Randomized Trial of Augmented Pelvic Fixation in Patients Undergoing Thoracolumbar Fusion for Adult Spine Deformity: Initial Results from a Multicenter Randomized Trial.

BACKGROUND: The optimal configuration for spinopelvic fixation during multilevel spine fusion surgery for adult spine deformity remains unclear. Postoperative sacroiliac (SI) joint pain, S2AI screw loosening and implant breakage could be related to continued motion of the SI joint with use of only a single point of fixation across the SI joint. METHODS: Prospective, international, multicenter randomized controlled trial of 222 patients with adult spine deformity scheduled for multilevel (4 or more levels) spine fusion surgery with pelvic fixation. Subjects were randomized to sacroalar (S2) iliac (S2AI) screws alone for pelvic fixation or S2AI + triangular titanium implants placed cephalad to S2AI screws. Quad rod techniques were not allowed or used. Baseline spinal deformity measures were read by an independent radiologist. Site-reported perioperative adverse events were reviewed by a clinical events committee. Quality of life questionnaires and other clinical outcomes are in process with planned 2-year follow-up. RESULTS: One hundred thirteen participants were assigned to S2AI and 109 to S2AI + titanium triangular implants (TTI). 35/222 (16%) of all subjects had a history of SI joint pain or were diagnosed with SI joint pain during preoperative workup. Three-month follow-up was available in all but 4 subjects. TTI placement was successful in 106 of 109 (98%) subjects assigned to TTI. In 2 cases, TTI could not be placed due to anatomical considerations. Three TTI ventral iliac breaches were observed, all of which were managed non-surgically. One TTI subject had a transverse sacral fracture and 1 TTI subject had malposition of the implant requiring removal. CONCLUSIONS: SI joint pain is common in patients with adult spinal deformity who are candidates for multilevel spine fusion surgery. Concurrent placement of TTI parallel to S2AI screws during multilevel spine fusion surgery is feasible and safe. Further follow-up will help to determine the clinical value of this approach to augment pelvic fixation.

Visualization and Experimental Characterization of Wrapping Layer Using Planar Laser-Induced Fluorescence.

Droplets on nanotextured oil-impregnated surfaces have high mobility due to record-low contact angle hysteresis (∼1-3°), attributed to the absence of solid-liquid contact. Past studies have utilized the ultralow droplet adhesion on these surfaces to improve condensation, reduce hydrodynamic drag, and inhibit biofouling. Despite their promising utility, oil-impregnated surfaces are not fully embraced by industry because of the concern for lubricant depletion, the source of which has not been adequately studied. Here, we use planar laser-induced fluorescence (PLIF) to not only visualize the oil layer encapsulating the droplet (aka wrapping layer) but also measure its thickness since the wrapping layer contributes to lubricant depletion. Our PLIF visualization and experiments show that (a) due to the imbalance of interfacial forces at the three-phase contact line, silicone oil forms a wrapping layer on the outer surface of water droplets, (b) the thickness of the wrapping layer is nonuniform both in space and time, and (c) the time-average thickness of the wrapping layer is ∼50 ± 10 nm, a result that compares favorably with our scaling analysis (∼50 nm), which balances the curvature-induced capillary force with the intermolecular van der Waals forces. Our experiments show that, unlike silicone oil, mineral oil does not form a wrapping layer, an observation that can be exploited to mitigate oil depletion of nanotextured oil-impregnated surfaces. Besides advancing our mechanistic understanding of the wrapping oil layer dynamics, the insights gained from this work can be used to quantify the lubricant depletion rate by pendant droplets in dropwise condensation and water harvesting.

Droplet attraction and coalescence mechanism on textured oil-impregnated surfaces.

Droplets residing on textured oil-impregnated surfaces form a wetting ridge due to the imbalance of interfacial forces at the contact line, leading to a wealth of phenomena not seen on traditional lotus-leaf-inspired non-wetting surfaces. Here, we show that the wetting ridge leads to long-range attraction between millimeter-sized droplets, which coalesce in three distinct stages: droplet attraction, lubricant draining, and droplet merging. Our experiments and model show that the magnitude of the velocity and acceleration at which droplets approach each other horizontally is the same as the vertical oil rise velocity and acceleration in the wetting ridge. Moreover, the droplet coalescence mechanism can be modeled using the classical mass-spring system. The insights gained from this work will inform future fundamental studies on remote droplet interaction on textured oil-impregnated surfaces for optimizing water harvesting and condensation heat transfer.

Quantitative Spectroscopic Characterization of Near-UV/visible E. coli (pYAC4), B. subtilis (PY79), and Green Bread Mold Fungus Fluorescence for Diagnostic Applications.

