Objective To set up a neural network model and system to be applied in color selection of anterior porcelain prosthesis, and to improve its cosmetic effect. Methods The image was automatically captured by digtal camera, and pre processed. The values based on the three stimulation value were adopted for the colour selection and tooth colour matches from nine zone colors with 21 point smoothly transitional calculation. The three dimension view of the teeth was recovered. Tooth colors storage was set up and the characteristics for sample teeth and lost teeth were selected and retrieved to match the colour through artificial neural network automatically for personalized design of teeth colour. Results The method of anterior prosthesis for computerized color selection based on artificial neural network had a higher accuracy. By comparision, the satisfaction of patients, dentists and viewers was much higher than that without computer aided design, and patients' eveluation for the prosthesis was higher than that of dentists. Conclusion The design system for colour selection of the front tooth prosthesis has a great value in clinical application, and it has developed the theory of artificial neural network used in the field of stomatology.

Objective:To explore the efficacyof direct anterior approach (DAA) combined with direct posterior approach (DPA) for the treatment of Pipkin IV fracture.Methods:Data of 18 patients with Pipkin IV fracture treated through DAA combined with DPA from January 2016 to April 2019 was retrospectively analyzed. There were 13 males and 5 females, with an average age of 43.2 years (range,19-56 years). Fractures were caused by traffic accident in 15 and by falling in 3. The fracture lines of 13 cases were located below the fovea of the femoral head and 5 cases were located above the fovea. According to Letournel-Judet classification for acetabular fractures, there were 14 cases of posterior acetabular wall fractures, 2 cases of posterior wall fractures involving posterior column, and 2 transverse plus posterior wall fractures. The operation was performed through DAA approach to treat the femoral head fractures, and DPA approach was used to treat acetabular fractures. Radiographs and CT scans of the pelvis were reexamined after surgery, and fracture reduction, healing, and complications such as femoral head necrosis, sciatic nerve injury, superior gluteal neurovascular injury and heterotopic ossification were evaluated. Quality of acetabular reduction was evaluated according to the criteria proposed by Matta. Thompson-Epstein scoring system was used to evaluate hip function.Results:The average operation time was 133 min (range, 75-205 min). And the average blood loss was 371 ml (range, 240-600 ml). All 18 patients were followed up for 6 to 36 months, with an average period of 15.7 months. All fractures healed 10 to14 weeks after surgery. Three patients had symptoms of sciatic nerve injury after the injury, who recovered 6 to 12 weeks after the operation. All femoral head fractures were reduced. According to Matta criteria of reduction quality, anatomic reduction was gained in 13 cases, and satisfactory reduction was obtained in 3 cases, while unsatisfactory reduction was found in 2 cases, and the overall satisfactory rate was 88.9%(16/18). Two patients had Brooker I level heterotopic ossification. There was no iatrogenic vascular injury, avascular necrosis of femoral head, infection, internal fixation failure or other complications. According to the Thompson-Epstein scoring system at the latest follow-up, the functional results of the affected hip were excellent in 7 cases, good in 8, fair in 2 and poor in 1.Conclusion:Treatment of Pipkin IV fractures through DAA combined with DPA approach reduces surgical invasion. And it can directly reduce and fix the femoral head and posterior acetabular fracture, and protect the important structures such as the arteriae circumflexa femoris medialis, sciatic nerve and lateral femoral cutaneous nerve, and reduce the occurrence of complications such as femoral head necrosis and heterotopic ossification. Therefore, DAA combined with DPA is aneffective method for the treatment of Pipkin IV fractures.

