Finite element optimization analysis of minimally invasive screw treatment for Sanders typeⅡcalcaneal fracture / 中国骨伤

OBJECTIVE@#To explore biomechanical characteristics of minimally invasive different screw fixations in treating Sanders typeⅡcalcaneal fractures.@*METHODS@#Dicom data of calcaneus by CT scan were input into Mimics 21.0 software and Ansys15.0 software to construct three-dimensional finite element digital model of calcaneus;this model was input into UG NX 10.0 software, and calcaneus was cut according to Sanders classification to establish Sanders typeⅡ calcaneus model with posterior articular surface collapse;then simulated minimally invasive screw internal fixation after calcaneal fracture:a screw from posterior articular surface was used to outside-in fix sustentaculum tali, other 4 screws were used to fix calcaneus by different methods through calcaneal tuberosity, and 4 different calcaneal models were obtained. Under the same conditions, 4 types of internal fixation models were loaded respectively, and nonlinear finite element analysis was performed to calculate the stress distribution of different internal fixation models.@*RESULTS@#Under the same condition of loading, the model 3 had smaller displacement value, maximum calcaneus displacement value and maximum equivalent stress value of the screw than other three internal fixation models, and the stress was more dispersed.@*CONCLUSION@#In minimally invasive screw internal fixation of calcaneus fracture, after 1 sustentaculum tali screw fixation, 2 screws crossed fix posterior articular surface from calcaneal tuberosity, 2 screws fix parallelly calcaneocuboid joint from calcaneal tuberosity are more suitable for biomechanical requirements, and could provide basic theory for clinical treatment.

Application of reverse dermal revascularization combined with vacuum sealing drainage in the large area of skin avulsion of the lower extremities / 中国骨伤

OBJECTIVE@#To summarize the clinical effect of emergency subcutaneous vascular network reverse skin replantation combined with vacuum sealing after drainage of large area skin avulsion injury.@*METHODS@#Clinical data of 30 patients with extensive skin avulsion of the lower limb treated between July 2010 and March 2018 were collected. There were 20 males and 10 females, ranging in age from 16 to 67 years old, with an average of(48±13) years old. Cause of injury: 19 cases of car accident injury, 11 cases of crush injury. The surgery time was 3 to 10 h, with an average of (5±1) h. All cases were completely debrided in stage I. The subdermal vascular network was reversed and skin grafted with multiple incision drainage combined with negative pressure closed drainage technique for 7 to 10 days. The wounds were removed by VSD observation:if the necrotic area is large, debridement is required. After the granulation growth of the wound is satisfactory, the skin grafting is performed again after electrification; the small area of necrotic skin strengthens the dressing and heals.@*RESULTS@#30 patients were followed up for 7 to 48 months, with an average of (20±11) months.No infection in 1 case appeared, 30 patients, living area more than 85% of the wound after treatment survival in the stage I; The skin necrosis ranged from about 12% in 5 patients in the stage II. The second stage was healed after redebriding free skin grafts. The other patients were healed after the dressing, capillary meshwork layer of skin color, good elasticity, feeling, wearable pressure, each joint activities is good, no obvious skin adhesion cause physical activity is limited.@*CONCLUSIONS@#Reverse skin grafting combined with VSD for the treatment of large skin avulsion of lower limb can greatly reduce wound infection rate, promote the application of skin and wound, conducive to drainage, improve the survival rate of reverse skin grafting and improve the function of lower limb joints.

biomechanical study of rupture of achilles tendon and repair by different suture techniques

Objective: To study the biomechanical properties of different suture methods, and to provide evidence for the clinical application of this suture methods in repairing acute Achilles tendon rupture

Methods: Twenty four fresh frozen cadaver Achilles tendon specimens were collected and randomly divided into three groups [n=8], Group-A Bunnell suture method, Group-B Bosworth suture and Group-C anchor suture respectively. 5 N tensions were applied to tighten the tendon. The actual length of the tendon between the upper and lower clips was measured with a ruler. The length of the long axis and the short axis of the three sections of the tendon was measured by vernier caliper. The cross sectional area of the tendon was calculated according to the elliptical area formula and the mean value was obtained