Ultraviolet (UV)-excited visible fluorescence is an attractive option for low-cost, low-complexity, rapid imaging of bacterial and fungal samples for imaging diagnostics in the biomedical community. While several studies have shown there is potential for identification of microbial samples, very little quantitative information is available in the literature for the purposes of diagnostic design. In this work, two non-pathogenic bacteria samples (E. coli pYAC4, and B. subtilis PY79) and a wild-cultivated green bread mold fungus sample are characterized spectroscopically for the purpose of diagnostic design. For each sample, fluorescence spectra excited with low-power near-UV continuous wave (CW) sources, and extinction and elastic scattering spectra are captured and compared. Absolute fluorescence intensity per cell excited at 340 nm is estimated from imaging measurements of aqueous samples. The results are used to estimate detection limits for a prototypical imaging experiment. It was found that fluorescence imaging is feasible for as few as 35 bacteria cells (or [Formula: see text]30 µm3 of bacteria) per pixel, and that the fluorescence intensity per unit volume is similar for the three samples tested here. A discussion and model of the mechanism of bacterial fluorescence in E. coli is provided.

Orthopaedics and neurosurgery: Is there a difference in surgical outcomes following anterior cervical spinal fusion?

OBJECTIVE: The superiority of neurosurgical over orthopaedic spinal procedures is a point of contention. While there is the perception that neurosurgeons are more specifically trained to deal with spinal pathology, no study has directly compared outcomes of spinal surgeries performed by both groups. METHODS: We sought to evaluate the differences in length of surgery, hospital stay, complications, mortality, and readmission for anterior cervical decompression and fusion (ACDF) performed by neurosurgeons versus orthopaedic surgeons. RESULTS: 17,967 ACDF procedures were analyzed. Neurosurgeons performed 74.3% of the fusions with a trend towards longer operative times and significantly more patients that were discharged to extended care facilities. There was no significant difference in the length of stay, overall complications, mortality, readmission, or reoperation when comparing the two specialties. CONCLUSION: Despite a significantly higher volume of ACDF performed by neurosurgeons, outcomes are comparable following orthopaedic and neurosurgical procedures.

Accuracy of radiographic determination of the posterior femoral wall integrity in anterior cruciate ligament reconstruction.

OBJECTIVE: To evaluate the accuracy of radiographs in determining integrity of the posterior femoral cortex following ACL reconstruction. METHODS: Fifty adult volunteers undergoing primary arthroscopic transtibial ACL reconstructions were prospectively enrolled into this study. Plain radiographs and fine-cut CT of the operative knee were obtained post-operatively. Three blinded orthopaedic surgeons were asked to measure the distance from the femoral tunnel to the posterior cortex on lateral radiographs. Inter/intra-observer reliabilities were assessed with the interclass correlation coefficient. The true measurement of the posterior wall was determined on CT. For each, a measurement was made at the aperture, 5 mm, and 10 mm along the tunnel. Plain radiographic measurements were compared to the CT measurement of back wall using a paired t-test. RESULTS: All measurements made on the lateral radiograph were significantly different from those from the respective CT scans for each surgeon (p < 0.0001) at all points. When radiographic measurements were compared to CT at the level of the intra-articular aperture, 29 subjects showed violation of the posterior cortex, with only one being identified on plain films. At 5 mm, 7 subjects demonstrated posterior cortical violation, and none were identified on lateral radiographs. The posterior cortex remained intact in all cases at 10 mm. CONCLUSION: Lateral radiographs of the knee are insufficient for evaluation of the posterior cortical integrity following primary ACL reconstruction. Direct visualization of the femoral tunnel remains the gold standard for evaluation of the posterior wall and may be supplemented by CT scan if there remains concern over graft fixation.

Biomechanical comparison of a novel C1 posterior U-construct with four other techniques in a C1-C2 fixation model.

BACKGROUND: Compare the biomechanical stability of a novel "U" posterior cervical fixation construct to four other posterior cervical atlantoaxial fixation constructs. METHODS: Eight fresh frozen human cadaver spines were tested after a simulated odontoid fracture, and following stabilization with each construct. RESULTS: All constructs significantly decreased flexion-extension and axial rotation compared to the destabilized spine. The U construct provided significantly more axial stability than the Brooks wire technique. CONCLUSION: The novel U construct demonstrated comparable biomechanical stability to the existing constructs in all three planes of motion with the exception of axial rotation, in which it was inferior to TAS.

Outcomes Following Multilevel Cervical Disc Arthroplasty in the Young Active Population.

