A Novel growth guidance system for early onset scoliosis: a preliminary in vitro study.

PURPOSE: The purpose of the study was to describe a novel growth guidance system, which can avoid metal debris and reduce the sliding friction forces, and test the durability and glidability of the system by in vitro test. METHOD: Two major modifications were made to the traditional Shilla system, including the use of ultra-high molecular weight polyethylene (UHMWPE) gaskets to avoid direct contact between the screw and rod, and polishing the surface of the sliding part of the rod. We tested the durability of the system by a fatigue test, which the samples were test on the MTS system for a 10 million cycle of a constant displacement. Pre and post-testing involved weighing the UHMWPE gaskets and observing the wear conditions. The sliding ability were measured by a sliding displacement test. The maximum sliding displacement of the system was measured after a 300 cycles of dynamic compressive loads in a sinusoidal waveform. RESULTS: After the fatigue test, all the UHMWPE gaskets samples showed some of the fretting on the edge of the inner sides, but its still isolated and avoided the friction between the screws and rods. There was no production of metallic fretting around the sliding screws and rods. The average wear mass of the UHMWPE gaskets was 0.002 ± 0.001 g, less than 1.7% of the original mass. In the sliding test, the novel growth guidance system demonstrated the best sliding ability, with an average maximum sliding distance(AMSD) of 35.75 ± 5.73 mm, significantly better than the group of the traditional Shilla technique(AMSD 3.65 ± 0.46 mm, P < 0.0001). CONCLUSION: In conclusion, we modified the Shilla technique and designed a novel growth guidance system by changing the friction interface of sliding screw and rod, which may significantly reduce the metallic debris and promote spine growth. The fatigue test and sliding dislocation test demonstrated the better durability and glidability of the system. An in vivo animal experiment should be performed to further verify the system.

Effects of Proline on Internal Friction in Simulated Folding Dynamics of Several Alanine-Based α-Helical Peptides.

We have studied in silico the effect of proline, a model cosolvent, on local and global friction coefficients in (un)folding of several typical alanine-based α-helical peptides. Local friction is related to dwell times of a single, ensemble-averaged hydrogen bond (HB) within each peptide. Global friction is related to energy dissipated in a series of configurational changes of each peptide experienced by increasing the number of HBs during folding. Both of these approaches are important in relation to future atomic force microscopic-based measurements of internal friction via force-clamp single-molecule force spectroscopy. Molecular dynamics (MD) simulations for six peptides, namely, ALA5, ALA8, ALA15, ALA21, (AAQAA)3, and H2N-GN(AAQAA)2G-COONH2, have been conducted at 2 and 5 M proline solutions in water. Using previously obtained MD data for these peptides in pure water as well as upgraded theoretical models, we obtained variations of local and global internal friction coefficients as a function of solution viscosity. The results showed the substantial role of proline in stabilizing the folded state and slowing the overall folding dynamics. Consequently, larger friction coefficients were obtained at larger viscosities. The local and global internal friction, i.e., respective, friction coefficients approximated to zero viscosity, was also obtained. The evolution of friction coefficients with viscosity was weakly dependent on the number of concurrent folding pathways but was rather dominated by a stabilizing effect of proline on the folded states. Obtained values of local and global internal friction showed qualitatively similar results and a clear dependency on the structure of the studied peptide.

From Admission to Discharge-A Total Friction Burn Review from a Single Institution.

While most friction burns are adequately managed in an outpatient setting, many may require hospital admission, operative excision, and extended care. To this day, there is a wide variance in friction burn management. Our goal is to review the etiology, management, and outcomes of such burns warranting hospitalization. We conducted a retrospective review of all friction burns admitted to a single, American Burn Association-verified burn center from January 1, 2016 to December 31, 2020. A total of 28 (34%) patients required surgery for their friction burns and 15 (18%) ultimately required a split-thickness skin graft. The mean number of operations was 2.4 (95% CI 1.6-3.1). Overall, the operative group was younger (29.9 vs 38.3 years, P = .026), more likely to have a concomitant traumatic brain injury (25% vs 7%, P = .027), and had a longer hospital length of stay (17.5 vs 3.9 days, P < .001). Both groups had a similar overall TBSA (8.5% vs 10.0%, P = .35), but the operative group had a larger surface area comprised of third-degree burns (3.05% vs 0.2%, P < .001). Overall, friction burns resulting in hospital admission are associated with high-energy traumatic mechanisms and concomitant injuries. Patients who need operative intervention for their burns typically require multiple procedures often culminating in a split-thickness skin graft. While non-operative management of friction burns with topical agents has been found to be successful, patients with higher injury severity scores should be monitored very closely as they may require surgical excision.

