Surgical outcomes of robotic thyroidectomy for thyroid tumors over 4 cm via the bilateral axillo-breast approach.

The study investigated the feasibility of robotic bilateral axillo-breast approach (BABA) thyroidectomy for patients with thyroid tumors larger than 4 cm. BABA thyroidectomy has previously shown safety and effectiveness for thyroid surgeries but lacked extensive data on its application to larger tumors. Between October 2008 and August 2022, there were 74 patients underwent robotic BABA thyroidectomy due to thyroid nodules exceeding 4 cm in size. The mean patient age was 40.3 years. Fine needle aspiration results classified the tumors as benign (50.0%), atypia of undetermined significance (27.0%), follicular neoplasm (16.2%), suspicious for malignancy/malignancy (5.4%), or lymphoma (1.4%). The average tumor size was 4.9 cm, with the majority (85.1%) undergoing thyroid lobectomy, and the rest (14.9%) receiving total thyroidectomy. The mean total operation time was 178.4 min for lobectomy and 207.3 min for total thyroidectomy. Transient vocal cord palsy (VCP) was found in 3 patients (4.1%), and there was no permanent VCP. Among patients who underwent total thyroidectomy, transient hypoparathyroidism was observed in three (27.2%), and permanent hypoparathyroidism was observed in one (9.1%). There were no cases of open conversion, tumor spillage, bleeding, flap injury, or tumor recurrence. In conclusion, robotic BABA thyroidectomy may be a safe treatment option for large-sized thyroid tumors that carries no significant increase in complication rates.

Outcomes of bilateral axillo-breast approach robotic parathyroidectomy versus open parathyroidectomy for primary hyperparathyroidism: a single-institution retrospective study.

Purpose: Bilateral axillo-breast approach robotic parathyroidectomy (BABA-RP) aims to remove overactive or enlarged parathyroid glands with no visible neck collar incision. In this study, we compared the safety and surgical outcomes of BABA-RP vs. those of an open surgery group to ascertain whether BABA-RP is a safe and feasible surgical approach for patients with primary hyperparathyroidism (pHPT). Methods: This single-institution retrospective cohort study included 74 patients with primary HPT who underwent open parathyroidectomy (n = 37) or BABA-RP (n = 37) at our institution between November 2014 and March 2023. Patient demographics, biochemical cure rates, operative time, blood loss rates, and complication rates were examined and compared. Results: The patients in the BABA-RP group were younger and had a longer mean operative time. Regarding complication events, 2 patients in the open surgery group and 1 patient in the BABA-RP group had transient hypoparathyroidism. All 74 patients achieved biochemical cure at <6 months, regardless of the approach used. Two patients in the BABA-RP group and 1 patient in the open surgery group had carcinoma on surgical pathology. All 3 patients with parathyroid carcinoma remained recurrence-free at 1-year follow-up. Conclusion: Compared with the open procedure, BABA-RP is a safe and feasible procedure that provides an excellent biochemical cure rate for patients with pHPT and has superior cosmetic benefits with equivalent surgical outcomes.

TSH receptor antibody as a predictor of difficult robotic thyroidectomy in patients with Graves' disease.

Thyroidectomy in Graves' disease can be challenging due to greater thyroid size and vascularity. While thyroid stimulating hormone receptor antibody (TRAb) level is associated with disease severity and thyroid vascularity, its impact on operative outcomes remains unclear. This study aimed to compare challenging factors for robotic thyroidectomy (RT) and open thyroidectomy (OT) in Graves' disease patients, including TRAb as a predictive factor for difficult thyroidectomy. This retrospective study included Graves' disease patients who underwent total thyroidectomy between September 2013 and January 2023. The clinical characteristics and operative outcomes were compared between patients who received OT and bilateral axillo-breast approach RT. Factors affecting operation time and estimated blood loss (EBL) were evaluated in both groups using regression analyses. A total of 85 patients received either OT (n = 48) or RT (n = 37). Median thyroid volumes in the OT and RT groups were 72.4 g and 57.6 g, respectively. Operation time was affected by thyroid volume in both groups. Additionally, higher thyroid hormone levels and bilateral central neck node dissection prolonged operation time in the RT group. EBL was marginally associated with thyroid volume in the OT group. However, in the RT group, TRAb level was independently associated with greater EBL (p = 0.04), while no significant association was found with thyroid volume. Predictive factors for difficult thyroidectomy differed by operation approaches. TRAb significantly predicted intraoperative bleeding in RT, while this association was absent in OT. Caution is warranted when performing RT on Graves' disease patients with high TRAb levels.

