A Retrospective Observational Study to Evaluate Adjacent Segmental Degenerative Change with the Dynesys-Transition-Optima Instrumentation System.

BACKGROUND: This study evaluates the impact of hybrid dynamic stabilization using the Dynesys-Transition-Optima (DTO) system on adjacent segment disease (ASD) in lumbar spinal stenosis patients with spondylolisthesis. METHODS: From 2012 to 2020, 115 patients underwent DTO stabilization at a single center by a single neurosurgeon. After exclusions for lack of specific stabilization and incomplete data, 31 patients were analyzed. Follow-up was conducted at 6, 12, and 24 months postoperatively, assessing disc height, listhesis distance, and angular motion changes at L2-L3, L3-L4, and L5-S1. RESULTS: L3-L4 segment (the index level), demonstrated a delayed increase in listhesis distance, contrasting with earlier changes in other segments. At two years, L3-L4 exhibited less increase in listhesis distance and less disc height reduction compared to L2-L3 and L5-S1. Notably, the L3-L4 segment showed a significant reduction in angular motion change over two years. CONCLUSIONS: In conclusion, while ASD was not significantly prevented, the study indicates minor and delayed degeneration at the index level. The L3-L4 segment experienced reduced angular change in motion, suggesting a potential benefit of DTO in stabilizing this specific segment.

Triage body temperature and its influence on patients with acute myocardial infarction.

BACKGROUND: Fever can occur after acute myocardial infarction (MI). The influence of body temperature (BT) after hospital arrival on patients with acute MI has rarely been investigated. METHODS: Patients who were diagnosed with acute MI in the emergency department (ED) of a tertiary teaching hospital between 1 January 2020 and 31 December 2020 were enrolled. Based on the tympanic temperature obtained at the ED triage, patients were categorized into normothermic (35.5°C-37.5°C), hypothermic (< 35.5°C), or hyperthermic (> 37.5°C) groups. The primary outcome was in-hospital cardiac arrest (IHCA), while the secondary outcomes were adverse events. Statistical significance was set at p < 0.05. RESULTS: There were 440 enrollees; significant differences were found among the normothermic (n = 369, 83.9%), hypothermic (n = 27, 6.1%), and hyperthermic (n = 44, 10.0%) groups in the triage respiratory rate (median [IQR]) (20.0 [4.0] cycles/min versus 20.0 [4.0] versus 20.0 [7.5], p = 0.009), triage heart rate (88.0 [29.0] beats/min versus 82.0 [28.0] versus 102.5 [30.5], p < 0.001), presence of ST-elevation MI (42.0% versus 66.7% versus 31.8%, p = 0.014), need for cardiac catheterization (87.3% versus 85.2% versus 72.7%, p = 0.034), initial troponin T level (165.9 [565.2] ng/L versus 49.1 [202.0] versus 318.8 [2002.0], p = 0.002), peak troponin T level (343.8 [1405.9] ng/L versus 218.7 [2318.2] versus 832.0 [2640.8], p = 0.003), length of ICU stay (2.0 [3.0] days versus 3.0 [8.0] versus 3.0 [9.5], p = 0.006), length of hospital stay (4.0 [4.5] days versus 6.0 [15.0] versus 10.5 [10.8], p < 0.001), and infection during hospitalization (19.8% versus 29.6% versus 63.6%, p < 0.001) but not in IHCA (7.6% versus 14.8% versus 11.4%, p = 0.323) or any adverse events (50.9% versus 48.1% versus 63.6%, p = 0.258). Multivariable analysis showed no significant association of triage BT with IHCA or any major complication. CONCLUSION: Triage BT did not show a significant association with IHCA or adverse events in patients with acute MI. However, triage BT could be associated with different clinical presentations and should warrant further investigation.

Nail-stem construct method for periprosthetic humeral fractures with recalcitrant nonunion after total elbow arthroplasty: A surgical technique.

