ObjectiveTo explore the mechanical stability of the three-dimensional (3-D) external fixator for osteoporotic fracture so as to provide the biomechanical basis for clinical application. MethodsForty-five fresh frozen adult tibial specimens were selected to rapidly prepare the extracorporal tibia osteoporotic fracture models, and were randomly divided into 3 groups (n=15). Fractures were fixed with 3-D external fixators (3-D external fixators group), intramedullary nails (intramedullary nail group), and plate (plate group) respectively. Five specimens randomly from each group were used to do axial compression test, three-point bending test, and torsion test with microcomputer control electronic universal testing machine, then the mechanical parameters were calculated. ResultsIn the axial compression test, the displacement of 3-D external fixator group and intramedullary nail group were shorter than plate group, showing significant differences (P<0.05); but no significant difference was found between 3-D external fixator group and intramedullary nail group (P>0.05). In the three-point bending test and torsion test, the deflection and the torsional angle of 3-D external fixator group and intramedullary nail group were smaller than plate group, showing significant differences (P<0.05); but no significant difference was found between 3-D external fixator group and intramedullary nail group (P>0.05). ConclusionThe 3-D external fixator can fix fracture three-dimensionally from multiple plane and it can offer strong fixing. It is biomechanically demonstrated to be suitable for osteoporotic fracture.
目的:评价外固定支架治疗桡骨远端骨折的疗效。方法:2004年3月至2008年8月以外固定支架或辅以克氏针、可吸收螺钉内固定治疗桡骨远端骨折３7例。结果:31例获得4～28 个月(平均14 个月)的随访,所有骨折均临床愈合,平均愈合时间8周。腕关节功能按Sarmiento标准进行评定,优17例,良9例,可4例,差1例,优良率839%。结论:外固定支架治疗桡骨远端骨折疗效可靠,值得推广。
Objective To compare the clinical results of locking compress plate (LCP) as an external fixator and standard external fixator for treatment of tibial open fractures. Methods Between May 2009 and June 2012, 59 patients with tibial open fractures were treated with LCP as an external fixator in 36 patients (group A), and with standard external fixator in 23 patients (group B). There was no significant difference in gender, age, cause of injury, affected side, type of fracture, location, and interval between injury and surgery between 2 groups (P gt; 0.05). The time of fracture healing and incision healing, the time of partial weight-bearing, the range of motion (ROM) of knee and ankle, and complications were compared between 2 groups. Results The incidence of pin-track infection in group A (0) was significantly lower than that in group B (21.7%) (P=0.007). No significant difference was found in the incidence of superficial infection and deep infection of incision, and the time of incision healing between 2 groups (P gt; 0.05). Deep vein thrombosis occurred in 5 cases of group A and 2 cases of group B, showing no significant difference (χ2=0.036, P=0.085). All patients were followed up 15.2 months on average (range, 9-28 months) in group A, and 18.6 months on average (range, 9-47 months) in group B. The malunion rate and nonunion rate showed no significant difference between groups A and B (0 vs. 13.0% and 0 vs. 8.7%, P gt; 0.05); the delayed union rate of group A (2.8%) was significantly lower than that of group B (21.7%) (χ2=5.573, P=0.018). Group A had shorter time of fracture healing, quicker partial weight-bearing, greater ROM of the knee and ankle than group B (P lt; 0.05). Conclusion The LCP external fixator can obtain reliable fixation in treating tibial open fracture, and has good patients’ compliance, so it is helpful to do functional exercise, improve fracture healing and function recovery, and reduce the complication incidence.
