Objective To explore the optimal screw fixation of anterior column lag screw fixation in the treatment of acetabular anterior column fractures by finite element method.Methods Firstly,CT scanning images from one healthy adult volunteer (male 30),were transferred into Materialise Mimics Innovation Suite 16.0 software,then three-dimensional (3D) models of pelvic were reconstructed and stored in stereolithography format.Then Imageware 12.0 software (EDS,USA) was used to produce the optimal and safe channel of the screw for acetabulum anterior column fixation.Three types of screw fixation were generated,i.e.(1) geometric algorithm screw channel,(2) in-out-in channel,(3) free screw channel.Secondly,all model data were transferred into Ansys 12.0 software to establish the finite element model.Gravity load were defined as 600 N,1 200 N,and 2 400 N,and the Von Mises the parameters of peak stress and deformation were recorded.Results Respectively load of 600 N,1 200 N,2 400 N force to normal hip and geometric algorithm screw channel, in-out-inscrew channel,free screw channel,the comparison between groups of hip by stress and hip deformation,with a given loading force of hip by stress and hip deformation increase gradually,the two were positively correlated,including screw by stress at slightly higher than that of normal hip,while the stress of hip by geometric algorithm screw channel andin-out-inscrew channel were similar,and that by free screw channel increased significantly.There was no significant difference between groups in the hip deformation.With a given loading force (600 N,1 200 N,2 400 N) on geometric algorithm screw channel、 in-out-inscrew channel and free screw channel,the deformation is gradually increased,and there were positively correlated.With the stress on geometric algorithm screw channel,it was significantly reduced compared with the latter two,and in-out-in screw channel suffered the biggest stress.Conclusion Through the finite element analysis,the geometric algorithm screw channel can be used as a safe and effective way for acetabulum anterior column fracture.

Objective To analyze and determine the optimal osseous pathway for anterograde screwing in the acetabulum posterior column.Methods Recruited for this study were 40 healthy adult volunteers,20 nales and 20 females,aged from 18 to 56 years (average,34.6 years).Firstly,their abdomen CT scanning images were transformed into Materialise Mimics Innovation Suite 16.0 software to obtain the 3D reconstruction images of the pelvis (.stl file).The Imageware 12.0 software (EDS,USA) was used to produce the optimal osseous pathway for anterograde screwing in the acetabulum posterior column.The diameter and length of the pathway were measured and statistically analyzed.Secondly,after 10 adult fresh pelvic specimens were scanned,the optimal osseous pathway for anterograde screwing in the acetabulum posterior column was determined in the same way as the above.A navigation template for anterograde screwing in the acetabular posterior column was manufactured.The screwing in the posterior column of the acetabulum was conducted using Kirschner wire with the aid of the navigation template.Imaging evaluation was performed after fixation.Results The projection of the safe zone in the acetabular posterior column was irregularly triangle;there were no significant differences regarding the projection size between different ages (P ＞ 0.05).The maximum diameter and the maximum length of the left optimal pathway in males were respectively 22.37 ± 1.42 mm and 131.27 ± 3.63 mm,and those of the right optimal pathway in males respectively 23.16 ± 1.39 mm and 129.23 ± 3.27 mm.The maximum diameter and the maximum length of the left optimal pathway in females were respectively 17.58 ± 1.83 mm and 112.56 ±2.77 mm,and those of the right optimal pathway in females respectively 16.92 ± 1.66 mm and 114.41 ± 2.98 mm.There were no significant differences between the left and right sides for the same item in the same gender (P ＞ 0.05).There were significant differences between males and females for the same item in the same side (P ＜ 0.05).No penetration into the cortex or the hip joint happened.Conclusion The optimal osseous pathway for anterograde screwing in the acetabulum posterior column can be determined by digital techniques,leading to a simple and safe procedure for the treatment of fractures of the acetabular posterior column.