Objectives: The objective of this study was to describe the surgical technique using an innovative nail-stem construct in treatment of periprosthetic humeral fractures with recalcitrant nonunion after total elbow arthroplasty (TEA). Materials and Methods: Patients diagnosed with humeral recalcitrant nonunion in periprosthetic fractures and stem loosening after TEA were retrospectively recruited between 2018 and 2019. The demographic data and related clinical outcomes were recorded. We use a cutting length of the nail pushing into the humeral canal and then pull back distally to dock the tip of the humeral stem. The cement was packed into the humeral canal, and the periprosthetic bone defect was impacting with harvested allograft chip. Results: Patient age, gender, lesion site, number of previous surgeries, and the time period from the primary TEA to the nail-stem reconstruction were allocated. Moreover, the range of motion, degree of elbow stability, and level of pain were evaluated for each patient following this procedure. All the four patients achieved an optimal range of motion and secure stability with painless elbow at final follow-up. Conclusion: Our proposed nail-stem construct with double allogenous bone plate is a feasible alternative for revisional TEA in patients with implant loosening, periprosthetic humeral fractures, and recalcitrant nonunion.

Global Compressive Loading from an Ultra-Thin PEEK Button Augment Enhances Fibrocartilage Regeneration of Rotator Cuff Enthesis.

A PEEK button is developed to improve the tendon-to-bone compression area. In total, 18 goats were divided into 12-week, 4-week, and 0-week groups. All underwent bilateral detachment of the infraspinatus tendon. In the 12-week group, 6 were fixed with a 0.8-1 mm-thick PEEK augment (A-12, Augmented), and 6 were fixed with the double-row technique (DR-12). Overall, 6 infraspinatus were fixed with PEEK augment (A-4) and without PEEK augment (DR-4) in the 4-week group. The same condition was performed in the 0-week groups (A-0 and DR-0). Mechanical testing, immunohistochemistry assessment, cell responses, tissue alternation, surgical impact, remodeling, and the expression of type I, II, and III collagen of the native tendon-to-bone insertion and new footprint areas were evaluated. The average maximum load in the A-12 group (393.75 (84.40) N) was significantly larger than in the TOE-12 group (229.17 (43.94) N) (p < 0.001). Cell responses and tissue alternations in the 4-week group were slight. The new footprint area of the A-4 group had better fibrocartilage maturation and more type III collagen expression than in DR-4 group. This result proved the novel device is safe and provides superior load-displacement to the double-row technique. There is a trend toward better fibrocartilage maturation and more collagen III secretions in the PEEK augmentation group.

Biomechanical comparisons of dynamic fixators with rod-rod and screw-spacer joints on lumbar hybrid fixation.

BACKGROUND: Hybrid fixators with quite different joint design concepts have been widely to suppress adjacent segment degeneration problems. The kinematic and kinetic responses of the adjacent and transition segments and contact behaviors at the bone-screw interfaces served as the objective of this study. METHODS: The moderately degenerated L4/L5 and mildly degenerative L3/L4 segments were respectively immobilized by a static fixator and further bridged by the rod-rod (Isobar) and screw-spacer (Dynesys) fixator. The joint stiffness and mobility of the rod-rod system and the cable pretension of the screw-spacer system were systematically varied. FINDINGS: The flexion of the screw-spacer system provided higher mobility to the transition segment, reducing adjacent-segment problems. The cable pretension had a minor effect on the construct behavior. However, due to limited joint mobility, the rod-rod system showed higher constraints to the transition segment and induced more adjacent-segment compensations. The increased mobility of the rod-rod joint caused it to behave as a more dynamic fixator that increased adjacent-segment compensations at the transition segment. Comparatively, increasing the joint mobility showed more significant effects on the construct behaviors than decreasing the joint stiffness. Furthermore, increased constraint by the rod-rod joint induced higher stress and risk of loosening at the bone-screw interfaces INTERPRETATION: If the protection of the transition segment is the major concern, the rod-rod system can be used to constrain the intervertebral motion and share the higher loads through the fixator. Otherwise, the screw-spacer system is recommended in situations where higher loads onto the transition disc are allowable.