Objective To investigate the antibacterial and osteogenic capabil ities in vivo of hydroxyapatite (HA)/silver (Ag) coating. Methods HA/Ag coating (Ag qual ity percentage was 3%) and HA coating were deposited to external fixator Schanz screws. The tibial fracture model was establ ished in right hindl imb of 18 adult male Beagle dogs (weighing 15-20 kg). Thetibia was stabil ized with an external fixator and 2 Schanz screws of HA coating at proximal tibia (control group, n=18) and HA/Ag coating at distal tibia (experimental group, n=18), and every screw incision was infected with Staphylococcus aureus. Infection in screw holes and the changes of bone-screw interface were observed by wound grading and X-ray films. Results In control group, wounds infection became worse with time (χ2=13.492, P=0.001), while in experimental group, no obvious change was observed (χ2=0.208, P=0.901). The wound grading of experimental group was significantly better than that of the control group at 1, 2, and 3 weeks (P lt; 0.05). Laser scanning confocal microscope showed that there was bacterial adhesion on the surface of screws in 2 groups, viable becteria mainly in control group and non-viable becteria mainly in experimental group. The scanning electron microscope (SEM) observation results of the fractured sclerous tissue section showed that an obvious transparent boundary between screw and bone in control group, but no obvious boundary in experimental group. The osseointegration ratios were 76.23% ± 15.54% in control group and 93.42% ± 5.53% in experimental group, showing significant difference (t=8.843, P=0.000). The SEM observation showed that HA/Ag coating integrated with new bone and the surface of implant was filled with new bone in experimental group; obvious interspace was seen between the HA coating and new bone in control group. Conclusion HA/Ag coating has good antibacterial and osteogenic capabil ities, so it can take effects in preventing infection in screw holes and loosening of implants.
To provide the scientific theoretical basis for cl inical practice by comparing biomechanicalcharacteristics of single compressed plate with intramedullary pin, locking intramedullary nail and simple arm externalfixator with simple internal fixation devices. Methods Eighteen wet humeral bone specimens of adult cadaver were madecompl icated fracture models of humeral shaft and divided into 3 groups according to fixation methods. Fracture was fixed by single compressed plate with intramedullary pin in plate group, by locking intramedullary nail in intramedullary nail group and by external fixator with simple internal fixation devices in external fixator group. The intensity and rigidity of compl icated fracture models of humeral shaft was measured in compress test and torsion test. Results In compress test, the maximum load in plate group (6 162.09 ± 521.06) N and in intramedullary nail group (6 738.32 ± 525.89) N was significantly larger than that in external fixator group (2 753.57 ± 185.59) N (P lt; 0.05); but there was no significant difference between plate group and intramedullary nail group (P gt; 0.05). Under 600 N physiological compress load, the rigidity was (171.69 ± 6.49) N/mm in plate group, (333.04 ± 36.85) N/mm in intramedullary nail group and (132.59 ± 2.93) N/mm in external fixator group; showing no significant difference between plate group and external fixator group (P gt; 0.05), and showing significant difference between intramedullary nail group and plate, external fixator groups (P lt; 0.05). In torsion test, the maximum torque in plate group (38.24 ± 7.08) Nm was significantly larger than those in intramedullary nail group (17.12 ± 5.73) Nm and external fixator group (20.26 ± 6.42) Nm (P lt; 0.05), but there was no significant difference between intramedullary nail group and external fixator group (P gt; 0.05). Under 0.80 Nm physiological torque, the rigidity was (16.36 ± 2.07) Ncm/° in plate group and (18.79 ± 2.62) Ncm/° in external fixator group, which was significantly larger than that in intramedullary nail group (11.45 ± 0.22) Ncm/° (P lt; 0.05); but there was no significant difference between plate group and external fixator group (P gt; 0.05). Conclusion Those fracture models fixed by single compressed plate with intramedullary pin have better compress and torsion intensity, they also have better torsion rigidity but less compress rigidity. Those fracture models fixed by locking intramedullary nail have better compress intensity but less torsion intensity, they also have better compress rigidity but less torsion rigidity. Those fracture models fixed by external fixator with simple internal fixation device have less compress and torsion intensity, they also have less compress rigidity but better torsion rigidity.
