Nail Diameter Research Articles

Experimental and numerical studies on the thermal performance of structural insulated panel splines

This paper presents the experimental and numerical studies on the thermal performance of structural insulated panel (SIP) splines. Typical SIPs are comprised of two structural facings of oriented strand board (OSB) and an insulation layer of expanded polystyrene (EPS). Splines with steel nails used to connect the panels reduce the thermal performance of the SIP wall. The thermal transmittance of three types of splines commonly used in SIP wall was measured experimentally. Then the finite element model of an affected area unit of the spline was established, and a parametric study was conducted to investigate the effect of the materials' thermal conductivity, insulation layer thickness, nail spacing, and nail diameter on the thermal performance of the spline. The insulation layer was found to be the most significant factor on the thermal performance of the spline, and weakened the effect of the thermal bridge caused by nails. The nail had only a slight effect on the thermal performance of the spline. The thermal performance of the spline could be improved by reducing the materials’ thermal conductivity, increasing the thickness of the insulation layer and the nail spacing, and reducing the nail diameter.

Laboratory Investigation of Hollow and Solid Shaft Helical Soil Nail by Displacement Controlled Pullout Testing

A sequence of laboratory pullout tests was conducted to examine the installation and pullout behavior of hollow and solid shaft helical soil nails. The methodology involves installation and corresponding pullout testing of 12 mm, 14 mm, 16 mm and 18 mm hollow and solid shaft helical soil nails with varying number of helical plates between single to triple and shaft surface roughness from smooth to rough using a displacement-controlled apparatus. A total of 18 different helical soil nail combinations were investigated under surcharge pressures 5 kPa, 12.5 kPa, 25 kPa, and 50 kPa to examine the influence of shaft dimeter, shaft roughness, number of helices, pitch, interaction friction angle, embedment depth ratio on both installation and pullout capacity. Using the pullout capacities and corresponding installation torque, capacity-to-torque ratio (Kt) relationship was also established which yielded ranges of 19 m−1 to 61 m−1 and 23 m−1 to 58 m−1 for hollow and solid shafts, respectively. Moreover, interaction friction angles depicted that with similar number of helices, an increase of 25% in diameter of hollow shaft helical soil nail renders equivalent reinforcing action to a corresponding solid shaft. Also, for both hollow and solid shafts, double helical soil nails were observed to show the maximum efficiency, while the effect of number of helices was found to diminish beyond the embedment ratio of 11. Within the pitch range of 30–35.5 mm, pullout response for both hollow and solid shafts were found to be linearly dependent on its installation.

L’effet du remplissage médullaire sur le déplacement en varus d’une fracture intertrochantérienne AO 31A3 (obliquité inverse) traitée avec des clous céphalomédullaires

ObjectiveCephalomedullary nails are tools commonly used for surgical fixation in proximal femoral fractures. The most common complications in their use are varus collapse and screw cutout of the femoral head. The objective of this study is to examine the effects of intramedullary nail movement on varus collapse and screw cutout. Materials and MethodsThe study was conducted on 70 composite femur models treated with PFNA. We divided the femurs into 4 groups based on the differences in nail diameter, fracture type and filling of the distal intramedullary area. All femurs were exposed to axial cyclic loading. Each femur was examined in terms of intramedullary nail movement and amount of erosions in femoral medulla (amount of erosion in femoral head (FT distance), amount of erosion in femoral neck (FB distance), amount of erosion in trochanteric major (TB distance) and expansion of trochanter tip (TT distance)). ResultsWe found that degree of nail movement in the intramedullary region was inversely correlated with nail diameter and directly correlated with instability of fracture. One of the parameters used to evaluate varus development, FB distance, was affected by the degree of intramedullary nail movement and fracture type. TB distance was affected by nail diameter. ConclusionsNail diameter and fracture type are effective in intramedullary nail movement. Varus collapse progress is accelerated by the increase in nail movement in the intramedullary region. Thus, we conclude that it is important to strengthen diaphyseal adherence, which decreases intramedullary movement of the nail. Level of evidenceIII; well-design case control study.

Limb Lengthening for Congenital Deficiencies Using External Fixation Combined With Flexible Intramedullary Nailing: A Multicenter Study.