High Accuracy and Safety of Intraoperative CT-Guided Navigation for Transpedicular Screw Placement in Revision Spinal Surgery.

BACKGROUND: Intraoperative CT-guided navigation (iCT-navigation) has been reported to improve the accuracy and safety of transpedicular screw placement in primary spinal surgery. However, due to a disrupted bony anatomy and scarring tissue, revision spinal surgery can be challenging. The purpose of this study was to evaluate the accuracy and safety of iCT-navigation for screw placement at the virgin site versus the revision site in revision thoracolumbar spinal surgery. METHOD: In total, 254 screws were inserted in 27 revision surgeries, in which 114 (44.9%) screws were inserted at the site with previous laminectomy or posterolateral fusion (the revision site), 64 (25.2%) were inserted at the virgin site, and 76 (29.9%) were inserted to replace the pre-existing screws. CT scans were conducted for each patient after all screws were inserted to intraoperatively confirm the screw accuracy. RESULTS: In total, 248 (97.6%) screws were considered accepted. The rate of accepted screws at the virgin site was 98.4% (63/64) versus 95.6% (109/114) at the revision site (p: 0.422). There were six (2.4%) unaccepted screws, which were immediately revised during the same operation. There was no neurological injury noted in our patients. CONCLUSION: With the use of iCT-navigation, the rate of accepted screws at the revision site was found to be comparable to that at the virgin site. We concluded that iCT-navigation could achieve high accuracy and safety for transpedicular screw placement in revision spinal surgery and allow for the immediate revision of unaccepted screws.

Biomechanical Comparison between Isobar and Dynamic-Transitional Optima (DTO) Hybrid Lumbar Fixators: A Lumbosacral Finite Element and Intersegmental Motion Analysis.

Biomechanical performance of longitudinal component in dynamic hybrid devices was evaluated to display the load-transfer effects of Dynesys cord spacer or Isobar damper-joint dynamic stabilizer on junctional problem based on various disc degenerations. The dynamic component was adapted at the mildly degenerative L3-L4 segment, and the static component was fixed at the moderately degenerative L4-L5 segment under a displacement-controlled mode for the finite element study. Furthermore, an intersegmental motion behavior was analyzed experimentally on the synthetic model under a load-controlled mode. Isobar or DTO hybrid fixator could reduce stress/motion at transition segment, but compensation was affected at the cephalic adjacent segment more than the caudal one. Within the trade-off region (as a motion-preserving balance between the transition and adjacent segments), the stiffness-related problem was reduced mostly in flexion by a flexible Dynesys cord. In contrast, Isobar damper afforded the effect of maximal allowable displacement (more than peak axial stiffness) to reduce stress within the pedicle and at facet joint. Pedicle-screw travel at transition level was related to the extent of disc degeneration in Isobar damper-joint (more than Dynesys cord spacer) attributing to the design effect of axial displacement and angular rotation under motion. In biomechanical characteristics relevant to clinical use, longitudinal cord/damper of dynamic hybrid lumbar fixators should be designed with less interface stress occurring at the screw-vertebral junction and facet joint to decrease pedicle screw loosening/breakage under various disc degenerations.

In Vitro and In Vivo Comparison of Bone Growth Characteristics in Additive-Manufactured Porous Titanium, Nonporous Titanium, and Porous Tantalum Interbody Cages.

