Robotic-Assisted Anastomosis in Orthoplastic Surgery: Preliminary Data.

BACKGROUND: The evolution of microsurgery has relied on advancements in operating microscopes and surgical instruments. Pioneering advancements, however, especially within the domain of "super-microsurgery", challenge the limits of human dexterity by dealing with anastomoses between vessels smaller than 0.8 mm. Based on these premises, the Symani robotic system was designed and developed. This platform utilizes teleoperation and motion-scaled movement to provide surgeons with precision and accuracy in manipulating millimetre and submillimetre-sized anatomical structures. In this study, we present our experience in performing robotic-assisted anastomoses using the Symani Surgical System in free flap reconstruction. METHODS: We present a comprehensive analysis of all reconstructive procedures involving microsurgical free flaps performed using the Symani robotic platform at the orthoplastic unit of the Rizzoli Orthopaedic Institute from 1 October 2022 to 1 May 2023. RESULTS: Sixteen microsurgical reconstructions using free flaps were performed, involving a total of 40 anastomoses on vessel calibres ranging from 0.6 mm to 2.5 mm. In each case, the anastomosis was executed with the assistance of the robotic platform, achieving a 100+% success rate in patent anastomoses, and no major complications occurred.Conclusion The Symani system has proven to be safe and reliable in performing microsurgical anastomoses. While this platform demonstrated successful in various vessel calibres, its most promising potential lies in anastomoses below the size of a millimetre. Larger patient cohorts and extended investigation periods will be essential to explore whether robotics in microsurgery offers advantages across all microsurgical procedures or should be reserved for selected cases.

A chimeric medial femoral condyle chondro-osseus flap with two thin periosteal flaps to reconstruct partial necrosis of talar body: A case report.

Total talar extrusion is a rare complication of high-energy traumas. A consequence of this injury can be avascular necrosis (AVN) of the talus. Patients are confronted with pain, limited range of motion and post-traumatic arthritis. As AVN progresses the talus is gradually destroyed. This report presents the use of a chimeric medial femoral condyle chondro-osseus flap with two thin periosteal flaps to increase vascular supply to the traumatized area, accelerate bone formation, flap integration, and restore articular surfaces in a patient with partial necrosis of talar body. The patient was a 26-year-old female with open left lateral talar extrusion after a motor-vehicle accident that developed a partial avascular necrosis, at the level of the subtalar and ankle joint with altered talar dome surface with partial depression of 2 cm. The patient was in pain and not able to walk. The medial femoral condyle chondro-osseus portion was placed in the talar dome depression to restore the subtalar joint, the periosteal flaps were placed on top to reconstruct the ankle joint restoring the articular surfaces and the correct weight-bearing distribution. No complications or morbidity of donor site were observed. One year after the operation, the patient walks free, without pain. Post-operatory x-ray performed, evidenced progressive bone healing and reduction of the AVN. In the intent of performing a joint-saving procedure, the presented chimeric flap might be effective in the short-term with excellent clinical and radiographic outcomes.

Gender dysphoria: Quality of online information for gender reassignment surgery.

An ever-increasing number of patients are using the Internet to learn about medical conditions. This study aimed to evaluate the quality of Internet-based patient information on gender reassignment surgery for people who suffer from gender dysphoria. Twenty websites identified using Google and Yahoo search engines were selected and evaluated based on the modified Ensuring Quality Information for Patients (EQIP) instrument (36 items). The EQIP tool comprises 36 questions to which the answer can be "yes" or "no". The final score for each website can be between 0 and 36. An overall score of 26 or above was considered high, because it co-related to the 72nd percentile. The average of the scores turned out to be 22.5 points, lower than our target; 7 (35%) sites were rated higher than the average and 13 (65%) were rated lower. The assessment of the websites included in the study showed a lack of information about the sequence of the medical procedures, perioperative criticalities and qualitative risks and side-effects descriptions. The overall quality of published information on gender reassignment surgery is very low. We believe that the Internet should not be used as the main source of medical information, and physicians should maintain the leadership in guiding patients affected by gender dysphoria. Level of Evidence: Level IV, case study.

Current fluctuations in stochastically resetting particle systems.

