BACKGROUND:For unstable intertrochanteric fracture repair, there are two views:extramedul ary fixation or intramedul ary fixation. Theoretical y, intramedul ary fixation is in line with the principles of minimal y invasive, more mechanical and biological advantages. However, evidence-based medicine and related studies have shown that compared with the extramedul ary fixation, intramedul ary fixation did not reflect the proper theoretical advantage. OBJECTIVE:To compare the biomechanical performance of two kinds of internal fixation systems:dynamic hip screw and Gamma nail which commonly used in repair of intertrochanteric fractures by finite element method, and to evaluate the advantages and disadvantages of dynamic hip screw and Gamma nail in treatment of unstable intertrochanteric fracture. METHODS:Three-dimensional finite element model of human femur unstable intertrochanteric fractures (31-A2;AO fracture classification), and the three-dimensional finite element models of dynamic hip screw and Gamma nail were established respectively, and were fixed according to the requirement of orthopedic surgery. The reference load which the joint bearing was at the peak time in adult step state period with the body mass of 700 N was stimulated. The stress distribution of bone, bone-internal fixation model, nail or screw, the strain and deformation of fracture location on the surface of the bone and bone-internal fixation model, the stress distribution along the femur and the loading transfer condition along the internal fixator and the like were analyzed. RESULTS AND CONCLUSION:Dynamic hip screw and Gamma nail have good sliding compression features which could make the continuous and dynamical y axial compression of the fractured section. Under the load conditions, the displacement value of dynamic hip screw was larger. In the treatment of unstable intertrochanteric fracture, Gamma nail was stronger than dynamic hip screw. Two kinds of internal fixations al make the bearing load of the proximal femur reduce. In the treatment of 31-A2 type unstable intertrochanteric fractures, we should choose dynamic hip screw for fixation if the femoral calcar was not seriously crushed, little defect or no defects and can immediately rebuild the stability of femoral calcar during operation, otherwise, stronger internal fixation, namely Gamma nail fixation should be chosen.

BACKGROUND: Compared with the metal screws, absorbable screws have more obvious advantages, such as does not have to conduct internal fixation removal, non-metal ic components, no influence on the magnetic resonance imaging of patients after implantation, relatively simple operations, namely dril ing-tapping-screws fixation, more in line with the principles of minimal y invasive in orthopedics. OBJECTIVE: To investigate the biomechanical characteristics of absorbable screw fixation in repair of simple lateral mal eolus fractures by means of finite element technology. METHODS: The three-dimensional model of simple lateral mal eolus fractures and absorbable screw model were established, and then fixed according to standard orthopedic surgical techniques. The reference load when the load bearing of fibulotalar joint reaching the peak value in a normal adult gait cycle was loaded. The stress distribution and displacement of fibula and absorbable screws were analyzed. RESULTS AND CONCLUSION: There were total y 38 542 units, 8 790 nodes in the single screw fixation model. When the articular facet of lateral mal eolus loading 300 N, the maximum stress of screws was 89.35 MPa, the maximum displacement was 0.5 mm, the maximum displacement of the distal fracture was 0.5 mm. When the articular facet of lateral mal eolus loading 450 N, the maximum stress of screws was 152.58 MPa, the maximum displacement was 0.59 mm, the maximum displacement of the distal fracture was 0.77 mm. There were total y 43 115 units, 9 496 nodes in the double screws fixation model. When the articular facet of lateral mal eolus loading 300 N, the maximum stress of screws was 38 MPa, the maximum displacement was 0.44 mm, the maximum displacement of the distal fracture was 0.44 mm. When the articular facet of lateral mal eolus loading 450 N, the maximum stress of screws was 66.68 MPa, the maximum displacement was 0.48 mm, the maximum displacement of the distal fracture was 0.49 mm. The experiment verified the biomechanical feasibility of absorbable screw fixation in repair of simple lateral mal eolus fractures. For simple involving only the lower lateral fibular fracture, absorbable screw fixation is entirely feasible, and usual y requires at least two screws to maintain the stability of the articular surface of the reset.