Influence of a single locking throw on the in vitro holding security of five friction throws.

OBJECTIVE: To compare the in vitro security of four different friction throws (square, surgeon's, Miller's, and strangle), with and without a locking throw, and a slip knot, on a vascular ligation model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Nine groups with nine samples per group. METHODS: Four throws (square, surgeon's, Miller's, and strangle), with and without a locking throw, and a square throw locked in slip knot fashion, were tested to measure leakage pressure. RESULTS: The square and surgeon's throws leaked at a lower pressure than the Miller's and strangle throws (p < .0001). The leakage pressure was below physiologic arterial pressure for the square and the surgeon's throws. After the addition of a locking throw, the five knots leaked at a similar pressure (p = .5233) above physiologic arterial pressure. CONCLUSION: Following the addition of a locking throw, all the constructs tested in this study leaked at a similar pressure. The leakage pressure for all knots exceeded physiologic arterial pressures. CLINICAL SIGNIFICANCE: Any throw tested may be appropriate for secure vascular ligation if the initial throw is applied correctly.

Friction Dynamics of Human Skin Treated with Oil under Nonlinear Motion.

Moisturization causes physiological changes that improve the barrier function of human skin and mechanical changes, including skin friction characteristics. This study evaluated petrolatum- or silicone oil-treated human skin to determine the effect of moisturizing on the friction dynamics. The friction force on the human skin was measured using a contact probe with a sinusoidal motion. The contact probe was used to rub the skin of the upper arm of 20 subjects. The water content of the stratum corneum, softness, and barrier function of the skin were measured using a corneometer, cutometer, and tewameter, respectively. Both oils reduce the frictional force on the human skin. Simultaneously, silicone oil also reduced the delay time δ, which is the standardized time difference between the frictional force response to contact probe movement. Three typical friction patterns were also discovered, which were significantly changed by the treatment with oil. These changes were attributed to the lubrication effect and elimination of adhesion at the true contact point between the skin and the contact probe.

Study of Tissue Damage Induced by Insertion of Composite-Coated Needle.

Medical interventions have significantly progressed in developing minimally invasive techniques like percutaneous procedures. These procedures include biopsy and internal radiation therapy, where a needle or needle-like medical device is inserted through the skin to access a target inside the body. Ensuring accurate needle insertion and minimizing tissue-damage or cracks are critical in these procedures. This research aims to examine the coated needle effect on the force required to insert the needle (i.e., insertion force) and on tissue-damage during needle insertion into the bovine kidney. Reducing the needle insertion force, which is influenced by needle surface friction, generally results in a reduction in tissue-damage. Surgical needles were coated with a composite material, combining Polytetrafluoroethylene, Polydopamine, and Activated Carbon. Force measurement during needle insertion and a histological study to determine tissue-damage were conducted to evaluate the effectiveness of the coating. The insertion force was reduced by 49 % in the case of the coated needles. Furthermore, a histological analysis comparing tissue-damage resulting from coated and uncoated needles revealed an average 39 % reduction in tissue-damage with the use of coated needles. The results of this study demonstrate the potential of coated needles to enhance needle insertion and safety during percutaneous procedures.

Fabrication of a novel aesthetic orthodontic bracket and evaluation of friction properties between PEEK and stainless steel wires.