Carbon plate shows even distribution of stress, decreases screw loosening, and increases recovery of preoperative daily feed intake amount in a rabbit model of mandibular continuity defects.

INTRODUCTION: The aim of this study was to compare a carbon plate (CP) and a titanium mandibular reconstruction plate (TMRP) in finite element analysis and an animal model. MATERIALS AND METHODS: Twelve rabbits were used for this experiment. After a mandible continuity defect was created, either a CP or a TMRP was used for mandibular reconstruction. Postoperatively, daily feed intake amount (DFIA) was measured for 4 weeks. Radiographic images were also acquired to evaluate screw loosening. For the analysis of the stress distribution, a simple continuity defect model was used, and finite element analysis was performed. RESULTS: The CP group had 0.80 ± 0.45 lost screws in an animal during the 4 weeks postoperative observation; however, the TMRP group had 1.86 ± 0.69 lost screws (p = 0.014). Overall, the 5 out of 5 of rabbits in the CP group and 3 out of 7 in the TMRP group exhibited preoperative levels of DFIA during the 4 week observation (p = 0.038). The finite element analysis showed that the stress was more evenly distributed in the CP than in the TMRP model. CONCLUSIONS: The CP group showed decreased screw loosening and increased recovery of preoperative DFIA compared to the TMRP group in a rabbit model of mandibular continuity defects. Perfect adaptation of CP during the operation could not be achieved in spite of reshaping to the mandibular curvature. This disadvantage of the CP system can be overcome by the prefabricated technique using a prototype model.

Fast tool for evaluation of iliac crest tissue elastic properties using the reduced-basis methods.

Computationally expensive finite element (FE) methods are generally used for indirect evaluation of tissue mechanical properties of trabecular specimens, which is vital for fracture risk prediction in the elderly. This work presents the application of reduced-basis (RB) methods for rapid evaluation of simulation results. Three cylindrical transiliac crest specimens (diameter: 7.5 mm, length: 10-12 mm) were obtained from healthy subjects (20 year-old, 22 year-old, and 24 year-old females) and scanned using microcomputed tomography imaging. Cubic samples of dimensions 5×5×5 mm(3) were extracted from the core of the cylindrical specimens for FE analysis. Subsequently, a FE solution library (test space) was constructed for each of the specimens by varying the material property parameters: tissue elastic modulus and Poisson's ratio, to develop RB algorithms. The computational speed gain obtained by the RB methods and their accuracy relative to the FE analysis were evaluated. Speed gains greater than 4000 times, were obtained for all three specimens for a loss in accuracy of less than 1% in the maxima of von-Mises stress with respect to the FE-based value. The computational time decreased from more than 6 h to less than 18 s. RB algorithms can be successfully utilized for real-time reliable evaluation of trabecular bone elastic properties.

Assessing the susceptibility to local buckling at the femoral neck cortex to age-related bone loss.

Although it is known that long cortical bone structurally alter their area moment of inertia with age related bone loss maintaining their bending strength, the incidence of fragility fractures associated with cortical thinning still prevails. We hypothesize that cortical thinning with aging increases the local buckling susceptibility under abnormal or eccentric loads, and initiates fracture. The paper presents a series of 3D geometrical model derived from CT scans of a human femoral neck used to simulate age-related bone loss. The purpose of the model is to predict the susceptibility of local buckling at the femoral neck in falls by elderly folks. Geometric three-dimensional models of femoral neck cortices were developed from 7 human cadaver femurs (4 female, 3 male, 52-68 years). Three age related femoral neck models were simulated by either reducing (young age-related model) or increasing (old age-related model) the outer cortical surfaces in the radial-direction, by 1-mm. The control model was the middle-age related model. The inner cortex diameter was also adjusted to equilibrate the compressive stresses, based on the load-profile of a single-legged stance. Based on the old age related model, two additional "fragile" models were simulated by reducing the compressive load profile by 10 and 20% changing the inner cortex diameter, respectively. Using these models for each specimen, the consequence of a fall on the greater trochanter was evaluated. The Finite Strip Method (FSM) was used to investigate the association between local buckling at the femoral neck and the load to failure. Under constant loading, buckling progressively reduced the load to failure with aging, as seen in 2/7 of the middle age (by 9-15%) and 5/7 of the old age (by 7-32%) related models. In the fragile models, a 51% reduction in the load to failure was noted. Structural adaptation to age-related bone loss might preserves the bending strength under physiologic loads, but cortical thinning effects the buckling ratio reaching a critical threshold that would make the bone susceptible to local buckling at the femoral neck increasing the risk of fracture in a fall.