Objective:To evaluate the follow-up clinical results of W-shaped acetabular angular plate for the treatment of acetabular posterior wall fractures through a direct posterior approach (DPA).Methods:Fifteen cases (10 males and 5 females, average aged 42.1±10.0 years) were involved in this study, with acetabular posterior wall fractures treated by using the W-shaped acetabular angular plate through a DPA between March 2017 and June 2019. Nine patients with fractures were injured by traffic accidents and the other 6 cases by falling. Based on the three-column classification for acetabular fractures, all of the cases belonged to posterior wall fractures (A2.1), which included 6 cases of simple fractures and 9 cases of comminuted fractures. The mean time interval between injury and surgery was 5.6±1.1 (range, 4-8) days. The DPA was adopted in all cases. The posterior wall fractures of the acetabulum were reduced and fixed with W-shaped acetabular angular plates. The reduction quality of the acetabulum was evaluated by X-ray and CT scan during follow-up visits according to the criteria proposed by Matta. The function of the hip joint was assessed by the Merle d'Aubigné-Posteal score modified by Matta.Results:The length of the surgical incision was 9.5±1.1 (range, 8-12) cm. The operation time was 45.3±10.1 (range, 35-75) mins. The amount of intraoperative blood loss was 248.0±94.7 (range, 100-380) ml. All the patients who were followed up for 20.5±6.3 (range, 16-38) months. All cases were evaluated according to Matta's reduction quality criteria, the satisfactory ratio of reduction was 100%. Among cases, 10 cases were matched the anatomic reduction, and the other 5 cases have belonged to satisfy. All cases of fractures had healed (the mean of healing time was 9.4±1.3 (range, 8-12 weeks). At the final follow-up visit, the mean of modified Merle d'Aubigne-Postel score was 16.9±1.6 (range, 13-18). Excellent clinical outcomes were obtained in 10 cases, good in 3 cases, and fair in 2 cases. One case had deep venous thrombosis of the lower extremities. The clots disappeared after anticoagulation treatment. One case had the heterotopic ossification, Brooker grade I, without any special treatment due to not affecting the hip joint activity in the follow-up visits. One patient had incision fat liquefaction and the wound healed after intensive dressing change. No internal fixation loosening or losing of fracture reduction was found at the follow-up visits.Conclusion:This study shows that using W-shaped acetabular angular plate for the treatment of acetabular posterior wall fractures through the DPA could obtain early satisfactory clinical outcomes.

Objective:To investigate the clinical efficacy of lateral-rectus approach(LRA) for vertical shear fracture of pelvis combined with lumbosacral plexus nerve injury.Methods:A retrospective study was conducted of the 37 patients who had been treated at Department of Orthopaedics, The Third Affiliated Hospital to Southern Medical University for vertical shear pelvic fracture combined with lumbosacral plexus nerve injury from August 2010 to August 2018. They were 25 males and 12 females, aged from 18 to 61 years (mean, 36.2 years). By the Tile classification, there were 31 cases of type C1.3, 5 cases of type C2 and one of type C3. LRA was used in all the patients to explore and release the lumbosacral plexus nerve and to reduce the sacral fracture. The posterior ring was fixated with an anterior iliac plate or sacral screws before fixation of the anterior ring and treatment of the acetabular fracture. The operation time, intraoperative bleeding volume, quality of fracture reduction, fracture union time and recovery of nerve and muscle strength were recorded.Results:For this cohort, the operation time ranged from 105 to 228 minutes (mean, 155.0 minutes) and the intraoperative bleeding volume from 680 to 2, 440 mL (mean, 1, 070 mL). Thefollow-up time ranged from 1 to 8 years (average, 2 years). According to the Matta criteria, the quality of fracture reduction was evaluated as excellent in 21 cases, as good in 12 cases and as fair in 4 cases, giving an excellent and good rate of 89.2%. Follow-ups revealed reduction loss in 4 patients, nonunion and reduction loss in one patient and bony union in the other 32 patients after 8 to 12 weeks (mean, 10.1 weeks). According to the criteria by the Nerve Injuries Committee of the British Medical Research Council (BMRC), the recovery of nerve and muscle strength achieved M5 (full recovery of neurological symptoms) in 22 cases, M4 (fine recovery of neurological symptoms) in 7 cases, M1, M2 and M3 (partial recovery of neurological symptoms) in 5 cases, and M0 (no recovery of neurological symptoms) in 3 cases.Conclusion:LRA is an ideal surgical approach for treatment of pelvic vertical shear fractures complicated with lumbosacral plexus nerve injury, because it can well expose the medial pelvic joint from the sacroiliac joint to the symphysis pubis, allow direct release of the lumbosacral plexus nerve compressed and stretched, and, together with traction of the lower limbs, lead to satisfactory fracture reduction.