Autogenous bone grafts are the gold standard for interbody fusion implant materials; however, they have several disadvantages. Tantalum (Ta) and titanium (Ti) are ideal materials for interbody cages because of their biocompatibility, particularly when they are incorporated into a three-dimensional (3D) porous structure. We conducted an in vitro investigation of the cell attachment and osteogenic markers of self-fabricated uniform porous Ti (20%, 40%, 60%, and 80%), nonporous Ti, and porous Ta cages (n = 6) in each group. Cell attachment, osteogenic markers, and alkaline phosphatase (ALP) were measured. An in vivo study was performed using a pig-posterior-instrumented anterior interbody fusion model to compare the porous Ti (60%), nonporous Ti, and porous Ta interbody cages in 12 pigs. Implant migration and subsidence, determined using plain radiographs, were recorded before surgery, immediately after surgery, and at 1, 3, and 6 months after surgery. Harvested implants were assessed for bone ingrowth and attachment. Relative to the 20% and 40% porous Ti cages, the 60% and 80% cages achieved superior cellular migration into cage pores. Among the cages, osteogenic marker and ALP activity levels were the highest in the 60% porous Ti cage, osteocalcin expression was the highest in the nonporous Ti cage, and the 60% porous Ti cage exhibited the lowest subsidence. In conclusion, the designed porous Ti cage is biocompatible and suitable for lumbar interbody fusion surgery and exhibits faster fusion with less subsidence compared with porous Ta and nonporous Ti cages.

An Early Predictive Scoring Model for In-Hospital Cardiac Arrest of Emergent Hemodialysis Patients.

BACKGROUND: Patients undergoing hemodialysis are prone to cardiac arrests. METHODS: This study aimed to develop a risk score to predict in-hospital cardiac arrest (IHCA) in emergency department (ED) patients undergoing emergency hemodialysis. Patients were included if they received urgent hemodialysis within 24 h after ED arrival. The primary outcome was IHCA within three days. Predictors included three domains: comorbidity, triage information (vital signs), and initial biochemical results. The final model was generated from data collected between 2015 and 2018 and validated using data from 2019. RESULTS: A total of 257 patients, including 52 with IHCA, were analyzed. Statistical analysis selected significant variables with higher sensitivity cutoff, and scores were assigned based on relative beta coefficient ratio: K > 5.5 mmol/L (score 1), pH < 7.35 (score 1), oxygen saturation < 85% (score 1), and mean arterial pressure < 80 mmHg (score 2). The final scoring system had an area under the curve of 0.78 (p < 0.001) in the primary group and 0.75 (p = 0.023) in the validation group. The high-risk group (defined as sum scores ≥ 3) had an IHCA risk of 47.2% and 41.7%, while the low-risk group (sum scores < 3) had 18.3% and 7%, in the primary and validation databases, respectively. CONCLUSIONS: This predictive score model for IHCA in emergent hemodialysis patients could help healthcare providers to take necessary precautions and allocate resources.

Simultaneous Bilateral Total Knee Arthroplasty Becomes Safer after Institution of Optimal Perioperative Management: A Longitudinal Cohort Study.

Simultaneous bilateral total knee arthroplasty (SBTKA) increases the rates of procedure-related complications and mortality compared with unilateral TKA. There are no well-defined guidelines for selecting patients to avoid mortality and proposing an upgrade treatment to decrease complication rates. This study aimed to evaluate whether optimal perioperative management could improve the safety of SBTKA. From 2005 to 2017, 1,166 cases of SBTKA were identified from 14,209 TKA procedures. We retrospectively examined the SBTKA patients' demographics, comorbidity profiles, procedure-related complications, and perioperative management during two time periods. Optimal perioperative workup for managing SBTKA significantly decreased the incidences of major complication from 6.2 to 2.4% (p = 0.001) and minor complications from 28.9 to 21.5% (p = 0.004) during period I and period II, respectively. The efficiency of less tourniquet use along with intraarticular tranexamic acid injection was demonstrated by the decreases of hemoglobin (Hb) change in the first 2 days after surgery (p = 0.005) and blood transfusion requirement (p = 0.035) during the SBTKA. Furthermore, the less tourniquet use group had less thigh pain (visual analog scale decreased from 6.0 to 4.2, p = 0.003), shorter duration of hospital stay (decreased from 7.8 to 7.1, p < 0.001), and lower coagulation time (decrease from 3.5 to 2.9, p < 0.001) than the routine tourniquet use group. Patient's screening must be performed carefully for cardiopulmonary compromise in patients aged >80 years and with an American Society of Anesthesiologists score of 3. Additionally, hospitalists should consider developing methods for the eligibility, testing, and perioperative monitoring of patients who undergo SBTKA with the aim of avoiding complications and improving outcomes.

