Tensile strength and failure load of sutures for robotic surgery.

BACKGROUND: Robotic surgical platforms have seen increased use among minimally invasive gastrointestinal surgeons (von Fraunhofer et al. in J Biomed Mater Res 19(5):595-600, 1985. doi: 10.1002/jbm.820190511 ). However, these systems still suffer from lack of haptic feedback, which results in exertion of excessive force, often leading to suture failures (Barbash et al. in Ann Surg 259(1):1-6, 2014. doi: 10.1097/SLA.0b013e3182a5c8b8 ). This work catalogs tensile strength and failure load among commonly used sutures in an effort to prevent robotic surgical consoles from exceeding identified thresholds. Trials were thus conducted on common sutures varying in material type, gauge size, rate of pulling force, and method of applied force. METHODS: Polydioxanone, Silk, Vicryl, and Prolene, gauges 5-0 to 1-0, were pulled till failure using a commercial mechanical testing system. 2-0 and 3-0 sutures were further tested for the effect of pull rate on failure load at rates of 50, 200, and 400 mm/min. 3-0 sutures were also pulled till failure using a da Vinci robotic surgical system in unlooped, looped, and at the needle body arrangements. RESULTS: Generally, Vicryl and PDS sutures had the highest mechanical strength (47-179 kN/cm2), while Silk had the lowest (40-106 kN/cm2). Larger diameter sutures withstand higher total force, but finer gauges consistently show higher force per unit area. The difference between material types becomes increasingly significant as the diameters decrease. Comparisons of identical suture materials and gauges show 27-50% improvement in the tensile strength over data obtained in 1985 (Ballantyne in Surg Endosc Other Interv Tech 16(10):1389-1402, 2002. doi: 10.1007/s00464-001-8283-7 ). No significant differences were observed when sutures were pulled at different rates. Reduction in suture strength appeared to be strongly affected by the technique used to manipulate the suture. CONCLUSIONS: Availability of suture tensile strength and failure load data will help define software safety protocols for alerting a surgeon prior to suture failure during robotic surgery. Awareness of suture strength weakening with direct instrument manipulation may lead to the development of better techniques to further reduce intraoperative suture breakage.

The Incidence of Urgent Tube Shunt Surgery for Diabetic Neovascular Glaucoma at a Tertiary Academic Medical Center.

Background: Diabetic neovascular glaucoma is a secondary glaucoma that may require immediate correction of elevated intraocular pressure to control pain and protect the optic nerve. While there is a seasonal trend to glucose levels, it is unknown if a seasonal trend exists for diabetic neovascular glaucoma. Objective: This study evaluates the incidence of urgent glaucoma tube shunt implantation in diabetic neovascular glaucoma in a tertiary academic referral center in Southern California. Methods: Electronic medical records were queried for urgent glaucoma tube shunt surgery from 2014 to 2021. The number of cases were separated by month of occurrence, and average hemoglobin A1c values were calculated per month. Data were analyzed via ANOVA tests and one-tailed t-tests. Results: A total of 127 cases were identified. The months of March and April contained the most cases averaging 3 and 2.75 cases, respectively. April had statistically significant higher case numbers than that of other months (P = .041). ANOVA tests excluding April showed no statistically significant difference between the remaining months (P = .901). Average hemoglobin A1c values were highest in the months of April and March at 9.8 and 9.6%, respectively. Conclusion: Emergency glaucoma tube shunt surgery for diabetic neovascular glaucoma occurs most frequently in April. This observation may provide insight into disease prevention through diabetes management and help improve surgical operations such that staffing and resources are allocated accordingly.

Progressive Flaccid Paraplegia in a Toddler due to Chiari Type I Malformation Complicated with Hydrocephalus and Syringomyelia. A Case Report.

Chiari malformation is a clinico-radiological entity defined by herniation of rhombencephalic structures through the foramen magnum. The most common type, Chiari I, involves herniation of the cerebellar tonsils specifically. We present the case of a 2-year-old with three weeks of progressive bilateral leg weakness, absent reflexes, and the inability to walk. The patient was found to have Chiari I with hydrocephalus and syringomyelia. This is the youngest patient reported in the literature presenting with a clinical picture of spinal shock. Early recognition of this entity allows for proper treatment and improved outcomes.