BACKGROUND: Polyetheretherketone (PEEK) is a polyaromatic semi-crystalline thermoplastic polymer with mechanical and lubrication properties favorable for biomedical applications. Despite of its aesthetic appearance, ceramic brackets are unsatisfactory in brittleness and thickness, while PEEK is a potential material for aesthetic orthodontic brackets. OBJECTIVE: To fabricate a novel aesthetic orthodontic bracket and evaluate friction properties of PEEK and stainless steel wires. METHODS: All polyether ether ketone (PEEK) and ceramic samples disks were made into disks (diameter, 5 mm; thickness, 2 mm). The tested surfaces of PEEK were ground with #600, #800 and #1200 SiC papers, followed by polishing with Sof-Lex kit (3M ESPE, USA). The surface roughness was tested using a laser profilometer device (VK-X200, Keyence, Japan). The COFs of the specimens and stainless steel (SS) archwires were tested using a Universal Micro-Tribotester (UMT-3, Bruker, USA). The wear scratches on the materials' surfaces were examined by using a scanning electron microscope (SEM) (Hitachi SU8010). The elastic modulus and hardness of samples were examined with a nano-indenter (XP, Keysight Technologies, USA). RESULTS: The mean surface roughness of PEEK and Ceramic are 0.320 ± 0.028 µm and 0.343 ± 0.044 µm, respectively. PEEK has a lower Friction coefficient than Ceramic and the difference between the two groups was statistically significant (P< 0.05). The abrasive wear of Ceramic was the main wear style and was characterized by the observation of chipping fractures, while PEEK surface looked smooth without obvious scale-like desquamations and granular debris, indicating adhesive wear. CONCLUSION: Within the limitations of the present study, PEEK shows lower coefficient of friction than ceramic. PEEK has excellent properties such as low friction coefficient, smooth surface and good mechanical properties, and thus meets the requirements for orthodontic brackets. It is considered as a potential bracket material with both low friction and aesthetic performance.

Physically cross-linked organo-hydrogels for friction interfaces in joint replacements: design, evaluation and potential clinical applications.

This paper investigates physically crosslinked organo-hydrogels for total hip replacement surgery. Current materials in artificial joints have limitations in mechanical performance and biocompatibility. To overcome these issues, a new approach based on hydrogen bonds between polyvinyl alcohol, poly(2-hydroxyethyl methacrylate), and glycerin is proposed to develop bioactive organo-hydrogels with improved mechanical properties and biocompatibility. This study analyzes local pathological characteristics, systemic toxicity, and mechanical properties of the gels. The results show that the gels possess excellent biocompatibility and mechanical strength, suggesting their potential as an alternative material for total hip replacement surgery. These findings contribute to improving patient outcomes in joint replacement procedures.

Outcome of lateral retinacular nerve transection combined with release for recalcitrant iliotibial band friction syndrome.

In this retrospective study, a technique consisting in neurolysis of the lateral retinacular nerve combined with a partial release through elliptic excision of the iliotibial band (ITB) is evaluated for efficacy in recalcitrant ITB friction syndrome and compared with results from other techniques reported in literature. From April 2014 to December 2017, 21 patients suffering from recalcitrant ITB friction syndrome were surgically treated with the aforementioned technique. 15 patients (15 knees) were available for a written retrospective reassessment after completion of a follow-up period of at least 12 months. Residual pain was scored using the Visual Analogue Scale (VAS). The functional outcome was evaluated by two patient reported outcome measurement scales (PROMs), the Lysholm and the International Knee Documentation Committee (IKDC) score. Return to sport was analysed by duration of the inactivity period as well as by the Tegner score. Overall satisfaction was evaluated using a modified Boyden scale. At final follow-up of one year, the performed intervention resulted in a pain reduction (VAS 4.2 (1-8) to 1.4 (0-6)) and improved knee function (Lysholm 59.53 to 87.73, IKDC 75) with return to sport (Tegner 4.3 to 5.4) after a median of 23.8 weeks (6 to 52). Twelve patients reported good or excellent results (80%) at final follow-up, and 12 patients (80%) would undergo surgery again, if necessary. The treatment of recalcitrant ITB friction syndrome by combining neurectomy of the lateral retinacular nerve with elliptic excision of the ITB resulted in good to excellent results in 80% of treated cases with return to sport in 93%.

Impact of hyaluronic acid injection on the knee joint friction.

