• Clinics in Shoulder and Elbow
• /
• v.20 no.4
• /
• pp.236-239
• /
• 2017

After dual plating with a locking compression plate for comminuted intraarticular fractures of the distal humerus, the incidence of ulnar nerve injury after surgery has been reported to be up to 38%. This can be reduced by an anterior transposition of the ulnar nerve but some surgeons believe that extensive handling of the nerve with transposition can increase the risk of an ulnar nerve dysfunction. This paper reports ulnar nerve injuries caused by the incomplete insertion of a screw head in dual plating without an anterior ulnar nerve transposition for AO/OTA type C2 distal humerus fractures. When an anatomical locking plate is applied to a distal humeral fracture, locking screws around the ulnar nerve should be inserted fully without protrusion of the screw because an incompletely inserted screw can cause irritation or injury to the ulnar nerve because the screw head in the locking system usually has a slightly sharp edge because screw head has threads. If the change in insertion angle and resulting protruded head of the screw are unavoidable for firm fixation of fracture, the anterior transposition of the ulnar nerve is recommended over a soft tissue shield.

• Journal of Trauma and Injury
• /
• v.26 no.3
• /
• pp.163-169
• /
• 2013

Purpose: This study was conducted to confirm the anatomic conformity of the new periarticular locking plates designed by Zimmer on Korean adult bones and to identify the structures at risk during the application of these implants. Methods: The study was performed on the humerus, radius, and tibia of 10 adult cadavers(6 males and 4 females) procured from the cadaveric lab of our hospital. Anteroposterior (AP) and lateral X-rays were taken to confirm that the cadavers were free of any unusual lesions or anatomic variations. We used the 3.5-mm proximal humerus plate, 2.7-mm distal radius plate, 3.5- and 5.0-mm proximal tibia plates, and 3.5-mm distal tibia plate developed by Zimmer, Inc. (Zimmer periarticular locking plate). The longest plate from each group was used to confirm anatomical conformity. Standard approaches were used for each area, and soft tissue was retracted in order to pass the plate beneath the muscle. The position of the plate was confirmed using standard AP and lateral view X-rays. After this procedure had been completed, the region was dissected along the length of the implant to determine the conformity of the implant to bone and the penetrations of screws into the articular surface or violations of any vital structures, such as nerves, blood vessels, or tendons. Results: Excellent anatomical conformity was observed with Zimmer periarticular locking plates for Korean adults. The tibial nerve and the posterior tibial artery were found to be structures at risk when applying a distal tibial plate. Conclusion: Additional posterolateral fixation is recommended when dealing with cases of tibial plateau fracture when the fracture line extends to the posterolateral cortex. We recommend taking proper views using 10~15 degrees of internal rotation to ensure correct screw length and, thus, avoid penetration of vital structures and tendons.

• Clinics in Shoulder and Elbow
• /
• v.18 no.2
• /
• pp.68-74
• /
• 2015

Background: The purpose of our study was to evaluate the functional and radiologic outcomes of additive augmentation sutures through rotator cuff for proximal humeral fractures stabilized locking plate in elderly patients. Methods: We enrolled 74 patients over the age of 60 years who received internal fixation using locking plates for proximal humeral fractures. Of these, 50 patients had additive augmentation sutures through rotator cuff. The mean age at the time of surgery was 72.1 years (range, 60-89 years), and the mean follow-up period was 17.5 months (range, 12-62 months). The humeral neck-shaft angle and humeral head height were used as radiological markers to assess the effect of additive augmentation sutures through rotator cuff. We allocated the patients who received additive augmentation sutures into group A and those who did not into group B. Results: At the final follow-up, the mean Korean Showlder Society score and Constant scores were $88.96{\pm}12.1$ and $86.6{\pm}11.9$, respectively, in group A and $86.21{\pm}11.8$ and $85.3{\pm}11.7$, respectively, in group B (p=0.368, 0.271). At the final follow-up, the mean loss in humeral neck-shaft angle from the time of immediate postoperative measurement was $1.6^{\circ}$ in group A and $4.8^{\circ}$ in group B, whereas the mean loss in humeral head height was 0.82 mm in group A and 0.52 mm in group B (p=0.029, 0.178). Conclusions: The surgical outcomes of internal fixation using locking plates for proximal humeral fractures were clinically and radiologically good in elderly patients over the age of 60 years without any observable complications. Further, the loss of humeral head shaft angle at the final follow-up from its initial postoperative measurement was significantly smaller in patients who received an additive augmentation suture than in those who did not. Thus, we conclude that augmentation sutures are a beneficial option for elderly patients that clinicians can consider at the time of surgical decision making.