We consider a system of noninteracting particles on a line with initial positions distributed uniformly with density ρ on the negative half-line. We consider two different models: (i) Each particle performs independent Brownian motion with stochastic resetting to its initial position with rate r and (ii) each particle performs run-and-tumble motion, and with rate r its position gets reset to its initial value and simultaneously its velocity gets randomized. We study the effects of resetting on the distribution P(Q,t) of the integrated particle current Q up to time t through the origin (from left to right). We study both the annealed and the quenched current distributions and in both cases, we find that resetting induces a stationary limiting distribution of the current at long times. However, we show that the approach to the stationary state of the current distribution in the annealed and the quenched cases are drastically different for both models. In the annealed case, the whole distribution P_{an}(Q,t) approaches its stationary limit uniformly for all Q. In contrast, the quenched distribution P_{qu}(Q,t) attains its stationary form for QQ_{crit}(t). We show that Q_{crit}(t) increases linearly with t for large t. On the scale where Q∼Q_{crit}(t), we show that P_{qu}(Q,t) has an unusual large deviation form with a rate function that has a third-order phase transition at the critical point. We have computed the associated rate functions analytically for both models. Using an importance sampling method that allows to probe probabilities as tiny as 10^{-14000}, we were able to compute numerically this nonanalytic rate function for the resetting Brownian dynamics and found excellent agreement with our analytical prediction.

Cost of Diffusion: Nonlinearity and Giant Fluctuations.

We introduce a simple model of diffusive jump process where a fee is charged for each jump. The nonlinear cost function is such that slow jumps incur a flat fee, while for fast jumps the cost is proportional to the velocity of the jump. The model-inspired by the way taxi meters work-exhibits a very rich behavior. The cost for trajectories of equal length and equal duration exhibits giant fluctuations at a critical value of the scaled distance traveled. Furthermore, the full distribution of the cost until the target is reached exhibits an interesting "freezing" transition in the large-deviation regime. All the analytical results are corroborated by numerical simulations. Our results also apply to elastic systems near the depinning transition, when driven by a random force.

CT Perfusion as a Predictor of the Final Infarct Volume in Patients with Tandem Occlusion.

BACKGROUND: CT perfusion (CTP) is used in patients with anterior circulation acute ischemic stroke (AIS) for predicting the final infarct volume (FIV). Tandem occlusion (TO), involving both intracranial large vessels and the ipsilateral cervical internal carotid artery could generate hemodynamic changes altering perfusion parameters. Our aim is to evaluate the accuracy of CTP in the prediction of the FIV in TOs. METHODS: consecutive patients with AIS due to middle cerebral artery occlusion, referred to a tertiary stroke center between March 2019 and January 2021, with an automated CTP and successful recanalization (mTICI = 2b - 3) after endovascular treatment were retrospectively included in the tandem group (TG) or in the control group (CG). Patients with parenchymal hematoma type 2, according to ECASS II classification of hemorrhagic transformations, were excluded in a secondary analysis. Demographic, clinical, radiological, time intervals, safety, and outcome measures were collected. RESULTS: among 319 patients analyzed, a comparison between the TG (N = 22) and CG (n = 37) revealed similar cerebral blood flow (CBF) > 30% (29.50 ± 32.33 vs. 15.76 ± 20.93 p = 0.18) and FIV (54.67 ± 65.73 vs. 55.14 ± 64.64 p = 0.875). Predicted ischemic core (PIC) and FIV correlated in both TG (tau = 0.761, p < 0.001) and CG (tau = 0.315, p = 0.029). The Bland-Altmann plot showed agreement between PIC and FIV for both groups, mainly in the secondary analysis. CONCLUSION: automated CTP could represent a good predictor of FIV in patients with AIS due to TO.

Soft Tissue Reconstruction of the Posterior Trunk after Tumor Excision: A Surgical Algorithm.

BACKGROUND: The posterior trunk has been considered a challenging area to reconstruct following soft tissue tumor excision because of the shortage of local donor sites. The advent of innovative procedures such as perforator flaps has radically changed this perspective and offered a new approach to the problem. METHODS: Upon a review of the literature and the personal experiences of the senior author, an algorithm is developed according to the most updated procedure, combined with more conventional options that maintain a role in decision-making. RESULTS: The upper back latissimus dorsi and trapezium flap are still the most reliable approaches, while perforator flaps based either on the circumflex scapular arteries or the transverse cervical artery represent a more refined option. In the middle third, few indications remain for the reverse latissimus dorsi, while the gold standard is represented by local perforator flaps based on the posterior intercostal system. In the lower back, conventional VY advancement flaps are still a safe and effective option in the sacral area, and perforator flaps based on posterior intercostal arteries, lumbar arteries and superior gluteal arteries are the first choice in most cases. CONCLUSIONS: Using perforator flaps significantly improved soft tissue reconstruction in the posterior trunk.