Full Endoscopic Uniportal Unilateral Laminotomy for Bilateral Decompression in Degenerative Lumbar Spinal Stenosis: Highlight of Ligamentum Flavum Detachment and Survey of Efficacy and Safety in 2 Years of Follow-up.

OBJECTIVE: Conventional laminectomy for spine decompression involves inherent complications resulting from perioperative traumatization of posterior structures. Minimally invasive decompression was developed to address these issues. Full endoscopic spine surgery has shifted the paradigm from disc pathology to spinal stenosis by overcoming the limitation of bony procedures with evolving endoscopic instruments. However, a steep learning curve restricts the development of endoscopic decompression. The purpose of this study is to describe full endoscopic uniportal unilateral laminotomy for bilateral decompression through the interlaminar approach and to evaluate its efficacy and safety in 2 years of follow-up. METHODS: A total of 106 patients (45 men, 61 women) with degeneration lumbar stenosis involving 165 segments were enrolled from April 2015 to June 2017, and treated by full endoscopic uniportal unilateral laminotomy for bilateral decompression. We made an 8-mm incision and used a general-size endoscope (working channel 4.3 mm) to avoid neurological compromise during the demonstration. RESULTS: The visual analogue scale (VAS) results for back pain revealed a significant reduction from preoperative 6.8 ± 2.1 to 1.7 ± 1.7 after 2 years (P < 0.001). The VAS results for leg pain revealed a significant reduction from preoperative 7.6 ± 1.3 to 1.3 ± 1.6 after 2 years (P < 0.001). The Oswestry Disability Index showed significant improvement from preoperative 62.0 ± 13.9 to 14.6 ± 15.7 after 2 years (P < 0.001). The average operation time was 68.9 ± 10.0 minutes per level. One case had iatrogenic durotomy, 1 case underwent revision surgery due to incomplete decompression, and 2 cases had delayed wound healing. CONCLUSIONS: This procedure obtained successful and satisfactory outcomes for patients, and was more feasible for surgeons.

Using Percutaneous Endoscopic Outside-In Technique to Treat Selected Patients with Refractory Discogenic Low Back Pain.

BACKGROUND: Controversy is not uncommon in the diagnosis of discogenic low back pain (DLBP) and in the identification of the location of the pain source for the symptomatic disc in patients with DLBP. Various techniques, from minimally invasive procedures to fusion surgery, are used to treat chronic DLBP, but the clinical outcomes are variable. Percutaneous endoscopic discectomy by transforaminal or interlaminar approach is considered to be an effective method to treat DLBP, but the evidence is limited; the lack of clear evidence may be associated with patient selection and surgical technique. OBJECTIVES: The purpose of this study is to evaluate the clinical results of percutaneous endoscopic treatment for annular tear in selected patients with DLBP by using the outside-in technique. STUDY DESIGN: A prospective study and retrospective observations were performed on 24 consecutive patients with a minimum 2 years of follow-up. This study was approved by the Institutional Review Board (IRB) of Buddhist Dalin Tzu-Chi General Hospital Foundation (IRB number: 10504004) and written informed consent was obtained from all patients. SETTING: This research took place within an interventional pain management and spine practice. METHODS: Twenty-four consecutive patients with single-level DLBP diagnosed by positive high-intensity zone on magnetic resonance imaging, positive provocative discography, and block test underwent a percutaneous endoscopic procedure from January 2014 to December 2015. The transforaminal approach or interlaminar approach was selected according to the location of the annular tear. The torn lesions were visualized directly and treated by puncture and debridement of the inflammatory tissues from the outer annulus fibrosus to the inner nucleus using the outside-in technique. The Visual Analog Scale (VAS) score and Oswestry Disability Index (ODI) score were evaluated before and after surgery. The clinical global outcomes were assessed on the basis of modified MacNab criteria. RESULTS: These patients included 13 men and 11 women with a mean age of 43.8 years (range, 32-55 yrs). There were 15 lesion levels at L4/L5 and 9 lesion levels at L5/S1. Among them, 15 levels were accessed by transforaminal approach and 9 levels by interlaminar approach. No serious complications were observed during the follow-up periods. All except 2 patients experienced significant symptomatic and functional improvements at the 2-year follow-up with a success rate of 91.7%. LIMITATIONS: Significant limitations include nonrandom format and small sample size. Future research may focus on controlled prospective studies with larger sample sizes and long-term follow-up to examine the validity of this protocol. CONCLUSIONS: The percutaneous endoscopic procedure provides a safe and effective treatment for selected patients with DLBP. The outside-in technique allows the surgeons to visualize and treat the torn or inflammatory lesions directly, and the success rate is high at 2 years follow-up. KEY WORDS: Transforaminal, interlaminar, outside-in technique, endoscopic discectomy, discogenic low back pain.

