Role of finite element analysis for selection of single point fixation in zygomaticomaxillary complex fracture.

BACKGROUND: One-point fixation was superior to the two and three-points fixation in minimally displaced zygomaticomaxillary complex (ZMC) fracture regarding the cost, invasiveness, scaring, number of wounds, and operation time. Accordingly, this study aimed to predict which one-point fixation is the most stable in managing minimally displaced ZMC fracture. MATERIAL & METHODS: This study simulated the different one-point fixation approaches on three ZMC models after fracture reduction and application of all forces exerted on the fractured area. The findings were represented as stress impact on the ZMC fracture and plating system as well as the inter-fragments micro-motion. RESULTS: The von misses stresses of plates for the zygomaticofrontal, infra-orbital rim, and zygomaticomaxillary buttress model were (66.508, 1.285, and1.16 MPa) respectively. While the screws' von misses for the infraorbital rim, zygomaticofrontal, and zygomaticomaxillary buttress models were (13.8, 4.05, and 1.60 MPa) respectively. Whereas, the maximum principles stress at zygomaticofrontal, zygomaticomaxillary buttress, and infraorbital rim models were (37.03, 37.01, and 34.46 MPa) respectively. In addition, the inter-fragment micro-motion for zygomaticomaxillary buttress, infraorbital rim, and zygomaticofrontal models were (0.26, 0.25, and 0.15 mm) respectively. CONCLUSION: One-point fixation at zygomaticomaxillary buttress is the preferred point because it is exposed to low stresses, and the inter-fragment micro-motion is within the approved limit with the elements in the same direction of fixation which indicates the rigid fixation. In addition, it is less palpable and scarless. TRIAL REGISTRATION: clinical trial.gov (NCT05819372) at 19/04/2023.

Cauda equina syndrome after use of dural sealant in revision lumbar decompression surgery.

OBJECTIVE: We report a case of cauda equina syndrome related to the use of fibrin glue dural sealant "TISSEEL". BACKGROUND: Incidental durotomy (ID) is not uncommon in revision spinal surgery. Augmentation of the dural repair after primary closure is gaining popularity. The use of dural sealants is not risk-free. METHOD: A 65-year old man who underwent revision lumbar decompression surgery developed postoperative cauda equina syndrome. He had urinary retention, bilateral leg pain and perianal numbness on the third postoperative day. We believe this complication was related to the use of fibrin glue to manage an ID. RESULT: After the urgent surgical removal of the fibrin glue patch, the patient fully recovered with no residual neurological deficit. CONCLUSION: Cauda equina syndrome development is a potential complication after the use of fibrin glue to augment intraoperative ID. Surgeons should be aware of this potential risk so it can be managed in a timely fashion.

Finite Element Analysis of the Stresses Induced by One-Piece and Two-Piece Dental Implants Supporting All-on-4 Implant-Supported Prostheses.

PURPOSE: To find out the difference in the stresses induced by one-piece monophasic and two-piece dental implants supporting All-on-4 implant-supported prostheses using finite element analysis. MATERIALS AND METHODS: Two finite element maxillary models were designed: In the two-piece model, two-piece dental implants were used, and in the one-piece model, one-piece dental implants were used. The dental implants were placed according to the All-on-4 treatment concept. The anterior implants were axially placed; however, the posterior implants were placed with a distal inclination of 15 degrees. In each model, the prosthetic superstructure was designed to be a titanium implant prosthesis with zirconia crowns. Three loading scenarios were applied in this study. The first scenario simulated biting function with a total load of 250 N. The second scenario simulated incision function in which 90-N horizontal static load was applied to the palatal surface of central incisors. The third scenario simulated biting in the presence of a cantilever. RESULTS: In the three loading scenarios, the stresses were higher in the two-piece model. Higher stress values were recorded posteriorly rather than anteriorly in both models. CONCLUSION: One-piece dental implants induce lower stress values compared with two-piece dental implants when used in All-on-4 implant-supported prostheses.

Stresses induced by one piece and two piece dental implants in All-on-4® implant supported prosthesis under simulated lateral occlusal loading: non linear finite element analysis study.