BACKGROUND: Three-dimensional (3D) printing technique has showed unparalleled advantages in the field of tissue engineering scaffold preparation because of its outstanding merits of convenience, efficiency, controllability and ability to construct complex shapes.OBJECTIVE: To fabricate Fe-containing mesoporous calcium-silicate (MCS) /poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) composite scaffolds using the 3D printing technique and to test the characterization and cellular biocompatibility of the composite scaffolds.METHODS: Four groups of Fe-containing MCS/PHBHHx composite scaffolds were fabricated using 3D printing technique. The molar percentage of Fe in these four groups was 0%, 5%, 10%, 15%, respectively and they were marked as 0Fe-MCS/PHBHHx, 5Fe-MCS/PHBHHx, 10Fe-MCS/PHBHHx and 15Fe-MCS/PHBHHx. The scanning electron microscopy was used to observe the microstructure of the scaffolds after being soaked in the simulated body fluid.Osteoblast cell lines MC3T3-E1 were seeded on these four groups of scaffolds as well. Cell counting kit-8 method was adopted to test the cell proliferation at 1, 3, 7 days of culture. Intracellular alkaline phosphatase activity was tested at 7 and 14 days of culture.RESULTS AND CONCLUSION: (1) Compared with the scaffolds with no soaking process, spherical particles were formed on the scaffolds because of mineralization after soaking 3 days in the simulated body fluid. (2) At 1 day of culture,there was no difference in cell proliferation among the four groups. At 3 days of culture, the proliferation rate of the 15Fe-MCS/PHBHHx scaffold was remarkably higher than that of the rest three groups (P < 0.05). At 7 days of culture,the proliferation rate was significantly higher in the 10Fe-MCS/PHBHH and 15Fe-MCS/PHBHHx scaffolds than the 0Fe-MCS/PHBHH scaffold (P < 0.05), as well as significantly higher in the 15Fe-MCS/PHBHHx scaffold than the 10Fe-MCS/PHBHH scaffold (P < 0.05). (3) At 7 days of culture, no difference in alkaline phosphatase activity could be found among these four groups of scaffolds; however, at 14 days, the 5Fe-MCS/PHBHHx, 10Fe-MCS/PHBHHx and 15Fe-MCS/PHBHHx scaffolds exhibited an enhanced alkaline phosphatase activity compared with the 0Fe-MCS/PHBHHx scaffold. Meanwhile, the 15Fe-MCS/PHBHHx showed the highest alkaline phosphatase activity.These findings indicate that the MCS/PHBHH scaffolds containing Fe could promote the proliferation and osteogenic differentiation of the MC3T3-E1 cells.

BACKGROUND:Macropore morphology of a composite scaffold prepared by the three-dimensional printing technique is of great importance in determining the physicochemical and biological properties of tissue engineering scaffolds.OBJECTIVE:To fabricate strontium-containing mesoporous (Sr-MBG) bioactive glass (PCL) scaffolds by the three-dimensional printing technique, and to explore the effect of these scaffolds on MC3T3-E1 proliferation and osteogenic differentiation, thereby to find out the optimal macropore morphology.METHODS: Sr-MBG/PCL composite scaffolds were fabricated by the three-dimensional printing technique. The angles between fibrous latitudes and longitudes were set to 45°, 60° and 90°. Then the proliferation and alkaline phosphatase activity of MC3T3-E1 cells on the scaffolds were tested.RESULTS AND CONCLUSION: Cell counting kit-8 results showed that MC3T3-E1 cells could proliferate on all the three kinds of scaffolds. The proliferation rate of MC3T3-E1 cells on the 45° Sr-MBG/PCL scaffolds was just slightly higher than that on the 60° and 90° Sr-MBG/PCL scaffolds at days 1 and 4 (P > 0.05), but there was a significant increase at day 7 (P < 0.05). The 45° Sr-MBG/PCL scaffolds exhibited a significant increase in alkaline phosphatase activity of MC3T3-E1 cells compared to the 60° and 90° Sr-MBG/PCL scaffolds at day 14 (P < 0.05), while there was no significant difference among three groups at day 21 (P > 0.05). These results indicate that the 45° Sr-MBG/PCL scaffold is more suitable to promote the proliferation and osteogenic differentiation of the MC3T3 cells than the 60° and 90° Sr-MBG/PCL scaffolds.

