Effect of loading direction and anatomical location on the ultimate tensile stress, fracture toughness, and failure patterns of knee meniscus

BACKGROUND

Rupture of the knee menisci is a common injury that can have implications for other conditions, such as osteoarthritis. The fracture toughness of soft tissue (Jc) is a mechanical property that characterizes its resistance to tear extension. To date, Jc of the meniscus has not been quantified.

METHODS

Cyclic tensile tests were conducted on meniscus samples to determine Jc and explore its characteristics. Initially, the study investigated the impact of an initial notch on the ultimate tensile stress. This allowed for an understanding of how the presence of a notch affects its structural integrity. Subsequently, Jc was measured in both the radial and circumferential directions to assess its loading direction dependency. Furthermore, the study assessed the effect of anatomical location by comparing samples collected from the femoral and tibial layers.

RESULTS

Defect tolerance of the meniscus is influenced by the loading direction. In the circumferential direction, the presence of an initial notch did not affect the ultimate stress, and no crack expansion was observed. In radial samples with a notch length of 40% or more of the total width, crack propagation occurred, leading to a decrease in the ultimate stress (p< 0.01). Additionally, Jc was found to be higher in the femoral layer compared to the tibial layer (p= 0.017).

CONCLUSION

The study also examined the failure patterns of the meniscus to enhance our understanding of its pathology. These insights contribute to a better comprehension of meniscus injuries and can aid in the development of more effective treatment strategies.

Definitive radiotherapy in patients with clinical T1N0M0 esophageal squamous cell carcinoma: A multicenter retrospective study (KROG 21-10)

PURPOSE

To assess the failure pattern and analyze the treatment scheme of definitive radiation therapy (RT) for T1N0M0 esophageal squamous cell carcinoma (ESCC).

METHODS

We performed a multi-institutional retrospective analysis in T1N0M0 ESCC patients who underwent definitive RT from 2010 to 2019. Patterns of failure were demonstrated as in-, and out-field locoregional, and distant metastasis. In the analysis, freedom-from locoregional recurrence (FFLRR) and their association with clinicopathologic factors were evaluated. Propensity score matching in cT1b patients was done.

RESULTS

168 patients were included with a median follow-up of 34.0 months, and 26 cT1a, 116 cT1b disease. The rates of 3-year all and locoregional recurrence for cT1a were 30.5% and 24.1% and those for cT1b were 27.1% and 25.9%, respectively. Among 116 cT1b patients, 69 patients received elective nodal irradiation (ENI) and 47 received involved field irradiation (IFI). After propensity score matching, the 3-year FFLRR rate was 84.5%. There was no difference between ENI and IFI in FFLRR (P = 0.831) and OS (P = 0.525). The 3-year FFLRR was 83.8% (95% Confidence interval (CI), 61.8-93.8%) in IFI group and 85.3% (95% CI, 65.1-94.3%) in ENI group. In multivariate analysis, concurrent chemotherapy use was marginally associated with FFLRR (Hazard ratio, 0.16; P = 0.064).

CONCLUSION

cT1a patients who cannot receive endoscopic resection showed similar failure rates as cT1b patients, questioning the staging accuracy and raised the need for thorough treatment like chemoradiotherapy. In cT1b patients, IFI with 50 to 60 Gy and concurrent chemotherapy could be reasonable.

The chemical damage of sandstone after sulfuric acid-rock reactions with different duration times and its influence on the impact mechanical behaviour