Novel approach of predicting fracture load in the human proximal femur using non-invasive QCT imaging technique.

This paper presents an analysis of predicting the load-bearing capacities of human femurs using quantitative computer tomography (QCT)-based beam theory. Cross-sectional images of 12 human cadaver femurs (intact bones, age: 39-77 years; male = 8, female = 4) were scanned in conjunction with a calcium hydroxyapatite phantom which has five chambers of known densities. The apparent densities obtained from the scans were used to evaluate the Young's modulus (E) by applying the established empirical relationships. The fracture load of a configuration that simulated single-legged stance was measured experimentally and compared with the predicted failure load using a composite beam theory, plane stress model of the femur. In this model, the failure was assumed to occur at the weakest cross-section through the bone determined from QCT-based structural analysis. In contrast to the other experimental investigations, the setup used in this study considers the entire length of a human femur and also incorporates a novel mechanical jig to mimic the realistic physiological scenario. In one of our earlier studies, simulated lytic defects of varying size were created at the inter-trochanteric region of femurs and their load-bearing capacities were calculated based on their structural properties. Both the results obtained from the current study as well as the ones from our previous study were used to assess the viability of the methodology. A high degree of correlation was observed when the predicted failure loads obtained from the intact femurs and previously studied defective femurs were compared with the ex vivo fracture loads. The coefficients of determination (R(2)) of QCT-derived predicted loads with respect to the measured failure loads were 0.80 for the intact femurs and 0.87 for the defective femurs. The results suggest that the QCT-derived beam analysis provides a viable approach for the assessment of load-bearing capacity in various clinical scenarios.

Zonal changes in the three-dimensional morphology of the chondron under compression: the relationship among cellular, pericellular, and extracellular deformation in articular cartilage.

The pericellular matrix (PCM) is a narrow region of tissue that completely surrounds chondrocytes in articular cartilage. Previous theoretical models of the "chondron" (the PCM with enclosed cells) suggest that the structure and properties of the PCM may significantly influence the mechanical environment of the chondrocyte. The objective of this study was to quantify changes in the three-dimensional (3D) morphology of the chondron in situ at different magnitudes of compression applied to the cartilage extracellular matrix. Fluorescence immunolabeling for type-VI collagen was used to identify the boundaries of the cell and PCM, and confocal microscopy was used to form 3D images of chondrons from superficial, middle, and deep zone cartilage in explants compressed to 0%, 10%, 30%, and 50% surface-to-surface strain. Lagrangian tissue strain, determined locally using texture correlation, was highly inhomogeneous and revealed depth-dependent compressive stiffness and Poisson's ratio of the extracellular matrix. Compression significantly decreased cell and chondron height and volume, depending on the zone and magnitude of compression. In the superficial zone, cellular-level strains were always lower than tissue-level strains. In the middle and deep zones, however, tissue strains below 25% were amplified at the cellular level, while tissue strains above 25% were decreased at the cellular level. These findings are consistent with previous theoretical models of the chondron, suggesting that the PCM can serve as either a protective layer for the chondrocyte or a transducer that amplifies strain, such that cellular-level strains are more homogenous throughout the tissue depth despite large inhomogeneities in local ECM strains.

The pericellular matrix as a transducer of biomechanical and biochemical signals in articular cartilage.

The pericellular matrix (PCM) is a narrow tissue region surrounding chondrocytes in articular cartilage, which together with the enclosed cell(s) has been termed the "chondron." While the function of this region is not fully understood, it is hypothesized to have important biological and biomechanical functions. In this article, we review a number of studies that have investigated the structure, composition, mechanical properties, and biomechanical role of the chondrocyte PCM. This region has been shown to be rich in proteoglycans (e.g., aggrecan, hyaluronan, and decorin), collagen (types II, VI, and IX), and fibronectin, but is defined primarily by the presence of type VI collagen as compared to the extracellular matrix (ECM). Direct measures of PCM properties via micropipette aspiration of isolated chondrons have shown that the PCM has distinct mechanical properties as compared to the cell or ECM. A number of theoretical and experimental studies suggest that the PCM plays an important role in regulating the microenvironment of the chondrocyte. Parametric studies of cell-matrix interactions suggest that the presence of the PCM significantly affects the micromechanical environment of the chondrocyte in a zone-dependent manner. These findings provide support for a potential biomechanical function of the chondrocyte PCM, and furthermore, suggest that changes in the PCM and ECM properties that occur with osteoarthritis may significantly alter the stress-strain and fluid environments of the chondrocytes. An improved understanding of the structure and function of the PCM may provide new insights into the mechanisms that regulate chondrocyte physiology in health and disease.