BACKGROUND: Correct choice of the implant design and the occlusal scheme is important for the success of implant supported restorations. So, the aim of the current study was to find out the difference in the stresses induced by the one piece dental implants designed to be used in the All-on-4® concept and the conventional two piece ones under simulated lateral occlusal schemes using nonlinear finite element analysis. METHODS: Two finite element models of the maxilla, implants, and prostheses were designed according to the All-on-4® concept. In the model TP, two piece dental implants were placed while in the model OP one piece dental implants were used. Two loading scenarios were applied to each model; the first one simulated a group function occlusal scheme while the second scenario simulated a canine guided one. RESULTS: The highest stress value was recorded in the model TP with the group function occlusion and the lowest stress value was in the model OP with the canine guidance occlusion. CONCLUSION: The one-piece dental implants can be concluded to induce less stress compared to the two piece dental implants when used in the All-on-4® implant supported prosthesis in the different lateral occlusal schemes. Canine guided occlusion can be concluded to cause lower stress values in comparison to the group function occlusal scheme.

Management of Ankle Charcot Neuroarthropathy: A Systematic Review.

BACKGROUND: Charcot neuroarthropathy is a non-infective, destructive process occurring in patients rendered insensate by peripheral neuropathy, which is caused mainly by diabetes. Repetitive trauma from standing and walking provides a neuro-traumatic stimulus that leads to dislocation, or peri-articular fracture, or both, within the ankle. This review concentrates on the management protocols regarding the ankle only. METHODS: A Pubmed search for clinical trials performed to manage ankle Charcot neuroarthropathy and a systematic review of these articles were undertaken. RESULTS: Twenty papers met the inclusion criteria: four of them describe non-surgical management, while the rest show different surgical management options of ankle Charcot neuroarthropathy. CONCLUSIONS: Surgical algorithms for the treatment of CN of the ankle are based almost entirely on level four. There is inconclusive evidence concerning the timing of treatment and the use of different fixation methods. Instability and ulceration are the main precursors for surgical interventions. Prospective series and randomized studies, albeit difficult to perform, are necessary to support and strengthen current practice.

The Stress Concentration and Biomechanical Properties of the Intraoral Distractors and the Extraoral Distractors Used in Treatment of Hemifacial Microsomia Patients: A Simulation Finite Element Analysis Study.

THE AIM OF THE STUDY: Finite element analysis of the stresses subjected to both the intraoral and the extraoral distractors devices used in the mandibular distraction of hemifacial microsomia patients. METHODOLOGY: Two models were included in the current study. The first model was an extraoral distractor and the second model was an intraoral distractor model. To generate the results in the simulated models; 2 vertical loads were applied (222.7 and 137.78 N) on the defective and normal side, respectively. RESULTS: The intraoral system observed lower stress (6.85 MPa) in the mandibular bone compared to the extraoral system (13.21 MPa). The intraoral distractor had a higher stress concentration on the distractor fixing screws (352 MPa) compared to the extraoral distractor fixing pins (15 MPa). The extraoral distractor had a higher displacement effect on the mandibular bone around the pins of 263.35 µm in comparison to the intraoral distractor effect which was 77.87 µm. CONCLUSIONS: Internal oral distractor provides a sort of stress shielding to the distracted bone and less displacement, so it is more advisable to be used in general. The external devices are advised only in extralong distraction distance because the distractor is subjected to lower stresses compared to intraoral counterparts.

The Stress Concentration and Biomechanical Properties of the Intra-oral Distractors and the Extra-oral Distractors Used in Treatment of Post Ankylosis Facial Asymmetric Patients: A Finite Element Analysis Study.

ABSTRACT: Assessment of stress and micromotions using finite element analysis along both the intraoral and the extraoral distractors devices used in the mandibular distraction of post temporomandibular joint ankylosis deformed mandible patients. The process of finite element analysis was carried out to assess distraction models. The first model was an extraoral mandibular distraction model and the second model was an intraoral mandibular distraction model. To analyze the stress state, 2 vertical loads were applied on the defective and normal side respectively by a 3D finite element ball model. The intraoral system observed lower stress (4.5 MPa) in the mandibular bone compared to the extra-oral system (11.5 MPa). The results revealed that the intraoral system observed higher stress on the distractor fixing points (392.21 MPa) compared to the extra-oral fixing points (12.62 MPa). The results revealed that the extra-oral system reflected higher displacement on the bone surrounding the screws of about 3720 µm compared to the intraoral system 1414.6 µm. Internal devices give better shielding to the bone and induce fewer stresses over the mandibular, so it is more advisable to be used. The external devices permit greater distraction length because the pins and the distractor main body are subjected to fewer stresses.