PURPOSE: The purpose of this in vitro study was to investigate whether or not hyaluronic acid supplementation improves knee joint friction during osteoarthritis progression under gait-like loading conditions. METHODS: Twelve human cadaveric knee joints were equally divided into mild and moderate osteoarthritic groups. After initial conservative preparation, a passive pendulum setup was used to test the whole joints under gait-like conditions before and after hyaluronic acid supplementation. The friction-related damping properties given by the coefficient of friction µ and the damping coefficient c (in kg m2/s) were calculated from the decaying flexion-extension motion of the knee. Subsequently, tibial and femoral cartilage and meniscus samples were extracted from the joints and tested in an established dynamic pin-on-plate tribometer using synthetic synovial fluid followed by synthetic synovial fluid supplemented with hyaluronic acid as lubricant. Friction was quantified by calculating the coefficient of friction. RESULTS: In the pendulum tests, the moderate OA group indicated significantly lower c0 values (p < 0.05) under stance phase conditions and significantly lower µ0 (p = 0.01) values under swing phase conditions. No degeneration-related statistical differences were found for µend or cend. Friction was not significantly different (p > 0.05) with regard to mild and moderate osteoarthritis in the pin-on-plate tests. Additionally, hyaluronic acid did not affect friction in both, the pendulum (p > 0.05) and pin-on-plate friction tests (p > 0.05). CONCLUSION: The results of this in vitro study suggested that the friction of cadaveric knee joint tissues does not increase with progressing degeneration. Moreover, hyaluronic acid viscosupplementation does not lead to an initial decrease in knee joint friction.

Design and Evaluation of a Balanced Compliant Laparoscopic Grasper.

In laparoscopic surgery, quality of haptic feedback is reduced compared to conventional surgery, leading to unintentional tissue damage during grasping. From the perspective of haptics, poor mechanical design of laparoscopic instrument joints induces friction and a nonlinear actuation-tip force relation. In this study, a novel laparoscopic grasper using compliant joints and a magnetic balancer is presented, and the reduction in hysteresis and friction is evaluated. The hysteresis loop of the novel compliant grasper and two conventional laparoscopic graspers (high quality leading commercial brand and low quality unbranded grasper) were measured. In order to assess quality of haptic feedback, the lowest grasper tip load perceivable by instrument users was measured with the novel and the conventional laparoscopic graspers. The hysteresis loop measurement yielded a mechanical efficiency of 43% for the novel grasper, compared to- 25% and 23% for the Aesculap and the unbranded grasper, respectively. The forces perceivable by the user through the novel grasper were significantly lower (mean 1.37N, SD 0.44N) than those of conventional graspers (mean 2.15N, SD 0.71N and mean 2.65N, SD 1.20N, respectively). The balanced compliant grasper technology has the ability to improve the quality of haptic feedback compared to conventional laparoscopic graspers. Research is needed to relate these results to soft and delicate tissue grasping in a clinical setting, for which this instrument is intended.

Comparison of stainless steel and titanium-molybdenum alloy closing loop archwires using numeric simulation model based on finite element method.

INTRODUCTION: The objective of this study was to determine and compare the moment-to-force (Mc/F) ratio and the type of tooth movement generated in the anterior and posterior segments in orthodontic space closure with stainless steel and titanium-molybdenum alloy loop archwires. METHODS: Three-dimensional model of the maxilla from which the first premolar was extracted, 18 × 25-mil slot stainless steel brackets, and 16 × 22-mil stainless steel and ß titanium-molybdenum alloy (TMA) closing loop archwires with anterior gable bend of 15° and posterior gable bend of 25° were constructed. The archwires were engaged in the brackets, and 1-mm activations were carried out, which were repeated 5 times. The anterior and posterior segment Mc/F ratio and the type of tooth movement generated by the 2 wires were compared. RESULTS: It was found that the Mc/F ratio for the anterior segment was approximately 5 mm, and for posterior teeth was approximately 10 mm for both stainless steel and TMA closing loop archwire. The anterior teeth exhibited controlled tipping, whereas the posterior teeth showed bodily tooth movement, which was in accordance with the Mc/F ratio that was obtained. CONCLUSIONS: The Mc/F ratio and the type of tooth movement exhibited by stainless steel and TMA closing loop archwires were similar in both anterior and posterior segments.

Lesiones cervicales no cariosas: una revisión sistemática / Non carious cervical lesions: a systematic review