Viscoelastic confinement induces periodic flow reversals in active nematics.

We use linear stability analysis and hybrid lattice Boltzmann simulations to study the dynamical behavior of an active nematic confined in a channel made of viscoelastic material. We find that the quiescent, ordered active nematic is unstable above a critical activity. The transition is to a steady flow state for high elasticity of the channel surroundings. However, below a threshold elastic modulus, the system produces spontaneous oscillations with periodic flow reversals. We provide a phase diagram that highlights the region where time-periodic oscillations are observed and explain how they are produced by the interplay of activity and viscoelasticity. Our results suggest experiments to study the role of viscoelastic confinement in the spatiotemporal organization and control of active matter.

Nonlinear-cost random walk: Exact statistics of the distance covered for fixed budget.

We consider the nonlinear-cost random-walk model in discrete time introduced in Phys. Rev. Lett. 130, 237102 (2023)10.1103/PhysRevLett.130.237102, where a fee is charged for each jump of the walker. The nonlinear cost function is such that slow or short jumps incur a flat fee, while for fast or long jumps the cost is proportional to the distance covered. In this paper we compute analytically the average and variance of the distance covered in n steps when the total budget C is fixed, as well as the statistics of the number of long or short jumps in a trajectory of length n, for the exponential jump distribution. These observables exhibit a very rich and nonmonotonic scaling behavior as a function of the variable C/n, which is traced back to the makeup of a typical trajectory in terms of long or short jumps, and the resulting entropy thereof. As a by-product, we compute the asymptotic behavior of ratios of Kummer hypergeometric functions when both the first and last arguments are large. All our analytical results are corroborated by numerical simulations.

Time to reach the maximum for a stationary stochastic process.

We consider a one-dimensional stationary time series of fixed duration T. We investigate the time t_{m} at which the process reaches the global maximum within the time interval [0,T]. By using a path-decomposition technique, we compute the probability density function P(t_{m}|T) of t_{m} for several processes, that are either at equilibrium (such as the Ornstein-Uhlenbeck process) or out of equilibrium (such as Brownian motion with stochastic resetting). We show that for equilibrium processes the distribution of P(t_{m}|T) is always symmetric around the midpoint t_{m}=T/2, as a consequence of the time-reversal symmetry. This property can be used to detect nonequilibrium fluctuations in stationary time series. Moreover, for a diffusive particle in a confining potential, we show that the scaled distribution P(t_{m}|T) becomes universal, i.e., independent of the details of the potential, at late times. This distribution P(t_{m}|T) becomes uniform in the "bulk" 1≪t_{m}≪T and has a nontrivial universal shape in the "edge regimes" t_{m}→0 and t_{m}→T. Some of these results have been announced in a recent letter [Europhys. Lett. 135, 30003 (2021)0295-507510.1209/0295-5075/ac19ee].

Diagnostic Accuracy of the Five-Word Test for Mild Cognitive Impairment Due to Alzheimer's Disease.

New diagnostic methods have been developed for the early diagnosis of Alzheimer's disease (AD) with the primary purpose of intercepting the transition-phase (mild cognitive impairment, MCI) between normal aging and dementia. We aimed to explore whether the five-word test (FWT) and the mini-mental state examination (MMSE) are predictive for the early diagnosis of MCI due to AD (AD-MCI). We computed ROC analyses to evaluate the sensitivity and specificity of MMSE and FWT in predicting abnormal CSF (t-Tau, p-Tau181, Aß1−42) and amyloid-PET biomarkers. AD-MCI patients showed lower MMSE and FWT scores (all p < 0.001) than non-AD-MCI. The best predictor of amyloid plaques' presence at amyloid-PET imaging was the encoding sub-score of the FWT (AUC = 0.84). Both FWT and MMSE had low/moderate accuracy for the detection of pathological CSF Aß42, t-Tau and p-Tau181 values, with higher accuracy for the t-Tau/Aß1−42 ratio. In conclusion, the FWT, as a single-domain cognitive screening test, seems to be prompt and moderately accurate tool for the identification of an underlying AD neuropathological process in patients with MCI, supporting the importance of associating biomarkers evaluation in the work-up of patients with dementing neurodegenerative disorders.