BACKGROUND: Cervical radiculopathy is a common disorder that portends significant morbidity. The presence of radiculopathy can have a debilitating effect on patients as well as a significant economic impact. Active duty military patients with increased physical occupational demands can be significantly impacted by cervical disease. The resulting disability can have a strong negative impact on operational readiness. Several studies have demonstrated comparably good functional outcomes between cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion for single-level disease. To date, no study has specifically evaluated the functional and occupational outcomes following adjacent 2-level CDA in a young, active patient population as represented by the active duty military population. PURPOSE: To evaluate functional and occupational outcomes following adjacent 2-level CDA for cervical radiculopathy in the U.S. military population. We hypothesized that this population would have excellent symptomatic relief at the cost of a low return to duty rate. METHODS: We performed a case series with prospective follow-up of all patients who underwent adjacent two-level CDA at a single institution from 2011 to 2014. Each patient completed the Neck Disability Index questionnaire to assess functional outcome. Primary outcomes of interest were return to active military duty and complications. RESULTS: Follow-up was available for 18 of 21 (85.7%) patients. At an average follow-up of 21.4 ± 11.1 months, 12 patients (66.7%) reported complete symptomatic relief and were able to return to preoperative levels of function. Average self-reported pain score improved from 8.3 preoperatively to 1.1 postoperatively, and average postoperative Neck Disability Index score was 15.5 compared to 37.0 for those who medically retired. Radiographic analysis did not show any evidence of subsidence, migration of hardware, or heterotopic ossification. The average return to duty time was 9.6 weeks. DISCUSSION: We demonstrate that adjacent two-level CDA is capable of providing predictable symptomatic relief and maintenance of a high-demand preoperative level of function for cervical radiculopathy among a population of young and highly active individuals. Adjacent two-level CDA offers significant relief of symptoms with low risk of complication in a young, active, and high-demand cohort such as the U.S. military. Adjacent two-level CDA can be performed with the expectation of improving function, relieving symptoms, returning to preoperative levels of activity, and maintaining operational readiness.

Use of an Irrigation Pump System in Arthroscopic Procedures.

Since its inception, arthroscopic surgery has become widely adopted among orthopedic surgeons. It is therefore important to have an understanding of the basic principles of arthroscopy. Compared with open techniques, arthroscopic procedures are associated with smaller incisions, less structural damage, improved intra-articular visualization, less pain in the immediate postoperative period, and faster recovery for patients. Pump systems used for arthroscopic surgery have evolved over the years to provide improved intraoperative visualization. Gravity flow systems were described first and are still commonly used today. More recently, automated pump systems with pressure or dual pressure and volume control have been developed. The advantages of automated irrigation systems over gravity irrigation include a more consistent flow, a greater degree of joint distention, improved visualization especially with motorized instrumentation, decreased need for tourniquet use, a tamponade effect on bleeding, and decreased operative time. Disadvantages include the need for additional equipment with increased cost and maintenance, the initial learning curve for the surgical team, and increased risk of extra-articular fluid dissection and associated complications such as compartment syndrome. As image quality and pump systems improve, so does the list of indications including diagnostic and treatment modalities to address intra-articular pathology of the knee, shoulder, hip, wrist, elbow, and ankle joints. This article reviews the current literature and presents the history of arthroscopy, basic science of pressure and flow, types of irrigation pumps and their functions, settings, applications, and complications. [Orthopedics. 2016; 39(3):e474-e478.].

Coronal Spinal Balance in Adult Spine Deformity Patients With Long Spinal Fusions: A Minimum 2- to 5-Year Follow-up Study.

STUDY DESIGN: This study was a retrospective one. OBJECTIVE: The objective of the study was to analyze the causes, prevalence of, and risk factors for coronal decompensation in long adult lumbar spinal instrumentation and fusion (from thoracic or upper lumbar spine) to L5 or S1. SUMMARY OF BACKGROUND DATA: Coronal and sagittal decompensation after long fusions for spinal deformities can affect outcomes negatively. There is no study reporting the natural history of coronal spinal balance after long spinal fusions. METHODS: A single-center retrospective review of data from 54 patients with spinal deformity was performed. Inclusion criteria were patients over 18 years with long fusions (>4 segments) to L5 or the pelvis who had full spine standing radiographs before surgery and up to 2-5 years postoperatively. Radiographic data included C7PL, magnitude of scoliotic curve, shoulder or pelvic asymmetry in the coronal plane, thoracic kyphosis, lumbar lordosis, and pelvic parameters (pelvic incidence, pelvic tilt, sacral slope). Coronal imbalance (CI) was considered if the C7PL was >4 cm lateral to the central sacral line, and sagittal imbalance (SI) was considered when the C7 plumbline was >4 cm anterior to the middle of the upper sacral plate. Paired t test, χ test, and repeated measures regression analysis using demographic data (age, sex, body mass index), operative (previous fusion, posterior only or anteroposterior fusion, iliac fixation or not, decompression or not, osteotomy or not) and postoperative (complications, use of bracing) data, and radiographic parameters (including SI) were performed. RESULTS: Patients showing CI equaled 11 (19.3%) preoperatively, remained 11 (19.3%) (4 of whom were new patients with CI) at 6 weeks postoperatively, and increased (P<0.001) to 18 (31.6%) (8 of them without initial CI) at 2-5 years follow-up. However, in terms of numeric distance of C7PL from the midsacrum, there was no statistically significant change (P>0.05) from preoperative to last follow-up. SI showed significant improvement (P<0.05) from preoperative to 6 weeks postoperative and no statistical significant change (P>0.05) from 6 weeks to 2-5 years postoperatively. Repeated measures regression analysis showed that the presence of osteoporosis and the combination of anterior approach surgery with a history of previous surgery were significant (P<0.05) factors predictive of changes in coronal balance. CONCLUSIONS: After surgical correction of spinal deformities, coronal spinal decompensation appears in an increased number of patients at last follow-up postoperatively but without significant differences in coronal plane C7PL during the postoperative period. Attention should be paid to patients with osteoporosis and those with a combination of previous same site posterior spine surgery and new anterior approach surgery for changes of coronal balance postoperatively.

