PUNCHING CUPS WITH BOTTOM FLANGE BY DIRECT EXTRUSION WITH COUNTER-PUNCH. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS CRAMPED EXTRUSION PROCESS

The method of calculating the energy and deformation parameters of the process of constrained extrusion of glasses with a counter-punch is described. Extrusion of both non-hardening and hardening material is considered. In the latter case, accounting for the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as the total and specific deforming forces, maximum pressure on the matrix wall, and increase in yield stress.

Marcksl1 modulates endothelial cell mechanoresponse to haemodynamic forces to control blood vessel shape and size

The formation of vascular tubes is driven by extensive changes in endothelial cell (EC) shape. Here, we have identified a role of the actin-binding protein, Marcksl1, in modulating the mechanical properties of EC cortex to regulate cell shape and vessel structure during angiogenesis. Increasing and depleting Marcksl1 expression level in vivo results in an increase and decrease, respectively, in EC size and the diameter of microvessels. Furthermore, endothelial overexpression of Marcksl1 induces ectopic blebbing on both apical and basal membranes, during and after lumen formation, that is suppressed by reduced blood flow. High resolution imaging reveals that Marcksl1 promotes the formation of linear actin bundles and decreases actin density at the EC cortex. Our findings demonstrate that a balanced network of linear and branched actin at the EC cortex is essential in conferring cortical integrity to resist the deforming forces of blood flow to regulate vessel structure.

PUNCHING CUPS WITH BOTTOM FLANGE BY DIRECT EXTRUSION WITH COUNTER-PUNCH. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS FREE EXTRUSION PROCESS

The methodology for calculating the energy and deformation parameters of the processes of free extrusion of glasses with a counter-punch is described. Extrusion of both non-hardening and hardening material is considered. In the latter case, accounting for the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as the total and specific deforming forces, maximum pressure on the matrix wall, and increase in yield stress.

Marcksl1 modulates endothelial cell mechanoresponse to haemodynamic forces to control blood vessel shape and size

ABSTRACTThe formation of vascular tubes is driven by extensive changes in endothelial cell (EC) shape. Here, we have identified a novel role of the actin-binding protein, Marcksl1, in modulating the mechanical properties of EC cortex to regulate cell shape and vessel structure during angiogenesis. Increasing and depleting Marcksl1 expression level in vivo resulted in an increase and decrease, respectively, in EC size and the diameter of microvessels. Furthermore, endothelial overexpression of Marcksl1 induced ectopic blebbing on both apical and basal membranes, during and after lumen formation, that is suppressed by reduced blood flow. High resolution imaging revealed that Marcksl1 promotes the formation of linear actin bundles and decreases actin density at the EC cortex. Our findings demonstrate that a balanced network of linear and branched actin at the EC cortex is essential in conferring cortical integrity to resist the deforming forces of blood flow to regulate vessel structure.

Study of management of subtrochanteric fractures of femur with reconstruction nail

<p class="abstract"><strong>Background:</strong> Subtrochanteric fractures of femur are the fractures occurring from the inferior aspect of the lesser trochanter to 5 cm distally. They represent a challenge for surgeons due to the deforming forces acting on the region and the high rates of complications like non-union. This study evaluates the fixation of subtrochanteric fractures of femur with reconstruction nail which is a specialized antegrade intramedullary nail for femur.</p><p class="abstract"><strong>Methods:</strong> A prospective study conducted between October 2017 to May 2019 where 20 cases of subtrochanteric fractures of femur were treated with reconstruction nail and were followed up serially till 24 weeks radiologically and clinically.<strong></strong></p><p class="abstract"><strong>Results:</strong> The average time of union for patients was 5.15±1.14 months with 3 patients whose fractures didn’t unite where one went for frank non union, one had a refracture and one patient had reverse z effect. The functional outcome was excellent in 45% patients and good in 30% patients while poor in 3 (15%) patients.</p><p class="abstract"><strong>Conclusions:</strong> Reconstruction nail is a good device for subtrochanteric fractures of femur providing rigid fixation with low complication rates.</p>

