1.Extra-anatomical veno-venous surgical bypass for central vein occlusion in patients with ipsilateral arterio-venous fistula (AVF) for haemodialysis - A single centre experience
Saravana Kumar Selvanathan ; Zainal Ariffin Azizi
The Medical Journal of Malaysia 2017;72(1):3-6
Objective: Central vein occlusion is a common complication
related to central vein catheter insertion for haemodialysis
which can be unmasked by an ipsilateral fistula creation,
leading to a dysfunctional arteriovenous fistula (AVF). We
describe an extra-anatomical venous bypass surgical
procedure performed to maintain vascular access and
reduce the symptoms of swelling of the ipsilateral upper
limb, neck and face.
Materials and Methods: We report 20 consecutive patients
with end-stage renal failure (ESRF) who had central vein
occlusion and were not amenable to endovascular
intervention. They underwent extra-anatomical vein to vein
surgical bypass. The axillary and iliac or femoral veins were
approached via infraclavicular and extraperitoneal groin
incisions respectively. In all the patients, an externally
supported 6 or 8 mm polytetrafluoroethylene (PTFE) graft
was used as a conduit and was tunnelled extra-anatomical.
All patients had double antiplatelet (Aspirin and Clopidogrel)
therapy post-operatively.
Results: Substantial improvement in the facial, neck and
upper limb swelling was noticed following this diversion
surgery. The vein to vein bypass was patent at 12 months in
10 out of 20 patients. Graft infection occurred in two (10%)
cases. Re-thrombectomy or assisted patency procedure
(stent/plasty) was done in four (20%) cases. The patients
with preoperative fistula flow rate of more than 1500 ml/min
and post-operative graft flow rate of more than a 1000 ml/min
were patent at 12 months (P=0.025 and p=0.034
respectively).
Conclusion. Axillary to iliac/femoral vein bypass can salvage
functioning ipsilateral fistula threatened by occluded upper
central vein and relieve their upper limb obstructive venous
symptoms.
2.Evaluation of antiviral and cytotoxic activities of methanolic extract of S. grandiflora (Fabaceae) flowers
Arthanari Kumar Saravana ; Vanitha Jayachandran ; Ganesh Mani ; Venkateshwaran Krishnasamy ; Clercq De
Asian Pacific Journal of Tropical Biomedicine 2012;(z2):855-858
Objective: To investigate the cytotoxicity and antiviral activity of methanolic extract of S.grandiflora flowers using different cell lines and viruses. Methods: The methanolic flower extracts were prepared and evaluated for their antiviral and cytotoxic activities using viruses like herpes simplex-1 and 2, vaccinia, vesicular stomatitis, cox sackie, respiratory syncytical, feline corona, feline herpes, para influenza, reo-1, sindbis and punta toro viruses in different cell lines, like Hel, HeLa, Crandell Reus feline kidney and Vero cell cultures. Results: Among the viruses used the extract possessed strongest antiviral activity against herpes simplex 1 and 2, repiratory syncytical, para influenza, reo, sindbis, cox sackie and punta toro viruses that was (EC50=20 μg/mL and 45 μg/mL) and moderate activity for remaining viruses (EC50= 100 μg/mL). The antiviral activities assessed by calculating the selectivity index may be due to the presence of flavonoids in the extracts there by inhibit the virus cell fusion in the early and replication stages. The cytotoxicity effect was evaluated using MTT assay and the results revealed that the extracts exhibited cytotoxicity from the range of 20 to 100 μg/mL. Conclusions: Present results confirmed that the S. grandiflora used as a good antimicrobial agent in future.
3.Comparative Analysis of Effect of Density, Insertion Angle and Reinsertion on Pull-Out Strength of Single and Two Pedicle Screw Constructs Using Synthetic Bone Model.
Venkatesh KRISHNAN ; Vicky VARGHESE ; Gurunathan Saravana KUMAR
Asian Spine Journal 2016;10(3):414-421
STUDY DESIGN: Biomechanical study. PURPOSE: To determine the effect of density, insertion angle and reinsertion on pull-out strength of pedicle screw in single and two screw-rod configurations. OVERVIEW OF LITERATURE: Pedicle screw pull-out studies have involved single screw construct, whereas two screws and rod constructs are always used in spine fusions. Extrapolation of results using the single screw construct may lead to using expensive implants or increasing the fusion levels specifically in osteoporotic bones. METHODS: Single screw and two screw pull-out strength tests were carried out according to American Society for Testing and Materials F 543-07 on foam models to test the effect of density, insertion angle and reinsertion using poly axial pedicle screws. RESULTS: Bone density was the most significant factor deciding the pull-out strength in both single and two screw constructs. The difference in pull-out strength between single screw and two screw configurations in extremely osteoporotic bone model (80 kg/m3) was 78%, whereas in the normal bone model it was 48%. Axial pull-out value was highest for the single screw configuration; in the two screw configuration the highest pull-out strength was at 10°-15°. There was an 18% reduction in pull-out strength due to reinsertion in single screw configuration. The reinsertion effect was insignificant in the two screw configuration. CONCLUSIONS: A significant difference in response of various factors on holding power of pedicle screw between single and two-screw configurations is evident. The percentage increase in pull-out strength between single and two screw constructs is higher for osteoporotic bone when compared to normal bone. Reinsertion has no significant effect on pull-out strength in the two screw rod configuration.
