Press Fit Research Articles

SIMULTANEOUS VERSUS STAGED TOTAL HIP ARTHROPLASTY FOLLOWING ACETABULAR FRACTURE FIXATION: A COMPARISON OF OUTCOMES

Acetabular fractures present a challenge. Anatomical reduction can be achieved by open reduction and internal fixation (ORIF). However, in elderly patients with complex fracture patterns and osteoporotic bone stock, “fix and replace” has become an option in the management of these injuries. This involves ORIF of the acetabulum to enable insertion of a press fit cup and subsequent cemented femoral stem at the index surgery.A Retrospective analysis of all operatively managed acetabular fractures by a regional Pelvic and Acetabular Trauma service (01/01/2018-30/05/2023) STATA used for analysis. 34 patients undergoing “fix and replace” surgery. Of the 133 patients managed with ORIF, 21 subsequently required Total Hip Arthroplasty (THA). Mean follow up was 2.7 years versus 5.1. There was no statistical significance between the two groups with regards to BMI or sex. Mean age in the “fix and replace” group was 68 compared to 48 in the ORIF and subsequent THA group. This reached statistical significance between the two groups (p=0.001).ASA and Charlson Comorbidity Index (3 and 3 in “fix and replace” and 2 and 1.2 in ORIF to THA group) and Charlson Comorbidity Index both were statistically significantly different (p=0.006 and p=0.027, respectively). High energy mechanism of injury accounted for 56% of the “fix and replace” group compared to 48% in the ORIF to THA. 74% of “fix and replace” were associated fractures compared to 53% of ORIF to THA. Wait to surgery was 3 days for “fix and replace” while 186 days was the mean wait time from listing to THA for the ORIF to THA group. Complication rate was 41% versus 43% in the two groups. 14% in the ORIF to THA group developed PJI versus 6% in “fix and replace”.Fix and replace allows early mobilisation in frailer, elderly patients. Our results show fewer returns to theatre and less PJI in patients having arthroplasty as part of “fix and replace” than subsequent to Open reduction internal fixation.

Differences in Femoral Medullary Canal Dimensions in the USA and East Asian Populations

With emerging technologies and improved operative techniques, cementless total hip arthroplasty is becoming more popular and showing better results. The femoral prosthesis and intramedullary nail should precisely fit in the medullary canal to prevent micromotion and loosening. Most of the femoral prosthesis and nail designs are made from the data obtained from Caucasian femur and may not press fit if used in Asian populations. This study compares the femoral medullary canal diameter in American and Oriental populations at different bony levels. A total of 245 dry femora were collected which included 47 from United States, 77 from China, 44 from Japan, 50 from Korea and 27 from Taiwan, and plan radiographs were taken. Radiographs were digitized to measure the medullary canal width at 20% (lesser trochanter; LT), 35% (supra-isthmus; SI), 50% (mid-isthmus; MI), 65% and 80% of the total femur length. The results revealed significant differences in the medullary canal width between the US and East Asian Oriental populations. The medullary canal in the US population was significantly larger at the LT, SI, MI, and 65% but significantly smaller at 80% of the femoral shaft length compared to the East Asian populations. Among the East Asian populations, significant differences were obse4rved between the Chinese and Taiwanese populations as well as the Japanese and Taiwanese populations. The Taiwanese population had the smallest femoral medullary canal size among the east Asian populations. We conclude that there are significant differences in the femoral medullary width between the American and East Asian populations. These results will be useful for surgeons operating on the proximal or distal femur.

Assessment of Treatment Approaches for Oroantral Communication and Fistulas

Objective: The aim of this study was to investigate and compare the treatment methods of large size oroantral defects (OADs) and their clinical outcomes. Material and Methods: The patients who referred our clinic between 2017 and 2023 suffering from oroantral fistula (OAF) and the cases which was occurred oroantral communication (OAC) larger than 5mm during oral procedures were included in the study. The size, type and cause of OAD, treatment method, the patient’s demographic data was recorded. VAS scale, analgesic requirement, the edema, and mouth opening measurements were obtained from preoperative day and postoperative records at 3, 7, 10 days after surgery. Results: 23 patient (8 OAF, 15 OAC) was included in this study. 9 of them was treated with buccal advancement flap (BAF), 10 with buccal fat pad (BFP) and 4 with press-fit technique. No problem was occurred at the healing process. Only in one patient BFP application was failed, and after 2 months second surgery was performed, and the area was fully covered. According to postoperative clinical outcomes, any statistically significance wasn’t observed between groups in the terms of vas scale, analgesic requirement, edema and trismus at any timepoint (p 0.05). Although there was insignificance at all parameters between treatment groups, VAS scale and analgesic requirement was less than BAF and BFP in press fit. Conclusion: BAF, BFP and press-fit methods are reliable and well-known techniques for OAD management, however, further clinical studies with larger sample sizes are needed to create treatment algorithm for OAD.