Hydroxyapatite (HA) coated flexible intramedullary nailing (FIN) stimulates osteogenic activity. The role of HA-coated intramedullary nails remains unclear in normal bone lengthening. The goal of this study was to quantify the influence of FIN on the External Fixation Index (EFI) in patients with congenital lower limb discrepancy. Patients with femoral deficiency and fibular hemimelia underwent lengthening by the combined technique of external fixation with titanium (Ti) FIN or HA coated FIN and returned for follow-up at least 12 months after frame removal. Seventy patients (mean age of 12.6 y) were included: 19 monofocal femoral lengthenings, 35 tibial monofocal lengthenings, 16 tibial bifocal lengthenings. The mean EFI's for those treated with and without HA-coated nails were not significantly different. The Conover posthoc analysis did not reveal a significant influence of the type of FIN on EFI in any subgroup. However, 2-way analysis of variance revealed simultaneous effects of nail types and age on the EFI in tibial bifocal lengthening.Significant positive correlation between the ratio "nail diameter/medullary shaft diameter" and EFI in tibial bifocal non-HA-coated FIN lengthening, and a significant positive correlation between age and EFI for femoral non-HA-coated FIN lengthening, tibial monofocal and bifocal HA-coated FIN lengthening were revealed.There were 4 cases of fracture at lengthening site required unscheduled surgery. In the non-HA-coated group, there was a statistically significant negative correlation between nail diameter and fracture occurrence at the lengthening site after frame removal. A ratio of <0.15 likely does not ensure required mechanical stability and support. Both Ti-nail and HA-coated nail lengthening provide good and excellent outcomes for femoral and tibial monosegmental lengthening procedures and ensure reduced EFI. In congenital disorders which were not associated with abnormal bone, there are no differences with regard to EFI using HA-coated or non-HA-coated FIN. The ratio of "elastic Ti-nail diameter/medullary canal diameter at narrowest site" <0.15 seems to be associated with higher risk of fracture at the lengthening site after frame removal.

ASSESSMENT OF RESULTS OF TREATMENT OF PAEDIATRIC FEMORAL DIAPHYSEAL FRACTURES WITH TITANIUM ELASTIC NAILS

Introduction: Femoral fractures are among the most common fractures of long bones. The management of pediatric femur fractures depends basically on the age group of the child although the age of bone and size of the child also determines the treatment choice. The choice of management may also be determined by surgical experience and local trends in practice. Study aimed to assess the results of treatment of paediatric femoral diaphyseal fractures with titanium elastic nails. Material And Methods: The study was conducted at Orthopaedics Department of PMCH, Patna, Bihar. A total of 22 patients with closed shaft femur fractures and age ranging between 5-16 years scheduled to undergo treatment with titanium elastic nails were selected for the study. Children with open fractures, outside this age group with concomitant head injury, bilateral femur fracture or associated fracture of either limb whose xation was done after 7 days were excluded from the study. No control group was used. They were treated by retrograde TENS xation using two nails of equal diameter for each fracture. Pre-operative evaluation includes full length radiograph of the fractured femur both antero–posterior (A–P) and lateral views. Results: In the present study, 22 patients with closed shaft femur fractures were treated with titanium elastic nails. The mean age of the patient was 13.23 years. We observed that in regards to fracture location, proximal fracture was seen in 5 patients, midshaft fracture in 14 patients and distal fracture in 3 patients. However, in regards to pattern of location, transverse fracture was seen in 6 patients, oblique fracture in 8 patients, spiral fracture in 5 patients and comminuted fracture in 3 patients. Conclusion: From this study we can conclude that Intramedullary nailing of the pediatric femoral diaphyseal fractures using titanium elastic nail is an effective surgical modality, with advantages of minimal incisional scar, minimal soft tissue damage, with early union time and excellent union rates, and without affecting shoulder and elbow function.