The low-permeability characteristic of sandstone-type uranium deposits has become the key geological bottleneck during the in-situ leaching mining, seriously restricting the development and utilization of uranium resources in China. At present, the blasting-enhanced permeability (BEP) and acidizing-enhanced permeability (AEP) are confirmed to be mainstream approaches to enhance the reservoir permeability of low-permeability sandstone-type uranium deposit (LPSUD). To clarify the synergistic effect of BEP and AEP, the acid-rock reaction and dynamic impact experiments were conducted, aiming to study the effect of chemical reactions on pore structure, dynamic mechanical properties and failure pattern of sandstone. Results show that with the increasing acid-rock reaction time, the total pore volume of samples is promoted largely and exhibits obvious chemical damage. The change of pore volume depends on the pore size, the 100-1000 nm and 1000-10000 nm pores are more susceptible to acid-rock reactions. The dynamic peak strength and the dynamic elastic modulus are decreased and the dynamic peak strain and strain rate are increased when lengthening the acid-rock reaction time, whose evolution laws can be fitted by the logistic expression, the linear expression and the exponential expression, respectively. The acid-rock reactions also have an influence on the fracture development of samples after the dynamic impact. The damaged fractures on the end faces of samples grow from the isolated short fracture, the isolated long fracture to the fracture network, and the damaged fractures on the sides of samples develop from the non-penetration fractures, penetration fractures to the multi-branch fractures. This study clarifies the physical and chemical combined damage mechanism, demonstrates the potential of reservoir stimulation by uniting the BEP and the AEP, and provides a theoretical reference for the reservoir stimulation of LPSUD.

Does stem profile have an impact on the failure patterns in revision total knee arthroplasty?

INTRODUCTION

Revision total knee arthroplasty (RTKA) has been increasing continuously. The results of RTKA still remain unsatisfactory. Failure patterns and risk factors in RTKA were thoroughly analyzed, with periprosthetic joint infections (PJI) and aseptic loosening remaining at the forefront of re-revision (ReRTKA) causes. While there is evidence that stem profile impacts the revisability of cemented implants, its association with the modes of RTKA failure is unknown.

METHODS

50 consecutive ReRTKA performed in a single orthopedic center during 2016-2017 were retrospectively analyzed. The cases were stratified according to age, sex, number of preexisting revisions, fixation technique, stem design and causes of re-revision. All explanted implants with conical vs. cylindrical stem profiles were compared.

RESULTS

Mean age was 67 ± 11.5, and 54% were females. 72% of the cases had ≥ 3 previous revisions. 88% were full-cemented, 3% hybrid and 9% press-fit stems. 36% of the RTKA had conical, 58% cylindrical and 6% combined stem profiles. 92% of the RTKA components were removed. Removal causes were: PJI (52.2%), aseptic loosening (34.8%), implant malposition (9.8%), painful knee (1.1%) and instability (2.2%). While the overall RTKA failure patterns were equally distributed between conical and cylindrical stems, subgroup analysis of only cemented ReRTKA revealed a higher incidence of aseptic loosening within cylindrical stem profiles (46.7% vs. 25.7%, P = 0.05).

CONCLUSION

Stem profile may have an impact on the process of aseptic loosening in cemented non-metaphyseal engaging RTKA, with cylindrical designs tending to worse outcomes than conical designs. Large cohort studies could provide more clarity on current observation.

Failure patterns for thymic carcinoma with completed resection and postoperative radiotherapy

BACKGROUND AND PURPOSE

We aimed to evaluate the pattern and risk factors of disease failure in patients with thymic carcinoma after complete resection and postoperative radiotherapy (PORT).

MATERIALS AND METHODS

We retrospectively analyzed 127 patients with thymic carcinoma who underwent PORT after complete resection between 2003 and 2020 in our center. Data on clinical characteristics and radiation fields were collected. Failure patterns were recorded as locoregional (disease appearing in the tumor bed or regional lymph nodes), pleural, or distant failure (including hematogenous metastasis and nonregional lymph node metastasis).

RESULTS

All patients underwent tumor bed irradiation. During a median follow-up period of 64 months, disease failure was observed in 51 patients (40.2 %). The 5-year disease-free survival (DFS) and overall survival rates were 58.9 % and 85.0 %, respectively. The sequence of failure patterns was distant (n = 41, 32.3 %), pleural (n = 28, 22.0 %), and locoregional failure (n = 19, 15.0 %). Of the locoregional failure patients, failures occurred in-field in three patients (2.4 %), marginal failure in one patient (0.8 %), out-of-field failure in nine patients (7.1 %), synchronous in-field and out-of-field failures in two patients (1.6 %), synchronous marginal and out-of-field failures in two patients (1.6 %), and unknown failure fields in two patients (1.6 %). Multivariate analysis showed that Masaoka stage (hazard ratio [HR], 3.88; p = 0.000) and adjuvant chemotherapy (HR, 0.47; p = 0.015) were independent predictors of DFS.

