Finite element analysis of the use of two new types of internal fixation for acetabular fractures.

BACKGROUND: Both-column fracture is a common type of acetabular fracture and is sometimes accompanied by a comminuted fracture of the quadrilateral area. Such fractures are difficult to anatomically reduce and securely fix. In this study, the authors compared the application value and mechanical properties of the Bespoke 3D-printed titanium alloy plates and Union Plate in acetabular both-column fractures. METHODS: A both-column fracture model of the acetabulum was established, and the Bespoke 3D-printed titanium alloy plates, Union Plate and a common reconstruction plate were used for fixation. External loads were applied to the model at different angles, and the effects on the plates and the stress and displacement of the screws were determined. RESULTS: Under different states of hip joint activity, the maximum stress experienced by the Bespoke 3D-printed titanium alloy plates and Union Plate was significantly smaller than the maximum stress experienced by the common reconstruction plate. The Bespoke 3D-printed titanium alloy plates experienced the lowest maximum stress under different hip joint motions. There was no statistically significant difference between the maximum displacement of the Bespoke 3D-printed titanium alloy plates and Union Plate and that of the common reconstructed plate. CONCLUSIONS: The design of the Bespoke 3D-printed titanium alloy plates imparts a smaller maximum stress and better mechanical properties when repairing acetabular both-column fractures.

Both-column Acetabular Fractures with Posterior Wall Involved can be Managed through Single Anterior Approach by Evaluation of Computer-assisted Virtual Surgery Technique.

OBJECTIVE: Posterior wall (PW) fractures were sometimes associated in both-column acetabular fractures. How to evaluate pre-operatively the necessity for the performance of the posterior approach was an issue to be solved. In order to solve this issue, the computer-assisted virtual surgery technique was used to evaluate if the involved PW in both-column acetabular fractures (BACF) should be managed through posterior approach and verify the feasibility of this method. METHODS: Data of a consecutive cohort of 72 patients with both-acetabular fractures from January 2012 to January 2020 was collected for retrospective study, of which 44 patients had concomitant acetabular PW fractures, and patients without PW fractures were labeled as the BCAF group. Computer-assisted virtual surgery technique was performed pre-operatively to evaluate the necessity for performance of posterior approach in 44 patients, and posterior approach was required if more than 3 mm of displacement was still present in the reduced 3D model. The 23 patients without treatment through posterior approach were labeled as the BCAF-PW- group, and the 21 patients with treatment through posterior approach were labeled as the BCAF-PW+ group. Operation-related and post-operative parameters were recorded. The quality of reduction and functional outcomes were assessed by the Matta scoring system and modified Merle d'Aubigné and Postel scoring system. The measurement data were analyzed using the t-test of independent samples and rank-sum test of ranked data between every two groups. Also, the one-way analysis of variance (ANOVA) was used to analyze data between the three groups. RESULTS: Comparing operation-related and post-operative parameters in the three groups, some PW fractures in both-column acetabular fractures could be ignored, and which could be evaluated pre-operatively for necessity of an additional posterior approach. Operative time (271.2 ± 32.8 mins) and intra-operative blood loss (1176.7 ± 211.1 mL) were significantly higher in the BCAF-PW+ group. The excellent/good of reduction (25/28 of the BCAF group, 21/23 of the BCAF-PW- group, 19/21 of the BCAF-PW+ group) and functional outcomes (24/28 of the BCAF group, 18/23 of the BCAF-PW- group, 18/21 of the BCAF-PW+ group) of three groups were similar. The incidence of complications, such as deep vein thrombosis (4/28 of the BCAF group >3/23 of the BCAF-PW- group >1/21 of the BCAF-PW+ group) and injury of lateral femoral cutaneous nerve (3/23 of the BCAF-PW- group >2/28 of the BCAF group >0/21 of the BCAF-PW+ group), was no significant difference. CONCLUSION: The partial both-column acetabular fractures with PW involvement could be managed through a single anterior approach without another posterior approach by evaluation of computer-assisted virtual surgery technique.

Biomechanical study of different fixation constructs for anterior column and posterior hemi-transverse acetabular fractures: a finite element analysis.

