, and systemic steroid use were identified as risk factors. Independent risk factors for a prolonged hospitalization were preoperatively high CRP, prolonged postoperative IMC stay, and revision surgery. Spinal stabilization/fusion surgery, particularly if involving the lumbosacral spine, age, and length of surgery were associated with a blood loss>500mL. Higher surgical complexity, involvement of the pelvis in instrumentation, ASA class≥3, and higher creatinine levels preoperatively were associated with a postoperative IMC stay>24 hours. CONCLUSION The present study confirms several modifiable and non-modifiable risk factors for peri- and early post-operative morbidities in spine surgery, among which surgical factors (complexity, revision surgery, instrumentation (including the pelvis etc.)) play a crucial role. A classification of surgical complexity is proposed and validated

Merits of different anatomical landmarks for correct numbering of the lumbar vertebrae in lumbosacral transitional anomalies

PURPOSE: Anatomical landmarks and their relation to the lumbar vertebrae are well described in subjects with normal spine anatomy, but not for subjects with lumbosacral transitional vertebra (LSTV), in whom correct numbering of the vertebrae is challenging and can lead to wrong-level treatment. The aim of this study was to quantify the value of different anatomical landmarks for correct identification of the lumbar vertebra level in subjects with LSTV. METHODS: After IRB approval, 71 subjects (57 ± 17 years) with and 62 without LSTV (57 ± 17 years), all with imaging studies that allowed correct numbering of the lumbar vertebrae by counting down from C2 (n = 118) or T1 (n = 15) were included. Commonly used anatomical landmarks (ribs, aortic bifurcation (AB), right renal artery (RRA) and iliac crest height) were documented to determine the ability to correctly number the lumbar vertebrae. Further, a tangent to the top of the iliac crests was drawn on coronal MRI images by two blinded, independent readers and named the 'iliac crest tangent sign'. The sensitivity, specificity and the interreader agreement were calculated. RESULTS: While the level of the AB and the RRA were found to be unreliable in correct numbering of the lumbar vertebrae in LSTV subjects, the iliac crest tangent sign had a sensitivity and specificity of 81 % and 64-88 %, respectively, with an interreader agreement of k = 0.75. CONCLUSION: While anatomical landmarks are not always reliable, the 'iliac crest tangent sign' can be used without advanced knowledge in MRI to most accurately number the vertebrae in subjects with LSTV, if only a lumbar spine MRI is available

A reliable measurement for identifying a lumbosacral transitional vertebra with a solid bony bridge on a single-slice midsagittal MRI or plain lateral radiograph

The purpose of this study was to devise a simple but reliable radiological method of identifying a lumbosacral transitional vertebra (LSTV) with a solid bony bridge on sagittal MRI, which could then be applied to a lateral radiograph. The vertical mid-vertebral angle (VMVA) and the vertical anterior vertebral angle (VAVA) of the three most caudal segments of the lumbar spine were measured on MRI and/or on a lateral radiograph in 92 patients with a LSTV and 94 controls, and the differences per segment (Diff-VMVA and Diff-VAVA) were calculated. The Diff-VMVA of the two most caudal vertebrae was significantly higher in the control group (25° (sd 8) than in patients with a LSTV (type 2a+b: 16° (sd 9), type 3a+b: -9° (sd 10), type 4: -5° (sd 7); p < 0.001). A Diff-VMVA of ≤ +10° identified a LSTV with a solid bony bridge (type 3+4) with a sensitivity of 100% and a specificity of 89% on MRI and a sensitivity of 94% and a specificity of 74% on a lateral radiograph. A sensitivity of 100% could be achieved with a cut-off value of 28° for the Diff-VAVA, but with a lower specificity (76%) on MRI than with Diff-VMVA. Using this simple method (Diff-VMVA ≤ +10°), solid bony bridging of the posterior elements of a LSTV, and therefore the first adjacent mobile segment, can be easily identified without the need for additional imaging

Associations between lumbosacral transitional anatomy types and degeneration at the transitional and adjacent segments