One-step Management of Severely Deformed, Long-Neglected Club Feet

Category: Other Introduction/Purpose: Early management of the club foot using the Ponsetti technique has almost eliminated severe residual deformities from this problem. Unfortunately, in remote regions of the world patients may not have been afforded the benefits of this technique. The consequences are severely deformed, long-neglected foot deformities. Interventions to mitigate this problem have included talectomies, osteotomies, tendon transfers, gradual corrections using Ilizarov principles and as a last resort, transtibial amputations. All have undesirable features such as inadequate corrections with residual deformities, need for additional surgeries, intensive post-operative management and/or need for custom orthotics or prostheses. We propose a one-stage, single setting approach to this problem that fully realigns the foot and requires minimum of post-operative management. Methods: During a 2017 humanitarian mission to Vietnam, six patients with severely deformed, long-neglected club feet were managed at a remote orthopaedic rehabilitation facility using our one-stage, single surgery approach. The six-step procedure included: 1) Percutaneous tri-hemisections (Hoke) of the Achilles tendon, 2) Excision of lateral ulcers/bursas, 3) Minimally invasive releases of all constricting soft tissues structures, 4) Closing wedge osteotomy at apex of deformity, 5) Manual reduction to achieve plantigrade foot, and 6) Maintenance of correction with temporary spanning external fixation in five patients and percutaneous Steinmann pins in a four-year old patient. No tendon transfers were done. No tourniquets or perioperative antibiotics were used with these minimally invasive and percutaneous interventions. At six weeks, the external fixation was removed, walking casts were applied with minimal manipulations to optimally position the feet. At 12 weeks the casts were removed, patients allowed to use footwear of their choosing. Results: Follow-ups initially obtained weekly, then monthly through e-mails by a co-author fluent in Vietnamese were supplemented with photographs. Near-plantigrade feet axially aligned with the leg were obtained with all the initial corrections. By 48 hours pain was reported as minimal even though marked tension occurred across intact joint capsules in order to achieve the corrections. One skin, pin tract infection was reported that resolved once the pin was removed. Follow-up information at six months report that the corrections have been maintained with high satisfaction in all patients. Conclusion: Our innovative approach to deformed, neglected club feet is supported by appreciating the biomechanics of the problems. Dynamic deforming forces (tendons and muscles) must be released. Tendon transfers are inadequate to correct contractures. Bony deformities must be osteotomized. Viscoelasticity of ligaments and joint capsules deform with time and need not be released; corrections initially obtained using the fixators become permanent with time. Our experiences support the use of our approach for the patient population with which we dealt and suggest that earlier soft tissue releases of dynamic deforming forces be done in conjunction with the Ponsetti technique.

Botox and Thumb MCP Radial Collateral Ligament Reconstruction

Background We report the use of botulinum toxin to aid in the treatment of chronic radial collateral ligament insufficiency of the thumb. Case Description Treatment included autograft tendon reconstruction and cast immobilization. Six weeks postoperatively, prior to hand therapy, the patient underwent an ultrasound-guided botulinum neurotoxin A injection into the adductor pollicis muscle to negate its deforming forces on the reconstruction. The patient made an excellent recovery and 1 year postoperatively was pain free and had a stable radial collateral ligament (RCL) upon examination. Literature Review The outcomes of RCL repair and reconstruction are unpredictable, in part, due to the strong opposing forces of the adductor pollicis. Clinical Relevance The use of Botox injection may enhance the outcomes of RCL repair or reconstruction by neutralizing the deforming forces of the adductor muscle.

Evaluation of Fibular Fracture Type vs Location of Tibial Fixation of Pilon Fractures

Background: Comminuted fibular fractures can occur with pilon fractures as a result of valgus stress. Transverse fibular fractures can occur with varus deformation. No definitive guide for determining the proper location of tibial fixation exists. The purpose of this study was to identify optimal plate location for fixation of pilon fractures based on the orientation of the fibular fracture. Methods: One hundred two patients with 103 pilon fractures were identified who were definitively treated at our institution from 2004 to 2013. Pilon fractures were classified using the AO/OTA classification and included 43-A through 43-C fractures. Inclusion criteria were age of at least 18 years, associated fibular fracture, and definitive tibial plating. Patients were grouped based on the fibular component fracture type (comminuted vs transverse), and the location of plate fixation (medial vs lateral) was noted. Radiographic outcomes were assessed for mechanical failures. Results: Forty fractures were a result of varus force as evidenced by transverse fracture of the fibula and 63 were due to valgus force with a comminuted fibula. For the transverse fibula group, 14.3% mechanical complications were noted for medially placed plate vs 80% for lateral plating ( P = .006). For the comminuted fibular group, 36.4% of medially placed plates demonstrated mechanical complications vs 16.7% for laterally based plates ( P = .156). Time to weight bearing as tolerated was also noted to be significant between groups plated medially and laterally for the comminuted group ( P = .013). Conclusions: Correctly assessing the fibular component for pilon fractures provides valuable information regarding deforming forces. To limit mechanical complications, tibial plates should be applied in such a way as to resist the original deforming forces. Level of Evidence Level III, comparative study.