BACKGROUND: To compare the biomechanical properties and stability, using a finite element model, of four fixation constructs used for the treatment of anterior column and posterior hemi-transverse (ACPHT) acetabular fractures under two physiological loading conditions (standing and sitting). METHODS: A finite element model simulating ACPHT acetabular fractures was created for four different scenarios: a suprapectineal plate combined with posterior column and infra-acetabular screws (SP-PS-IS); an infrapectineal plate combined with posterior column and infra-acetabular screws (IP-PS-IS); a special infrapectineal quadrilateral surface buttress plate (IQP); and a suprapectineal plate combined with a posterior column plate (SP-PP). Three-dimensional finite element stress analysis was performed on these models with a load of 700 N in standing and sitting positions. Biomechanical stress distributions and fracture displacements were analysed and compared between these fixation techniques. RESULTS: In models simulating the standing position, high displacements and stress distributions were observed at the infra-acetabulum regions. The degree of these fracture displacements was low in the IQP (0.078 mm), as compared to either the IP-PS-IS (0.079 mm) or the SP & PP (0.413 mm) fixation constructs. However, the IP-PS-IS fixation construct had the highest effective stiffness. In models simulating the sitting position, high fracture displacements and stress distributions were observed at the regions of the anterior and posterior columns. The degree of these fracture displacements was low in the SP-PS-IS (0.101 mm), as compared to the IP-PS-IS (0.109 mm) and the SP-PP (0.196 mm) fixation constructs. CONCLUSION: In both standing and sitting positions, the stability and stiffness index were comparable between the IQP, SP-PS-IS, and IP-PS-IS. These 3 fixation constructs had smaller fracture displacements than the SP-PP construct. The stress concentrations at the regions of quadrilateral surface and infra-acetabulum suggest that the buttressing fixation of quadrilateral plate was required for ACPHT fractures.

Finite element analysis of posterior acetabular column plate and posterior acetabular wall prostheses in treating posterior acetabular fractures.

BACKGROUND: The purpose of this study was to investigate the mechanical stability of the posterior acetabular column plate and different posterior acetabular wall prostheses used in treating posterior acetabular fractures with or without comminution. METHODS: The unilateral normal ilium was reconstructed, and a model of posterior acetabular wall fracture was established on this basis. The fracture fragment accounted for approximately 40% of the posterior acetabular wall. The posterior acetabular column plate and different posterior acetabular wall prostheses were also designed. Using static and dynamic analysis methods, we observed and compared the changes in the stress and displacement values of different models at different hip joint flexion angles under external forces. RESULTS: At different hip flexion angles, the stress of each model mainly fluctuated between 37.98 MPa and 1129.00 MPa, and the displacement mainly fluctuated between 0.076 and 6.955 mm. In the dynamic analysis, the nodal stress‒time curves of the models were nonlinear, and the stress changed sharply during the action time. Most of the nodal displacement‒time curves of the models were relatively smooth, with no dramatic changes in displacement during the action time; additionally, most of the curves were relatively consistent in shape. CONCLUSIONS: For simple posterior acetabular wall fractures, we recommend using a posterior acetabular column plate. In the case of comminuted posterior acetabular fractures, we recommend the use of a nonflanked posterior acetabular prosthesis or a biflanked posterior acetabular prosthesis. Regarding the method of acetabular prosthesis design, we propose the concept of "Break up to Make up" as a guide.

Laminin α1 as a target for the treatment of epidural fibrosis by regulating fibrotic mechanisms.

Excessive proliferation and migration of fibroblasts in the lumbar laminectomy area can lead to epidural fibrosis, eventually resulting in failed back surgery syndrome. It has been reported that laminin α1, a significant biofunctional glycoprotein in the extracellular matrix, is involved in several fibrosis­related diseases, such as pulmonary, liver and keloid fibrosis. However, the underlying mechanism of laminin α1 in epidural fibrosis remains unknown. The present study aimed to explore the effect and mechanism of laminin α1 in fibroblast proliferation, apoptosis and migration, and epidural fibrosis. Following the establishment of a laminectomy model, hematoxylin and eosin, Masson's trichrome and immunohistochemical staining were performed to determine the degree of epidural fibrosis, the number of fibroblasts, collagen content and the epidural expression levels of laminin α1, respectively. Furthermore, a stable small interfering RNA system was used to knock down the expression of laminin α1 in fibroblasts. The transfection efficiency was confirmed by reverse transcription­quantitative PCR and immunofluorescence staining. Western blot analysis, scratch wound assay, EdU incorporation assay, flow cytometric analysis and Cell Counting Kit 8 assay were performed to assess the proliferation, apoptosis, migration and viability of fibroblasts, as well as the expression levels of the AKT/mechanistic target of rapamycin (mTOR) signaling­related proteins. In vivo experiments revealed that laminin α1 was positively and time­dependently associated with epidural fibrosis. In addition, laminin α1 knockdown attenuated cell proliferation, viability and migration, and promoted apoptosis. Furthermore, the results revealed that the activation of the AKT/mTOR signaling pathway was involved in the aforementioned processes. Overall, the current study illustrated the positive association between laminin α1 and epidural fibrosis, and also verified the effect of laminin α1 on fibroblast proliferation, apoptosis and migration. Furthermore, the results suggested that the AKT/mTOR signaling pathway may serve a significant role in regulating the behavior of laminin α1­induced fibroblasts.