Objective: To explore surgical technique and clinical results of the direct posterior approach (DPA) for acetabular fractures involving posterior column, posterior wall, or posterior column and wall. Methods: From January 2016 to June 2017, data of 10 cases (7 males, 3 females, an average age of 37 years, ranging from 17 to 54 years) with posterior acetabular fractures treated by the DPA were retrospectively analyzed. Fractures were caused by traffic accident in 6 cases and by falling in 4 cases. According to Letournel-Judet classification of acetabular fractures, there were 6 cases of posterior acetabular wall fractures, 4 cases of posterior wall fractures involving posterior column. A straight skin incision was made from the middle of the line between the posterior margin of the tip of the femoral greater trochanter and the posterior superior iliac spine, to the posterior margin of the femoral greater trochanter. The gluteus maximus muscle was cleaved longitudinally. A view of the area from hip capsule to the superior margin of the greater sciatic foramen was obtained by entering along the interspace of the gluteus medius and pyriformis muscle, and the superior gluteal neurovascular bundle was protected. Acetabular posterior column and posterior wall fractures were reduced and fixed under direct vision. The fracture reduction, fracture healing, femoral head necrosis, sciatic nerve injury, superior gluteal neurovascular injury and heterotopic ossification were evaluated by the postoperative X-ray and CT examination. The function of hip joint was assessed by the Merle d’Aubigné-Posteal score modified by Matta. Results: The average operative incision length was 9.6 cm (range, 8-11 cm). The average operation time was 50 min (range, 35-80 min). The average blood loss was 310 ml (range, 200-440 ml). The time of follow-up was 12-30 months. All the patients were healed within 8-12 weeks without any complications such as superior gluteal nerve injury, superior gluteal vessel injury, or sciatic nerve injury. One case of acetabular posterior wall and posterior column fracture with posterior dislocation of hip joint, suffered from femoral head necrosis at the 9th months after surgery, which was treated by total hip arthroplasty and was recovered one year after surgery. In one case of actebular posterior wall and posterior column fracture, heterotopic ossification occurred 3 month after operation, without any special treatment and the hip joint activity was not affected at the follow-up of 15 months after surgery. During the 12-month follow-up after surgery, the Merle d’Aubigné-Postel score modified by Matta was 13-18, among which there were excellent in 6 cases, good in 2, acceptable in 2, with an overall excellent and good rate of 80% (8/10). Conclusion The direct posterior approach for posterior acetabular fractures can obtain satisfactory clinical results. The advantages of the DPA include decreasing trauma, shortening operation time, reduing blood loss and decreasing risks of iatrogenic injury to the gluteus medius muscle, the external rotators, the arteriae circumflexa femoris medialis and sciatic nerves as well as reducing and fixing the fractures under direct vision. Thus, the DPA is a relatively safe surgical approach for acetabular posterior wall/column fracture.

Objective:To construct a microfluidic organ-on-a-chip and evaluate its capability in simulating subchondral bone remodeling during the progression of osteoarthritis.Methods:The chip′s main body was designed based on the microfluidic technology and cell co-culture technique. MC3T3-E1 cells were cultured adherently within the cell seeding micro-chamber, with the culture medium perfused at a flow rate of 0.5 ml/min at the bottom of the micro-chamber. Evaluation metrics were as follows: (1) Assessment of the microfluidic organ-on-a-chip: The growth culture medium was perfused and simulation experiments were conducted to test the concentration differences and equilibrium times of the fluid inside and at the bottom of the cell seeding micro-chamber at various time points; live-dead staining was performed to observe the biocompatibility of cells cultured continuously for 3 days and 7 days at a set flow rate, which was divided into 3-day and 7-day groups. (2) Osteogenic potential of the microfluidic organ-on-a-chip: The osteogenic induction medium was perfused, and ALP staining and PCR were performed to compare the number of the black alkaline phosphatase (ALP)-positive cells and the expression levels of osteogenesis-related marker genes including osteoblast-specific transcription factor 2 (RUNX2), type I collagen (COL1A1), bone morphogenetic protein-2 (BMP-2), and osteocalcin (OCN) under static, 3-day and 7-day perfusion conditions, which was divided into static non-induced, static-induced and perfusion-induced groups. (3) Characterization of morphology and size, and biocompatibility of extracellular vesicles (EVs) of three osteoblast subtypes: Three