Bone Density
;
Osteoporosis
;
Pedicle Screws*
;
Spine
4.Comparative Analysis of Effect of Density, Insertion Angle and Reinsertion on Pull-Out Strength of Single and Two Pedicle Screw Constructs Using Synthetic Bone Model.
Venkatesh KRISHNAN ; Vicky VARGHESE ; Gurunathan Saravana KUMAR
Asian Spine Journal 2016;10(3):414-421
STUDY DESIGN: Biomechanical study. PURPOSE: To determine the effect of density, insertion angle and reinsertion on pull-out strength of pedicle screw in single and two screw-rod configurations. OVERVIEW OF LITERATURE: Pedicle screw pull-out studies have involved single screw construct, whereas two screws and rod constructs are always used in spine fusions. Extrapolation of results using the single screw construct may lead to using expensive implants or increasing the fusion levels specifically in osteoporotic bones. METHODS: Single screw and two screw pull-out strength tests were carried out according to American Society for Testing and Materials F 543-07 on foam models to test the effect of density, insertion angle and reinsertion using poly axial pedicle screws. RESULTS: Bone density was the most significant factor deciding the pull-out strength in both single and two screw constructs. The difference in pull-out strength between single screw and two screw configurations in extremely osteoporotic bone model (80 kg/m3) was 78%, whereas in the normal bone model it was 48%. Axial pull-out value was highest for the single screw configuration; in the two screw configuration the highest pull-out strength was at 10°-15°. There was an 18% reduction in pull-out strength due to reinsertion in single screw configuration. The reinsertion effect was insignificant in the two screw configuration. CONCLUSIONS: A significant difference in response of various factors on holding power of pedicle screw between single and two-screw configurations is evident. The percentage increase in pull-out strength between single and two screw constructs is higher for osteoporotic bone when compared to normal bone. Reinsertion has no significant effect on pull-out strength in the two screw rod configuration.
Bone Density
;
Osteoporosis
;
Pedicle Screws*
;
Spine
5.Identification of Pedicle Screw Pullout Load Paths for Osteoporotic Vertebrae
Venkatesh KRISHNAN ; Vicky VARGHESE ; Gurunathan Saravana KUMAR ; Narayan YOGANANDAN
Asian Spine Journal 2020;14(3):273-279
Results:
Pullout strength decreased by 36% when the size of the revision screw was increased by 1 mm, while it increased by 35% when the size of the revision screw was increased by 2 mm compared to the index screw value. While the morphologies of the load paths were similar in all cases, they differ between the two groups: the larger screw responded with generally elevated stiffer path than the smaller screw, suggesting that revision surgery using a larger screw has more purchase along the inserted body-pedicle axis.
Conclusions
A larger screw enhances strength and increases biomechanical stability in revision surgeries, although the final surgical decision is made by the clinician, which includes the patient’s anatomy and associated characteristics.
6.Rare Isolated Jejunal Injury Following Blunt Abdominal Trauma
Anurag ROY ; Arun Kumar M ; Kshitij JYOTI ; A Saravana SANTHOSH ; Vitesh POPLI
Journal of Acute Care Surgery 2024;14(3):122-125
Blunt trauma to the abdomen can result in various injuries which are potentially fatal if not promptly recognized and treated. Mechanism of injury, anatomical location, patient demographics, and clinical profile play crucial roles in diagnosis and management. The article presents 2 cases illustrating the challenges, and successful management of isolated jejunal injuries, and highlight the significance of early recognition and surgical intervention. These injuries are rare and there needs to be a high index of suspicion, especially in cases with atypical presentation. The cases in this article underscore the critical role of early surgical intervention in achieving optimal recovery and reducing the morbidity and mortality associated with isolated jejunal injuries. Clinicians need to consider the possibility of small bowel perforation following apparently trivial injuries, and employ a comprehensive approach to managing abdominal trauma.