Bone-cartilage transfer for osteochondritis dissecans of the humeral capitellum

Treatment of focal cartilage defects of the humeral capitellum with autologous bone-cartilage cylinders to prevent development of arthritis of the elbow joint. High-grade, unstable lesions (> 50% of the capitellum, gradeIII-IV according to Dipaola), including those involving the lateral edge of the capitellum and with adepth of up to 15 mm. Stable lesions and generalized osteochondritis of the capitellum (including Panner's disease), as well as arelative contraindication for lesions > 10 mm, as the largest punch has amaximum diameter of 10 mm. Arthroscopy of the elbow joint, transition to open surgery. First, the size of the cartilage defect in the capitellum is determined. Then, one (or several) osteochondral cylinders (OATS Arthex) are removed, which as far as possible completely encompass the defect zone. Corresponding intact bone-cartilage cylinders are obtained from the ipsilateral proximal lateral femoral condyle, each with a0.3 mm larger diameter via an additive miniarthrotomy. The "healthy" cylinders are then inserted into the defect zone in a"press fit" technique. An upper arm cast in neutral position of the hand for 10-14days, simultaneously beginning physiotherapy (active-assisted movements) and lymphatic drainage. As soon as painless range of motion (ROM) is restored (goal: by week6), isometric training can be started. Resistance training starts from week12. Competitive sports are only recommended after 6(-8) months. The current state of research on the surgical treatment of OCD of the humeral capitellum using autologous osteochondral grafts shows mostly promising results. Arecent meta-analysis of 24studies reports asignificantly higher (p < 0.01) rate of return to sports (94%) compared to fragment fixation (64%) or microfracture and debridement (71%) [41]. However, the increased donor-site morbidity must be taken into account (ca. 7.8%).

Tuberosity healing in reverse shoulder arthroplasty for proximal humerus fractures with a diaphyseal press-fit humeral stem

BackgroundReverse shoulder arthroplasty (RSA) is a viable option for proximal humerus fractures (PHFs) in the elderly, and cemented humeral fixation is the standard of care. This study evaluates the influence of a diaphyseal press-fit stem with a 142° humeral inclination on tuberosity healing (TH) and functional outcome in RSA for PHF. MethodsTwenty-three patients received an RSA for PHF by a single surgeon at one center over a 2-year period. The humeral stem design was intended for diaphyseal press fit with a 142° humeral inclination. The tuberosities were repaired for each patient with bone graft and a standard suture technique. Patients’ clinical and radiographic outcomes were collected with a minimum 12-month follow-up. ResultsNineteen of 23 patients (83%), with a mean age of 75 + years, were available for follow-up at an average of 14 months. Radiographic analysis showed 68% of patients had evidence of TH. Grade 1 scapular notching was found in 32% of patients. There was no implant loosening or subsidence noted. Average range of motion was 163° ± 15° degrees of forward flexion, 113° ± 24° of abduction, internal rotation to the waist, and an average external rotation of 7 ± 1.5 as measured by the Constant-Murley score. The average American Shoulder and Elbow Surgeons score was 81.8, and the average Constant-Murley score was 67.9. While not significant, those with TH trended toward better clinical outcomes. There was a 0% revision rate. ConclusionA press-fit stem designed for diaphyseal fixation provides consistent reliable results in RSA for PHF. A high percentage of TH was appreciated with a 142° humeral inclination, neutral glenosphere construct, and a standardized bone grafting, suture technique. TH is associated with improved patient outcomes.

An Investigation of Increased Power Transmission Capabilities of Elastic–Plastic-Designed Press–Fit Connections Using a Detachable Joining Device

An Investigation of Increased Power Transmission Capabilities of Elastic–Plastic-Designed Press–Fit Connections Using a Detachable Joining Device

Development of a cascaded multitask physics-informed neural network (CM-PINN) to construct the muti-physical field model of rubber bushing press fitting

Development of a cascaded multitask physics-informed neural network (CM-PINN) to construct the muti-physical field model of rubber bushing press fitting

Effect of Press-Fit Size on Insertion Mechanics and Cartilage Viability in Human and Ovine Osteochondral Grafts.