The effect of medullary fill on varus collapse in AO 31A3 intertrochanteric (reverse obliquity) fracture treated with cephalomedullary nails

ObjectiveCephalomedullary nails are tools commonly used for surgical fixation in proximal femoral fractures. The most common complications in their use are varus collapse and screw cutout of the femoral head. The objective of this study is to examine the effects of intramedullary nail movement on varus collapse and screw cutout. Materials and methodsThe study was conducted on 70 composite femur models treated with PFNA. We divided the femurs into 4 groups based on the differences in nail diameter, fracture type and filling of the distal intramedullary area. All femurs were exposed to axial cyclic loading. Each femur was examined in terms of intramedullary nail movement and amount of erosions in femoral medulla [amount of erosion in femoral head (FT distance), amount of erosion in femoral neck (FB distance), amount of erosion in trochanteric major (TB distance) and expansion of trochanter tip (TT distance)]. ResultsWe found that degree of nail movement in the intramedullary region was inversely correlated with nail diameter and directly correlated with instability of fracture. One of the parameters used to evaluate varus development, FB distance, was affected by the degree of intramedullary nail movement and fracture type. TB distance was affected by nail diameter. ConclusionsNail diameter and fracture type are effective in intramedullary nail movement. Varus collapse progress is accelerated by the increase in nail movement in the intramedullary region. Thus, we conclude that it is important to strengthen diaphyseal adherence, which decreases intramedullary movement of the nail. Level of evidenceIII; well-design case control study.

Anatomical and biomechanical parameters relating to migration of the helical blade in proximal femoral fractures fixed by proximal femoral nail anti-rotation

Introduction: Proximal femoral fractures fixation pose dilemma on fixation device to use. Western designed copied proximal femoral nail anti rotation is being used in South-East Asian population extensively. The study aims to study of migration in our population representative of the developing nations. Methods: 92 patients enrolled in prospective cross-sectional study for 9 months; 89 were evaluated for final migration studies as 3 major complications occurred. The effects of age, fracture, tip-apex distance, quadrant position in femoral head, blade size and length and Neck Shaft angle on migration were analyzed. Results: There were 42 males and 50 females with the mean age was 68.14 years. At the time of fixation mean Tip Apex Distance was 12.2 mm (7.0mm – 25mm). At 6 months follow-ups, migration occurred in 78.65%. On univariate analysis, there was no effect of fracture pattern on migration (p=0.524). Femoral-Neck shaft angles were fixed in varus in 7, 5 in valgus and 77 within normal range. Relatively higher migration did occur with varus fixation but was not statistically significant (p=0.306). Multivariate analyses were done for nail diameter, nail length, old age and fracture patterns with no statistically significant interactions. The position of helical blade in the quadrant of the femoral head with center-center having minimum migration (p= 0.000). Major complications occurred in 3 patients. Conclusions: All helical blades do migrate but within acceptable range provided fixation in acceptable Tip Apex Distance. Bone Mineral Density should be kept as co-variable in further studies.

Biomechanical evaluation of the docking nail concept in periprosthetic fracture fixation around a stemmed total knee arthroplasty

Intramedullary femoral nails provide an ideal mechanical axis for periprosthetic fracture fixation. Slotted nails allow a connection to a total knee arthroplasty (TKA) stem. This study aims to compare implant and construct stiffness, interfragmentary movement and cycles to failure between an antegrade slotted femoral nail construct docked to a TKA stem and a distal femoral locking plate in a human periprosthetic femoral fracture model.In eight pairs of fresh-frozen human femora with stalked TKA, a 10 mm transverse osteotomy gap was set simulating a Rorabeck type II, Su type I fracture. The femora were pairwise instrumented with either an antegrade slotted nail coupled to the prosthesis stem, or a locking plate. Cyclic testing with a progressively increasing physiologic loading profile was performed at 2 Hz until catastrophic construct failure. Relative movement at the osteotomy site was monitored by means of optical motion tracking. In addition, four-point bending implant stiffness, torsional implant stiffness and frictional fit of the stem-nail connection were investigated via separate non-destructive tests.Intramedullary nails exhibited significantly higher four-point bending and significantly lower torsional implant stiffness than plates, P < 0.01. Increasing difference between nail and stem diameters decreased frictional fit at the stem-nail junction. Nail constructs provided significantly higher initial axial bending stiffness and cycles to failure (200 ± 83 N/mm; 16'871 ± 5'227) compared to plate constructs (93 ± 35 N/mm; 7'562 ± 1'064), P = 0.01. Relative axial translation at osteotomy level after 2'500 cycles was significantly smaller for nail fixation (0.14 ± 0.11 mm) compared with plate fixation (0.99 ± 0.20 mm), P < 0.01.From a biomechanical perspective, the docking nail concept offers higher initial and secondary stability under dynamic axial loading versus plating in TKA periprosthetic fracture fixation.