Objective To provide a method to modify accurately the Reverdin osteotomy template for hallux valgus using 3D reconstruction and printing.Methods From June 2015 to June 2016,11 patients (16 feet) with hallux valgus at our departments underwent weight-bearing X-ray examination and continuous spiral CT scanning of the feet.The outer turning angle of hallux averaged 33.50° ± 6.80°,the first intermetatarsal angle 12.20°± 2.90° and the distal metatarsal articular angle 15.20°± 2.60°.Their imaging Dicom data were imported into Materialise Mimics Innovation Suite v16.0 software for generation of 3D models of the pelvis which were then stored in stereolithography format and imported into Imageware 12 software.After optimal templates were reversely rebuilt to have the best angles and range for Reverdin osteotomy in the 3D models,they were manufactured by a rapid prototyping machine.The osteotomy templates were used in surgery to guide the osteotomy of hallux valgus.Correction of hallux valgus,bone union at the osteotomy sites and weight-bearing walk were observed postoperatively.Results Accurate angles of osteotomy were confirmed by postoperative radiography in all the 16 feet.Follow-ups for 6 to 12 months showed in the 16 feet a mean outer turning angle of hallux of 7.31 °±0.33° (from 5° to 11 °) and a mean correction of 21.92°± 4.8° (from 13° to 24°).Bone union was fine at the osteotomy sites and no pain was reported during weight-bearing walk.Conclusion 3D reconstruction and printing can produce a patient-specific template for accurate Reverdin osteotomy for hallux valgus,leading to increased contact area and fine union of the osteotomy ends.

Objective:To investigate the application value of dual-source CT urography with stellar photon detectors in the diagnosis of gout.Methods:Forty patients who were diagnosed with gout according to American College of Rheumatology Guideline for the Diagnosis of Gout and received treatment between April 2018 and May 2020 were included in the observation group. Forty patients who were concurrently diagnosed with osteoarthritis and received treatment in the same hospital were included in the control group. All patients underwent dual-source CT urography with stellar photon detectors and corresponding biochemical index detection. Blood levels of uric acid, urea nitrogen, creatinine, total cholesterol, and triglyceride were compared between the observation and control groups.Results:Blood levels of uric acid, creatinine, urea nitrogen, total cholesterol, and triglyceride in the observation group were (519.38 ± 97.91) μmol/L, (110.21 ± 18.29) μmol/L, (12.21 ± 3.29) mmol/L, (6.49 ± 1.22) mmol/L, (3.45 ± 1.89) mmol/L, respectively, which were significantly higher than those in the control group (310.45 ± 61.40) μmol/L, (86.22 ± 13.12) μmol/L, (6.82 ± 1.75) mmol/L, (4.75 ± 0.56) mmol/L, (1.98 ± 0.85) mmol/L, respectively ( t = 11.43, 6.741, 9.148, 8.198, 4.486, all P < 0.05). Dual-source CT urography with stellar photon detectors revealed that urate crystals (color coded as green) were detected in 3 and 36 patients from the control and observation groups, respectively, with the detection rate of 7.5% (3/40) and 90% (36/40), respectively. There was significant difference in urate crystal detection rate between the observation and control groups ( χ2 = 24.993, P < 0.05). In the control group, no obvious destruction of bone, tendon and ligament were observed, urate deposition, total volume of (1.023 ± 0.83) cm 3, was found in feet and knee joint of a small number of patients. In the observation group, there were 30 patients with uric acid crystals and bone destruction in the metatarsophalangeal joint ( n = 6), distal tibia ( n = 7), distal fibula ( n = 3), proximal talus ( n = 4), proximal calcaneus ( n = 6), and wrist joint ( n = 4). There were 20 patients with ligament or tendon damage, involving deltoid ligament ( n = 2), Achilles tendon ( n = 10), and extensor and flexor tendon ( n = 53). Total volume of uric acid crystals was (32.22 ± 5.83) cm 3. The volume of uric acid crystals deposited in the hand, elbow, feet and knee was (8.00 ± 4.92) cm 3, (5.32 ± 2.75) cm 3, (36.00 ± 15.54) cm 3, and (13.31 ± 9.14) cm 3, respectively. Conclusion:Dual-source CT urography with stellar photon detectors has a high sensitivity in the diagnosis of gout, can accurately locate and quantify uric acid crystals and is of high application value in the diagnosis of gout.