Resource Consumption and Remuneration Aspects in Navigated Screw Fixation Procedures with or without Additional Sacroplasty for Fragility Fractures of the Sacrum-A Prospective Clinical Study.

Surgical treatment for sacral fragility fractures using navigation-assisted screw fixation (NSF) is a modern, technically demanding procedure. Additional sacroplasty (ASP) has been shown to provide only insignificant clinical benefits for patients. This investigation highlights procedural economic aspects and evaluates results with regard to resource scarcity in order to be able to decide, whether ASP has a justification in NSF procedures beyond clinical aspects. From February 2011 to May 2017, all individuals with sacral fragility fractures surgically treated using 3D-fluoroscopy for NSF (n = 26) or NSF + ASP (n = 26) were enrolled. Outcome parameters were operative time, 3D-/2D-radiation dose, 2D-fluoroscopy time, material costs and reimbursement. In the two groups, a total of 52 individuals with 124 fragility fracture sites in sacral vertebrae I and II were surgically treated with similar numbers of screws inserted (p ≈ 0.679) requiring similar 3D- (p ≈ 0.546) and 2D-fluoroscopy radiation doses (p ≈ 0.236). In procedures with ASP, average 2D-fluoroscopy time (46.6 s vs. 32.7 s, p ≈ 0.004), and mean surgical duration (119 min vs. 96 min, p ≈ 0.011) were significantly longer. Mean implant costs (EUR 668.68 vs. EUR 204.34, p < 0.001), and reimbursement (EUR 8416.01 vs. EUR 6584.49, p ≈ 0.006) were significantly higher. Although comparison of costs and reimbursements indicated a positive financial balance, profitability was not confirmed, because financial expense for extended operative time prevented an economic advantage of procedures with ASP in this investigation. A formula was developed based on presented study data to allow similar economical decisions in other health care systems or institutions with differing resource costs.

Navigated Transsacral Screw Fixation for the Treatment of Bilateral Sacral Insufficiency Fractures.

Nondisplaced and minimally displaced sacral insufficiency fractures are increasingly being recognized as a cause of immobilizing low back pain in the elderly. These insufficiency fractures are most accurately diagnosed by visualizing sacral bone marrow edema on magnetic resonance imaging, which is the radiologic imaging modality with the highest sensitivity for identifying these fractures. Successful treatment options range from nonsurgical (eg, bed rest, pain medication, mobilization, antiosteoporotic medication, low-intensity-pulsed ultrasound, etc.) to surgical management (ie, sacroplasty and/or osteosynthesis with iliosacral screws or lumbosacral hinge fixation with or without application of reinforcing bone cement). The appropriate surgical treatment for frail subjects requires a less-invasive technique that establishes full weight-bearing stability for successful early remobilization of affected elderly and multimorbid individuals. Iliosacral screw osteosynthesis with a single C-arm is a common surgical technique for stabilizing the posterior pelvic ring after traumatic instabilities or fractures of the sacrum. Bilateral injuries are generally addressed from both sides of the pelvis. This article describes the surgical technique of 3D image-guided transsacral screw fixation for unilateral and bilateral nondisplaced sacral insufficiency fractures in the elderly using a single-sided approach, and specifies the associated preoperative and postoperative management. The procedure is illustrated in an instructional video that demonstrates step-by-step, how the navigated surgical procedure is performed.

Gender-Associated Differences in Sacral Morphology Do Not Affect Feasibility Rates of Transsacral Screw Insertion. Radioanatomic Investigation Based on Pelvic Cross-sectional Imaging of 200 Individuals.