The keystone flap: A multi-centric experience in elderly patients treatment.

Soft tissue reconstruction in elderly patients must be rapid and reliable. The keystone island flap (KF) offers an effective solution, with low complication rates and quick recovery. This multi-centric study aims to show authors' experience with KFs in treating soft tissue defects of trunk and limbs. Patients with soft tissue defects suitable for KF reconstruction were recruited from March 2019 to December 2019. Active inflammation and previous surgeries in the same region were considered exclusion criteria. Complications that occurred during follow-up were recorded, and their incidence pattern was assessed with the Fisher test. Seventy-two patients with mean age of 76.2 years old were selected. They presented lesions in torso (46; 63.9%) or in upper (4; 5.6%) or lower (22; 30.6%) limb regions. Fifteen (20.8%) wounds were non-oncologic lesions, and the others were oncologic lesions, mostly non-melanoma skin cancers. KF type I was carried out in 42 (58.3%) cases, KF type II-A in 13 (18%) cases, double opposed type III KF in 16 (22.2%) patients, and 1 (1.4%) case required partial flap's undermining (IV KF). Mean post-operative recovery period was 4.3 days (range, 1-9 days). Post-surgical complications occurred in 15 (20.8%) cases, 7 (9.7%) of them were considered major complications. No statistically significant difference in complications' incidence, nor among different surgical sites nor among KF types, was registered. Reconstructive surgeons have to adapt their work to elderly patients. The KF allows rapid operative times, low morbidity rates, and short post-operative recovery time, thus appearing as a feasible solution.

Breast Reconstruction after Mastectomy with the Use of an Implant and Serratus Anterior Fascia Flap-Initial Clinical Evaluation.

Prosthesis-based techniques are the predominant form of breast reconstruction worldwide. The most performed surgical technique involves the placement of the expander in a partial submuscular plane. The coverage of the implant remains a difficult management problem that can lead to complications and poor outcomes. The use of the serratus fascia flap may be the best choice to create a subpectoral pocket for the placement of a tissue expander, with excellent results in terms of morbidity and cost-effectiveness. A total of 20 breast reconstructions with the inferolateral coverage with the serratus fascia were performed. Patients demonstrated a low overall complication rate (9.5%), such as seroma and infection, with complete resolution during the follow-up and no major complications. The US examination of the soft tissues over the implant reported thickness measurements that demonstrated a good coverage over the inferolateral area. Our study shows that using the serratus fascia flap to create a pocket with the pectoralis major for the placement of the tissue expander is an effective technique during two-stage breast reconstruction. The resulting low rate of morbidity and the US findings collected reveal the safety of this procedure. Its success relies on appropriate patient selection and specific intraoperative technique principles.

Condensation transition in the late-time position of a run-and-tumble particle.

We study the position distribution P(R[over ⃗],N) of a run-and-tumble particle (RTP) in arbitrary dimension d, after N runs. We assume that the constant speed v>0 of the particle during each running phase is independently drawn from a probability distribution W(v) and that the direction of the particle is chosen isotropically after each tumbling. The position distribution is clearly isotropic, P(R[over ⃗],N)→P(R,N) where R=|R[over ⃗]|. We show that, under certain conditions on d and W(v) and for large N, a condensation transition occurs at some critical value of R=R_{c}∼O(N) located in the large-deviation regime of P(R,N). For RR_{c} is typically dominated by a "condensate," i.e., a large single run that subsumes a finite fraction of the total displacement (supercritical condensed phase). Focusing on the family of speed distributions W(v)=α(1-v/v_{0})^{α-1}/v_{0}, parametrized by α>0, we show that, for large N, P(R,N)∼exp[-Nψ_{d,α}(R/N)], and we compute exactly the rate function ψ_{d,α}(z) for any d and α. We show that the transition manifests itself as a singularity of this rate function at R=R_{c} and that its order depends continuously on d and α. We also compute the distribution of the condensate size for R>R_{c}. Finally, we study the model when the total duration T of the RTP, instead of the total number of runs, is fixed. Our analytical predictions are confirmed by numerical simulations, performed using a constrained Markov chain Monte Carlo technique, with precision ∼10^{-100}.