Guidelines for management of pediatric acute hyperextension spinal cord injury.

Pediatric acute hyperextension spinal cord injury (SCI) named as PAHSCI by us, is a special type of thoracolumbar SCI without radiographic abnormality and highly related to back-bend in dance training, which has been increasingly reported. At present, it has become the leading cause of SCI in children, and brings a heavy social and economic burden. Both domestic and foreign academic institutions and dance education organizations lack a correct understanding of PAHSCI and relevant standards, specifications or guidelines. In order to provide standardized guidance, the expert team formulated this guideline based on the principles of science and practicability, starting from the diagnosis, differential diagnosis, etiology, admission evaluation, treatment, complications and prevention. This guideline puts forward 23 recommendations for 14 related issues.

Small Intestinal Submucosa Biomimetic Periosteum Promotes Bone Regeneration.

BACKGROUND: Critical bone defects are a significant problem in clinics. The periosteum plays a vital role in bone regeneration. A tissue-engineered periosteum (TEP) has received increasing attention as a novel strategy for bone defect repairs. METHODS: In this experiment, a biomimetic periosteum was fabricated by using coaxial electrospinning technology with decellularized porcine small intestinal submucosa (SIS) as the shell and polycaprolactone (PCL) as the core. In vitro, the effects of the biomimetic periosteum on Schwann cells, vascular endothelial cells, and bone marrow mesenchymal stem cells were detected by a scratch test, an EdU, a tube-forming test, and an osteogenesis test. In vivo, we used HE staining to evaluate the effect of the biomimetic periosteum on bone regeneration. RESULTS: In vitro experiments showed that the biomimetic periosteum could significantly promote the formation of angiogenesis, osteogenesis, and repaired Schwann cells (SCs). In vivo experiments showed that the biomimetic periosteum could promote the repair of bone defects. CONCLUSIONS: The biomimetic periosteum could simulate the structural function of the periosteum and promote bone repair. This strategy may provide a promising method for the clinical treatment of skull bone defects.

The novel infra-pectineal buttress plates used for internal fixation of elderly quadrilateral surface involved acetabular fractures.

OBJECTIVES: In geriatric acetabular fractures, the quadrilateral surface (QLS) was frequently involved in acetabular fracture patterns and accompanied by medial displacement. It was important to buttress the medial displaced QLS and reconstruct the congruity of the affected acetabulum. To evaluate the clinical effectiveness of the novel infra-pectineal quadrilateral surface buttress plates for the treatment of geriatric acetabular fractures. METHODS: Twenty-three geriatric patients who were treated for acetabular fractures involving QLS with the novel infra-pectineal buttress plates (NIBP) through a single supra-ilioinguinal approach between January 2015 and June 2019 were retrospectively analyzed; all patients received at least 1 year's follow-up. All patients were aged ≥60 years old and including 18 males and five females. Radiologic and clinical outcomes of patients involved in the study were collated and analyzed according to the Matta scoring system and the Merle D'Aubigné-Postel scoring system. The functional recovery scoring was compared using q-test. RESULTS: All 23 consecutive patients had relatively satisfactory clinical treatment effectiveness. Average ages, length of incision, operation time, and intraoperative blood loss were 69.8 ± 6.1 years, 12.1 ± 2.6 cm, 166.5 ± 43.5 min, and 500 (500,700) ml, respectively. According to the Matta scoring system, 14 cases of reduction were graded as excellent, five as good, and four as fair. At the last follow-up, the clinical outcome evaluation was excellent in 13 cases, good in seven cases, and poor in three cases with the use of the Merle D'Aubigné-Postel scoring system. The difference of modified Merle D'Aubigne-Postel score at 3 months, 6 months and last follow up was statistically significant (F = 21.56, p < 0.05). Postoperative lateral femoral cutaneous nerve injury occurred in three patients and heterotopic ossification occurred in one patient. CONCLUSIONS: For the treatment of geriatric acetabular fractures, the NIBP could provide stable and effective fixation to the QLS involved acetabular fractures, and related satisfactory clinical results with few complications were noted.

Acute hyperextension myelopathy in children: Radiographic predictors of clinical improvement.

