[Finite element analysis of artificial ankle elastic improved inserts].

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.

Biomechanical assessment of disease outcome in surgical interventions for medial meniscal posterior root tears: a finite element analysis.

BACKGROUND: The adverse consequences of medial meniscus posterior root tears have become increasingly familiar to surgeons, and treatment strategies have become increasingly abundant. In this paper, the finite element gait analysis method was used to explore the differences in the biomechanical characteristics of the knee joint under different conditions. METHODS: Based on CT computed tomography and MR images, (I) an intact knee (IK) model with bone, cartilage, meniscus and main ligaments was established. Based on this model, the posterior root of the medial meniscus was resected, and (ii) the partial tear (PT) model, (iii) the entire radial tear (ERT) model, and (iv) the entire oblique tear (EOT) model were established according to the scope and degree of resection. Then, the (v) meniscus repair (MR) model and (vi) partial meniscectomy (PM) model were developed according to the operation method. The differences in stress, displacement and contact area among different models were evaluated under ISO gait loading conditions. RESULTS: Under gait loading, there was no significant difference in the maximum stress of the medial and lateral tibiofemoral joints among the six models. Compared with the medial tibiofemoral joint stress of the IK model, the stress of the PM model increased by 8.3%, while that of the MR model decreased by 18.9%; at the same time, the contact stress of the medial tibiofemoral joint of the ERT and EOT models increased by 17.9 and 25.3%, respectively. The displacement of the medial meniscus in the ERT and EOT models was significantly larger than that in the IK model (P < 0.05), and the tibial and femoral contact areas of these two models were lower than those of the IK model (P < 0.05). CONCLUSIONS: The integrity of the posterior root of the medial meniscus plays an important role in maintaining normal tibial-femoral joint contact mechanics. Partial meniscectomy is not beneficial for improving the tibial-thigh contact situation. Meniscal repair has a positive effect on restoring the normal biomechanical properties of the medial meniscus.

Characteristics and Management of Spinal Tuberculosis in Tuberculosis Endemic Area of Guizhou Province: A Retrospective Study of 597 Patients in a Teaching Hospital.

BACKGROUND: Tuberculosis (TB) is an endemic disease in Guizhou. Spinal TB accounts for approximately 50% cases of skeletal TB. The purpose of this study was to investigate the characteristics and management of patients treated for spinal TB in a certain hospital and to provide guidance for the prevention and treatment of spinal TB. METHODS: The clinic records of all patients diagnosed with spinal tuberculosis in a teaching hospital between January 2010 and December 2018 were collected. The epidemiology, clinical characteristics, imaging and laboratory findings, treatment methods, and prognosis were recorded and analyzed. RESULTS: During this nine-year period, 597 patients with spinal TB were identified. There were 313 males and 284 females with an average age of 43 years. The largest number of patients fell in the age group of 21-30 years; mean time from symptom onset to diagnosis in the hospital was 17 months. Back pain was the main clinical manifestation (89.34%). The most common imaging technique was computed tomography (CT, 96.80%), followed by magnetic resonance imaging (MRI, 84.01%). Majority of the lesions involved the lumbar spine (47.30%), followed by the thoracic spine (40.95%). 178 (29.82%) patients in this study had varying degrees of neurological impairment. 22.78% of the patients selected conservative treatment, and surgical treatment was performed in 483 patients (80.90%). CONCLUSIONS: The incidence of spinal TB was generally on the rise throughout the study period. After diagnosed with spinal TB, all patients got appropriate treatment and achieved good efficacy, but most of the patients did not pay much attention to the disease and receive timely treatment. Thus, it is essential to strengthen the TB preventive strategies, improve the health awareness of residents and universal resident health examination.

Cervical langerhans cell histiocytosis mimicking cervical tuberculosis: A Case report.

RATIONALE: Langerhans cell histiocytosis (LCH) involving adult cervical vertebrae is relatively rare clinically. PATIENT CONCERNS: An 18-year-old male patient exhibited a 1-month history of neck pain, restricted neck mobility, and numbness and weakness of both upper limbs. The patient reported no pain at other sites, exhibited no fever or night sweats, and was unable to recall any recent injury. DIAGNOSES: On the basis of the radiological features of the lesion and laboratory tests, there was a high possibility that the patient had a tuberculosis lesion. Postoperative GeneXpert and Mycobacterium tuberculosis (MTB) culture results showed MTB negative. Postoperative pathological results showed: (Cervical 4 vertebrae) LCH. INTERVENTIONS: Our department did an anterior approach operation. The patient was treated with prednisone combined with vincristine after operation. OUTCOMES: The patient was discharged from the hospital with complete remission of cervical pain and rapid relief of neurological symptoms. LESSONS: Computed tomography-guided biopsy of lesion tissue must be performed when a suspected infection occurs in young patients. If possible, the lesion tissue obtained during the operation should be cultured and pathologically examined for early diagnosis.

Analysis of Treatment and Prognosis of 863 Patients with Spinal Tuberculosis in Guizhou Province.

The objective of this study was to investigate the treatment and prognosis of patients with spinal tuberculosis in Guizhou province. A total of 863 patients with spinal tuberculosis admitted to our hospital from 2006 to 2017 were included in this study. All patients underwent standardized quadruple antituberculosis treatment. Eighty patients were lost to follow-up due to a change of their contact information or noncompliance. A total of 783 patients completed the follow-up. The average follow-up period was 20.33 ± 8.77 months (range: 6 to 38 months). Among these patients, 145 patients underwent conservative treatment, while 638 patients underwent surgical treatment. All patients in the surgery group were treated with lesion removal, bone graft fusion, and internal fixation. Preoperative and postoperative standard quadruple antituberculosis treatment was administered. The clinical efficacy was evaluated according to erythrocyte sedimentation rate (ESR), c-reactive protein (CRP), visual analogue scale (VAS), Cobb angle correction, neurological functional recovery, and interbody fusion with bone graft and tuberculosis outcome. A total of 608 patients achieved clinical cure. The symptoms, physical signs, blood tests and imaging findings were improved in 143 patients. Twenty patients showed refractory clinical symptoms, and 12 patients had local tuberculosis recurrence. Conservative and surgical treatments are the mainstream treatments for spinal tuberculosis. According to the patients' individual conditions, individualized treatments should be used to achieve good efficacy. Standardized antituberculosis treatment should be applied over the course of spinal tuberculosis.