Objective: To evaluate the minimally invasive splayed incisions in the internal fixation with a conventional calcaneal plate for calcaneal fractures of sanders types Ⅱ and Ⅲ. Methods: This prospective study was conducted from May 1st, 2016 to December 1st, 2017 in the 40 patients with calcaneal fracture at Department of Orthopedics, Shanghai Pudong Hospital. Their ages ranged from 23 to 55 years (average, 39.5 years). According to the Sanders classification, 27 fractures were type Ⅱ and 13 type Ⅲ. They were all treated with a conventional calcaneal plate through minimally invasive splayed incisions. The Böhler and Gissane angles, the height, width and length of the affected calcaneus were compared between preoperation, 3 months after operation and the last follow-up; the clinical function of the affected feet was graded using the Maryland foot score; postoperative complications were observed. Results: The 40 patients were followed up for an average of 12.5 months (from 11 to 16 months). All the skin incisions healed well with no skin necrosis or wound infection. No injury to the sural nerve occurred. All the fractures healed after an average of 8 weeks (from 7 to 10 weeks). All the patients resumed their routine daily activities and returned to their former work post after an average time of 4.1 months (from 3 to 6 months). At pre-operation, 3 months after operation and the last follow-up, their Böhler angles were respectively 19.2°±6.3°, 30.5°±6.4° and 29.9°±6.5°; their Gissane angles 103.9°±14.8°, 119.3°±5.6° and 119.8°±6.3°; their calcaneal heights (32.5±3.5) mm, (36.8±1.5) mm and (36.5±1.8) mm; their calcaneal widths (36.8±3.4) mm, (33.1±3.8) mm and (33.0±3.2) mm; their lengths (61.4±4.5) mm, (65.5±6.9) mm and (65.5±9.4) mm. In all the patients, the Böhler and Gissane angles and the calcaneal heights and lengths increased significantly while the calcaneal widths decreased significantly at 3 months after operation and the last follow-up (P<0.05). There were no significant differences between 3 months after operation and the last follow-up in the Böhler or Gissane angle, the height, width or length of the affected calcaneus (P>0.05). Their Maryland foot scores showed 35 excellent cases, 4 good cases and one fair case, giving an excellent and good rate of 97.5%. Conclusions A conventional calcaneal plate plus minimally invasive splayed incisions can be effective for calcaneal fractures of Sanders types Ⅱ and Ⅲ, leading to reduced wound complications, anatomical restoration of calcaneal morphology, and smooth subtalar articular surface.