STUDY DESIGN: Retrospective case series SETTING: Three hospitals in China. OBJECTIVE: Previous research indicates that only neurological status on admission determines prognosis of acute hyperextension myelopathy (AHM). The object of this study is to analyze other unfavorable predictors of AHM in children. METHODS: The clinical data of children with AHM were retrospectively analyzed. The ASIA impairment scale (AIS) grade was recorded upon admission and at last follow-up. Intramedullary lesion length (IMLL) was measured in the sagittal T2-weighted imaging (T2WI) within two weeks after onset; gadolinium enhancement in the cord was recorded for each patient. Relationships among AIS grade, IMLL, gadolinium enhancement in the cord, and clinical improvement were assessed. RESULTS: A total of 33 patients were included in this retrospective study. IMLL between complete and incomplete injury was significantly different (p < 0.01) in the subacute stage, and no difference was observed in the acute stage. Correlation analysis revealed that AIS grade on admission (r = 0.906, p < 0.001) was significantly positively correlated with clinical improvement. IMLL (r = -0.608, p < 0.001) and abnormal gadolinium enhancement (r = -0.816, p < 0.001) in the cord in the subacute stage were significantly negatively correlated with clinical improvement. There were no associations between IMLL in the acute stage and clinical improvement (r = -0.248, p = 0.242). The statistically significant predictors of clinical improvement were AIS grade on admission, IMLL in the subacute stage, and abnormal gadolinium enhancement. CONCLUSION: IMLL in the subacute stage and abnormal gadolinium enhancement in the cord are two other prognostic predictors of AHM in children.

Finite element analysis of the Union Plate in treating elderly acetabular fracture patients.

BACKGROUND: Elderly acetabular fractures are one of the more difficult types of fractures to resolve. For patients at this age, the more common type of fracture is comminuted. How to better fix this type of fracture has always been an issue of concern. This study was performed to observe the mechanical properties of different internal fixation methods used in treating elderly acetabular fracture patients. METHODS: A model of a comminuted acetabular fracture in osteoporosis was established, consisting of an anterior column-posterior hemitransverse fracture with disruption of the quadrilateral surface. Fixation of the acetabular fracture model using a reconstruction plate and Union Plates was simulated. For the different internal fixation methods, static and transient modal analyses were performed under different loads, with an action time of 0.21 s and an analysis time of 0.7 s. The stress of the model was observed in the static analysis, and the displacement of the nodes and the entire model in the U1 direction was observed in the transient modal analysis. RESULTS: In the static analysis, the stress of the osteoporosis model, the suprapectineal pelvic reconstruction plate model, the infrapectineal quadrilateral surface buttress plate model, and the suprapectineal quadrilateral surface buttress plate model were 42.62 MPa, 37.49 MPa, 44.39 MPa, and 46.15 MPa, respectively. The stress was mainly distributed near the suprapubic branch. The corresponding displacement in the U1 direction was 0.1500 mm, 0.1020 mm, 0.0836 mm, and 0.0990 mm, respectively. In the transient modal analysis, there was a significant difference in displacement between the different models (P < 0.05). When different loads were applied with the same fixation method, there was no significant difference in model displacement (P > 0.05). CONCLUSION: Static and transient modal analyses show that the infrapectineal quadrilateral surface buttress plate or the suprapectineal quadrilateral surface buttress plate has an advantage in maintaining the stability of fracture fragments when fixing comminuted acetabular fractures in elderly individuals. The infrapectineal quadrilateral surface buttress plate also presents better biomechanical results.

Detection and Analysis of Perfusion Pressure through Measuring Oxygen Saturation and Requirement of Dural Incision Decompression after Laminectomy.

BACKGROUND: Traumatic spinal cord injury (SCI) can continue and transform long after the time of initial injury. Preventing secondary injury after SCI is one of the most significant challenges, and early intervention to return the blood flow at the injury site can minimize the likelihood of secondary injury. OBJECTIVE: The purpose of this study is to investigate whether laminectomy can achieve the spinal cord blood flow by measuring the spinal blood oxygen saturation intraoperatively without the presence of light. METHODS: Between June and August 2021, eight patients were admitted after traumatic spinal cord injury for surgical treatment. We explored the effectiveness of laminectomy and whether the patients required further procedures or not. We used a brain oxygen saturation monitor at the spine injury site under dark conditions. RESULTS: Eight cervical trauma patients, six males and two females, underwent laminectomy decompression. Three patients' ASIA grade improved by one level, and one patient showed slight motor-sensory improvement. Oxygen saturation was in the normal range. CONCLUSION: Performing bony decompression can show good results. Therefore, finding an examination method to confirm the improvement of blood perfusion by measuring oxygen saturation at the injury site after laminectomy is essential to avoid other complications.