Experiments on laminated bamboo lumber nailed connections

Laminated bamboo lumber (LBL) nailed connection made with LBL main member and sandwiched by LBL side members is introduced, which plays an essential role in the safe and reliability of bamboo buildings. However, little research attention has been paid on to the mechanical behavior of connections. This paper reports an experimental study on the effect of parameters on reference loads (yield load and maximum load), stiffness and load-slip behavior of the connections, including nail diameter, number of lines and rows of nails. For single nail connection, nail pull-through and plastic hinges forms in LBL members. Mode cross-over from ductile response to brittle failure is observed in multi-nail connections with one or more splitting cracks develop from the nails hole edges toward the ends of the side or middle members. A decreasing ductility of connections is investigated with increasing diameter and number of nails. The capacity of effective number of nails in a row is evaluated and compared with that obtained from existing analytical formulas. Predictions from existed various theoretical modes are compared with experimentally determined capacities of nailed connection per shear plane per nail and conclude that the load carrying capacity of connections with laterally load nails can be applied to accurately estimate using European yield models (EYMs). Furthermore, the model developed by Folz is capable of predicting the load-slip relationship of LBL nailed connections. The findings of this study will provide the scientific basis and useful information for the design and finite element numerical simulation of engineered bamboo structures containing LBL nailed connections and promote the rational use of bamboo resources in the field of civil engineering.

Does Size Matter for Cephalomedullary Nails in Geriatric Intertrochanteric Fractures?

To evaluate the need for reoperation of geriatric intertrochanteric hip fractures treated with 10-mm cephalomedullary nails versus those treated with nails larger than 10 mm. Retrospective review at a single institution. Level I trauma center. All patients age 60 and over treated with cephalomedullary fixation for an intertrochanteric femur fracture at a single institution. Cephalomedullary fixation with variable nail diameters. Reoperation rates of geriatric intertrochanteric fractures treated with a size 10-mm diameter cephalomedullary nail compared with patients treated with nails larger than 10 mm. There were no significant differences in reoperation rates when the 10-mm cohort was compared with an aggregate cohort of all nails larger than 10 mm (P = 0.99). This result was true for both all-cause reoperation and noninfectious reoperation. There was no difference between cohorts in regards to age, gender, or fracture pattern. A 10-mm cephalomedullary nail can be used in lieu of a larger diameter fixation in patients age 60 and older with intertrochanteric femur fractures while still maintaining a comparable rate of reoperation. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Stryde Weight-bearing Internal Lengthening Nail

Since May 2018, 106 patients (187 limb segments) have completed internal lengthening with the Stryde implant. Fifty-seven skeletally mature patients (12 female and 45 male) underwent cosmetic stature lengthening of the femur (41), tibia (4), or combined bilateral femur and tibia (12). Forty-nine other patients (ages 9 to 60 y) with a variety of limb length discrepancy etiologies including metabolic, congenital, genetic, and posttraumatic, underwent unilateral lengthening of the femur (37) or tibia (12). All patients undergoing lengthening alone were allowed immediate full weight-bearing as tolerated. Patients with secondary ipsilateral acute deformity corrections had restricted weight-bearing until sufficient healing was present at the metaphyseal site. The mechanical axis deviation following lengthening was not statistically significantly related to limb segment, patient weight, nail diameter, or distraction amount, but tended towards varus in the femurs and valgus in the tibias. Fifty-two stature patients and 43 unilateral patients lengthened to within 10 and 5 mm of their goals, respectively. One tibial nail stopped functioning prematurely and was exchanged to complete the lengthening. Seven patients required secondary unplanned operations. Successful outcomes were achieved in all patients. Strict adherence to careful preoperative planning, and postoperative lengthening protocols including specialized limb lengthening physiotherapy are important to the success. There were no issues related to biological incompatibility of the Biodur 108 alloy stainless steel from which the implant was fabricated.