CONCLUSION

The most common failure was distant, the Masaoka stage and adjuvant chemotherapy were independent predictors of DFS, and low locoregional failure-supported tumor bed irradiation was sufficient for patients with thymic carcinoma after complete resection.

Overview of adjuvant radiotherapy on survival, failure pattern and toxicity in stage I to II endometrial carcinoma: a long-term multi-institutional analysis in China

Background

This research aimed to provide an overview of the impact of adjuvant vaginal brachytherapy (VBT) and external beam pelvic radiotherapy (EBRT) with or without VBT on survival in stage I to II EC patients in China from a long-term multi-institutional analysis.

Methods

We retrospectively analyzed stage I to II EC patients from 13 institutions treated between 2003 and 2015. All patients underwent surgical staging and received adjuvant RT. Patients were divided into groups of low-risk (LR), intermediate-risk (IR), high-intermediate-risk (HIR) and high-risk (HR). Survival statistics, failure pattern, and toxicity of different radiation modalities in different risk groups were analyzed.

Results

A total of 1048 patients were included. HR disease represented 27.6%, HIR 17.7%, IR 27.7% and LR 27.1%, respectively. Endometrioid adenocarcinoma (EAC) and non-endometrioid carcinoma (NEC) accounted for 92.8 and 7.2%. A total of 474 patients received VBT alone and 574 patients received EBRT with or without VBT.

As for EAC patients, the 5-year overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) rate was: 94.6, 90.4, 93.0 and 91.6%, respectively. For LR patients, EBRT (with or without VBT) seemed to be a risk factor. With the higher risk category, the survival benefit of EBRT gradually became remarkable. EBRT (with or without VBT) significantly increased DFS, LRFS and DMFS compared to VBT alone in the HR group (p < 0.05). Distant metastasis was the main failure pattern for all risk groups. As for NEC patients, the 5-year OS, DFS, LRFS and DMFS rate was: 93.4, 87.2, 91.7 and 89.3%, respectively. As for toxicity, EBRT (with or without VBT) significantly increased the incidence of grade 1–2 gastrointestinal, urinary, and hematological toxicity.

Conclusions

For stage I to II EC patients, EAC accounted for the majority and had better prognosis than NEC. For EAC patients, VBT alone resulted in comparable survival to EBRT in the LR, IR and HIR groups, while EBRT significantly increased survival in the HR group. EBRT had higher rate of toxicity than VBT.

Local control and failure patterns after intensity modulated radiotherapy with reduced target volume delineation after induction chemotherapy for patients with T4 nasopharyngeal carcinoma

•

Induction chemotherapy combined with radiotherapy achieved excellent local control.

•

In-field recurrence is major local failure pattern for T4 nasopharyngeal carcinoma.

•

Radiotherapy with reduced target volume after induction chemotherapy is feasible.

Background

The delineation of target volume after induction chemotherapy(IC) for nasopharyngeal carcinoma(NPC) is currently controversial. In this study, we aimed to analyze the long-term local control(LC) and failure patterns of T4 NPC treated with reduced target volume radiotherapy after IC.

Methods

From September 2007 to January 2013, 145 patients with T4 NPC were retrospectively reviewed. All patients received at least 1 cycle of IC followed by intensity modulated radiotherapy(IMRT). The gross tumor volume(GTV) was delineated according to the post-IC images for intracavity tumors and lymph nodes. The LC and overall survival (OS) rates were calculated using the Kaplan-Meier method. The location and extent of local failures were transferred to the pretreatment planning computed tomography (CT) for dosimetric analysis.

Results

With a median follow-up time of 95 months (range, 16–142 months), 23 local failures were found. The estimated 10-year LC and OS rates were 81.1%and 54.8% respectively. Among the 20 local failures with available diagnostic images, 18(90%) occurred within the 95% isodose lines and were considered in-field failures and 2(10%) were marginal. There was no outside-field failure.