BACKGROUND: The relation between specific types of lumbosacral transitional vertebra and the degree of degeneration at and adjacent to the transitional level is unclear. It is further unknown whether the adjacent cephalad segment to a transitional vertebra is prone to greater degeneration than a normal L5/S1 level. PURPOSE: To evaluate the relation between specific lumbosacral transitional vertebra subtypes according to the Castellvi classification and the severity of degeneration at the transitional level and the adjacent cephalad segment. STUDY DESIGN: Retrospective review. PATIENT SAMPLE: 92 subjects with lumbosacral transitional vertebra grade 2 or higher and 94 controls without were retrieved from a PACS search. OUTCOME MEASURES: Disc degeneration parameters at the transitional and at the adjacent cephalad level. METHODS: After IRB approval, 92 (42 male; mean age 57±16 years) subjects with lumbosacral transitional vertebra grade 2 or higher and 94 (41 male; 51±16 years) controls without were retrieved from a PACS search. Degeneration of the last two segments of the lumbar spine was quantified using the Pfirrmann, and Modic classifications, along with documentation of annular tears, disc herniations and disc heights, and compared between the two groups. Further, L5/S1 levels of the controls were compared to the adjacent cephalad segments of the transitional vertebrae for the same parameters. RESULTS: While the controls at L5/S1 had moderate to severe degeneration by Pfirrmann grades (31%) and Modic changes (MC: 20%), compared, the discs at the transitional level of the lumbosacral transitional vertebra group demonstrated significant less degeneration (3% and 1%,each p<0.05). The adjacent cephalad segments of the lumbosacral transitional vertebra group showed significantly greater degeneration (Pfirrmann grade 5: 39%; MC: 30%) compared to the L4/5 level in controls (16%; 11%; each p<0.05). The severity of disc degeneration using all parameters correlated with the type of lumbosacral transitional vertebra. The degree of degeneration of L5/S1 in controls was similar to the adjacent cephalad segment in lumbosacral transitional vertebrae. CONCLUSION: Increasing mechanical connection of a lumbosacral transitional vertebra protects the disc at the transitional level and predisposes the adjacent cephalad segment to greater degeneration. The adjacent cephalad segment had comparable degree of degeneration as the L5/S1 level of controls

Pull-out strength of patient-specific template-guided vs. free-hand fluoroscopically controlled thoracolumbar pedicle screws: a biomechanical analysis of a randomized cadaveric study

PURPOSE To assess the pull-out strength of thoracolumbar pedicle screws implanted via either a patient-specific template-guided or conventional free-hand fluoroscopically controlled technique in a randomized cadaveric study, and to evaluate the influence of local vertebral bone density, quantified by Hounsfield units (HU), on pedicle screw pull-out strength. METHODS Thoracolumbar pedicles of three spine cadavers were instrumented using either a free-hand fluoroscopically controlled or a patient-specific template-guided technique. Preoperative bone density was quantified by HU measured on CT. Pedicle perforation was evaluated on postoperative CT scans by an independent and blinded radiologist. After dissected vertebrae were embedded in aluminum fixation devices, pull-out testing was initiated with a preload of 50 N and a constant displacement rate of 0.5 mm/s. Subgroup analyses were performed excluding pedicle screws with a pedicle breach (n = 47). RESULTS Pull-out strength was significantly different with 549 ± 278 and 441 ± 289 N in the template-guided (n = 50) versus fluoroscopically controlled (n = 48) subgroups (p = 0.031), respectively. Subgroup analysis limited to screws with an intrapedicular trajectory revealed a tendency toward a higher pull-out strength in the template-guided (n = 30) versus fluoroscopically controlled screws (n = 21) with 587 ± 309 and 454 ± 269 N (p = 0.118), respectively. There was a trend toward a higher pull-out strength (709 ± 418 versus 420 ± 149 N) in vertebrae with a bone density of (>171 HU) versus (<133 HU), respectively (p = 0.061). CONCLUSIONS There was a significantly higher pull-out strength of thoracolumbar pedicle screws when inserted via a patient-specific template-guided versus conventional free-hand fluoroscopically controlled technique, potentially associated with screw trajectory