STUDY DESIGN: Retrospective radioanatomic single-center cohort study. OBJECTIVE: To investigate sex-specific differences in transsacral corridor dimensions, determine feasibility rates of transsacral screw placement without extended safety zones around planned screw positions, and develop an index defining sacral dysmorphism (SD) irrespective of transsacral corridor diameters. SUMMARY OF BACKGROUND DATA: Previously reported SD definitions used radiologically identifiable pelvic characteristics or predefined minimum diameter thresholds of transsacral corridors in the upper sacral segment including safety zones for screw placement. Technical progress of surgical 3D image guidance improved sacral screw insertion accuracy questioning established minimum diameter threshold-based SD definitions. METHODS: Datasets from cross-sectional pelvic imaging of 100 women and 100 men presenting to a general hospital from July 2018 through August 2018 were included in a database to evaluate transsacral trajectory rates, and dimensions of transsacral corridor lengths, widths (TSCWs), and heights (TSCHs) in sacral segments I to III (S1-3). SD was assumed, if no transsacral trajectory was found in S1 with a corridor diameter of at least 7.5 mm. RESULTS: Women presented significantly higher rates of transsacral trajectories in the inferior sector of S1 (P = 0.03), and larger transsacral corridor lengths in S2 (superior sector, P = 0.045), and S3 (central position, P = 0.02). In men, significantly higher feasibility rates were found for the placement of two transsacral screws in S2 (P = 0.0002), and singular screws in S3 (P = 0.006), with larger S1- (P = 0.0002), and central S2-TSCWs (P = 0.006). SD was prevalent in 17% of women, and 16% of men (P = 0.85). Calculating TSCW ratios of S1 and S2 was significantly indicative for SD at values below a threshold of 0.8 in women (P < 0.00001), and men (P = 0.0004). CONCLUSION: SD is independent of sex despite significant differences in sacral morphology. An index defining SD irrespective of absolute transsacral corridor dimensions is presented to reliably differentiate dysmorphic from nondysmorphic sacra in women and men. LEVEL OF EVIDENCE: 2.

3D image-guided surgery for fragility fractures of the sacrum.

OBJECTIVE: Stabilizing sacral fragility fractures without radiation exposure to the surgical team. INDICATIONS: Non-displaced or minimally displaced unilateral or bilateral transalar, transforaminal or central sacral fractures in weak and osteoporotic bone. CONTRAINDICATIONS: Displaced or highly unstable sacral fractures. Patients under therapeutic anticoagulation. Patients needing fast track orthopedic surgery. SURGICAL TECHNIQUE: Prone position. Reference clamp installation on posterior iliac crest. Initial 3D scan of posterior pelvic ring. Image-guided virtual determination of 2-3 interforaminal iliosacroiliac trajectories in sacral vertebrae I and II. Lateral transgluteal mini-open approach. 3D image-guided insertion of 2-3 guide wires along planned trajectories. 3D-scan for controlling guide wire positions. Virtual determination of screw lengths. Cortical drilling and cannulated screw insertion along guide wires. Radiological documentation. FOLLOW-UP: Clinical and radiological follow-up after 12 weeks, 12 and 24 months including radiographs in anteroposterior, lateral, inlet and outlet views. RESULTS: From October 2011 until October 2016 a total of 124 sacral fracture sites (in sacral vertebrae I and II) were treated with 120 navigated sacral screws in 52 patients (48 females, 4 males; mean age 76 ± 10 years, range 36-90 years) using 3D image guidance for screw placement. Image-guidance accuracy was 99.2% (119/120 screws correctly placed). Complications comprised revision surgery for subfascial hematoma evacuation (n = 1) and screw removal due to loosening after 12 weeks (n = 2). Four patients died before final follow-up. Mean pain visual analogue scale (VAS) decreased from 8.9 ± 1.1 (presurgery value) over 3.6 ± 1.7 (postsurgery value) to 1.8 ± 1.9 (2-year follow-up value), mean Oswestry disability index (ODI) improved from 86.2 ± 4.9% (presurgery value) over 28.5 ± 9.5% (postsurgery value) to 23.3 ± 13.7% (2-year follow-up value).

Additional Sacroplasty Does Not Improve Clinical Outcome in Minimally Invasive Navigation-Assisted Screw Fixation Procedures for Nondisplaced Insufficiency Fractures of the Sacrum.