The osteochondral allograft procedure uses grafts constructed larger than the recipient site to stabilize the graft, in what is known as the press-fit technique. This research aims to characterize the relationships between press-fit size, insertion forces, and cell viability in ovine and human osteochondral tissue. Human (4 donors) and ovine (5 animals) articular joints were used to harvest osteochondral grafts (4.55 mm diameter, N = 33 Human, N = 35 Ovine) and create recipient sites with grafts constructed to achieve varying degrees of press fit (0.025-0.240 mm). Donor grafts were inserted into recipient sites while insertion forces were measured followed by quantification of chondrocyte viability and histological staining to evaluate the extracellular matrix. Both human and ovine tissues exhibited similar mechanical and cellular responses to changes in press-fit. Insertion forces (Human: 3-169 MPa, Ovine: 36-314 MPa) and cell viability (Human: 16%-89% live, Ovine: 2%-76% live) were correlated to press-fit size for both human (force: r = 0.539, viability: r = -0.729) and ovine (force: r = 0.655, viability: r = -0.714) tissues. In both species, a press-fit above 0.14 mm resulted in reduced cell viability below a level acceptable for transplantation, increased insertion forces, and reduced linear correlation to press-fit size compared to samples with a press-fit below 0.14 mm. Increasing press-fit size required increased insertion forces and resulted in reduced cell viability. Ovine and human osteochondral tissues responded similarly to impact insertion and varying press-fit size, providing evidence for the use of the ovine model in allograft-related research.

Development of single-pin, un-barbed, pole-tagging of free-swimming dolphins and sharks with satellite-linked transmitters

BackgroundTo tag large marine vertebrates, without the need to catch them, avoiding using barbs for tag retention, and precisely controlling tag location, the remote Tag Attachment Device on a pole (TADpole) was developed. This allows single-pin tags (Finmount, Wildlife Computers) to be attached to the dorsal fins of free-swimming large marine vertebrates.ResultsTADpole comprises a pole-mounted holster that carries a tag. It uses compressed air, and a micro-controller, to rapidly insert a stainless-steel pin through a corrodible metal retaining ring in the first tag attachment wing, the animal’s dorsal fin, and then a press fit Delrin retaining ring in the tag wing on the other side of the fin. Tagging only occurs when the trailing edge of the dorsal fin touches a trigger bar in the holster, ensuring optimal pin placement. It was developed using fins from cadavers, then trialed on briefly restrained coastal dolphins that could be followed in successive days and weeks, and then on free-swimming animals in the field. The latter showed very short touch/response intervals and highlighted the need for several iterative revisions of the pneumatic system. This resulted in reducing the total time from triggering to tag application to ~ 20 ms. Subsequent efforts expanded the TADpole’s applicability to sharks. One free-swimming Atlantic spotted dolphin, two white sharks, and one whale shark were then tagged using the TADpole.ConclusionsBeing able to tag free-swimming dolphins and sharks remotely and precisely with satellite-linked telemetry devices may contribute to solving conservation challenges. Sharks were easier to tag than dolphins. Dolphin touch-to-response times were 28 ms or less. Delphinid skin has unique polymodal axon bundles that project into the epidermis, perhaps a factor in their uniquely fast response, which is 10 × faster than humans. Their primary reaction to tagging is to abduct the flippers and roll the fin out of the TADpole holster. This device has the potential to deliver high-quality tag data from large vertebrates with dorsal fins without the stress and logistics associated with catch-and-release, and without the trauma of tags that use barbs for retention. It also collects a dorsal fin biopsy core.

Uncemented reverse shoulder arthroplasty in proximal humeral fractures: comparative study of two different press fit stems

BackgroundReverse shoulder arthroplasty (RSA) has extended its indications in recent years to include complex proximal humerus fractures (PHFs) in elderly patients. The traditional approach in cases of PHF has been to cement the stem but, as in orthopedic surgery, the current trend in PHF is to avoid cementing the humeral stem as well. MethodsWe evaluated 63 patients (representing 63 shoulders) who underwent RSA with uncemented stem after acute fracture of the proximal humerus. We analyzed the clinical and radiological outcomes, as well as medium-term complications, using two different prosthesis models. ResultsThe mean postoperative follow-up period was 21-23 months, and the mean age of the patients was 74.5 years. The average Constant Score was 56.94 points; there were no statistical significant differences in Constant Score depending on the prosthesis model used. No cases of aseptic loosening were observed. However, there was evidence of stress-shielding in prostheses with diaphyseal fixation, although this phenomenon did not appear to have functional or clinical consequences for the patients. Intraoperative complications occurred in 6.35% of cases, and postoperative complications were noted in 4.92%. ConclusionBased on the results of this study, we can affirm that the use of RSA with cementless stems in PHF can be a safe alternative, providing satisfactory clinical, functional, and radiographic results in the short term without the need to use cement in their fixation. The choice of prosthesis model may influence the occurrence of radiographic phenomena but does not seem to affect clinical outcome.

