Biomechanical characteristics of the meniscocapsular junction of the posterior segment of the medial meniscus.

PURPOSE: Despite extensive literature available on the mechanical properties of knee ligaments and menisci, research on the mechanical properties of the meniscus-capsular junction (MCJ) is lacking. This study aims to investigate the biomechanical behavior of the MCJ of the medial meniscus using a tensile failure test. MATERIALS AND METHODS: Seven dissected cadaveric knees were used for biomechanical analysis. Tensile failure tests were performed using an INSTRON ElectroPuls E1000 stress system to measure stress/strain curves, maximum load at failure, elastic limit load, elongation at break, elongation at the elastic limit, and linear stiffness, were collected and analyzed. RESULTS: All ruptures occurred at the MCJ. The MCJ displayed similar mechanical properties to knee ligaments. Average values were: maximum load at failure (63.9 ± 3.2 N), yield load (52.9 N ± 2.6 N), elongation at break (2.5 mm ± 0.3 mm), elongation at the elastic limit (1.25 mm ± 0.15 mm), strain at break (47.0% ± 3.5%), strain at yield (23.2% ± 2.3%), and stiffness (56.6 ± 9. N/mm-1). CONCLUSION: The meniscus-capsular junction's mechanical properties are similar to other knee ligaments and may play a role in knee stability. The findings provide insights into the the behavior of the meniscus-capsular junction could have clinical implications for diagnosing and surgical treatment of meniscocapsular lesions.

Predicting the risk of post-hepatectomy portal hypertension using a digital twin: A clinical proof of concept.

BACKGROUND & AIMS: Despite improvements in medical and surgical techniques, post-hepatectomy liver failure (PHLF) remains the leading cause of postoperative death. High postoperative portal vein pressure (PPV) and portocaval gradient (PCG), which cannot be predicted by current tools, are the most important determinants of PHLF. Therefore, we aimed to evaluate a digital twin to predict the risk of postoperative portal hypertension (PHT). METHODS: We prospectively included 47 patients undergoing major hepatectomy. A mathematical (0D) model of the entire blood circulation was assessed and automatically calibrated from patient characteristics. Hepatic flows were obtained from preoperative flow MRI (n = 9), intraoperative flowmetry (n = 16), or estimated from cardiac output (n = 47). Resection was then simulated in these 3 groups and the computed PPV and PCG were compared to intraoperative data. RESULTS: Simulated post-hepatectomy pressures did not differ between the 3 groups, comparing well with collected data (no significant differences). In the entire cohort, the correlation between measured and simulated PPV values was good (r = 0.66, no adjustment to intraoperative events) or excellent (r = 0.75) after adjustment, as well as for PCG (respectively r = 0.59 and r = 0.80). The difference between simulated and measured post-hepatectomy PCG was ≤3 mmHg in 96% of cases. Four patients suffered from lethal PHLF for whom the model satisfactorily predicted their postoperative pressures. CONCLUSIONS: We demonstrated that a 0D model could correctly anticipate postoperative PHT, even using estimated hepatic flow rates as input data. If this major conceptual step is confirmed, this algorithm could change our practice toward more tailor-made procedures, while ensuring satisfactory outcomes. LAY SUMMARY: Post-hepatectomy portal hypertension is a major cause of liver failure and death, but no tool is available to accurately anticipate this potentially lethal complication for a given patient. Herein, we propose using a mathematical model to predict the portocaval gradient at the end of liver resection. We tested this model on a cohort of 47 patients undergoing major hepatectomy and demonstrated that it could modify current surgical decision-making algorithms.

Indocyanine Green Fluorescence Imaging to Predict Graft Survival After Orthotopic Liver Transplantation: A Pilot Study.

The incidence of primary nonfunction (PNF) after liver transplantation (LT) remains a major concern with the increasing use of marginal grafts. Indocyanine green (ICG) fluorescence is an imaging technique used in hepatobiliary surgery and LT. Because few early predictors are available, we aimed to quantify in real time the fluorescence of grafts during LT to predict 3-month survival. After graft revascularization, ICG was intravenously injected, and then the fluorescence of the graft was captured with a near infrared camera and postoperatively quantified. A multiparametric modeling of the parenchymal fluorescence intensity (FI) curve was proposed, and a predictive model of graft survival was tested. Between July 2017 and May 2019, 76 LTs were performed, among which 6 recipients underwent retransplantation. No adverse effects of ICG injection were observed. The parameter a150 (temporal course of FI) was significantly higher in the re-LT group (0.022 seconds-1 (0.0011-0.059) versus 0.012 seconds-1 (0.0001-0.054); P = 0.01). This parameter was the only independent predictive factor of graft survival at 3 months (OR, 2.4; 95% CI, 1.05-5.50; P = 0.04). The best cutoff for the parameter a150 (0.0155 seconds-1 ) predicted the graft survival at 3 months with a sensitivity (Se) of 83.3% and a specificity (Spe) of 78.6% (area under the curve, 0.82; 95% CI, 0.67-0.98; P = 0.01). Quantitative assessment of intraoperative ICG fluorescence on the graft was feasible to predict graft survival at 3 months with a good Se and Spe. Further prospective studies should be undertaken to validate these results over larger cohorts and evaluate the clinical impact of this tool.

Ramp Lesions of the Posterior Segment of the Medial Meniscus: What Is Repaired? A Qualitative Histological Study of the Meniscocapsular and Meniscotibial Attachments.