Management of Infected Transforaminal Lumbar Interbody Fusion Cage in Posterior Degenerative Lumbar Spine Surgery.

BACKGROUND: The postoperative infection rates for transforaminal lumbar interbody fusion (TLIF) have ranged from <2% to 4%. However, no consensus has been reached on the treatment strategies. TLIF cage preservation or revision surgery for lumbar spine reconstruction are 2 possible treatments. We aimed to determine the most effective method for organ/space infection control. METHODS: The data from 4923 patients who had undergone TLIF with cage and posterior pedicle-screw instrumentation for spondylolysis or degenerative spondylolisthesis from January 2008 to December 2015 were retrospectively analyzed. Of the 4923 patients, 32 (0.65%) had developed organ/space infection of the interbody cage and were divided into 2 groups: those whose interbody cage was removed for revision (group 1) and those who interbody cage was retained (group 2). We compared the initial management of both groups in terms of age, sex, elapsed time to diagnosis, changes in spinal lordotic angle, visual analog scale score, fusion status, and Kirkaldy-Willis functional outcomes. RESULTS: The 32 patients with organ/space infection had a mean age of 66.3 years and a follow-up period of 23.8 months. Significant differences were observed in the mean elapsed time to diagnosis (P = 0.004), lordotic angle correction at the disease level (P = 0.03), and Kirkaldy-Wallis functional outcomes (P = 0.01). Of the 17 patients undergoing debridement for implant retention, 9 (52.9%) exhibited poor results. CONCLUSIONS: The most important factor contributing to TLIF cage retention failure was epidural fibrosis of the previous transforaminal route and biofilm adhesion on interbody devices affecting infection clearance. Thus, we would recommend a combined anterior and posterior approach or the transforaminal route for radical debridement with cage removal and fusion to achieve better clinical outcomes.

Postoperative Infection in Patients Undergoing Posterior Lumbosacral Spinal Surgery: A Pictorial Guide for Diagnosis and Early Treatment.

Surgical site infections after posterior spinal surgery may lead to spondylodiscitis, pseudarthrosis, correction loss, adverse neurological sequelae, sepsis, and poor outcomes if not treated immediately. Infection rates vary depending on the type and extent of operative procedures, use of instrumentation, and patients' risk factors. Image evaluation is crucial for early diagnosis and should be complementary to clinical routes, laboratory survey, and treatment timing. Magnetic resonance imaging detects early inflammatory infiltration into the vertebrae and soft tissues, including hyperemic changes of edematous marrow, vertebral endplate, and abscess or phlegmon accumulation around the intervertebral disk, epidural, and paravertebral spaces. Aggressive surgical treatment can eradicate infection sources, obtain a stable wound closure, decrease morbidity, and restore spinal integrity. Organ/space infection is defined as any body parts opened to manipulate other than superficial/deep incision. Advanced magnetic resonance imaging evaluating abnormal fluid accumulation, heterogenous contrast enhancement of the endplate erosion due to cage/screw infection is categorized to inform a presumptive diagnosis for early implant salvage. However, patients' defense response, infection severity, bacteriology, treatment timing, spinal stability, and available medical and surgical options must be fully considered. Revision surgery is indicated for pseudarthrosis, implant loosening with correction loss, recalcitrant spondylodiscitis, and adjacent segment diseases for infection control.