Anterior Cruciate Ligament Reconstruction: 3-Incision Technique With Allograft Quad Tendon ACL Reconstruction

Background: Anterior cruciate ligament (ACL) ruptures are becoming more common in younger and older athletes. Approximately 250,000 ACL injuries occur each year, requiring the need for an effective and reproducible surgical technique. Indications: The 3-incision outside-in technique utilizes the donor quadriceps tendon, an extraordinarily strong graft, without damage from autogenous harvesting of patellar tendon or hamstrings. While some data suggest higher re-rupture risk with donor tissue, this is counterbalanced by avoiding secondary surgical site damage. Technique Description: The ruptured ACL is removed and the intercondylar notch is cleaned to visualize the anatomical ACL insertion site. Using the 3-tunnel technique a gaff is passed through the intercondylar notch, through a puncture hole (incision 1) and a rear entry guide hooked to its tip. The guide point is pulled into the knee and placed in posterior aspect of the anatomic footprint of the native ACL. Through incision 2, a guide pin is drilled to this point and overdrilled with a 10-mm drill. The edges of the hole in the intercodylar notch are smoothed with a currette. The tibial footprint is cleared, a tibial aiming guide placed. Through incision 3, a guide pin is placed and over drilled with a 10-mm drill followed by a Gore-Tex reamer to ensure no impingement would inhibit graft passage. The proximal bone of a quadriceps tendon graft is sized through a 10-mm sizer and compacted. Two holes are drilled to hold sutures for the proximal aspect of the femoral graft. The quadriceps tendon graft is sized to fit through a 9-mm tunnel and the free end whipped with a stitch before being passed from outside-in through the smoothed tunnels. The femoral bone block is tapped to have a press fit initially and then is fixed with a Milagro screw. The knee is cycled ten times to remove slack and the interference fit guide pin is placed on the anterior aspect of the graft, and fixed with the knee at 15° to 30° of flexion. Stability is tested with confirmation of no impingement, and then an extra-articular reconstruction with a semitendinosus allograft is performed. The extra articular reconstruction is placed at the point between Gerdy's tubercle and the fibular head, passed under the skin and the iliotibial band, and then inserted just anterior and superior to the ACL femoral drill hole. Results: Patient outcomes in our initial experience are comparable to our autogenous bone-tendon-bone (BTB) procedures without anterior knee pain. Return to sport is similar with autogenous procedures, with a delay of 6 to 12 months. In addition, there is a possibility for acceleration of healing with the addition of platelet-rich plasma and hyaluronic acid between 1 and 3 months postsurgery. We have insufficient data so far to determine if the re-rupture rate will decline compared with reported outcomes. Conclusion: The 3-incision technique with allograft quadriceps tendon for ACL reconstruction is a reproducible surgical technique that avoids harvest from the patient's own body. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Inspection of press joints based on the analysis of their deformation patterns under local thermal loading

The results of experimental studies of the possibility of using strain gauges under local pulsed thermal loading to evaluate the tension of the press connections of bearing rings with shafts are presented. Samples of press joints with tightness in the range from 38 to 118 microns were made. As a result of the study of the patterns of heat flow propagation in bearing rings and tension samples by contact method and means of thermal imaging, the possibility of separating deformations associated with the influence of temperature on the deformation measurement area and the temperature gradient in the heating area is shown. The methods of inspecting the press joint when exposed to a heater ring with a heat power capacity of 80 kJ and a temperature of 200°C and measuring the deformations of the ring and shaft by an opto-polarizing sensor with a base of 60 mm and a resolution of 2×10 — 7 relative deformations have been experimentally implemented. A correlation has been established between the time of reaching the maximum of local deformations of the shaft with the tightness of the press joints and the sign of deformations of the bearing ring with the tightness of the press fit, the gap between the ring and the shaft.

Areal bone mineral density is not associated with femoral stem subsidence in patients younger than 70years undergoing total hip arthroplasty.