STUDY DESIGN: Prospective single-center cohort study (noninferiority study). OBJECTIVE: To compare clinical results of navigation-assisted screw fixation (NSF) to those of NSF with additional sacroplasty (NSF + SP) for immobilizing nondisplaced insufficiency fractures of the sacrum. SUMMARY OF BACKGROUND DATA: NSF for sacral insufficiency fractures is a new, technically demanding procedure requiring surgical skills and experience. Up to date, controversies exist about the benefit of additional sacroplasty in surgically stabilized insufficiency fractures of the sacrum. METHODS: From February 2011 to May 2017, all individuals with immobilizing nondisplaced sacral insufficiency fractures surgically treated using 3D-fluoroscopy for 3D-real-time navigation and postinstrumentation screw control in the form of NSF (I) or NSF + SP (II) were enrolled. SP was performed only in absence of transforaminal or central fractures. Outcome parameters were postsurgical pain relief determined by visual analog scale, postsurgical improvement of disability evaluated using the Oswestry Disability Index, and length of postsurgical hospital stay. RESULTS: In 2 groups of 26 individuals, each, a total of 124 insufficiency fractures of sacral vertebrae were surgically treated. Postoperative pain-level decrease was comparable in both groups (5.3 vs. 5.4 visual analog scale points). Extent of postoperative disability score improvement (53.4 vs. 57.7 Oswestry Disability Index points) led to successful remobilization after similar durations of postsurgical hospital stay (9.3 vs. 9.6 days). Minimum clinically important differences of outcome parameters were not reached in the comparison of study group results. In procedures with SP, no major complications occurred, in those without SP, no specific complications were observed. CONCLUSION: This comparative study indicates noninferiority of NSF compared to NSF + SP for sacral insufficiency fractures, and could not confirm clinical advantages of additional SP concerning pain relief, improvement of fracture-related disability, or time from surgery to discharge. Therefore, additional sacroplasty is not recommended to enhance the clinical benefit for patients receiving image-guided sacral screw fixation. LEVEL OF EVIDENCE: 2.

Learning curve analysis of 3D-fluoroscopy image-guided pedicle screw insertions in lumbar single-level fusion procedures.

INTRODUCTION: The implementation of 3D-navigation in the operating theater is reported to be complex, time consuming, and radiation intense. This prospective single-center cohort study was performed to objectify these assumptions by determining navigation-related learning curves in lumbar single-level posterior fusion procedures using 3D-fluoroscopy for real-time image-guided pedicle screw (PS) insertions. MATERIALS AND METHODS: From August 2011 through July 2016, a total of 320 navigated PSs were inserted during 80 lumbar single-level posterior fusion procedures by a single surgeon without any prior experience in image-guided surgery. PS misplacements, navigation-related pre- and intraoperative time demand, and procedural 3D-radiation dose (dose-length-product, DLP) were prospectively recorded and congregated in 16 subgroups of five consecutive procedures to evaluate improving PS insertion accuracy, decreasing navigation-related time demand, and reduction of 3D-radiation dose. RESULTS: After PS insertion and intraoperative O-arm control scanning, 11 PS modifications were performed sporadically without showing "learning curve dependencies" (PS insertion accuracies in subgroups 96.6 ± 6.3%). Average navigation-related pre-surgical time from patient positioning on the operating table to skin incision decreased from 61 ± 6 min (subgroup 1) to 28 ± 2 min (subgroup 16, p < 0.00001). Average 3D-radiation dose per surgery declined from 919 ± 225 mGycm (subgroup 1) to 66 ± 4 mGycm (subgroup 16, p < 0.0001). CONCLUSIONS: In newly inaugurated O-arm based image-guidance, lumbar PS insertions can be performed at constantly high accuracy, even without prior experience in navigated techniques. Navigation-related time demand decreases considerably due to accelerating workflow preceding skin incision. Procedural 3D-radiation dose is reducible to a fraction (13.2%) of a lumbar diagnostic non-contrast-enhanced computed tomography scan's radiation dose.

Time Demand and Radiation Dose in 3D-Fluoroscopy-based Navigation-assisted 3D-Fluoroscopy-controlled Pedicle Screw Instrumentations.