Mechanical Effect of Poller Screw in Metaphyseal Fractures of Tibia Fixed by Locking Intra-Medullary Nail

Abstract Background: Intramedullary nailing of metaphyseal frac-tures may be associated with deformity as a result instability after fixation. Our aim was to evaluate the clinical use of Poller screws (blocking screws) as a supplement to stability after fixation with statically locked intramedullary nails of small diameter. Aim of Study: To evaluate the mechanical effect and clinical outcome of poller screw in metaphyseal fractures of tibia fixed by locking intramedullary nail. Patients and Methods: 15 men and 5 women (20 fractures) aged 19 to 60 (mean, 36.25) years underwent fixation of tibial metaphysis by locking intramedullary nail and poller screw. The mechanisms of injury included motor car accident in thirteen patients, fall from height in two patients, direct trauma in five patients. Radiological and clinical outcome was eval-uated. Results: Twenty patients were followed-up in the outpatient clinic for assessment of fracture healing or the establishment of a nonunion. Union was defined as the healing of at least 3 of 4 cortices on a biplanar radiograph. All the twenty patients (100%) achieved union at average time twenty weeks (ranging from 16 to 24 weeks). Conclusion: Poller (blocking) screws are an important adjunct for intramedullary nailing; aiding fracture reduction at the metaphysis, and offsetting deforming forces that cause malalignment.

The effect of nail diameter on proximal femoral shortening after internal fixation of pertrochanteric hip fractures with short cephalomedullary nails

ObjectiveInvestigate the effect of distal nail diameter on proximal femoral shortening (PFS) after cephalomedullary nailing of hip fractures. MethodsA retrospective cohort study of 80 patients aged 50 years and older with pertrochanteric hip fractures treated with a 10 or 11 mm short cephalomedullary nail (CMN) was performed. We measured abductor lever arm shortening, femoral height shortening, and PFS. ResultsThere was no difference in abductor lever arm shortening (p = 0.09), femoral height shortening (p = 0.86), and PFS (p = 0.34) between the 10 and 11 mm groups. ConclusionsOur results suggest that distal nail diameter does not affect PFS. Level of evidenceIII.

Complications and Radiographic Outcomes After Tibiotalocalcaneal Fusion With a Retrograde Intramedullary Nail

Tibiotalocalcaneal (TTC) arthrodesis is a salvage reconstructive procedure for ankle and subtalar arthritis and deformity. This study aims to identify fusion rates and complications of TTC arthrodesis procedures performed at our institution using a specific retrograde intramedullary nail. Additionally, we analyzed the subpopulation that sustained an intramedullary nail break. A retrospective review was conducted of 45 patients who underwent 47 TTC arthrodesis procedures with intramedullary fixation using the Phoenix nail at our institution from October 2010 to September 2017. Patient age, body mass index, sex, smoking status, diabetes diagnosis, peripheral vascular disease, thyroid disease, inflammatory arthritis, steroid use, prior ankle fractures and procedures, fusion rates, nail diameter, time to hardware failure, preoperative coronal plane deformity, and return to work were obtained. Successful fusion was confirmed in 79% of tibiotalar, 70% of subtalar, and 66% of combined tibiotalar and subtalar joints. Eight of 47 (17%) TTC nails suffered nail breakage postoperatively. Although statistical analysis was not performed due to the small population size, patients with nail failure had lower rates of tibiotalar (38% vs 87% of patients without nail failure) and combined tibiotalar/subtalar fusion (25% vs 74%). Ten percent of patients without nail breakage required revision surgery, compared to 75% of patient with nail breakage. This study describes TTC arthrodesis outcomes at our institution. It demonstrates a high complication rate using a specific retrograde intramedullary nail, including nail breakage and non-union. Further analysis and improvement in technique and implant design may decrease revision rates and improve outcomes. Therapeutic, Level IV.