Femoral stem subsidence is a known complication after uncemented total hip arthroplasty (THA). The purpose of this study was to determine the frequency of osteoporosis and to investigate the relationship between areal bone mineral density (aBMD) and subsidence in a cohort of patients younger than 70years. One hundred consecutive patients (age 60 ± 6years; 52 female, 48 male) undergoing uncemented THA using a collarless press fit femoral stem were retrospectively reviewed. Dual-energy X-ray absorptiometry (DXA) was performed preoperatively at the proximal femur and lumbar spine, and if not feasible at these sites, at the distal radius. DXA results were compared to a cohort of 100 patients ≥ 70years scheduled for cemented THA. Age, sex, and body mass index (BMI), canal flare index (CFI), and canal fill ratio (CFR) were assessed. Analysis of stem subsidence and migration was performed on standardized, calibrated radiographs obtained postoperatively and at follow-up. The frequency of osteoporosis was considerably lower in the study cohort compared to patients ≥ 70years (7% vs. 19%, p = 0.02). Illustrated by the high CFR (mean 96 ± 4%) in the mid-stem region, a sufficient press fit was achieved. After a mean follow-up of 7.4months, the mean stem subsidence was 0.9 ± 0.9mm. Only two patients had subsidence greater than 3mm, one of whom was morbidly obese and the other diagnosed with severe osteoporosis. There were no correlations between any of the parameters (CFI, CFR, age, sex, BMI) and femoral stem subsidence. In addition, aBMD T-scores showed no correlations with subsidence. aBMD by DXA does not appear to be associated with stem subsidence in patients younger than 70years and withadequate press fit.

Improving bonding strength by non-thermal atmospheric pressure plasma-assisted technology for A5052/PEEK direct joining

The direct bonding of A5052 aluminum (Al) alloy to the engineering polymer poly(ether ether ketone) (PEEK) using an atmospheric pressure plasma-assisted process was demonstrated. The effect of plasma irradiation on the bonding surface of metal resin on the bonding strength following thermal press fitting method was investigated. Specimens bonded by plasma irradiation on the PEEK surface only showed a high tensile shear stress of 15.5 MPa. With increasing plasma irradiation time, the bond strength of the samples bonded to the PEEK surface by plasma irradiation increased. The increase in the bond strength between metals and polymers following direct bonding is caused by the addition of oxygen functional groups on the polymer. In contrast, specimens in which only the Al was exposed to the plasma showed a decrease in bond strength compared with unirradiated samples. This reduction in bond strength is attributed to the forming magnesium oxide, which forms in the early stages of participation due to plasma irradiation.

Comparison of three-versus two-dimensional pre-operative planning for total hip arthroplasty

BackgroundA successful clinical outcome for total hip arthroplasty (THA) depends on accurate sizing and positioning of the implants. Using three-dimensional (3-D) pre-operative planning with a computerized tomography (CT) scan has many potential advantages over conventional 2-D planning using radiographs, including potentially more accurate assessments of the size and anteversion of the acetabulum, as well as lateral femoral offset. The purpose of this study was to compare the accuracy of 3-D to 2-D templating with respect to acetabular and femoral size, as well as lateral femoral offset. MethodsPre-operative templating data was collected prospectively from a consecutive series of 290 primary THAs (acetabulum on all, femoral component on 255 of the cases using one specific stem). All cases were initially templated on a digital imaging picture archiving and communication (PACS) system with calibrated images to estimate the acetabular size, femoral size, and lateral femoral offset. The 3-D templating was then performed with software based on a CT scan, and the results were compared to what was surgically implanted. ResultsThe 3-D templating for the acetabulum was accurate 99.7% of the time based on the final implanted component. The 2-D templating for the acetabulum was accurate 39% of the time, with 46% templating larger and 15% templating smaller than the final implanted component. The 3-D templating of the femoral component was accurate 63% of the time, and within one size of final implant in 96% of cases. The 2-D templating of the femoral component was accurate 53% of the time and within one size of final implant in 94% of cases. Lateral femoral offset consistently matched the 3-D plan, with a 100% match rate. The 2-D templated femoral offset was accurate 87% of the time and was changed in 13% of cases after 3-D templating. ConclusionThe CT-based 3-D preoperative planning was superior to 2-D planning for THA with respect to acetabular size, femoral size, and lateral femoral offset. Precise acetabular component sizing conserves bone and allows for a more predictable press fit, while facilitating efficient inventory management. Lateral femoral offset is often difficult to measure on 2-D images, and 3-D templating consistently allows for accurate offset restoration, which is important for normal hip function and stability.