Propidium monoazide-polymerase chain reaction for detection of residual periprosthetic joint infection in two-stage revision.

False negative culture results in periprosthetic joint infection (PJI) are not uncommon particularly when patients have received long term antibiotics. Polymerase chain reaction (PCR) has a lower specificity partly due to detection of residual DNA from dead bacteria. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the PCR. This study aimed to determine the role of PMA in PCR for diagnosis of PJI. Clinical samples were tested by PCR with and without prior treatment with PMA and compared to conventional microbiological culture. The PCR assay included genus-specific primers for staphylococci and enterococci and species-specific primers for Cutibacterium acnes. The validated conditions of PMA treatment used in this study were 20 µM concentration and 5 and 10 min of dark incubation and photo-activation respectively. 202 periprosthetic tissues and explanted prostheses from 60 episodes in 58 patients undergoing revision arthroplasties for either PJI or non-infective causes were tested, by culture, PCR, and PMA-PCR. 14 of the 60 episodes satisfied the Musculoskeletal Infection Society (MSIS) criteria for PJI and 46 did not. Sensitivity of culture, PCR, and PMA-PCR were 50%, 71%, and 79% respectively. Specificities were 98%, 72%, and 89% respectively. All figures were calculated for episodes rather than samples. PMA-PCR enhanced both the specificity and the sensitivity of PCR. It has the potential to detect residual bacterial viability prior to reimplantation in the two-stage revision for PJI.

Comparison of different human tissue processing methods for maximization of bacterial recovery.

Tissues are valuable microbiological samples that have proved superiority over swabs. Culture of tissue samples is used in the diagnosis of a variety of infections. However, as well as factors such as the site of obtaining the sample, the number of samples, and previous antibiotic use, the method of tissue processing may have an important effect on sensitivity. Data from the literature comparing different tissue processing methods is very limited. This study aimed to compare different mechanical and chemical methods of tissue processing in terms of efficacy and retaining the viability of the bacteria in the tissues. Standard suspensions of Staphylococcus aureus and Escherichia coli were prepared and treated differently to test the effect of that treatment on bacterial viability. Artificially inoculated pork tissue and known infected human tissue samples were then processed by different methods prior to culture, and results were compared. Percentages of reduction in the number of viable bacteria compared to the control by homogenization was similar to 5-min dithiothreitol treatment but significantly lower than bead beating. Bacterial recovery from homogenized human tissues was significantly higher than from any other method of treatment. Although bead beating could be the most efficient method in obtaining a homogeneous tissue product, it significantly reduces the number of viable bacteria within tissues. Homogenization offers the most effective easily controllable retrieval of bacteria from tissue and retains their viability. Guidelines for diagnosing infections using tissue samples should include a standardized processing method.

Small-colony variant of Staphylococcus lugdunensis in prosthetic joint infection.

Prosthetic joint infection is usually caused by staphylococci. Among the coagulase-negative staphylococci, Staphylococcus lugdunensis is important because it behaves as a pathogen similar to S aureus. It also develops biofilms, and the biofilm phenotype can appear as small-colony variants. Although genetically indistinguishable, they differ in size and antibiotic susceptibility from the parent strain and are responsible for chronic persistent infection and failure of antibiotic treatment. They can also lead to misinterpretation of results. The patient reported here underwent total knee replacement and 2 years later presented with prosthetic joint infection. Tissue samples and prosthesis taken at revision grew S lugdunensis, the majority of which were small-colony variants. Recommendations are made for their detection and identification.

Effectiveness of arginase inhibitors against experimentally induced stroke.