"To Pre or Not to Pre": Introduction of a Prepectoral Breast Reconstruction Assessment Score to Help Surgeons Solving the Decision-Making Dilemma. Retrospective Results of a Multicenter Experience.

BACKGROUND: Implant-based reconstruction is the most performed breast reconstruction, and both subpectoral and prepectoral approaches can lead to excellent results. Choosing the best procedure requires a thorough understanding of every single technique, and proper patient selection is critical to achieve surgical success, in particular when dealing with prepectoral breast reconstruction. METHODS: Between January of 2014 and December of 2018, patients undergoing mastectomy and eligible for immediate prepectoral breast reconstruction with tissue expander or definitive implant, were selected. The Prepectoral Breast Reconstruction Assessment score was applied to evaluate patient-related preoperative and intraoperative risk factors that could influence the success of prepectoral breast reconstruction. All patients were scored retrospectively, and the results obtained through this assessment tool were compared to the records of the surgical procedures actually performed. RESULTS: Three hundred fifty-two patients were included; 112 of them underwent direct-to-implant immediate reconstruction, and 240 underwent the two-stage procedure with temporary tissue expander. According to the Prepectoral Breast Reconstruction Assessment score, direct-to-implant reconstruction should have been performed 6.2 percent times less, leading to an increase of 1.4 percent in two-stage reconstruction and 4.8 percent in submuscular implant placement. CONCLUSIONS: To date, there is no validated system to guide surgeons in identifying the ideal patient for subcutaneous or retropectoral breast reconstruction and eventually whether she is a good candidate for direct-to-implant or two-stage reconstruction. The authors processed a simple risk-assessment score to objectively evaluate the patient's risk factors, to standardize the decision-making process, and to identify the safest and most reliable breast reconstructive procedure. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Mean perimeter and area of the convex hull of a planar Brownian motion in the presence of resetting.

We compute exactly the mean perimeter and the mean area of the convex hull of a two-dimensional isotropic Brownian motion of duration t and diffusion constant D, in the presence of resetting to the origin at a constant rate r. We show that for any t, the mean perimeter is given by 〈L(t)〉=2πsqrt[D/r]f_{1}(rt) and the mean area is given by 〈A(t)〉=2πD/rf_{2}(rt) where the scaling functions f_{1}(z) and f_{2}(z) are computed explicitly. For large t≫1/r, the mean perimeter grows extremely slowly as 〈L(t)〉∝ln(rt) with time. Likewise, the mean area also grows slowly as 〈A(t)〉∝ln^{2}(rt) for t≫1/r. Our exact results indicate that the convex hull, in the presence of resetting, approaches a circular shape at late times due to the isotropy of the Brownian motion. Numerical simulations are in perfect agreement with our analytical predictions.

Dual-Plane Retro-pectoral Versus Pre-pectoral DTI Breast Reconstruction: An Italian Multicenter Experience.

BACKGROUND: The use of conservative mastectomies has risen significantly during the last few years. The reconstructive choice of direct-to-implant reconstruction has become more practicable with modern mastectomy techniques. The initial trend in Italian centers was to use dual-plane hybrid reconstruction. However, a high level of complications has been registered. From 2015 onward, in our centers, a pre-pectoral approach has been adopted. The authors sought to describe the Italian trend to gradually discard the sub-pectoral technique with lower lateral pole coverage of the prosthesis using ADMs comparing it with the pre-pectoral approach with ADMs, without any muscle dissection, in terms of complication rates. MATERIALS AND METHODS: A multicenter retrospective clinical study was performed from January 2010 to June 2018. The enrolled patients were divided into two groups: Cases with an ADM-only coverage pre-pectoral reconstruction made up the first group (Group 1). Those with the retro-pectoral muscular position + ADM implant coverage comprised the second one (Group 2). Complications such as seroma, hematoma, wound dehiscence, surgical site infection, reconstruction failure, animation deformity and capsular contracture were recorded. RESULTS: We performed 716 direct-to-implant reconstructions: 509 were partially sub-pectoral and 207 were pre-pectoral. Minimum follow-up was 1 year. Incidence of complications was higher in dual-plane reconstructions. There were statistical significant differences in the rates of seroma and hematoma. CONCLUSION: Using the pre-pectoral approach, the authors have experienced favorable aesthetics and superior clinical and functional outcomes. Retro-pectoral muscular ADM implant coverage has to be considered only in specific complicated second-stage surgeries. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .