Moon S. J.;Lee H. S.;Jun S. C.;Jung T. G.;Ahn S. Y.;Lee H.;Lee S. J.
Journal of Biomedical Engineering Research
/
v.26
no.2
/
pp.123-127
/
2005
Compression Hip Screw (CHS) is one of the most widely-used prostheses for the treatment of intertrochanteric fractures because of its strong fixation capability. Fractures at the neck and screw holes are frequently noted as some of its clinical drawbacks, which warrant more in-depth biomechanical analysis on its design variables. The purpose of this study was to evaluate changes in the strength with respect to the changes in design such as the plate thickness and the number of screw holes. Both mechanical test and FEM analysis were used to systematically investigate the sensitivities of the above-mentioned design variables. For the first part of the mechanical test, CHS (n=20) were tested until failure. The CHS specimens were classified into four groups: Group Ⅰ was the control group with the neck thickness of 6-㎜ and 5 screw holes on the side plate, Group Ⅱ 6-㎜ thick and 8 holes, Group Ⅲ 7.5-㎜ thick and 5 holes, and Group Ⅳ 7.5-㎜ thick and 8 holes. Then, the fatigue test was done for each group by imparting 50% and 75% of the failure loads for one million cycles. For the FEM analysis, FE models were made for each group. Appropriate loading and boundary conditions were applied based on the failure test results. Stresses were assessed. Mechanical test results indicated that the failure strength increased dramatically by 80% with thicker plate. However, the strength remained unchanged or decreased slightly despite the increase in number of holes. These results indicated the higher sensitivity of plate thickness to the implant strength. No fatigue failures were observed which suggested the implant could withstand at least one million cycles of fatigue load regardless of the design changes. Our FEM results also supported the above results by showing a similar trend in stress as those of mechanical test. In summary, our biomechanical results were able to show that plate thickness could be a more important variable in design for reinforcing the strength of CHS than the number of screw holes.
Kim, Taik-Seon;Kim, Hak-Jun;Park, Young-Hwan;Lim, Hyung-Tae
Journal of Korean Foot and Ankle Society
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v.15
no.2
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pp.62-67
/
2011
Purpose: The authors evaluated the differences between K-wires and Cannulated screw, plate for fixing the proximal metatarsal chevron osteotomy of moderate and severe hallux valgus. Materials and Methods: There were 62 patients (79 feetz) who were moderate and severe degree hallux valgus according to the classification of Mann. They all got the proximal chevron osteotomy when correcting the deformity. We divided the patients into 4 groups, Two K-wire fixed group as A, one cannulated screw fixed group as B. Two cannulated screw fixed group as C, Plate fixed group as D, Group A were patients (26 feet) and Group B were patients z(9 feet), Group C were patients (31 feet) and Group D were patients (13 feet). Preoperative, postoperative and follow-up hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured for each patient. ANOVA test and Student t-test were done for statistical analysis. Results: Mean follow up period was 43.8 months (range: 12~82 months). Preoperative mean IMA was $16.4{\pm}3.5$, $17.7{\pm}11.3$, $17.3{\pm}5.9$ and $16.6{\pm}2.3$ degrees in respectively group A, B, C, D. Immediate postoperative mean IMA was $5.6{\pm}3.4$, $7.3{\pm}4.4$, $7.6{\pm}4.4$ and $6.7{\pm}2.8$ degrees in respectively group A, B, C, D. The final mean IMA was $8.9{\pm}4.5$, $15.2{\pm}7.5$, $10.3{\pm}4.4$ and D $7.7{\pm}3.5$ degrees in respectively group A, B, C, D. There were significant statistical increase in final mean IMA of group B and C (p<0.05). Conclusion: The IMA was significantly increased in the group which used one or two cannulated screw for fixation on follow up, therefore more caution should be needed when using one or two cannulated screw fixation technique after proximal chevron osteotomy.
Kim, Min-Suck;Lee, Jong-Mun;Kim, Jong-Hwa;Kang, Il-Kwon;Kim, Dong-Soo
Journal of Fisheries and Marine Sciences Education
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v.19
no.1
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pp.129-136
/
2007
The component parts of the shell plate of a ship are steel. but the screw propeller or the bow thruster is a compound of bronze, nickel and aluminum. On account of the these different components between metals of the shell plate, the screw propeller and the bow thruster, which are underwater, the shell plate of a ship is corroded by the action of ionization. Authors investigated the corrosion loss of the zinc anodes which were attached to the bottom shell of the training ship Kaya for about two years. The obtained results were as follows:1. In case of the shell plate the difference of the corrosion loss according to port and starboard was almost nothing. But the corrosion loss of the forward part was more than that of the aftward part.2. There was little difference in the corrosion loss between the forward and the aftward part on the bilge keel.3. The corrosion loss of the fore, midship and aft part on the false keel were 24.7%, 22.4% and 23.9% respectively.4. The corrosion loss of the fore and the aft part on the false keel was more than that of the midship part.5. The corrosion loss of the bow thruster was greater than any other parts.6. The nearer the zinc anode to the screw propeller the more the corrosion loss on the stern frame, and the situation was also same as on the rudder.
Background: This study compared the clinical and radiological outcomes of the single calcar screw plate and Polarus nail techniques for the treatment of the proximal humerus fractures. Methods: Seventy-two patients diagnosed with displaced proximal humerus fracture were enrolled for the study. Of these, 50 patients underwent the locking plate surgery with a single calcar screw (plate group), whereas 22 patients underwent the Polarus nail surgery (nail group). The plate group was further divided into plate 1 group (with medial support), and plate 2 group (without medial support). The radiological and functional results of both groups were compared to the nail group. Results: The ${\alpha}$ angle 1 year after surgery was significantly different between plate 1 and plate 2, and plate 2 and nail groups (p=0.041, p=0.043, respectively). The ratio that does not satisfy the reference value of ${\gamma}$ angle was 2.8% in plate 1, 7.1% in plate 2 and 22.7% in nail group (p=0.007); there was a significant difference between plate 1 and nail group, and plate 2 and nail group (p=0.014, p=0.033, respectively). Conclusions: No significant differences were observed in the clinical results between locking plate and Polarus nail. However, in the plate 2 group and nail group, the rate of failure to maintain reduction during the 1-year period after surgery was statistically and significantly higher than the plate 1 group (level of evidence: level IV, case series, treatment study).
Journal of the Korean Association of Oral and Maxillofacial Surgeons
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v.29
no.6
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pp.438-443
/
2003
Purpose : This study evaluated the usefulness of resorbable plate and screw for treatment of maxillofacial bone fractures. Patients and methods : From july, 2000 to july, 2002, we used resorbable plates and screws($Biosorb^{(R)}$ FX, Bionix Inc, Finland) on 126 patients for treatment of maxillofacial bone fractures. Among them, 80 patients were capable of periodic following up to present season. We evaluated these patients with clinical, radiographic findings and subjective satisfaction. Results : 80 patients composed of 63 men and 17 women. Complication rates are 7.5%(6/80) recorded. 1 of bulging sensation, 3 of infection sign, 2 of the plate detachment were shown. The plates involved in such complications were removed. The other patients(92.5%) were not shown any problems. We could not find complete resorption of screw holes in the mandibular symphysis area even though two years later after surgery. Conclusion : Bioresorbable plates and screws are useful as fixation material at maxillofacial fractures although strength is thought to be weaker than titanium plate. But to reduce the possible complicaions, need to careful clinical and radiographical evaluations.
Objective : Craniovertebral junctional anomalies constitute a technical challenge. Surgical opening of atlantoaxial joint region is a complex procedure especially in patients with nuchal deformity like basilar invagination. This region has actually very complicated anatomical and functional characteristics, including multiple joints providing extension, flexion, and wide rotation. In fact, it is also a bottleneck region where bones, neural structures, and blood vessels are located. Stabilization surgery regarding this region should consider the fact that the area exposes excessive and life-long stress due to complex movements and human posture. Therefore, all options should be considered for surgical stabilization, and they could be interchanged during the surgery, if required. Methods : A 53-year-old male patient applied to outpatients' clinic with complaints of head and neck pain persisting for a long time. Physical examination was normal except increased deep tendon reflexes. The patient was on long-term corticosteroid due to an allergic disease. Magnetic resonance imaging and computed tomography findings indicated basilar invagination and atlantoaxial dislocation.The patient underwent C0-C3-C4 (lateral mass) and additional C0-C2 (translaminar) stabilization surgery. Results : In routine practice, the sites where rods are bound to occipital plates were placed as paramedian. Instead, we inserted lateral mass screw to the sites where occipital screws were inserted on the occipital plate, thereby creating a site where extra rod could be bound.When C2 translaminar screw is inserted, screw caps remain on the median plane, which makes them difficult to bind to contralateral system. These bind directly to occipital plate without any connection from this region to the contralateral system.Advantages of this technique include easy insertion of C2 translaminar screws, presence of increased screw sizes, and exclusion of pullout forces onto the screw from neck movements. Another advantage of the technique is the median placement of the rod; i.e., thick part of the occipital bone is in alignment with axial loading. Conclusion : We believe that this technique, which could be easily performed as adjuvant to classical stabilization surgery with no need for special screw and rod, may improve distraction force in patients with low bone density.
The various total replacement artificial discs have developed because spinal fusion has shown a lesser mobility of an operated segment and an accelerated degeneration at adjacent discs. But almost artificial discs have not yet been reached on the substitute surgery of fusion because many problems such as those clinical success rates were not more than them of fusion have not solved. In this paper, vertically inserted assemble-screw fixture in vertebrae was proposed to improve the fixed capability of artificial disc. And also, to evaluate the design suitability of newly designed screw-type, including fixtures of commercial discs such as wedge and plate type, the 1/4 finite element model with a vertebra and various implanted fixtures were generated, and next, 3 bending motions such as flexion, bending and twisting under the moment of 10Nm and compression under the force of 1000N were considered, respectively and finally, FE analyses were performed. Results of three fixture types were compared, such as Range of Motion and maximal stress, and so on. For ROM, the screw type was average 58% less than the wedge type and was average 42% less than the plate type under all loading conditions. For average stress ratio at closer nodes between vertebra and each fixture, the wedge type was the lowest as minimum 0.02 in twisting, screw types were the highest as maximum 0.28 in compression. As the results of using cement material, it was predicted that the instability problem of the wedge type was better solved. The screw type which could be increased by implanting depth according to the number of assembling mid screws, showed that the decreased tendency of ROMs and maximal cancellous bone stresses. In further study, controlling the number of assembling screws that was suitable for a patient's bone quality, development of surgical tools and keeping on design supplementations, which will be able to develop the competitive artificial disc.
Purpose: To evaluate the radiological and clinical results after open reduction and internal fixation with calcaneal F plate and locking calcaneal plate using lateral extensile approach in the treatment of intra-articular calcaneal fracture Materials and Methods: This study included 34 cases of 33 patients followed up for at least 6 months postoperatively. F plate was applied in 18 cases (Group 1), locking plate was used in 16 cases (Group 2) and compared radiological and clinical results between two groups. Results: Radiollogically, the mean Bohler angle was improved from $5.5^{\circ}$ preoperatively to $20.1^{\circ}$ postoperatively and $18.8^{\circ}$ at the last follow up in group 1 and $8.6^{\circ}$ preoperatively, $21.4^{\circ}$ postoperatively and $20.3^{\circ}$ at last follow up in group 2. Bone union was observed in all cases and 4 cases of screw loosening were noted in Group 1 with extended fracture to anterior process. At the last follow up, both groups showed clinical results in American orthopedic foot and ankle society ankle hindfoot score, 76(77 in Sanders type II and 75 in type III) in group 1 and 72(73 in type II and 70 in type III) in group 2. Conclusion: F plate and locking plate showed firm fixation and satisfactory clinical results in the treatment of intra-articular calcaneal fracture. We suggest applying locking plate in cases with extended fracture to anterior process, considering screw loosenings in those who were treated with F plate fixation.
Purpose: The purpose of this article is to assess the efficacy of a bioabsorbable polylactide (PLA) plate and screw for treating injuries of ankle fractures. Materials and Methods: 24 patients who underwent an open reduction and internal fixation operation for ankle fractures from July 2005 to March 2007 were enrolled into the study. There were 15 men and 9 women. The average age of the patients was 44 years and the average follow-up period was 16 years and two months (16.2 months). All cases were divided into low grade fracture patient (11) who belongs in type A and B of Danis-Weber classification and high grade fracture patient (13) who belongs in type C1, C2 of Danis-Weber classification, and each groups were analyzed by clinical (Meyer score) and radiological finding at the time of their last follow-up evaluation. Results: The clinical results according to Meyer scoring system, showed that all patient with low grade fracture had good to excellent result, but only 54% of patient with high grade fracture had good to excellent result. According to Cedell's radiologic finding, there were 91% cases above fair in low grade fracture. But there were 62% of patient above fair result in high grade fracture, the reduction losses were seen in 38% of patient with high grade fracture. Conclusion: Bioabsorbable PLA plate and screw is good internal fixation device which doesn't have additional operation for removal of implant because of slow absorption within the human body. It showed sufficient strength for acquisition and maintenance of reduction in low grade fracture, but need attention to use because of many cases of reduction loss in high grade fracture. So, it seems to be safe and effective when used in heeling of low grade fracture under considering about type of fracture sufficiently.
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