• Journal of Korean Foot and Ankle Society
• /
• v.17 no.1
• /
• pp.45-51
• /
• 2013

Purpose: The purpose of this study was to compare and analyze the results of midfoot arthrodesis with locking plate fixation and the other instruments. Materials and Methods: Twenty one patients, a total of 22 feet who underwent midfoot arthrodesis at our institution were reviewed retrospectively from January 2006 to December 2011. Locking plates were used in 9 cases, and the other instruments such as K-wires, screws, staples were used in 13 cases. Radiologic union time was evaluated and compared between both groups. Preoperative & postoperative AOFAS midfoot scores were evaluated and compared as clinical results. Results: The average AOFAS score was rising from 69.7 to 89.4 in locking plate group and from 67.6 to 80.7 in the other instrument group. There was no statistically significant difference in two groups (p=0.179). The mean radiologic union time was 10.2 weeks in locking plate group, 12.6 weeks in the other instrument group with no significant difference (p=0.062). One case of peroneal nerve irritation was detected as a complication in locking plate group. One case of peroneal nerve irritation and 1 case of superficial wound infection with skin sloughing were detected in the other instrument group. Conclusion: There was no statistically significant difference for union time and clinical results in both groups. A locking plate can be one of the useful option for midfoot arthrodesis.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.4
• /
• pp.493-500
• /
• 2001

Objective : Anterior cervical locking plates are the devices for achieving anterior cervical spinal fusion. This study was conducted to evaluate the locking plate system regarding its long-term advantages and disadvantages in the view of interbody fusion rate, hardware-related failures, vertebral change close to the fusion segment and postoperative complications. Method : Eight-six patients, operated from Jan., 1996 to Jun. 1998, were followed-up for more than two years. All of the cases were fused with iliac bone graft and ORION locking plate(Sofamor Danek USA, Inc., Memphis, TN) fixation. The patients were discharged or transferred to rehabilitation department 2-7 days after operation. A comprehensive evaluation of the interbody fusion state, instrument failure, vertebral change and postoperative complications were made by direct interview and cervical flexion-extension lateral plain films. Results : There were 55 male and 31 female with a mean age of 45 years(18-75 years). The mean follow-up period was 29 months(24-43 months). Various disorders that were operated were 40 cervical discs, 6 cervical stenosis including OPLL, 2 infections, and 38 traumas. Fusion level was single in 59 cases, two levels of each disc space in 15 cases, and two levels after one corpectomy in 12 cases. There was no instrument failure. Pseudoarthrosis was observed in two cases(2%) without radiological instability. The other patients(98%) showed complete cervical fusion with stable instrument. Mild settling of interbody graft with upward migration of screws was found in 12 cases(14%). Anterior bony growth at the upper segment was found in 5 cases(6%). Postoperative foreign body sensation or dysphagia was observed in 12 cases(4%), and disappeared within one month in 7 cases and within six months in 4 cases. One patient complained for more than six months and required reoperation to remove paraesophageal granulation tissue. Conclusion : The results show that Orion cervical locking plate has some disadvantages of upward migration of screws, anterior bony growth at the upper segment, or possibility of esophageal compression even though it has advantages of high interbody fusion rate or low instrument failure. Author believe that anterior cervical locking plate in the future should be thinner, and should have short end from the screw hole, and movable screw with adequate stability.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.2
• /
• pp.445-454
• /
• 1991

In this thesis, Mindlin plate element with nine nodes and three degrees-of-freedom at each node is formulated and is employed in eigen-analysis of a rectangular plates in order to alleviate locking phenomenon of eigenvalues. Eigenvalues and their modes may be locked if conventional $C_{0}$-isoparametric element is used. In order to reduce stiffness locking phenomenon, two methods (1, the general reduced and selective integration, 2, the new element that use of modified shape function) are studied. Additionally in order to reduce the error due to mass matrix, two mass matrixes (1, Gauss-Legendre mass matrix, 2, Gauss-Lobatto mass matrix) are considered. The results of eigen-analysis for two models (the square plate with all edges simply-supported and all edges built-in), computed by two methods for stiffness matrix and by two mass matrixes are compared with theoretical solutions and conventional numerical solutions. These comparisons show that the performance of the two methods with Gauss-Lobatto mass matrix is better than that of the conventional plate element. But, by considering the spurious rigid body motions, the element which employs modified shape function with full integration and Gauss-Lobatto mass matrix can elevate the accuracy and convergence of numerical solutions.