Conclusions

In-field failure was the major pattern of local failure for T4 NPC. IMRT with reduced target volume after IC seems to be feasible. Further researches exploring optimal volume and radiation dose for local advanced NPC in the era of IC are warranted.

Association between oligo-residual disease and patterns of failure during EGFR-TKI treatment in EGFR-mutated non-small cell lung cancer: a retrospective study

BACKGROUND

Local ablative therapy (LAT) may be beneficial for patients with epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC) with oligo-residual disease after treatment with EGFR tyrosine kinase inhibitor (EGFR-TKI). However, this has not been fully established. This study aimed to evaluate the predominant progressive disease (PD) pattern limited to residual sites of disease after treatment with EGFR-TKI.

METHODS

Patients with advanced EGFR-mutated NSCLC treated with EGFR-TKIs as first-line therapy were retrospectively analysed during a 7-year period. Oligo-residual disease was defined as the presence of 1 - 4 lesions (including the primary site) at 3 months from the start of EGFR-TKI treatment. The predictive factors of PD patterns after EGFR-TKI treatment were evaluated.

RESULTS

A total of 207 patients were included. Three months after the start of EGFR-TKI treatment, 66 patients (32%) had oligo-residual disease. A total of 191 patients had PD, 60 with oligo-residual disease and 131 with non-oligo-residual disease. Regarding the pattern, 44 patients (73%) with oligo-residual disease and 37 patients (28%) with non-oligo-residual disease had PD limited to the residual sites. Multivariate logistic regression analysis at 3 months from the start of EGFR-TKI treatment revealed that oligo-residual disease (P < 0.001), the lack of residual central nervous system metastases (P = 0.032), and initial treatment with osimertinib (P = 0.028) were independent predictors of PD limited to residual disease sites.

CONCLUSIONS

This study provided a rationale for LAT to all sites of residual disease in patients with oligo-residual disease during EGFR-TKI treatment.

Adhesive strength of fiberglass posts treated with thio-urethane-based experimental silanes

Purpose:

The aim of this study was to evaluate the adhesive bond strength of fiberglass posts treated with experimental silanes based on thio-urethane and submitted to thermo and mechanical cycles.

Materials and methods:

Bovine roots were divided into six groups: RX-RU2 (RelyX CP + RelyX U200); PETMP-HDDI-RU2 (PETMP-HDDI + RelyX U200); PETMP-BDI-RU2 (PETMP-BDI + RelyX U200); RX-RU (RelyX CP + RelyX Ultimate); PETMP-HDDI-RU (PETMP-HDDI + RelyX Ultimate); PETMP-BDI-RU (PETMP-BDI + RelyX Ultimate). One slice from each root third (n=10) was submitted to the push-out test and the values evaluated with R Program statistical analysis, while the failure pattern assessed in percentage.

Results:

Among root thirds, RX-RU2 promoted greater strength at the cervical and apical thirds; PETMP-HDDI-RU2 showed highest values at the three thirds; and PETMP-BDI-RU2 was strongest at the apical third. RX-RU presented higher strength at the apical third, and PETMP-HDDI-RU and PETMP-BDI-RU had similar values at the three thirds. In each root third, PETMP-HDDI-RU2 showed similar strength at all thirds, and similar strength at the apical third was observed for other associations. Mixed and adhesive failures predominated.

Conclusion:

Experimental silanes promoted different bond strength values in the adhesion of fiberglass posts to the root thirds, with better results for PETMP-HDDI silane. The root region did not influence the failure pattern and most slices showed mixed (MCDP) or adhesive (ADP) failure.

A matched cohort study of the failure pattern after laparoscopic and open gastrectomy for locally advanced gastric cancer: does the operative approach matter?

BACKGROUND

Due to lacking evidence for confirming the efficacy of performing laparoscopic surgery for locally advanced gastric cancer (LAGC). Therefore, this study aimed to compare the static and dynamic failure patterns after laparoscopic gastrectomy (LG) and open gastrectomy (OG) in LAGC.