Stroke is a lethal disease, but it disables more than it kills. Stroke is the second leading cause of death and the most frequent cause of permanent disability in adults worldwide, with 90% of survivors having residual deficits. The pathophysiology of stroke is complex and involves a strong inflammatory response associated with oxidative stress and activation of several proteolytic enzymes. The current study was designed to investigate the effect of arginase inhibitors (L-citruline and L-ornithine) against ischemic stroke induced in rats by middle cerebral artery occlusion (MCAO). MCAO resulted in alteration in rat behavior, brain infarct, and edema associated with disruption of the blood-brain barrier (BBB). This was mediated through overexpression of arginase I and II, inducible NOS (iNOS), malondialdehyde (MDA), advanced glycation end products (AGEs), TNF-α, and IL-1ß and downregulation of endothelial nitric oxide synthase (eNOS). Treatment with L-citruline and L-ornithine and the standard neuroprotective drug cerebrolysin ameliorated all the deleterious effects of stroke. These results indicate the possible use of arginase inhibitors in the treatment of stroke after suitable clinical trials are done.

Endoscopic Management of Chronic Frontal Sinusitis: Prospective Quality of Life Analysis.

BACKGROUND: Previous studies of endoscopic frontal sinus surgery have been primarily retrospective and focused on symptom relief only. OBJECTIVES: To prospectively assess the impact of endoscopic frontal sinus surgery on frontal sinus ostium patency and disease-specific quality of life as measured by the Rhinosinusitis Disability Index (RSDI). STUDY DESIGN: A 60-patient cohort with chronic frontal sinusitis (100 diseased frontal sinuses) was prospectively evaluated using the RSDI, computed tomography (CT) imaging, and endoscopic examination. Image-guided endoscopic frontal sinusotomy (Draf 2a) was performed in each case. Patients were assessed with RSDI and endoscopic assessment at least 6 months postoperatively. RESULTS: At a mean follow-up of 10 months, endoscopic assessment revealed patent frontal recesses in 90 of 100 frontal sinuses (90%), with significant improvement in the total RSDI score (41.98 ± 26.48 preoperatively to 17.15 ± 15.66 postoperatively) as well as each of its physical, emotional, and functional subscales from 16.3 ± 9.03, 12.23 ± 10.55, 13.45 ± 9.59 preoperatively to 5.95 ± 5.71, 5.55 ± 5.66, 5.65 ± 5.72 postoperatively, respectively. Similar improvement was seen in patients with asthma, polyps, and those undergoing revision sinus surgeries. CONCLUSIONS: With frontal recess mucosal preservation and meticulous postoperative endoscopic surveillance, endoscopic frontal sinusotomy results in high rates of frontal sinus ostium patency with significant improvement in quality of life.

Use of a Foley catheter balloon as a tool during endoscopic frontal sinus surgery in a resource-poor environment.

OBJECTIVE: This study aimed to evaluate the non-Food and Drug Administration-approved off-label use of a 10F Foley catheter as a tool during endoscopic frontal sinus surgery. METHOD: A cohort of 40 patients with chronic frontal rhinosinusitis was prospectively evaluated using the Sino-Nasal Outcome Test (SNOT-22), computed tomography (CT) imaging, and endoscopic examination. Endoscopic sinus surgery (ESS) was performed in the usual fashion, however, when approaching the frontal sinus, a 10F Foley catheter was inserted and the balloon inflated in the frontal outflow. Patients were assessed postoperatively with SNOT-22, CT imaging, and endoscopic assessment at 6 months. RESULTS: Successful intraoperative dilation of the frontal recess was achieved in 62 of 69 frontal sinuses (90%). No cerebrospinal fluid leak or orbital entry occurred. Six months postoperative, SNOT-22 scores showed significant improvement, whereas endoscopic assessment revealed patent frontal recess in 55 of 62 (89%) frontal sinuses. Computed tomography imaging was completed in 25 patients comprising 41 operated frontal sinuses with no mucosal thickening seen in 37 of 41 (90%). CONCLUSION: The 10F Foley catheter is an effective tool to dilate the frontal recess by compression of edema during ESS. It may be a safe and cost-effective alternative to high-cost commercially available sinus balloons, especially in resource-poor environments.