Modified fixations for distal femur fractures following total knee arthroplasty: a biomechanical and clinical relevance study.

PURPOSE: Distal femur fractures adjacent to total knee arthroplasty are a rare yet complex problem. Recently, extramedullary locking plate and retrograde intramedullary nail fixations have become popular options, but the complication rates associated with these procedures are 15-20 %. Modified fixations were assessed in an effort to reduce complications from unstable periprosthetic fractures. METHODS: Using experimental and finite element methods, this study compared the construct behaviours of a locking plate, a retrograde intramedullary nail, and their modifications (a spiral-blade supplemented in an intramedullary nail or a locking plate/allograft hybrid) when subjected to various fracture types, locations, loading conditions, and bony strength. The implanted models were used to assess construct stiffness, fracture micromotion, and implant stress under different osteoporotic conditions. Finally, we collected 40 cases for radiological analysis to indicate the appropriate procedure for treating periprosthetic fractures following total knee arthroplasty. RESULTS: Regardless of the fracture type, femoral constructs fixed with a conventional or spiral-blade supplemented intramedullary nail exhibited higher axial but lower torsional stiffness than those fixed with a locking plate. Torsional deformation occurred if the lower-positioned fracture had no medial support. The locking plate/allograft construct exhibited the highest stiffness and the least micromotion. A review of 40 clinical cases confirmed the above findings regarding the locking plate/allograft construct. CONCLUSION: The spiral-blade supplement of retrograde intramedullary nail and locking plate/allograft modified constructs significantly stabilizes the unstable fractured gaps. The locking plate/allograft is recommended for the periprosthetic fractures with deficient bone stock and severe osteoporosis to improve alignment and healing potentials.

Comparison of thresholding schemes for visible light communication using mobile-phone image sensor.

Based on the rolling shutter effect of the complementary metal-oxide-semiconductor (CMOS) image sensor, bright and dark fringes can be observed in each received frame. By demodulating the bright and dark fringes, the visible light communication (VLC) data logic can be retrieved. However, demodulating the bright and dark fringes is challenging as there is a high data fluctuation and large extinction ratio (ER) variation in each frame due. Hence proper thresholding scheme is needed. In this work, we propose and compare experimentally three thresholding schemes; including third-order polynomial curve fitting, iterative scheme and quick adaptive scheme. The evaluation of these three thresholding schemes is performed.

Visible light communication using mobile-phone camera with data rate higher than frame rate.

Complementary Metal-Oxide-Semiconductor (CMOS) image sensors are widely used in mobile-phone and cameras. Hence, it is attractive if these image sensors can be used as the visible light communication (VLC) receivers (Rxs). However, using these CMOS image sensors are challenging. In this work, we propose and demonstrate a VLC link using mobile-phone camera with data rate higher than frame rate of the CMOS image sensor. We first discuss and analyze the features of using CMOS image sensor as VLC Rx, including the rolling shutter effect, overlapping of exposure time of each row of pixels, frame-to-frame processing time gap, and also the image sensor "blooming" effect. Then, we describe the procedure of synchronization and demodulation. This includes file format conversion, grayscale conversion, column matrix selection avoiding blooming, polynomial fitting for threshold location. Finally, the evaluation of bit-error-rate (BER) is performed satisfying the forward error correction (FEC) limit.

Postoperative wound infection after posterior spinal instrumentation: analysis of long-term treatment outcomes.