METHODS

A total of 1792 LAGC patients who underwent radical resection between January 2010 and January 2017 were divided into the LG group (n = 1557) and the OG group (n = 235). Propensity score matching was performed to balance the two groups. Dynamic hazard rates of failure were calculated using the hazard function. Early and late failure were defined as failure occurring before and after 2 years since surgery, respectively.

RESULTS

A total of 1175 patients with LAGC were included after matching (LG group, n = 940; OG, n = 235). The failure rate of the whole cohort was 43.2% (508/1175), accounting for 41.4% (389/940) and 50.6% (119/235) in the LG and OG groups, respectively. Although the two groups showed no significant differences in failure rate for any failure type, landmark analysis showed a lower early distant recurrence rate in the stage IIa-IIIb subgroup of the LG group (OG versus LG: 30.3% versus 21.1%, P = 0.004). The dynamic hazard rate peaked at 9.4 months (peak rate = 0.0186) before gradually declining. In stage IIa-IIIb patients, the hazard rate of the OG group remained significantly higher than that of the LG group within the first 2 years in terms of distant recurrence (peak rate: OG versus LG, 0.0091 versus 0.0055).

CONCLUSION

Given the differences in early failure between LG and OG, more intensive surveillance for distant recurrence within the first 2 years should be considered for patients with stage IIa-IIIb after OG.

Patterns of regional lymph node failure of locally advanced hypopharyngeal squamous cell carcinoma after first-line treatment with surgery and/or intensity-modulated radiotherapy

Background

To identify the spatial patterns of regional lymph node failure of locally advanced hypopharyngeal squamous cell carcinoma (SCC) after first-line treatment with surgery and/or intensity-modulated radiotherapy (IMRT).

Methods

We retrospectively obtained the clinicopathological characters of 123 hypopharyngeal SCC patients, and investigated the patterns of regional lymph node failure. Univariate and multivariate logistic regression were used to determine the risk factors of regional lymph node failure.

Results

Forty patients (32.5% of total patients) were suffered regional lymph node failure. In these patients, the ipsilateral neck level II nodal failure account for 55.0% (22/40) followed by level III 30.0% (12/40), level VIb 15.0% (6/40), level VII 15.0% (6/40), and level IV 5.0% (2/40). In addition, 17.5% (7/40) patients suffered contralateral neck level II nodal failure and 7.5% (3/40) patients suffered level III nodal failure. The common failure levels were the II (7/46, 15.2%), III (4/46, 8.7%), VIb (4/46, 8.7%), and VII (5/46, 10.9%) for treatment by surgery. The lymph node recurrence and persistent disease at levels II (19/77, 24.7%) and III (10/77, 13.0%) remained the major cause of failure following curative intent of IMRT. The postoperative radiation significantly decreased the risk of regional lymph node failure (OR = 0.082, 95% CI: 0.007–1.000, P = 0.049); and the radiologic extranodal extension significantly increased the risk of regional lymph node failure (OR = 11.07, 95% CI: 2.870–42.69, P < 0.001).

Conclusions

Whatever the treatment modality, the lymph node failure at level II and III was the most popular pattern for hypopharyngeal SCC. Moreover, for patients who underwent surgery, the nodal failure at level VIb and VII was frequent. Thus, postoperative radiation of level VIb and VII may give rise to benefit to locally advanced hypopharyngeal SCC patients.

Fracture Resistance of Tilted Premolars Restored with Different Post-Core Systems

Aims and Objective:

To assess the effect of root tilt on the fracture resistance and failure pattern of endodontically-treated premolars restored with different post-core systems.

Materials and Methods:

Ninety endodontically-treated premolars were mounted in acrylic blocks with 0°, 12°, and 24° axial root tilt. Teeth in each group were restored in three subgroups with cast post-core, readymade metal posts and composite cores, and fiber post and composite cores. Crowns of all teeth were prepared coinciding with the long axis of the acrylic blocks to receive all-ceramic crowns. All restored teeth were stressed to record the maximum load at failure and the associated failure pattern. The collected data were statistically analyzed using two-way ANOVA, Tukey's, and Kruskal–Wallis tests at α = 0.05 on past software to detect any differences between subgroups.