【Abstract】 Objective To investigate the effect of the volar capsular l igament complex on stabil ity of the wrist jointand to provide basic biomechanical theoretical criteria for cl inic appl ication of the external fixator. Methods Nine upperl imbs specimens (left 6, right 3) were taken from fresh adult cadavers to make wrist joint-bone capsular l igament complex specimens. Firstly, soft tissues of forearms and hands were resected and capsular membranes and l igaments were reserved to make the bone-articular l igament complex (normal specimen). Secondly, the volar capsular l igament complex was cut off from radial malleolus to ulnar malleolus (impaired specimen). Thirdly, the impaired volar capsular l igament complex was interruptedly sutured by the use of 4# suture silk (repaired specimen). To simulate cl inical operation with external fixator, the biomechanical test was done according to the sequence (normal, impaired, repaired, repaired and fixed, impaired and fixed). Statistical significance was analyzed through selected loads at the three different shifts (1.5, 2.0, 2.5 cm). Results According to the sequence (normal, impaired, repaired, repaired and fixed, impaired and fixed), when the shift was 1.5 cm, the different respective loads were (60.74 ± 20.60), (35.23 ± 13.88), (44.36 ± 20.78), (168.40 ± 29.21) and (139.00 ± 33.18) N, respectively. When the shift was 2.0 cm, the different loads were (138.46 ± 12.93), (87.17 ± 24.22), (97.52 ± 23.29), (289.00 ± 54.29) and (257.98 ± 55.74) N, respectively. When the shift was 2.5 cm, the different loads were (312.87 ± 37.15), (198.16 ± 37.14), (225.66 ± 30.96), (543.15 ± 74.33) and (450.35 ± 29.38) N, respectively. There was no statistically significant difference between the impaired and repaired specimens (P gt; 0.05). Similarly, there was statistically significant difference among the rest specimens (P lt; 0.05). The same statistical results were obtained when the two different shifts were compared. There was statistically significant difference at the three different shifts for the same specimen (P lt; 0.05). Conclusion Volar capsular l igament complex is an important anatomic structure to keep stabil ity of the wrist joint. The carpal instabil ity arises out of the injured complex. Repairing the injured complex only can not immediately restore stabil ity of the wrist joint. The external fixator can effectively help to diminish the relative shift of the impaired capsular l igament complex, to reduce the load of the repaired complex and to protect the complex accordingly. The device plays an important role in maintaining stabil ity of the wrist joint.
Objective To compare effects, advantages and disadvantages of simple internal fixation to that of l imited internal fixation with external supporting frame fixation in the treatment of complex fractures of tibial plateau. Methods From July 2002 to August 2006, 66 cases of complex fractures of the tibial plateau were divided into the internal fixation group (n=39) and the external fixator group (n=27). The interal fixation group had 18 cases of IV, 7 cases V and 14 cases VI according to Schatzker, including 25 males and 14 females aged 18-79 years with an average of 45.4 years. The external fixator group had 13 cases of IV, 6 cases V and 8 cases VI according to Schatzker, including 18 males and 9 femles aged 18-64 years with an average of 44.2 years. No significant difference was evident between the two groups (P gt; 0.05). Patients were treated by using screws, steel plates or external supporting frame fixation strictly based on the princi ple of internalfixation. Results All patients were followed up for 1-5 years. Fracture healed with no occurrence of nonunion. Two cases inthe internal fixation group presented partial skin infection and necrosis, and were cured through the dressing change and flap displacement. Fracture heal ing time was 6-14 months with an average of 7.3 months. The time of internal fixator removal was 6-15 months with an average of 8.3 months. In the external fixation group, 11 cases had nail treated fluid 7 days to 3 months after operation, combining with red local skin; 3 cases had skin necrosis; and 3 cases had loose bolts during follow-up. Through debridement, dressing change and flap displacement, the skin wounds healed. Fracture heal ing time was 3-11 months with an average of 5.1 months. The time of external fixator removal was 5-11 months with an average of 6.4 months. At 8-14 months after operation, the knee function was assessed according to Merchant criteria. In the internal fixation group, 29 cases were excellent, 4 good, 5 fair and 1 poor, while in the external fixation group, 20 cases were excellent, 3 good, 2 fair and 2 poor. There was no significant difference between the two groups (P gt; 0.05). Conclusion The therapeutic effects of simple internal fixation and l imited internal fixation with external supporting frame fixation were similar in the treatment of complex fractures of tibial plateau. Fixation materials should be selected according to the state of injury and bone conditions for the treatment of tibial plateau fracture of type IV, V and VI based on Sehatzker classification.