A POLYNOMIAL METHOD FOR SOLVING THE PROBLEMS FOR LATERAL INSTABILITY OF CANTILEVER PLATES

The present article researches the problems of the lateral instability of cantilever rectangular plates under a concentrated force or a uniformly distributed load respectively. We select the polynomial (2.1) instead of the cosecant function in Ref. [1] as the flexural functions.The minimum critical load obtained here is more exact than the results obtained in Ref[1]

LATERAL INSTABILITY OF RECTANGULAR PLATES

This paper investituites the problems of lateral buckling of rectangular plates. In the text we discuss the minimum critical load of the lateral buckling occurring on under a concentrated force, uniformly distributed load and the concentrated couples, respectively. The energy method is used in this article.

Correlation of stress radiographs to injuries associated with lateral ankle instability

BACKGROUND Stress radiographs have demonstrated superior efficacy in the evaluation of ankle instability.AIM To determine if there is a degree of instability evidenced by stress radiographs that is associated with pathology concomitant with ankle ligamentous instability.METHODS A retrospective review of 87 consecutive patients aged 18-74 who had stress radiographs performed at a single institution between 2014 and 2020 was performed.These manual radiographic stress views were then correlated with magnetic resonance imaging and operative findings.RESULTS A statistically significant association was determined for the mean and median stress radiographic values and the presence of peroneal pathology(P=0.008 for tendonitis and P=0.020 for peroneal tendon tears).A significant inverse relationship was found between the presence of an osteochondral defect and increasing degrees of instability(P=0.043).CONCLUSION Although valuable in the clinical evaluation of ankle instability,stress radiographs are not an independent predictor of conditions associated with ankle in-stability.

A rigid-flexible coupling finite element model of coupler for analyzing train instability behavior during collision

Rail vehicles generate huge longitudinal impact loads in collisions.If unreasonable matching exists between the compressive strength of the intermediate coupler and the structural strength of the car body,the risk of car body structure damage and train derailment will increase.Herein,a four-stage rigid-flexible coupling finite element model of the coupler is established considering the coupler buckling load.The influence of the coupler buckling load on the train longitudinal-vertical-hori-zontal buckling behavior was studied,and the mechanism of the train horizontal buckling instability in train collisions was revealed.Analysis results show that an intermediate coupler should be designed to ensure that the actual buckling load is less than the compressive load when the car body structure begins to deform plastically.The actual buckling load of the coupler and the asymmetry of the structural strength of the car body in the lateral direction are two important influencing factors for the lateral buckling of a train collision.If the strength of the two sides of the car body structure in the lateral direction is asymmetrical,the deformation on the weaker side will be larger,and the end of the car body will begin to deflect under the action of the coupler force,which in turn causes the train to undergo sawtooth buckling.

Ankle Arthroscopy,Lateral Ligament Repair and Peroneal Tendon Reefing for Chronic Lateral Ankle Instability:The Triad vs Arthroscopy with Ligament Repair

Peroneal tendon and retinacular pathology contributes to chronic lateral ankle instability. The “gold standard” surgical treatment for chronic lateral ankle instability has been the Brostrom-Gould procedure with its modifications. An ankle arthroscopy is an adjuvant procedure to address any intra-articular pathology. We review our results of two study groups. The first group underwent an ankle arthroscopy and a Brostrom-Gould procedure. The second group (triad) underwent an ankle arthroscopy, the Brostrom-Gould procedure and excision of low lying peroneal muscle belly with tightening of the inferior peroneal retinaculum. The triad technique was performed on 97 patients and results compared to 71 ankle arthroscopies with the Brostrom-Gould procedure. The patients were contacted at a mean follow-up time of 30 months for postoperative ACFAS scores, VAS scores, and overall satisfaction. Patients were also asked to report incidence of ankle sprain recurrence. The average postoperative ACFAS hindfoot and ankle score was 92 for the triad group and 89 for the arthroscopic debridement and Brostrom-Gould group. The average overall satisfaction was 98% in the triad group and 91% in the scope and Brostrom group. There were 4 (4.3%) recurrences in the triad group and 12 (17.6%) in the Brostrom-Gould with scope group. Each group had a similar incidence of wound healing complications. Peroneal tendon and retinacular pathology contributes to continued ankle instability and pain. We believe that the triad procedure is superior to the Brostrom-Gould procedure.

Coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments

Delaminations in structures may significantly reduce the stiffness and strength of the structures and may affect their vibration characteristics. As structural components, beams have been used for various purposes, in many of which beams are often subjected to axial loads and static end moments. In the present study, an analytical solution is developed to study the coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments. Euler-Bernoulli beam theory and the ＂free mode＂ assumption in delamination vibration are adopted. This is the first study of the influences of static end moments upon the effects of delaminations on natural frequencies, critical buckling loads and critical moments for lateral instability. The results show that the effects of delamination on reducing natural frequencies, critical buckling load and critical moment for lateral instability are aggravated by the presence of static end moment. In turn, the effects of static end moments on vibration and instability characteristics are affected by the presence of delamination. The analytical results of this study can serve as a benchmark for finite element method and other numerical solutions.

A new method of anterior talofibular ligament reconstruction:Arthroscopically artificial ligament reconstruction with tensional remnant-repair

Purpose:To investigate the clinical effects of arthroscopically artificial ligament reconstruction with tensional remnant-repair in patients who are obese,and/or with demand for highly intensive sports,and/or with poor-quality ligament remnants.Methods:A retrospective case series study was performed on patients treated by arthroscopically anterior talofibular ligament(ATFL)reconstruction with tensional remnant repair technique from January 2019 to August 2021.General data,including demographics,surgical time,and postoperative adverse events,were recorded.The American Orthopaedic Foot and Ankle Society score(AOFAS),foot and ankle ability measure(FAAM),visual analog scale(VAS),and anterior talar translation were measured preoperatively and at 6 weeks,3 months,and 2 years postoperatively.Ultrasonography examination was performed preoperatively and 2 years postoperatively to evaluate the ATFL.Data were analyzed using SPSS 19.0.F test was used to analyze the pre-and postoperative VAS,FAAM,and AOFAS scores.The significance was set at p<0.05.Results:There were 20 males and 10 females among the patients with a mean age of(30.71±5.81)years.The average surgical time was(40.21±8.59)min.No adverse events were observed after surgery.At 2 years postoperatively,the anterior talar translation test showed grade 0 laxity in all patients.VAS score significantly decreased from preoperatively to 6 weeks,3 months,and 2 years postoperatively(p<0.001).Improvement of FAAM score and the AOFAS score from preoperatively to 6 weeks,3 months,and 2 years postoperatively was statistically significant(p<0.001).At 3 months postoperatively,most patients(23/30)could return to their pre-injured activities of daily living status.At 2 years postoperatively,all patients were able to return to their pre-injured activities of daily living status,and almost every patient(18/19)who expected highly intensive sports returned to sports with only 1 obese patient failing to achieve the goal.The ultrasonography examination at 2 years postoperatively showed that there was a linear band structure of soft tissue on the tension-rich fiber tape image from the fibular to the talar attachment sits of ATFL.Conclusion:The novel arthroscopically artificial ligament reconstruction with tensional remnant-repair technique for ATFL achieved satisfactory clinical outcomes in the short and medium term after operation,and allowed early return to pre-injured activities,which could be a reliable option for patients with chronic lateral ankle instability.