Introducción: las lesiones cervicales no cariosas (NCCL, por sus siglas en inglés) son un grupo de lesiones que afectan el área cervical del órgano dental causando hipersensibilidad dentinaria y defectos estéticos. Objetivo: analizar la literatura sobre las lesiones cervicales no cariosas, su etiología, consideraciones anatómicas, características morfológicas de la lesión y tratamientos no restaurativos. Material y métodos: se realizó una búsqueda en la base de datos PubMed, utilizando las palabras clave: non-carious cervical lesions OR noncarious cervical lesions OR tooth wear OR tooth erosion OR dental abfraction OR abfraction, recopilando un total de 78 artículos. Resultados: es necesario determinar la etiología antes de seleccionar las estrategias de tratamiento para las lesiones cervicales no cariosas. Conocer los distintos tipos de tejidos que componen al órgano dentario facilita la comprensión de los factores que participan en el desarrollo de las lesiones cervicales no cariosas. Esto permite que el tratamiento se enfoque más en la causa del problema que en los síntomas. Con esto podemos modificar diversos factores de manera interceptiva, los tratamientos de terapia con láser y compuestos tópicos son una estrategia mínimamente invasiva. Conclusiones: la mejor manera de describir a las lesiones cervicales no cariosas sería como una enfermedad multifactorial. Se debe prestar especial atención en los métodos de diagnóstico, identificando cofactores que propicien el avance de la lesión, como son la fricción y la biocorrosión. Esta revisión brinda datos que asocian a los factores oclusales como una de las principales causas de una enfermedad que afecta a más de la mitad de la población adulta (AU)

Introduction: non-carious cervical lesions (NCCL) are a group of lesions that affect the cervical area of the dental organ causing dentin hypersensitivity and cosmetic defects. Objective: to know, through a systematic review, the current state of non-carious cervical lesions. Material and methods: a search was conducted in the PubMed database, using the keywords: non-carious cervical lesions OR noncarious cervical lesions OR tooth wear OR tooth erosion OR dental abfraction OR abfraction, compiling a total of 78 articles. Results: determining etiology is necessary before selecting treatment strategies for non-carious cervical lesions (NCCL). Know the different types of tissues that make up the dentary organ, facilitate the understanding of the factors involved in the development of noncarious al cervical lesions. This allows treatment to focus more on the cause of the problem than on symptoms. With this we can modify various factors in an interceptive way, laser therapy treatments and topical compounds, are a minimally invasive strategy. Conclusions: the best way to describe non-carious al cervical lesions would be as a multifactorial disease to which special attention should be paid to both diagnostic methods, identifying cofactors that promote the progression of injury, such as friction and biocorrosion. This review provides data that associates occlusal factors as one of the main causes of a disease that affects more than half of the adult population (AU)

Feasibility of orbital friction stir welding on clad pipes of API X65 steel and Inconel 625.

Orbital friction stir welding (FSW) has been applied to clad pipes, which is certainly of interest to the oil and gas industry. In this context, an FSW system capable of performing sound joints in one pass with full tool penetration was developed. Orbital FSW was executed in 6 mm thick API X65 PSL2 steel clad pipes with 3 mm thick Inconel 625 using a polycrystalline cubic boron nitride (pcBN) tool. The metallurgical and mechanical properties of the joints were investigated. Sound joints with axial forces of 45-50 kN, tool rotational speeds of 400-500 rpm, and a welding speed of 2 mm/s were obtained, illustrating that the developed system can perform FSW joints without volumetric defects.

Effects of the surface layer of steel samples after ball burnishing on friction and wear in dry reciprocating sliding.

The effects of ball burnishing on tribological behaviour in dry reciprocating motion have not yet been studied. This work attempts to fill this gap. The steel disc samples after milling were ball burnished. Due to ball burnishing, the average surface height decreased to 85% and the microhardness increased to 20%. Burnishing also generated the compressive residual stresses that were responsible factor to enhance the hardness of the steel surface. Trbological tests were carried out in reciprocating motion under dry sliding conditions. A 10 mm diameter ceramic ball from WC material contacted the steel disc. Ball burnishing was found to lead to improvements in disc wear and friction of the sliding pair. The maximum decreases in friction coefficient and wear volume compared to the milled sample were 39% and 85%, respectively. Samples of the lowest amplitude and high microhardness led to the highest behaviour.

MXene/graphene oxide nanocomposites for friction and wear reduction of rough steel surfaces.

Development of solid lubricant materials that render reliable performance in ambient conditions, are amenable to industrial size and design complexities, and work on engineered surfaces is reported. These coatings are composed of Ti3C2Tx-Graphene Oxide blends, spray-coated onto bearing steel surfaces. The tribological assessment was carried out in ambient environmental conditions and high contact pressures in a ball-on-disc experimental set-up. The evaluation yielded that the use of Ti3C2Tx-Graphene-Oxide coatings led to substantial reduction in friction down to 0.065 (at 1 GPa contact pressure and 100 mm/s) in comparison to the uncoated of single-component-coated surfaces, surpassing the state-of-the-art. The coatings also provided excellent protection against wear loss of the substrate and counter-face. The results were explained based on the observations from Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and nanoindentation measurements. In operando formation of a dense, hard and stiff, dangling-bond-saturated tribolayer was observed to be the reason for the sustained lubricity even at high test loads and sliding speeds. This report presents the holistic exploration and correlation of structure-property-processing pertaining to the advancement of solid lubrication science.