PURPOSE: Postoperative spinal implant infection (PSII) places patients at risk for pseudarthrosis, correction loss, spondylodiscitis, adverse neurological sequelae, and even death; however, prognostic factors that predict long-term treatment outcomes have not been clearly investigated. In addition, few studies concerning the feasibility of reconstructing the failed spinal events have been published. METHODS: We performed a cohort study of 51 patients who contracted PSII in the posterolateral thoracolumbar region at a single tertiary center between March 1997 and May 2007. Forty-seven patients (92.2 %) had one or more medical problems. Isolated bacterial species, infection severity, treatment timing, and hosts' defense response were evaluated to assess their relationship with management outcomes. The use of implant salvage, or removal subsequent with a revision strategy depended on the patient's general conditions, infection control, and implant status for fusion. RESULTS: The most common infective culprit was Staphylococcus spp. found in 35 of 60 (58.3 %) isolates, including 20 methicillin-resistant species. Gram-negative bacilli and polymicrobial infection were found significantly in patients presenting early-onset, deep-site infection and myonecrosis. Prompt diagnosis and aggressive therapy were responsible for implant preservation in 41 of 51 cases (80.4 %), while implant removal noted in 10 cases (19.6 %) was attributed to delayed treatment and uncontrolled infection with implant loosening, correction loss, or late infection with spondylodesis. The number of employed debridements alone was not significantly correlated with successful implant preservation. Delayed treatment for infection >3 months significantly led to implant removal (p < 0.05) and a higher number of failed spinal events. Patients with significant comorbidities, malnutrition, severe trauma, neurological deficits, long-level instrumentation, and delayed treatment had poor outcomes. Sixteen patients (31.4 %) exhibited probable nonunion or pseudarthrosis, and eight symptomatic patients among them underwent successful revision surgery. CONCLUSIONS: Retention of the mechanically sound implants in early-onset infection permits fusion to occur, while delayed treatment, severe malnutrition and multiple comorbidities will most likely result in a lack of effectiveness in eradicating the infecting pathogens. Restoring optimal physiological conditions is imperative in high-risk patients to allow for further healing. When loosened screws cause peridiscal erosion and incapacitating motion pain, premature implant removal possibly results in failed fusion and correction loss. Reconstruction for a failed spinal event is feasible following infection control.

Finite element comparison of retrograde intramedullary nailing and locking plate fixation with/without an intramedullary allograft for distal femur fracture following total knee arthroplasty.

PURPOSE: Periprosthetic distal femur fracture after total knee arthroplasty due to the stress-shielding phenomenon is a challenging problem. Retrograde intramedullary nail (RIMN) or locking plate (LP) fixation with/without a strut allograft has been clinically used via less invasive stabilization surgery (LISS) for the treatment of these periprosthetic fractures. However, their biomechanical differences in construct stability and implant stress have not been extensively studied, especially for the osteoporotic femur. METHODS: This study used a finite-element method to evaluate the differences between RIMN, LP, and LP/allograft fixation in treating periprosthetic distal femur fractures. There were sixteen variations of two fracture angles (transverse and oblique), two loading conditions (compression and rotation), and four bony conditions (one normal and three osteoporotic). Construct stiffness, fracture micromotion, and implant stress were chosen as the comparison indices. RESULTS: The LP/allograft construct provides both lateral and middle supports to the displaced femur. Comparatively, the LP and RIMN constructs, respectively, transmit the loads through the lateral and middle paths, thus providing more unstable support to the construct and high stressing on the implants. The fracture pattern plays a minor role in the construct stabilization of the three implants. In general, the biomechanical performances of the RIMN and LP constructs were comparable and significantly inferior to those of the LP/allograft construct. The bone quality should be evaluated prior to the selection of internal fixators. CONCLUSIONS: The LP/allograft construct significantly stabilizes the fracture gap, reduces the implant stress, and serves as the recommended fixation for periprosthetic distal femur fracture.

Color-filter-free spatial visible light communication using RGB-LED and mobile-phone camera.

A novel color-filter-free visible-light communication (VLC) system using red-green-blue (RGB) light emitting diode (LED) and mobile-phone camera is proposed and demonstrated for the first time. A feature matching method, which is based on the scale-invariant feature transform (SIFT) algorithm for the received grayscale image is used instead of the chromatic information decoding method. The proposed method is simple and saves the computation complexity. The signal processing is based on the grayscale image computation; hence neither color-filter nor chromatic channel information is required. A proof-of-concept experiment is performed and high performance channel recognition is achieved.