STUDY DESIGN: Prospective single-center cohort study to record additional time requirements and radiation dose in navigation-assisted O-arm-controlled pedicle screw (PS) instrumentations. OBJECTIVE: The aim of this study was to evaluate amount of extra-time and radiation dose for navigation-assisted PS instrumentations of the thoracolumbosacral spine using O-arm 3D-real-time-navigation (O3DN) compared to non-navigated spinal procedures (NNSPs) with a single C-arm and postoperative computed tomography (CT) scan for controlling PS positions. SUMMARY OF BACKGROUND DATA: 3D-navigation is reported to enhance PS insertion accuracy. But time-consuming navigational steps and considerable additional radiation doses seem to limit this modern technique's attraction. A detailed analysis of additional time demand and extra-radiation dose in 3D-navigated spine surgery is not provided in literature, yet. METHODS: From February 2011 through July 2015, 306 consecutive posterior instrumentations were performed in vertebral levels T10-S1 using O3DN for PS insertion. The duration of procedure-specific navigational steps of the overall collective (I) and the last cohort of 50 consecutive O3DN-surgeries (II) was compared to the average duration of analogous surgical steps in 100 consecutive NNSP using a single C-arm. 3D-radiation dose (dose-length-product, DLP) of navigational and postinstrumentation O-arm scans in group I and II was compared to the average DLP of 100 diagnostic lumbar CT scans. RESULTS: The average presurgical time from patient positioning on the operating table to skin incision was 46.2 ±â€Š10.1 minutes (O3DN, I) and 40.6 ±â€Š9.8 minutes (O3DN, II) versus 30.6 ±â€Š8.3 minutes (NNSP) (P < 0.001, each). Intraoperative interruptions for scanning and data processing took 3.0 ±â€Š0.6 minutes. DLPs averaged 865.1 ±â€Š360.8 mGycm (O3DN, I) and 562.1 ±â€Š352.6 mGycm (O3DN, II) compared to 575.5 ±â€Š316.5 mGycm in diagnostic lumbar CT scans (P < 0.001 (I), P ≈ 0.81 [II]). CONCLUSION: After procedural experience, navigated surgeries can be performed with an additional time demand of 13.0 minutes compared to NNSP, and with a total DLP below that of a diagnostic lumbar CT scan (P ≈ 0.81). LEVEL OF EVIDENCE: 4.

Rate and mode of screw misplacements after 3D-fluoroscopy navigation-assisted insertion and 3D-imaging control of 1547 pedicle screws in spinal levels T10-S1 related to vertebrae and spinal sections.

PURPOSE: In the field of spinal surgery, 3D-fluoroscopy navigation-assisted pedicle screw (PS) insertion with intra-operative 3D-image control represents a modern application of contemporary navigation technology. In literature, sectional or vertebral accuracy limitations of this image-guidance approach are not profoundly specified. This observational study explicitly differentiates accuracy rates and misplacement mode between spinal sections and single vertebrae from T10 to S1 using a navigation-assisted approach. METHODS: From February 2011 through July 2015, all 3D-fluoroscopy navigation-assisted, 3D-image controlled PS insertions from T10 to S1 were prospectively recorded and evaluated for PS insertion depth, angulation, and entering-point modifications after intraoperative O-arm control scanning. Major complications requiring revision surgery for neurological damage/major bleedings, and procedure-related unintended violations of anatomical structures were recorded. RESULTS: In 1547 navigation-assisted PS insertions, thoracolumbar accuracy (96.4%) was significantly higher than sacral accuracy (92.6%, p ≈ 0.007) due to special requirements to exact PS (insertion depth) in S1 (p < 0.001). Vertebrae with modification rates above average were identified (T10, L5-S1) (p < 0.001). Major complications did not occur, anatomical structures were violated in 1.2% (19/1547 PS insertions). CONCLUSIONS: In navigation-assisted O-arm-controlled PS placements, correct PS insertion depths are less easily to achieve than correct trajectory or entering-points, which is important for bicortical PS anchorage in S1. Therefore, post-instrumentation PS control by 3D-imaging or at least intraoperative fluoroscopy is recommended for levels with special requirements to exact PS insertion depths (e.g. S1).

Hyperextension injuries of the thoracolumbar spine in diffuse idiopathic skeletal hyperostosis.