Influence of the Friction Coefficient on the Stress Distributions and Contact Pressure in Press-Fits via Finite Element Analysis

Press fits are a simple and effective method for assembling a shaft into a hub for different applications in the mechanical engineering field. This method consists of forcing to pass a shaft into a hub via axial insertion. As a result of the difference in the diameters of both components of the shaft and hub, a radial interference is generated, causing a contact pressure at the interface shaft–hub. Contact pressure and the friction coefficient are key factors influencing the maximum transmitted torque. So, in this study, different scenarios for the assembly of a press fit were simulated using finite elements (FE) in order to reveal the influence of this key parameter on the manufacturing-induced stresses in the hub. This way, different friction conditions were considered in terms of the friction coefficient from the frictionless case to a case of high dry friction. In addition, different hub geometries were analyzed including conventional hubs and chamfer hubs with optimal geometry that allows lowering the localized stress concentrations at the hub edges. This way, a more realistic estimation of the final stress state of a press fit is obtained. According to the obtained results, the friction coefficient is revealed as a key parameter in the resulting stress field, causing a non-uniform distribution of stress that can affect the mechanical performance of the press-fit assembly.

Effect of Interference Size on Contact Pressure Distribution of Railway Wheel Axle Press Fitting

Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame’s equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm.

Direct bonding of stainless steel and PEEK using non-thermal atmospheric pressure plasma-assisted joining technology

This work demonstrates the direct bonding of stainless steel (SUS304) to poly(ether ether ketone) (PEEK) using non-thermal atmospheric pressure plasma-assisted joining technology in association with thermal press fitting. The tensile shear stress values of specimens bonded after plasma treatment of both the SUS304 and PEEK surfaces were higher than those of untreated samples and samples for which only one of the two surfaces was exposed to the plasma. These results indicate that the surface physical and chemical changes induced by exposure to the radio frequency plasma jet significantly increased the bonding strength.

Effect of compressive residual stress and press fitting on residual life assessment of deep-rolled EA4T steel railway axles

Deep rolling surface strengthening is an effective way to introduce compressive residual stress (CRS) along the railway axle, which can improve the fatigue resistance of the material. The CRS field was rebuilt adopting the proportional-integral (PI) iteration method and the unit pressure method (UPM) to study the fatigue cracking behavior of deep-rolled EA4T railway axles. The remaining life prediction model and the stress intensity factor (SIF) solution method were then validated using simulations and testing with small-sized specimens. The remaining life of the EA4T railway axle was then calculated by applying a realistic vertical load spectrum. The results showed that CRS prevented crack propagation, enhanced the critical propagation size of railway axle cracks, and prolonged the remaining life of the axle. Additionally, the remaining life of the axle may not support the following maintenance period if a crack with an extendable size emerges at the unloading groove of the railway axle. This work provides a theoretical basis for the optimization of the non-destructive testing (NDT) interval of deep-rolled EA4T railway axles.

Osteochondral Allograft and Concurrent Meniscal Allograft Transplantation

Background: Symptomatic, full-thickness chondral defects often are associated with meniscal deficiencies. These are difficult problems to manage in the young, high-demand patient population. A number of differing techniques have been published with no consensus. While more recent techniques have favored minimally invasive approaches, an open approach with tubercle osteotomy to maximize visualization of all knee compartments can still provide favorable outcomes when using a careful technique and postoperative protocol. Indications: Young, high-demand patients with long-standing meniscal deficiency and resultant chondral defects are indicated for cartilage restoration and preservation procedures. A meniscal allograft transplantation is indicated in symptomatic patients with prior total or subtotal meniscectomy. It is important to address other concomitant pathology such as instability, alignment, and chondral defects. Concomitant procedures are often performed with meniscal transplants, including osteochondral allograft transplantation for larger defects. Technique Description: This surgical technique video demonstrates a tibial tubercle osteotomy approach to gain access to both the medial and lateral tibiofemoral compartments. An arthroscopic-assisted bone slot technique was performed for meniscal allograft transplantation. Appropriately sized osteochondral allograft bone plugs were then transplanted onto the medial and femoral condyles with a press fit technique. Results: At 1-year follow-up, the presented patient has regained full motion and are back to full activities. Discussion/Conclusion: Full-thickness chondral defects associated with meniscal deficiency in a young, high-demand patient is a difficult problem to manage. Recent results using minimally invasive approaches have demonstrated favorable mid- and long-term outcomes. In patients with pathology that may preclude a minimally invasive approach, an open technique with osteotomy can still have a promising outcome. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.