BACKGROUND: Lesions of the posterior segment of the medial meniscus are the most common intraarticular lesions associated with ACL injuries. Ramp lesions are tears in the peripheral attachment of the posterior horn of the medial meniscus. Such injuries are difficult to detect on preoperative MRI. Arthroscopically, the prevalence of these lesions can reach 24%. Anatomical descriptions of the posterior horn of the medial meniscus are becoming clearer, however, histological descriptions are lacking, especially with regard to the presence or absence of capillaries. QUESTIONS/PURPOSES: The present qualitative histologic study focused on the posterior segment of the medial meniscus and the meniscocapsular and meniscotibial junctions. Specifically, the objective of this study was to analyze the posterior segment of the medial meniscus and the meniscosynovial junction and to determine whether the meniscus tibial ligament exists. METHODS: We dissected 10 unpaired cadaveric knees (five male, five female, age range 55 to 66 years), five left and five right, from the French "Don du corps" body donation program via a posterior approach to the posteromedial capsule. We excluded specimens with intra-articular abnormalities (ACL rupture, meniscal tear, arthrosis) preceding dissection by arthrotomy. We thus accessed the posterior segment of the medial meniscus and the meniscosynovial junction. The proximal capsule, posterior segment of the medial meniscus, entire meniscal capsular-tibial junction, and a fragment of the tibia were removed en bloc. For each knee, three sagittal spaced sections of the posterior segment of the medial meniscus (Zone 4 as defined by Smigielski) were performed. Two experienced pathologists performed qualitative histological analysis on the 30 samples after Hematoxylin and eosin staining, and Safranin O staining. RESULTS: Macroscopically, the meniscotibial attachments were pellucid and homogeneous, as were the meniscocapsular attachments; however, the meniscocapsular attachments appeared to be denser in both the anterior and posterior regions of the capsule. Microscopy of the meniscosynovial junction revealed loose collagen fibers that were partially oriented but not parallel, a cellular network featuring a few fibroblasts and adipocytes, and several capillaries. No between-attachment histologic differences were apparent; both tissues shared a site of attachment to the posterior horn of the medial meniscus. We did not detect the meniscotibial ligament, macroscopically or microscopically. CONCLUSIONS: A ramp lesion may not be a ligamentous injury because the meniscotibial ligament was not detected. Rather, it appears that a ramp lesion is a tear in the common attachment point between the posterior horn of the medial meniscus and meniscocapsular and meniscotibial junctions. This structure is vascularized, and contains nonoriented low cellularity collagen of moderate density. CLINICAL RELEVANCE: Based on our results, a better rationale for the recommendation of surgical repair of a ramp appears to be needed, given the absence of a meniscotibial ligament, and the presence of capillaries in the meniscocapsular and meniscotibial attachments.

Efficacy of Percutaneous Treatment of Primary Aneurysmal Bone Cysts (ABCs): A Systematic Review and Meta-Analysis.

BACKGROUND: Percutaneous treatment for primary aneurysmal bone cysts (ABCs) has been widely accepted. The study aimed to evaluate the efficacy of various sclerotherapy agents on patients with primary ABCs. METHODS: A meta-analysis of relevant studies. A systematic search was conducted on five databases, resulting in the inclusion of 25 studies with different percutaneous agents. RESULTS: A total of 729 patients with primary ABCs were included. Patients were administered with Ethibloc, doxycycline, embolization, alcohol, polidocanol, and calcitonin with methylprednisolone, respectively. Overall, 542 (74.3%) patients with ABCs had complete healing, 120 (16.4%) had partial healing, 44 (6%) had no-ossification or failure, and 26 (3.5%) had a recurrence. However, there was a total of 45 (6.1%) patients who had surgical curettage after sclerotherapy. Among the sclerotherapy agents, doxycycline showed highly effective results with minimal complications and recurrence, but it required multiple injections per patient. Ethibloc and embolization also proved to be highly effective with fewer injections required but had a higher rate of complications. Absolute alcohol, polidocanol, and calcitonin with methylprednisolone had similar efficacity and favorable success with fewer complications and fewer injections. CONCLUSION: Percutaneous treatment showed promising results in treating primary ABCs. However, more robust research is needed to establish the best approach for sclerotherapy in clinical practice and to address the limitations of the current literature.

Partial orthotopic liver transplantation in combination with two-stage hepatectomy: A proof-of-concept explained by mathematical modeling.

BACKGROUND: Resection And Partial Liver Segment 2/3 Transplantation with Delayed total hepatectomy (RAPID) includes total hepatectomy in 2 steps with small graft transplantation at first stage. To avoid graft portal hyperperfusion, portal vein pressure monitoring is required after revascularization and right portal vein clamping. To date, portal flow modulation has not been reported but simulating hemodynamics in RAPID patients would be useful to anticipate these procedures. Our team developed hemodynamic 0D modeling; we aimed to assess if this mathematical model could be accurately used in the RAPID setting. METHODS: The modified 0D model was retrospectively tested on 3 patients. We compared our estimated portal vein pressures and portocaval gradients to those intraoperatively measured, as indication to modulate portal flow relies on these measures. FINDINGS: Portal pressures measured after right portal vein clamping (end of RAPID procedure) in patients 1, 2 and 3 were respectively of 14, 16 and 12 mmHg while the simulated pressures were of 13.1, 14.8 and 11.5 mmHg (p = 0.25). Portocaval gradients measured after right portal vein clamping in the 3 patients were respectively of 10, 11 and 7 mmHg while the simulated gradients were of 9.9, 11.6 and 8.3 mmHg (p = 0.5). INTERPRETATION: We succeeded to predict portal vein pressures and portocaval gradients after RAPID. This promising report demonstrates that 0D simulation could be a useful tool for human decision-making. Moreover, such a patient-specific model could be of importance if we transpose RAPID experience to hepatocellular carcinoma bearing cirrhotics, a population with high probability of portal hypertension after RAPID.