Patient-based and surgical characteristics associated with the acute development of deep venous thrombosis and pulmonary embolism after spine surgery.

STUDY DESIGN: Retrospective analysis of a prospectively collected data set. OBJECTIVE: Identify the incidence of, and risk factors for, deep venous thrombosis (DVT) and pulmonary embolism (PE) after spine surgery. SUMMARY OF BACKGROUND DATA: Determination of ideal candidates for chemoprophylaxis after spine surgery is limited by the state of the literature, including incomplete understanding regarding the incidence of DVT and PE, as well as an inability to quantify specific risk factors among patients. METHODS: The 2005 to 2011 data set of the National Surgical Quality Improvement Program was queried to identify all individuals having undergone spine surgery. Demographic data, medical comorbidities, surgical characteristics, and the presence of DVT, PE, and/or mortality were abstracted for all individuals meeting inclusion criteria. Unadjusted univariate analysis was performed to identify variables that were potentially associated with the development of DVT or PE after surgery. A multivariate logistic regression test, controlling for other factors present in the model, was subsequently performed. Predictor variables that maintained significance after multivariate testing were considered influential in the development of DVT and/or PE. RESULTS: There were 27,730 patients who received spine procedures in this cohort. The average age was 56.4 (± 15.1) years. Lumbar spine procedures made up 61% of interventions. Death occurred in 87 instances (0.3%). The venous thromboembolic rate was 1%, with 206 individuals (0.7%) sustaining DVT and 113 (0.4%) developing a PE. Body mass index 40 and greater, age 80 years and older, operative time exceeding 261 minutes, and American Society of Anesthesiologists classification 3 or higher were identified as significant independent predictors of DVT, whereas body mass index 40 and greater, operative time exceeding 261 minutes, and male sex were associated with the development of PE. CONCLUSION: Multiple independent risk factors for the development of DVT and/or PE after spine surgery were identified. Patients with these characteristics may require additional counseling, procedural modification, or prophylaxis against venous thromboembolic events.

Analysis of the mechanical properties of locking plates with and without screw hole inserts.

The purpose of this study was to determine if the use of screw hole inserts in empty locking screw holes improves the strength and failure characteristics of locking plates. Twenty 5-hole 1/3 tubular locking plates (Synthes, Paoli, Pennsylvania) were mounted on an oak dowel with a 1-cm gap simulating a fracture with comminution and bone loss. Ten of the 1/3 tubular plates had a screw hole insert placed in the center hole (centered over the simulated fracture), while 10 of the 1/3 tubular plates remained empty in the center hole. The plate-dowel constructs were placed in an Instron 8800 Material Testing Machine and subjected to a series of loading conditions, replicating physiologic loading. The torsional and axial stiffness of each plate-dowel construct was calculated. All plates were then loaded to failure. No significant differences were found in the mechanical properties of the 2 plate constructs. Both the filled screw-hole plate constructs and unfilled screw hole plate constructs demonstrated the same torsional and axial stiffness, before and after being subjected to a combined cyclic and axial torsional load. Additionally, there was no significant difference in ultimate compressive strength or load to failure. Locking plate technology is a relatively new innovation in orthopedic fracture fixation. The evolution of new and varied applications and implants continues. Persistent, fundamental questions exist concerning the basic locking plate design. This study demonstrates that the addition of screw hole inserts does not significantly change the stiffness, torsional strength, or axial loading strength of 1/3 tubular locking plates.