Objective A finite element analysis was conducted on the biomechanics of the locking plate and intramedullary nail fixation for the treatment of distal tibial fractures,and the resuhs were verified combined with clinical cases,so as to provide references for clinical treatment.Methods (1) Finite element analysis:the three-dimensional CT data of the lower limbs of a healthy male volunteer were used to establish a finite element model.The internal stress distribution of the tibial plateau was set to 60％ of the total load by intramedullary nail and locking plate respectively,and the tibia end was fixed effectively.400 N axial pressure load which equaled to that of adult knee joint during single axis standing was simulated.The equivalent stress and displacement of the model by different fixations were compared.(2) Clinical verification:a retrospective case control study was performed on the clinical data of 37 cases of distal tibia1 fractures treated with internal fixation from June 2015 to December 2016,including 17 cases in intramedullary nail group and 20 in locking plate group.The operation time,intraoperative blood loss,postoperative fracture healing time,and postoperative Johner-Wruhs score of patients were recorded for comprehensive assessment of recovery.Results (1) The finite element analysis results:the maximum stress value was 5.907 MPa for intramedullary nail and 5.821 MPa for locking plate model (P ＞0.05),respectively.The maximum displacement of intramedullary nail model was 2.313 mm,lower than that of locking plate fixation system (3.854 rmm) (P ＜ 0.05).(2) Clinical verification:the operation time and intraoperative blood loss of intramedullary nail were both lower than those of locking plate [(114.1 ±21.6)minutes):(129.8±21.4)minutes and (152.9 ±64.88)ml:(212.5 ±98.5)ml](P ＜0.05).The average fracture healing time was (17.7 ± 2.8)weeks for intramedullary nail and (20.6 ± 4.1) weeks for locking plate (P ＜ 0.05),respectively.In the intramedullary nail group,the Johner Wruhs score was excellent in 13 cases and good in four cases,with excellent and good rate of 100％,while in the locking plate group,nine cases were excellent,eight were good,and three were fair,with excellent and good rate of 85％ (P ＞ 0.05).Conclusions In terms of biomechanics and clinical effect,intramedullary nail fixation is superior than the medial locking plate fixation for the treatment of the distal tibial fractures.Intramedullary nail fixation can reduce surgical trauma and bone displacement after fixation and promote fracture healing.

Objective:To evaluate the clinical efficacy of channel screw guided by O-arm navigation for the treatment of type II fragile fracture of pelvis (FFP) in the elderly.Methods:A retrospective cohort analysis was performed on clinical data of 37 patients with type II FFP admitted to Shanghai Pudong Hospital, Fudan University Pudong Medical Center from September 2019 to April 2021. There were 9 males and 28 females, aged 65-82 years [(71.8±10.1)years]. A total of 15 patients receipt channel screw fixation under O-arm navigation (surgical group) and 22 patients were treated conservatively (non-surgical group). The visual analogue scale (VAS) and Majeed functional score were compared between the two groups at emergency visit and at 1 week, 1 month, 3 months, 6 months after treatment. The accuracy of screw insertion and complications were also recorded during treatment and follow-up.Results:All patients were followed up for 6-18 months [(13.2±5.1)months]. There were no significant differences in the VAS and Majeed functional score between the two groups at emergency visit (all P>0.05). In both groups, lower VAS and higher Majeed functional score were found at 6 month after treatment as compared with those at emergency visit (all P<0.01). The VAS in surgical group was 2(1, 4)points at 1 week after treatment, lower than 4(3, 5)points in non-surgical group ( P<0.01). The VAS in surgical group was 1(1, 2)points at 1 month after treatment, lower than 3(2, 5)points in non-surgical group ( P<0.05). The Majeed functional score in surgical group was (50.2±4.2)points at 1 week after treatment, higher than (40.2±5.6)points in non-surgical group ( P<0.01). The Majeed functional score in surgical group was (73.8±5.2)points at 1 month after treatment, higher than (62.4±5.0)points in non-surgical group ( P<0.01). The two groups had no significant differences in VAS and Majeed functional score at 3 months and 6 months after treatment (all P>0.05). The accuracy of screw insertion in surgical group was 93% (14/15). In surgical group, the complication rate was 13%(2/15), including urinary tract infection in 1 patient and intraoperative screw penetration in 1, with no screw loosening or nerve and vascular injuries. In non-surgical group, the complication rate was 50%(11/22), including urinary tract infection in 5 patients, penetrating pneumonia in 5 and deep vein thrombosis in 1. The complication rate was significantly different between the two groups ( P<0.05). Conclusions:Compared with non-surgical treatment, the channel screw insertion guided by O-arm navigation can achieve precise screw placement, relieve pain early, promote functional recovery, realize accurate insertion of the screw and reduce the complication rate for type II FFP in the elderly.