Results:

Analysis of the collected data indicated significant differences between the tested subgroups (ANOVA, P = 3.86). Further analysis showed significant difference between all test subgroups and the control (Tukey's, P < 0.05). In general, teeth with 0° tilt seemed more resistant to fracture than the tilted ones. For all groups, teeth restored with fiber post and composite cores (SG3) were more resistant to fracture compared to other post-core systems (SG1 and SG2) (Tukey's, P < 0.05). The root fracture was the most commonly seen mode of failure.

Conclusions:

Root tilting usually affects the fracture resistance of teeth restored with post-core systems. The fiber post and composite cores seemed to be the best choice to restore teeth with different root tilting possibilities.

Prognostic factors and failure patterns in non-metastatic nasopharyngeal carcinoma after intensity-modulated radiotherapy

Background

The prognostic values of staging parameters require continual re-assessment amid changes in diagnostic and therapeutic methods. This study aimed to identify the prognostic factors and failure patterns of non-metastatic nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era.

Methods

We reviewed the data from 749 patients with newly diagnosed, biopsy-proven, non-metastatic NPC in our cancer center (South China, an NPC endemic area) between January 2003 and December 2007. All patients underwent magnetic resonance imaging (MRI) before receiving IMRT. The actuarial survival rates were estimated using the Kaplan–Meier method, and survival curves were compared using the log-rank test. Multivariate analyses with the Cox proportional hazards model were used to test for the independent prognostic factors by backward eliminating insignificant explanatory variables.

Results

The 5-year occurrence rates of local failure, regional failure, locoregional failure, and distant failure were 5.4, 3.0, 7.4, and 17.4%, respectively. The 5-year survival rates were as follows: local relapse-free survival, 94.6%; nodal relapse-free survival, 97.0%; distant metastasis-free survival, 82.6%; disease-free survival, 75.1%; and overall survival, 82.0%. Multivariate Cox regression analysis revealed that orbit involvement was the only significant prognostic factor for local failure (P = 0.011). Parapharyngeal tumor extension, retropharyngeal lymph node involvement, and the laterality, longest diameter, and Ho’s location of the cervical lymph nodes were significant prognostic factors for both distant failure and disease failure (all P < 0.05). Intracranial extension had significant prognostic value for distant failure (P = 0.040).

Conclusions

The key failure pattern for NPC was distant metastasis in the IMRT era. With changes in diagnostic and therapeutic technologies as well as treatment modalities, the significant prognostic parameters for local control have also been altered substantially.

Spread patterns of lymph nodes and the value of elective neck irradiation for esthesioneuroblastoma

OBJECTIVES

This study was aimed to characterize patterns of lymphatic spread and assess the value of prophylactic elective neck irradiation (ENI) for esthesioneuroblastoma (ENB).

METHODS

A retrospectively analysis of 116 patients with newly diagnosed ENB at our institution over 35-year period was undertaken.

RESULTS

32 patients (28%) presented lymph node metastasis at initial diagnosis, the common sites involved were level II, Ib, level III and VIIa. Among 80 N-negative patients staged in Modified Kadish B/C, 50 patients were delivered with ENI, 30 patients were not. The 5-year regional failure-free survival was 98% in patients treated with ENI and 75% in patients without ENI (p=0.005), regional failure rate decreased significantly from 23% (7/30) to 2% (1/50) after ENI (p=0.002). Multivariate analysis also suggested that ENI was an independent favorable predictor for regional controlling (HR, 0.102; 95% CI: 0.012-0.848; p=0.035).

CONCLUSIONS

This is the largest cohort of ENB so far in a single institute, and also the first detailed description of nodal spread patterns of N-positive ENB. Elective neck irradiation reduced the regional failure significantly and should be recommended as a part of initial treatment strategy for patients staged with Modified Kadish B/C.