• Structural Engineering and Mechanics
• /
• v.43 no.2
• /
• pp.253-271
• /
• 2012

To analyze the bending and transverse shear effects of laminated composite plates, a thirteen nodes triangular element will be presented. The suggested formulations consider a parabolic variation of the transverse shear strains through the thickness. As a result, there is no need to use shear correction coefficients in computing the shear stresses. The proposed element can model both thin and thick plates without any problems, such as shear locking and spurious modes. Moreover, the effectiveness of $w_{,n}$, as an independent degree of freedom, is concluded by the present study. To perform the accuracy tests, several examples will be solved. Numerical results for the orthotropic materials with different boundary conditions, shapes, number of layers, thickness ratios and fiber orientations will be presented. The suggested element calculates the deflections and stresses more accurate than those available in the literature.

• Structural Engineering and Mechanics
• /
• v.15 no.2
• /
• pp.199-223
• /
• 2003

The formulation of a non-linear shear deformable shell element is presented for the solution of stability problems of stiffened plates and shells. The formulation of the geometrical stiffness presented here is exactly defined on the midsurface and is efficient for analyzing stability problems of thick plates and shells by incorporating bending moment and transverse shear resultant force. As a result of the explicit integration of the tangent stiffness matrix, this formulation is computationally very efficient in incremental nonlinear analysis. The element is free of both membrane and shear locking behaviour by using the assumed strain method such that the element performs very well in the thin shells. By using six degrees of freedom per node, the present element can model stiffened plate and shell structures. The formulation includes large displacement effects and elasto-plastic material behaviour. The material is assumed to be isotropic and elasto-plastic obeying Von Mises's yield condition and its associated flow rules. The results showed good agreement with references and computational efficiency.

• Clinics in Shoulder and Elbow
• /
• v.24 no.2
• /
• pp.66-71
• /
• 2021

Background: Extra-articular distal humerus locking plates (EADHPs) are precontoured anatomical plates widely used to repair distal humeral extra-articular diaphyseal fractures. However, EADHPs frequently cause distal protrusion and resulting skin discomfort. The purpose of this study was to predict the occurrence of anatomic fit mismatch. We hypothesized that the smaller the humerus size, the greater the anatomic fit mismatch with EADHP. Methods: Twenty humeri were analyzed in this study. Humeral length and distal humeral width were used as parameters of humeral size. Plate protrusion was measured between the EADHP distal tip and the distal humerus. We set the level of unacceptable EADHP anatomic fit mismatch as ≥10 mm plate protrusion. Results: A significant negative linear correlation was also confirmed between humeral size and plate protrusion, with a coefficient of determination of 0.477 for humeral length and 0.814 for distal humeral width. The cutoff value of humeral length to avoid ≥10 mm plate protrusion was 293.6 mm (sensitivity, 88.9%; specificity, 81.8%) and for distal humeral width was 60.5 mm (sensitivity, 100%; specificity, 81.8%). Conclusions: Anatomic fit mismatch in distal humeral fractures after EADHP fixation has a negative linear correlation with humeral length and distal humeral width. For patients with a distal humeral width <60.5 mm, ≥10 mm plate protrusion will occur when an EADHP is used, and an alternative implant or approach should be considered.

• Structural Engineering and Mechanics
• /
• v.40 no.2
• /
• pp.191-213
• /
• 2011

This paper presents an improved 8-node shell element for the analysis of plates and shells. The finite element, based on a refined first-order shear deformation theory, is further improved by the combined use of assumed natural strain method. We analyze the influence of the shell element with the different patterns of sampling points for interpolating different components of strains. Using the assumed natural strain method with proper interpolation functions, the present shell element generates neither membrane nor shear locking behavior even when full integration is used in the formulation. Further, a refined first-order shear deformation theory, which results in parabolic through-thickness distribution of the transverse shear strains from the formulation based on the third-order shear deformation theory, is proposed. This formulation eliminates the need for shear correction factors in the first-order theory. Numerical examples demonstrate that the present element perform better in comparison with other shell elements.