STUDY DESIGN: Retrospective study of a consecutive series of patients with thoracolumbar hyperextension injuries (TLHIs) complicated by diffuse idiopathic skeletal hyperostosis (DISH) presenting to a single institution during a 9-year period. OBJECTIVE: Assess epidemiological data, trauma mechanism, injury characteristics in hyperostotic spines, and short-term outcome. SUMMARY OF BACKGROUND DATA: An increase in TLHIs complicated by DISH was observed. In current literature, only case reports and small case series touch this topic. METHODS: All patients with TLHIs in the setting of DISH between January 2002 and December 2010 were reviewed retrospectively. Clinical and radiographical data during hospitalization including computed tomographic scans of all patients were analyzed as to epidemiological issues, trauma characteristics, neurological deficits, and short-term outcomes. Statistical analysis was performed to assess factors related to trauma characteristics. RESULTS: Twenty patients with 23 TLHIs were analyzed. Twelve injuries involved the thoracic region; 1, the lumbar region; and 10, the thoracolumbar junction. A total of 85.7% of injuries were due to high-energy impact. The distribution of transdiscal and transosseous injuries was almost equal (13/10). Patients with DISH with vertebral body fractures were significantly older than those with transdiscal injuries (78.3 yr vs. 69.8 yr, P < 0.026). Post-traumatic neurological deficit was present in 22.7% patients. Neurological complications did not occur in low-energy injuries. On average, spines were posteriorly stabilized over 2.1 segments. Twenty percent of the patients died within 3 months (average age, 80.7 ± 5.1 yr, range, 76-88 yr). CONCLUSION: To our knowledge, this is the largest series of TLHIs in DISH-altered spines in literature. The study helps to understand controversial findings in literature about morphological properties of TLHIs in DISH-affected spines. Surgeons should be aware of preexisting alterations in traumatized spines and the impact on therapeutic decisions. Because of the "aging population" and implications of metabolic diseases on an "aging spine," the incidence of TLHIs in DISH will probably rise.

Successful transpedicular lumbar interbody fusion by means of a composite of osteogenic protein-1 (rhBMP-7) and hydroxyapatite carrier: a comparison with autograft and hydroxyapatite in the sheep spine.

STUDY DESIGN: Transpedicular lumbar interbody fusion (TLIF) was performed in a sheep model comparing three treatment groups: a composite of osteogenic protein (OP)-1 and hydroxyapatite carrier (HA), HA without OP-1, and autograft. OBJECTIVE: To evaluate the efficacy of the composite of OP-1 and HA (HA-OP-1) in achieving reliable TLIF. SUMMARY OF BACKGROUND DATA: Anterior fusion techniques directly address disc-related problems and achieve primary axial stability. However, they are characterized by high morbidity. Alternatively, the theoretically advantageous posterior TLIF technique using autograft fails clinically because it lacks compressive stability. METHODS: In 36 sheep, lumbar vertebrae L4 to L6 were instrumented posteriorly. Endoscopically assisted TLIF of L4 to L5 was performed. In 12 sheep, the defect was filled with injectable HA-OP-1. Another 12 sheep were treated with HA and another 12 with autograft. Animals were killed at 8 weeks and evaluated by radiologic, histologic, and histomorphometric analysis and by fluorochrome labeling. RESULTS: Only 10 autograft sheep were available for evaluation. Radiologically and histologically, TLIF with HA-OP-1 led to a fusion rate of 10 in 12 compared with autograft (one in 10 fused) and HA (two in 12 fused) ( = 0.0016). Semiquantitative radiologic and histologic scoring also revealed significant differences with superiority of HA-OP-1 ( = 0.0011). Compared with HA, HA-OP-1 presented significantly more ossification at the bone-cement interface ( = 0.0003) and less cement resorption ( = 0.0209). In four of 12 HA sheep, excessive resorption was responsible for local aseptic inflammation. CONCLUSIONS: Biointegration of the osteoconductive HA does not occur, because shear forces cause early HA fracture, subsequent fragmentation, and gross resorption (initiating severe inflammation in four of 12 sheep). In contrast, osteoinductive effects of HA-OP-1 enable bio-integration, resulting in full osseous composite sheathing and solid fusion. By use of this composite, TLIF is successfully applied in sheep. Harvesting autograft and the anterior approach are avoided.