different subtypes of osteoblasts were obtained [endothelial-type osteoblasts (EnOB)-EVs, stromal-type osteoblasts (StOB)-EVs and mineralizing-type osteoblasts (MinOB)-EVs]. Their morphology and size were obtained through transmission electron microscopy and particle size analysis. Growth medium containing EVs of three different cell subtypes was perfused, and cell proliferation/apoptosis assay was performed to compare the biocompatibility of the addition of different EVs concentrations (1, 1.25, 2.5, and 5 μg/ml) for 24 hours, which was categorized into the EnOB-EVs group, StOB-EVs group and MinOB-EVs group. (4) Osteogenic effect of EVs from three subtypes of osteoblasts: Osteogenic induction media containing EVs from three different osteoblast subtypes were perfused for 3 days, and ALP staining and PCR were performed to compare the number of black ALP-positive cells and the expression levels of osteogenesis-related marker genes including RUNX2, COL1A1, BMP-2, and OCN, which was divided into non-EVs group, EnOB-EVs group, StOB-EVs group and MinOB-EVs group.Results:(1) Evaluation of the microfluidic organ-on-a-chip: Simulation results showed that the concentration in the top layer of the upper chamber reached more than 95% of that in the lower chamber and that the concentration in the bottom layer was about 96.5% of that in the lower chamber after 12 hours of continuous perfusion, reaching an equilibrium state of the concentration difference between the upper and lower chambers. The results of live-dead staining showed that the chip was biocompatible at a flow rate of 0.5 ml/min, and the cell survival rate at 3 and 7 days of perfusion was (99.48±0.12)% and (97.07±1.05)% ( P<0.01). (2) ALP staining results showed that at 3 days, the perfusion-induced group showed the highest number of black ALP-positive cells, followed by the static-induced group, and the least in the static non-induced group. At 7 days, the static-induced group had the highest number of black ALP-positive cells, followed by the perfusion-induced group, and the least in the static non-induced group. PCR results indicated that at 3 days, the expression levels of RUNX2, COL1A1, BMP-2, and OCN were 1.00±0.03, 1.00±0.12, 1.00±0.01, and 1.00±0.02 respectively in the static non-induced group; 1.80±0.04, 4.05±0.37, 9.80±1.94, and 4.38±0.89 respectively in the static-induced group, and 2.45±0.23, 5.48±0.42, 91.50±4.56, and 10.82±4.96 respectively in the perfusion-induced group ( P<0.01). At 7 days, the expression levels of RUNX2 was 1.00±0.01 in the static non-induced group, 1.46±0.46 in the static-induced group, and 1.11±0.08 in the perfusion-induced group ( P>0.05); the expression levels of COL1A1, BMP-2, and OCN were 1.00±0.03, 1.00±0.13, and 1.00±0.09 respectively in the static non-induced group, 9.38±0.25, 14.27±4.35, and 84.01±4.02 respectviely in the static-induced group, and 2.39±0.08, 133.64±8.87, and 86.64±8.36 respectively in the perfusion-induced group ( P<0.01). When comparing the static non-induced, static-induced, and perfusion-induced groups at both 3 and 7 days, the perfusion-induced group demonstrated the strongest osteogenic capability. (3) Characterization of morphology and size and biocompatibility of EVs from three osteoblast subtypes: Under the transmission electron microscope, EVs from EnOB-EVs, StOB-EVs, and MinOB-EVs all exhibited a typical saucer-shaped morphology. The particle sizes of EnOB-EVs, StOB-EVs, and MinOB-EVs were (91.3±14.7)nm, (106.0±16.0)nm, and (68.1±10.7)nm, respectively. Cell proliferation/apoptosis assay results indicated that the optimal administration concentration of EnOB-EVs, StOB-EVs, and MinOB-EVs was all 1.25 μg/mL. (4) Validation of osteogenic effect of the microfluidic organ-on-a-chip on three types of EVs: ALP staining results showed that the non-EVs group had the fewest black ALP-positive cells, followed by the EnOB-EVs group, then the StOB-EVs group, and the MinOB-EVs group had the most. PCR results showed that the expression levels of RUNX2, COL1A1, BMP-2, and OCN were 1.00±0.01, 1.00±0.03, 1.00±0.02, and 1.00±0.02 respectively in the non-EVs group, 1.95±0.11, 6.78±2.04, 7.99±0.57, and 6.93±3.83 repectively in the EnOB-EVs group, 0.79±0.12, 5.68±1.53, 12.59±3.15, and 25.59±0.95 respectively in the StOB-EVs group, and 0.68±0.10, 4.36±0.69, 18.75±3.21, and 34.74±3.98 repectively in the MinOB-EVs group ( P<0.01). Compared with the non-EVs group, EnOB-EVs group, StOB-EVs group, and MinOB-EVs group, the MinOB-EVs group showed the most significant osteogenic effect. Conclusions:The microfluidic organ-on-a-chip constructed using microfluidic technology and cell co-culture techniques is capable of maintaining the normal growth of MC3T3-E1 cells, enhancing their proliferation and osteogenic induction differentiation. EVs released by osteoblasts at different stages possess osteogenic effects and can accelerate the bone sclerosis in the remodeling of subchondral bone during the progression of osteoarthritis.