Study on thermal runaway mechanism of 1000 mAh lithium ion pouch cell during nail penetration

The safety issues of lithium ion batteries (LIBs) have been serious as the popularity of LIBs in portable electronics and electric vehicles. It is necessary to understand the thermal runaway mechanism to effectively prevent thermal runaway. A series of nail penetration experiments are conducted to study the thermal runaway mechanism of lithium ion pouch cell in this work. It is observed that the pouch cell experiences four processes including nail penetration, internal short circuit, chemical reaction and thermal runaway during nail penetration. Additionally, four parameters, including state of charge (SOC), penetration speed, penetration position and nail diameter, are taken in the experiments to investigate the effect on thermal runaway. The results show that the cells with higher SOC and penetrated by bigger nail are easier to be triggered into thermal runaway and obtain higher temperature. The penetration position decides the location of the short circuit and the temperature distribution, and the steel nail has an influence on the temperature distribution of the cell. The results provide suggestions for the transportation, safe use and design of the cell.

Horizontal Pullout Behavior of Novel Open-Ended Pipe Helical Soil Nail in Frictional Soil

The reinforcing action of soil nails is governed by its interaction with the surrounding soil generally investigated in terms of interface friction. The reported literature depicts that increase in interface friction enhances the reinforcing action of a soil nail. Thus, with the aim of utilizing additional interface friction from internal surface of a hollow pipe and bearing resistance from helical plates attached to it, the present work investigates the pullout behavior of newly developed open-ended pipe helical soil nails. The novel open-ended pipe helical soil nails are installed and subjected to pullout force in a test tank filled with frictional soil using installation/pullout machine. The present study also examined the effect of varying soil nail diameter, number of helices and phenomenon of soil plugging on pullout capacity. Additionally, torsional and axial strains developed during pullout are also observed. The installation torque and pullout capacity are correlated using a dimensionless factor called as ‘Torque factor (Kt)’ with values ranging from 27 to 55 m−1 in compression and 28.12–53.3 m−1 in tension. A theoretical torque model for open-ended helical soil nails is also developed and is verified by the laboratory test results. The test results indicate that soil plug contributes about 11.5% of the total mobilized skin friction during pullout. The pullout capacity increases with increase in the number of helices and nail shaft diameter. However, soil plug length is independent of number of helices. Besides, higher torsional and axial strains are found for helical nails with smaller diameter.

REAMED INTRAMEDULLARY EXCHANGE NAILING FOR ASEPTIC NON- UNION OF ISTHMUS &amp; ENHANCED DISTAL FIXATION EXCHANGE NAILING FOR NON- UNION OF DISTAL THIRD SHAFT FEMUR FRACTURES.

Background: The aim of this study was to evaluate the role of exchange nailing in isthmus and exchange nailing with poller screw fixation &amp; multiplanar interlocking screws for Distal Third shaft femur aseptic non union. The evaluation was addressed by measuring the clinical, functional and radiological outcome of our treatment methods in both non union groups.&#x0D; Design: Retrospective study.&#x0D; Methods: Between 2006 to 2014, 55 patients with Non Union of shaft femur were operated using a standardised protocol at our institute and followed up for functional and radiological outcome.&#x0D; 5 patients were lost to follow up and thus were excluded from this study. Out of 50 patients, 29 were cases of Isthmus Non union and remaining 21 were cases of Distal Third Non union. Our approach in Isthmus group was closed Exchange nailing with 2mm larger nail with medullary reaming. Some needed isthmus when radiological signs of healing were delayed.&#x0D; In Distal Third group, poller screws were used in conjugation with reamed exchange nailing with a 2mm larger diameter nail and interlocking screws in different planes. Out of the 50 patients, 48 were men and 2 women. Their mean post surgical procedure period at presentation of non union was 11.60 months.&#x0D; Results: Out of a total 55, 5 were lost to follow up- all from isthmus group. In isthmus group, healing was observed in 25 out of 29 patients with union achieved in a mean of 7.60 months. Delayed union was seen in 3 patients and addressed with dynamisation of distal screws leading to union in all cases in a mean of 13 months without further intervention.1 patient had superficial infection which resolved with debridement at 4 months. 1 patient required additional bone grafting for persistent non union and healed at 18 months. Non union was encountered in 3 patients who refused further treatment and accepted functional limitations. Harris Hip Score for this group was 87.40. In Distal Third group, all 21 patients achieved union in a mean time of 10.30 months. No patients required further revisions however 4 patients had superficial infection which was treated with antibiotics and debridement. No further complications were encountered in this group of patients and bony union was uneventful otherwise. Harris Hip Score of this group was 92.40.&#x0D; Conclusion: Using exchange nailing for isthmus and poller screw augmentation for Distal Third Shaft Femur Non union yields excellent clinical, functional and radiological outcome. Exchange nailing with or without poller screw augmentation is a less invasive method to treat aseptic non union of shaft femur fractures without additional complications.&#x0D; Keywords: Nonunion, exchange nailing, poller screw, femoral non union, aseptic non union.

