ABSTRACT
OBJECTIVE@#To discuss the influence of artificial ankle elastic improved inserts (hereinafter referred to as "improved inserts") in reducing prosthesis micromotion and improving joint surface contact mechanics by finite element analysis.@*METHODS@#Based on the original insert of INBONE Ⅱ implant system (model A), four kinds of improved inserts were constructed by adding arc or platform type flexible layer with thickness of 1.3 or 2.6 mm, respectively. They were Flying goose type_1.3 elastic improved insert (model B), Flying goose type_2.6 elastic improved insert (model C), Platform type_1.3 elastic improved insert (model D), Platform type_2.6 elastic improved insert (model E). Then, the CT data of right ankle at neutral position of a healthy adult male volunteer was collected, and finite element models of total ankle replacement (TAR) was constructed based on model A-E prostheses by software of Mimics 19.0, Geomagic wrap 2017, Creo 6.0, Hypermesh 14.0, and Abaqus 6.14. Finally, the differences of bone-metal prosthesis interface micromotion and articular surface contact behavior between different models were investigated under ISO gait load.@*RESULTS@#The tibia/talus-metal prosthesis interfaces micromotion of the five TAR models gradually increased during the support phase, then gradually fell back after entering the swing phase. The improved models (models B-E) showed lower bone-metal prosthesis interface micromotion when compared with the original model (model A), but there was no significant difference among models A-E ( P>0.05). The maximum micromotion of tibia appeared at the dome of the tibial bone groove, and the micromotion area was the largest in model A and the smallest in model E. The maximum micromotion of talus appeared at the posterior surface of the central bone groove, and there was no difference in the micromotion area among models A-E. The contact area of the articular surface of the insert/talus prosthesis in each group increased in the support phase and decreased in the swing phase during the gait cycle. Compared with model A, the articular surface contact area of models B-E increased, but there was no significant difference among models A-E ( P>0.05). The change trend of the maximum stress on the articular surface of the inserts/talus prosthesis was similar to that of the contact area. Only the maximum contact stress of the insert joint surface of models D and E was lower than that of model A, while the maximum contact stress of the talar prosthesis joint surface of models B-E was lower than that of model A, but there was no significant difference among models A-E ( P>0.05). The high stress area of the lateral articular surface of the improved inserts significantly reduced, and the articular surface stress distribution of the talus prosthesis was more uniform.@*CONCLUSION@#Adding a flexible layer in the insert can improve the elasticity of the overall component, which is beneficial to absorb the impact force of the artificial ankle joint, thereby reducing interface micromotion and improving contact behavior. The mechanical properties of the inserts designed with the platform type and thicker flexible layer are better.
Subject(s)
Adult , Male , Humans , Ankle , Ankle Joint/surgery , Finite Element Analysis , Tibia/surgery , Talus , Stress, Mechanical , Biomechanical PhenomenaABSTRACT
Objective:To explore the predictive factors for prepatellar subfascial gas in patients with closed patellar fracture and their impacts on the early infection following internal fixation.Methods:A retrospective analysis was performed in the 148 patients with closed patellar fracture who had been treated at Department of Orthopaedic Surgery, Zhangjiagang Hospital Affiliated to Soochow University from January 2018 through December 2021. All patients underwent preoperative three-dimensional CT examination of the knee joint and was treated by open reduction and internal fixation of patellar fractures. According to the presence or absence of gas in the prepatellar fascia, the patients were divided into 2 groups. In the gas group of 18 patients, there were 12 males and 6 females with an age of (58.3±14.5) years; in the gas-free group of 130 patients, there were 57 males and 73 females with an age of (60.5±14.6) years. The risk factors for prepatellar subfascial gas were screened out by comparing the gender, age, body mass index, injury mechanism, AO/OTA classification, diabetes, primary hypertension, neutrophil percentage, lymphocyte percentage, white blood cell count, neutrophil count, lymphocyte count, C-reactive protein, erythrocyte sedimentation rate, procalcitonin, and albumin before operation between the 2 groups. A receiver operating characteristic (ROC) curve for risk factors were made to identify the best screening points. The impacts of prepatellar subfascial gas were analyzed on early infection after internal fixation.Results:The preoperative neutrophil percentage was the risk factor for prepatellar subfascial gas ( P<0.05). The area under the ROC curve of preoperative neutrophil percentage for prediction of prepatellar subfascial gas was 0.700 (95% CI: 0.554 to 0.847), the optimal critical value was 78.45%, and the sensitivity and specificity were 0.556 and 0.831, respectively ( P=0.006). In the gas group, the incidence of early postoperative infection was insignificantly higher ( P=0.058) , but the time for postoperative antibiotic use was significantly longer and the dressing changes were significantly more frequent than those in the gas-free group ( P<0.05). Conclusions:In patients with closed patellar fracture, preoperative neutrophil percentage >78.45% can be used as an effective non-imaging indicator for prepatellar subfascial gas. A patient with prepatellar subfascial gas could be more prone to early postoperative infection.
ABSTRACT
Objective To compare open reduction and internal fixation (ORIF) with closed reduction and internal fixation (CRIF) for the treatment of displaced fractures of the femoral neck in children,using a Meta-analysis.Methods Cochrane Library,PubMed Data,CNKI,Chinese Biomedical Database,Wanfang Data and Vip Data were searched for studies on treating displaced fractures of the femoral neck in children with ORIF and CRIF.In addition,hand search was conducted in relevant journals.Time limit for search was set from the beginning till August 2017.After eligible studies were included,a database was established of the demographic and clinical data of the patients included.Software Revman 5.0 was used for heterogeneity test of the quality of the studies included and the pooled relative risk (RR) and 95％ confidence interval (CI) were calculated.Results Ten studies were ultimately included involving 309 patients.Of them,163 were treated by ORIF and 146 by CRIF.The results showed that ORIF led to a significantly higher rate of anatomical reduction [RR =0.33,95％ CI (0.22,0.49),P ＜ 0.05] and a significantly higher good to excellent rate by Ratliff's evaluation [RR =0.73,95％ CI (0.62,0.85),P ＜0.05] than CRIF did;ORIF also led to a significantly lower rate of avascular necrosis[RR =1.93,95％ CI (1.13,3.31),P ＜ 0.05],a significantly lower rate of coxa vara [RR =2.38,95％ CI (1.07,5.27),P ＜0.05] and a significantly lower rate of nonunion [RR =2.72,95％ CI (1.05,7.04),P ＜ 0.05] than CRIF did.Conclusion In the treatment of displaced fractures of the femoral neck in children,ORIF can lead to better reduction,fewer complications and a higher good to excellent rate of functional recovery than CRIF.