7.Rare Isolated Jejunal Injury Following Blunt Abdominal Trauma
Anurag ROY ; Arun Kumar M ; Kshitij JYOTI ; A Saravana SANTHOSH ; Vitesh POPLI
Journal of Acute Care Surgery 2024;14(3):122-125
Blunt trauma to the abdomen can result in various injuries which are potentially fatal if not promptly recognized and treated. Mechanism of injury, anatomical location, patient demographics, and clinical profile play crucial roles in diagnosis and management. The article presents 2 cases illustrating the challenges, and successful management of isolated jejunal injuries, and highlight the significance of early recognition and surgical intervention. These injuries are rare and there needs to be a high index of suspicion, especially in cases with atypical presentation. The cases in this article underscore the critical role of early surgical intervention in achieving optimal recovery and reducing the morbidity and mortality associated with isolated jejunal injuries. Clinicians need to consider the possibility of small bowel perforation following apparently trivial injuries, and employ a comprehensive approach to managing abdominal trauma.
8.Rare Isolated Jejunal Injury Following Blunt Abdominal Trauma
Anurag ROY ; Arun Kumar M ; Kshitij JYOTI ; A Saravana SANTHOSH ; Vitesh POPLI
Journal of Acute Care Surgery 2024;14(3):122-125
Blunt trauma to the abdomen can result in various injuries which are potentially fatal if not promptly recognized and treated. Mechanism of injury, anatomical location, patient demographics, and clinical profile play crucial roles in diagnosis and management. The article presents 2 cases illustrating the challenges, and successful management of isolated jejunal injuries, and highlight the significance of early recognition and surgical intervention. These injuries are rare and there needs to be a high index of suspicion, especially in cases with atypical presentation. The cases in this article underscore the critical role of early surgical intervention in achieving optimal recovery and reducing the morbidity and mortality associated with isolated jejunal injuries. Clinicians need to consider the possibility of small bowel perforation following apparently trivial injuries, and employ a comprehensive approach to managing abdominal trauma.
9.A novel pedicle screw design to maximize screw-bone interface strength using finite element analysis and design of experiment techniques
Arvind Kumar PRAJAPATI ; Parimanathukovilakom Ramavarma HARIKRISHNA VARMA ; Gurunathan SARAVANA KUMAR ; Chirathody Vayalappil MURALEEDHARAN ; Ganesh DIVAKAR
Asian Spine Journal 2024;18(6):765-776
Methods:
We conceptualized a novel pedicle screw considering vertebral bone morphology and strength differences. A validated FE model was developed and used in conjunction with DoE to determine the screw՚s optimum geometrical parameters. The FE model was validated through simulation and laboratory experiments using the control device. The optimized thread profiles for cortical bone and cancellous bone were determined, with pull-out force as the primary factor for screw design evaluation.
Results:
FE analysis results for the control device closely matched experimental results, with less than 5% difference. The chosen unique pitch/depth ratio showed maximum pull-out force for cortical bone, while DoE enabled the optimization of design parameters for cancellous bone. The optimized pedicle screw exhibited a 15% increase in pull-out force compared to the control device.
Conclusions
The study proposes a novel pedicle screw design with better pull-out strength than the control device. Combining FE analysis with DoE is an effective approach for screw design optimization, reducing the need for extensive prototyping tests. A two-variable analysis suffices for optimizing cortical bone design parameters, while a multi-variable analysis is more effective for optimizing cancellous bone design parameters.
10.A novel pedicle screw design to maximize screw-bone interface strength using finite element analysis and design of experiment techniques
Arvind Kumar PRAJAPATI ; Parimanathukovilakom Ramavarma HARIKRISHNA VARMA ; Gurunathan SARAVANA KUMAR ; Chirathody Vayalappil MURALEEDHARAN ; Ganesh DIVAKAR
Asian Spine Journal 2024;18(6):765-776
Methods:
We conceptualized a novel pedicle screw considering vertebral bone morphology and strength differences. A validated FE model was developed and used in conjunction with DoE to determine the screw՚s optimum geometrical parameters. The FE model was validated through simulation and laboratory experiments using the control device. The optimized thread profiles for cortical bone and cancellous bone were determined, with pull-out force as the primary factor for screw design evaluation.
Results:
FE analysis results for the control device closely matched experimental results, with less than 5% difference. The chosen unique pitch/depth ratio showed maximum pull-out force for cortical bone, while DoE enabled the optimization of design parameters for cancellous bone. The optimized pedicle screw exhibited a 15% increase in pull-out force compared to the control device.
Conclusions
The study proposes a novel pedicle screw design with better pull-out strength than the control device. Combining FE analysis with DoE is an effective approach for screw design optimization, reducing the need for extensive prototyping tests. A two-variable analysis suffices for optimizing cortical bone design parameters, while a multi-variable analysis is more effective for optimizing cancellous bone design parameters.