Limitations in Use of Elastic Stable Intramedullary Nailing (ESIN) in Children with Disorders of Bone Mineralization.

Elastic intramedullary nails (ESIN) have been the treatment of choice in many long bone fractures in children for more than 20 years. The introduction of ESIN has drastically reduced tissue traumatization during fracture fixation procedures and decreased the risk of growth cartilage damage, as well as allowing for preservation of the natural biology of closed fracture healing. The objective of the present report is to draw attention to a small group of patients with bone mineralization disorders, who consequently demonstrate decreased mechanical resistance of the skeletal system, in whom indications for using ESIN fixation are limited. The study group consisted of 6 patients who met the criteria for using ESIN fixation, but did not demonstrate a satisfactory outcome. The inclusion criteria included age below 18 years, appropriate ESIN nail insertion technique with correct calculation of nail diameter (2/5 of the medullary canal diameter), body mass &lt; 50 kg and achieving appropriate prebending that is the prerequisite of three-point intramedullary support. The patients' medical records and radiographs were analyzed and they were invited for clinical and radiological follow-up examinations. All six patients demonstrated a gradually increasing bending deformity of the long bone axis. Additionally, in three patients, there was intrusion of terminal parts of the nails into the bone. In one patient with bone fibrous dysplasia, the proximal epiphysis was perforated by the flattened ends of the nails. In all patients, the removal of the ESIN fixation was followed by single or double-level corrective osteotomies and Rush pin fixation. In cases of long bone fractures in children with metabolic bone disorders in whom the bone structure is weakened and the bones themselves are easily deformed, more rigid intramedullary fixation with Rush or Fassier-Duval type nails as primary osteosynthesis should be considered.

Measurement of Surface Velocity in a 150 mm × 1270 mm Slab Continuous-Casting Mold

Surface velocity in the continuous-casting mold needs to be studied to better control the quality of steel products. In this paper, the measurement of surface velocity in a 150 mm × 1270 mm slab continuous-casting mold was investigated. Taking the slag layer into consideration, a numerical simulation was performed which was validated by a particle image velocimetry test. A nail-board experiment was also conducted to measure surface velocity in the continuous-casting mold. The effect of nail diameter used in nail-board experiment on the measurement of the surface velocity was also discussed to improve the precision of nail-board experiment result. The results showed that the maximum surface velocity was 0.739 m/s around the mid-section of the free surface, and the results of nail-board experiments were more accurate when the steel nail diameter was 10 mm.

Thermal Runaway Behavior of Lithium Iron Phosphate Battery During Penetration

The nail penetration experiment has become one of the commonly used methods to study the short circuit in lithium-ion battery safety. A series of penetration tests using the stainless steel nail on 18,650 lithium iron phosphate (LiFePO4) batteries under different conditions are conducted in this work. The effects of the states of charge (SOC), penetration positions, penetration depths, penetration speeds and nail diameters on thermal runaway (TR) are investigated. And the accelerating rate calorimeter is applied to reveal the thermal runaway mechanism. The experimental results show that the higher the SOC of the battery, the higher the possibility and risk of TR of the battery, and there seems to be a critical penetration depth where TR occurs. The battery exhibits higher average temperature at higher penetration speeds. Whether the battery get into TR is not related to the penetration speed. When the penetration location near the positive pole and negative pole,the risk of thermal runaway is much higher than the centre position of the battery. The larger the diameter of the nail, the lower the overall temperature of the battery. What’s more, the results of the penetration tests under the condition of parameter coupling shows that the average temperature of battery are greatly affected by the parameters of SOC, penetration position. The temperature of the LiFePO4 battery is within 200°C when the TR occurs induced by the penetration, which is mainly due to the incomplete exothermic reaction inside the battery.