Comparison of pedicle screw fixation via paraspinal approach and traditional open approach for treatment of thoracolumbar fracture and dislocation / 中华创伤杂志

Objective To compare the clinical efficacy of posterior pedicle screw fixation through Wiltse paraspinal approach and posterior traditional open approach in the treatment of thoracolumbar fracture and dislocation.Methods A retrospective case control study was performed based on the clinical data of 40 patients with thoracolumbar fracture and dislocation admitted between January 2013 and January 2016.All the surgeries were performed through posterior midline incision,and they were divided into two groups according to different approaches.Patients in Group A received pedicle screw fixation through Wiltse paraspinal approach while Group B received fixed pedicle screw through open surgery.Group A was composed of 12 males and 8 females,aged 21-60 years [(41.5 ±9.6)years].Group B was composed of 13 males and 7 females,aged 18-58 years [(39.1 ± 13.1) years].The same surgical procedures were adopted in spinal decompression,reduction,and the spinal vertebral interbody bone graft and fusion surgery in the two groups.Operation duration,intraoperative blood loss,postoperative drainage volume,visual analogue scale (VAS),spinal canal patency at the last follow-up,percentage of postoperative injury of vertebral height recovery,and Cobb angle were compared.CT and MRI were used to evaluate postoperative paravertebral muscle atrophy,and American spinal injury association (ASIA) impairment scale was used to evaluate neurological function assessment.Results All patients were followed up for 9-33 months,with (19.3 ± 5.6) months for Group A and (22.5 ± 4.9) months for Group B (P ＞ 0.05).The operation duration was (240.5 ± 38.3) min in Group A and (258.5 ± 43.7) min in Group B (P ＞ 0.05).The intraoperative blood loss was (525.0 ± 168.2) ml in Group A,less than (770.0 ± 269.2) ml in Group B (P ＜ 0.05).Postoperative drainage volume was (190.1 ± 78.9) ml in Group A,less than (281.7 ± 122.3) ml in Group B (P ＜ 0.05).VAS score 24 hours after operation and at the last follow-up in Group A was (6.4 ± 1.0) points and (1.6 ± 0.5) points,respectively,better than those in Group B [(7.8 ± 0.7) points and (2.2 ± 0.4) points] (P ＜ 0.05).No significant differences were observed in terms of spinal canal patency at the last follow-up,percentage of postoperative injury of vertebral height recovery,and Cobb angle [Group A:(85.3 ± 3.7) ％,(85.5 ± 2.7) ％,and (4.7 ± 1.2)°;GroupB:(85.8±1.8)％,(88.8 ±1.3)％,and (5.3 ±1.5)°] (P＞0.05).In terms of MRI evaluation score of postoperative paravertebral muscle atrophy,Group A reported better results than Group B [(2.1 ± 0.6) points vs.(1.2 ± 0.6) points] (P ＜ 0.05).At the last follow-up,there were 7,5,6,1 and 1 patients in Group A,while 6,6,5,2 and 1 patients in Group B at ASIA grades A,B,C,D and E (P ＞ 0.05).Within the same group,significant difference was observed between the preoperative data and that at the last follow-up in terms of postoperative VAS score,spinal canal patency,percentage of injury of vertebral height,Cobb angle,and ASIA impairment scale (P ＜ 0.05).Conclusion For thoracolumbar fracture and dislocation,compared with traditional open approach,posterior pedicle screw fixation through Wiltse paraspinal approach can effectively restore the vertebral body height and spinal canal patency and can reduce the intraoperative bleeding,postoperative drainage,postoperative back pain,and paravertebral lesion.

Three-dimensional finite element analysis of bone stress distribution around the hip joint prosthesis with stepped stem / 生物医学工程学杂志

Based on the CT data, a medical treatment FE model of hip joint prosthesis with stepped stem was rebuilt according the anatomy of the hip joint. Under the loads of 1.5 times standard body weight (70kg), the mechanical behavior of the treatment model was calculated, and the influence of step structure and distribution for stepped stem on femur stress and stability of total hip replacement were analyzed by three-dimensional finite element analysis (3D-FEA). The results show that the step structure changs the bone stress transmission on the interface of stepped stem and femur, and benefits to reduce stress-shielding in the femur. For the same distribution of step, the reduction of stress-shielding for raised stepped stem is better than that for concave stepped stem. The raised stepped stem of which the steps is distributed one of third part of the stem is of the best effect of reduction of stress shielding in all of the analysis models, and is a beneficial mechanical design to relieves osteoporosis or osteopenia of femur caused by stress-shielding and improve the reliability of it in clinic.

A review of research progress on biological effects about nanometer scaffold for bone tissue engineering / 生物医学工程学杂志

Quite a few orthopedics experts have fabricated some novel bone scaffolds with nanotechnology and have carried out some researches on nano-biological effects. The study of the biological effects about nano-biomaterials can facilitate the understanding of the interaction between the biomaterials and the organism, and provide research ideas and direction to construct new biomaterials with physiological function. To better understand the interaction of nano biomaterials with protein, cells and bio-security, this review presents recent advances of biological effects about nano scaffold for bone tissue engineering.

Biomechanical evaluation of an injectable calcium phosphate cement incorporating DHS for osteoporotic intertrochanteric fracture:an in vitro study / 医用生物力学

Objective To evaluate the biomechanical effects of using a new injectable calcium phosphate cement to consolidate the fixation of osteoporotic intertrochanteric fracture.Method Five matchod pairs of human cadaver femora were used to produce the model of intertrochanteric fracture.All fractures were fixed with dynamic hip screws(DHS),and divided into two groups.In the CPC consolidation group of each pair,CPC was used to grout the hip screw and to fill the posteromedial defect.All femora were subjected to biomechanical test.Results Under the loading of 500 N,in the CPC consolidation group,the mean axial stiffness is(691.93±18.90)N/mm and the horizontal shear stiffness is(5553.84±27.47)N/mm.The mean lateral and medial strength is(5.15±0.35)MPa and(4.13±0.24)MPa.The torsion stiffness was 0.41 and the ultimate loading is(3580±286)N.In the control group,the mean axiak stiffness is(453.45±19.75)N/mm,the horizontal shear stiffness is(3848.87±22.63)N/mm,the mean lateral and medial strength is(3.12±0.37)MPa and(1.80±0.21)MPa,and,the torsion stiffness is 0.35 and the ultimate loading is(2512±189)N.Consolidation fixation with CPC increased each of the biomechanical efficiency(P＜0.05).Conclusions CPC consolidation of osteoprotic femoral head and the medial defect of intertrochanteric fracture can significantly improve the overall stability and decrease the rate of postoperative complication.