Bioinspired medical needles: a review of the scientific literature.

Needles are commonly used in medical procedures. However, current needle designs have some disadvantages. Therefore, a new generation of hypodermic needles and microneedle patches drawing inspiration from mechanisms found in nature (i.e. bioinspiration) is being developed. In this systematic review, 80 articles were retrieved from Scopus, Web of Science, and PubMed and classified based on the strategies for needle-tissue interaction and propulsion of the needle. The needle-tissue interaction was modified to reduce grip for smooth needle insertion or enlarge grip to resist needle retraction. The reduction of grip can be achieved passively through form modification and actively through translation and rotation of the needle. To enlarge grip, interlocking with the tissue, sucking the tissue, and adhering to the tissue were identified as strategies. Needle propelling was modified to ensure stable needle insertion, either through external (i.e. applied to the prepuncturing movement of the needle) or internal (i.e. applied to the postpuncturing movement of the needle) strategies. External strategies include free-hand and guided needle insertion, while friction manipulation of the tissue was found to be an internal strategy. Most needles appear to be using friction reduction strategies and are inserted using a free-hand technique. Furthermore, most needle designs were inspired by insects, specifically parasitoid wasps, honeybees, and mosquitoes. The presented overview and description of the different bioinspired interaction and propulsion strategies provide insight into the current state of bioinspired needles and offer opportunities for medical instrument designers to create a new generation of bioinspired needles.

Novel oral microscope gives mechanistic insights into colloidal drivers of friction in oral biofilms.

Texture and mouthfeel are central to the sensory enjoyment of food and beverages. Yet our incomplete understanding of how food boluses are transformed in the mouth limits our texture prediction ability. As well as thin film tribology, the interaction of food colloids with the oral tissue and salivary biofilms plays a key role in texture perception via mechanoreceptors in the papillae. In this study we describe the development of an oral microscope capable of quantitative characterization of the inactions of food colloids with papillae and their concurrent saliva biofilm. We also highlight how the oral microscope revealed key microstructural drivers of several topical phenomena (oral residue formation, coalescence in-mouth, grittiness of protein aggregates and finally microstructural origin of polyphenol astringency) in the domain of texture creation. The coupling of a fluorescent food grade dye with image analysis enabled specific and quantitative determination of the microstructural changes in mouth. Emulsions either underwent no aggregation, small aggregation, or extensive aggregation depending on whether their surface charge facilitated complexation with the saliva biofilm. Quite surprisingly cationic gelatin emulsions that were already aggregated with saliva in mouth underwent coalescence if subsequently exposed to tea polyphenols (EGCG). Large protein aggregates were found to aggregate with the saliva coated papillae, increasing their size tenfold and possibly explaining why there are perceived as gritty. An exciting observation was the oral microstructural changes that occurred upon exposure to tea polyphenols (EGCG). Filiform papillae shrunk, and the saliva biofilm was seen to precipitate/collapse, exposing a very rough tissue surface. These tentative early steps are the first in vivo microstructural insights into the different food oral transformations that are drivers of key texture sensation.

Research on force and position control performance of the tendon sheath system with time-varying parameters and flexible robotic arms.

BACKGROUND: The tendon-sheath-system (TSS) is an excellent medium for remote power transmission, which is widely used in laparoscopic surgery robots. Since the operation process requires the robot to move continuously, this time-varying characteristic further aggravates the force and position transmission loss caused by the nonlinear friction of TSS, which affects the control accuracy of the surgical robot. METHOD: A time-varying tendon-sheath transmission model (RT model) is proposed. A feedforward control system is designed to improve tendon-sheath transmission accuracy. Furthermore, a tendon-sheath transmission model with velocity characteristics (RV model) is established. RESULT: Force, position, and velocity experiments were carried out on the platform of TSS with a robotic arm. The results show that the R-square values of force and position compensation are at least 96.57% and 99.16%. CONCLUSION: The proposed RT and RV models are effective in compensating for the TSS transmission loss during the operation of the surgical robot.