Results: There was no significant difference in the length and cross-sectional area of each tendon among three groups [F=0.26, P=0.86; F=0.09, P=0.96]. There was no significant difference in the maximum load of tendon and failure displacement in Group A and B [P>0.05]. The maximal load of Group-C was significantly larger than that of Group A and B [P<0.05], and there was no significant difference between the failure displacement and Group A and B [P>0.05]

Conclusion: Three suture methods can provide good biomechanical properties, but the anchor suture is more effective in solving the shortcomings of traditional methods. It is a safe and effective method, and is worthy of promotion

Comparison of fixation of sustentaculum tali of calcaneus aided by director for sustentaculum tali screwing and ordinary screwing guide / 中国骨伤

<p><b>OBJECTIVE</b>To explore clinical outcomes of director for sustentaculum tali screwing for fixing sustentaculum tali of calcaneus.</p><p><b>METHODS</b>From May 2012 to October 2013, totally 50 patients (60 feet) with calcaneal fractures were analyzed, and divided into director for sustentaculum calcaneous tali screwing treatment group (group A) and ordinary screwing group(group B). In group A, there were 25 patients, including 22 males and 3 females, aged from 17 to 75 years old with an average of (45.08±11.98) years; according to Sanders classification, 9 feet were type II, 16 feet were type III, and 7 feet were type IV. In group B, there were 25 patients, including 20 males and 5 females, aged from 19 to 78 years old with an average of (46.36±15.74) years; according to Sanders classification, 8 feet were type II, 13 feet were type III, and 7 feet were type IV. Radiological change, operative time, postoperative complications were observed and compared, Maryland scoring at 1 year after operation was applied to evaluate clinical outcomes.</p><p><b>RESULTS</b>Fifty patients were followed up, group A was followed up from 12 to 24 months with an average of (17.72±4.08) months;while group B was followed up from 12 to 24 months with an average of (18.68±3.40) months;there was no significant difference between two groups in following-up time(>0.05). There were significant difference in operative time, complications and fluoroscopy times between two groups(<0.05). There were significant difference in Böhler angle and Gissanes angle between two groups before and after operation(<0.05). Maryland score at 1 year after operation in group A was (84.94±12.75) and (76.96±15.32) in group B, had significant meaning between two groups (<0.05).</p><p><b>CONCLUSIONS</b>Fixation of sustentaculum tali of calcaneus aided by director for sustentaculum tali screwing, has advantages of less operative time, fluoroscopy times, incidence of complications and good recovery of function, which could provide a new aiding method for treating intra-articular calcaneal fractures.</p>

Sustentaculum tali screw fixation for the treatment of Sanders type II and III calcaneal fractures / 中国骨伤

<p><b>OBJECTIVE</b>To explore the clinical outcomes of open reduction and internal fixation with calcaneal locking plates in treating Sanders type II and III calcaneal fractures.</p><p><b>METHODS</b>From January 2010 and October 2012, 38 calcaneal fractures with Sanders type II or III were treated with open reduction and internal fixation with calcaneal locking plate. According to the Sanders classification, 15 fractures were classified as type II, 23 fractures as type III. The patients were divided into two groups (group A and B) according to the different fixed methods. Sustentaculum tali was fixed with one screw in group A, including 13 males and 5 females, with a mean age of (38.56±8.03) years old (ranged, 25 to 55). And sustentaculum tali was not fixed in group B, including 16 males and 4 females, with a mean age of (42.35±8.29) years old (ranged, 29 to 53). Clinical effects were evaluated according to the changes of Böhler's angle and the Maryland Foot Score and VAS score.</p><p><b>RESULTS</b>All patients were followed up from 12 to 20 months with a mean of 14 months. Böhler's angles and subtalar joints obtained satisfactory reconstruction in all patients. One year after operation, the mean Maryland Foot Score was 88.61±7.59 in group A; and was 82.40±9.24 in group B; Maryland Foot Score of group A was higher and foot functional rehabilitation was better than group B. The mean VAS score was 13.39±11.47 in group A; and was 22.50±13.10 in group B; VAS score of group A was lower and foot pain was less than group B.</p><p><b>CONCLUSION</b>Sustentaculum tall screw fixation has advantages of strong fixed strength, high stability, less postoperative pain, rapid functional recovery in treating Sanders type II and III calcaneal fractures.</p>