BACKGROUND The purpose of open reduction and internal fixation of acetabulum posterior wall fractures is to restore anatomical structure and stability of the hip joint, in order to start weight bearing as soon as poss...BACKGROUND The purpose of open reduction and internal fixation of acetabulum posterior wall fractures is to restore anatomical structure and stability of the hip joint, in order to start weight bearing as soon as possible and prevent hip arthrosis; restoration of the anatomy should preserve function of the joint as well. Although "special shaped precontoured plates" have been developed in recent years for surgical treatment of this region, studies comparing the traditional plates with the newly designed precontoured plates are lacking.AIM To evaluate the biomechanical properties of precontoured anatomic buttress and conventional curved reconstruction plates(CCRPs) for posterior wall acetabulum fracture treatment.METHODS Twelve pelvis models were created for testing plate treatment of fracture in the posterior wall of the acetabulum. These 12 pelvis models were used to create 24 hemipelvis models(experimental) by cutting from the sagittal plane and passing over the center of gravity, after which the posterior wall acetabular fractures(of similar type and size) were created. In these experimental models, the right acetabulum was fixed with a 5-hole CCRP, while the left was fixed with a precontoured anatomic buttress plate(PABP). Samples were placed through thetest device and were subjected to static load testing, with a constant testing velocity of 2 mm/min until the load reached 2.3 kN or the acetabular fixation failed. Dynamic tests were also performed with sinusoidal wave load, with a maximal load of 2.3 kN and a load ratio of 0.1.RESULTS The average stiffness values were 460.83 ± 95.47 N/mm for the PABP and 291.99± 118.58 N/mm for the 5-hole CCRP. The precontoured anatomic acetabulum buttress plates had significantly higher rigidity than the CCRPs(P = 0.022). There was a statistically significant difference between the unloaded and 2.3 kN-loaded values of AL(posterosuperior fracture line vertical to the ground surface) and CL(posteroinferior fracture line vertical to the ground surface) parameters for both th展开更多
AIM: To determine whether use of a precontoured olecranon plate provides adequate fixation to withstand supraphysiologic force in a comminuted olecranon fracture model.METHODS: Five samples of fourth generation compos...AIM: To determine whether use of a precontoured olecranon plate provides adequate fixation to withstand supraphysiologic force in a comminuted olecranon fracture model.METHODS: Five samples of fourth generation composite bones and five samples of fresh frozen human cadaveric left ulnae were utilized for this study. The cadaveric specimens underwent dual-energy X-ray absorptiometry(DEXA) scanning to quantify the bone quality. The composite and cadaveric bones were prepared by creating a comminuted olecranon fracture and fixed with a pre-contoured olecranon plate with locking screws. Construct stiffness and failure load were measured by subjecting specimens to cantilever bending moments until failure. Fracture site motion was measured with differential variable resistance transducer spanning the fracture. Statistical analysis was performed with two-tailed Mann-Whitney-U test with Monte Carlo Exact test.RESULTS: There was a significant difference in fixation stiffness and strength between the composite bones and human cadaver bones. Failure modes differed in cadaveric and composite specimens. The load to failure for the composite bones(n = 5) and human cadaver bones(n = 5) specimens were 10.67 nm(range 9.40-11.91 nm) and 13.05 nm(range 12.59-15.38 nm) respectively. This difference was statistically significant(P ? 0.007, 97% power). Median stiffness for composite bones and human cadaver bones specimens were 5.69 nm/mm(range 4.69-6.80 nm/mm) and 7.55 nm/mm(range 6.31-7.72 nm/mm). There was a significant difference for stiffness(P ? 0.033, 79% power) between composite bones and cadaveric bones. No correlation was found between the DEXA results and stiffness. All cadaveric specimens withstood the physiologic load anticipated postoperatively. Catastrophic failure occurred in all composite specimens. All failures resulted from composite bone failure at the distal screw site and not hardware failure. There were no catastrophic fracture failures in the cadaveric specimens. Failure of 4/5 cadaveric specimens was defined whe展开更多
文摘BACKGROUND The purpose of open reduction and internal fixation of acetabulum posterior wall fractures is to restore anatomical structure and stability of the hip joint, in order to start weight bearing as soon as possible and prevent hip arthrosis; restoration of the anatomy should preserve function of the joint as well. Although "special shaped precontoured plates" have been developed in recent years for surgical treatment of this region, studies comparing the traditional plates with the newly designed precontoured plates are lacking.AIM To evaluate the biomechanical properties of precontoured anatomic buttress and conventional curved reconstruction plates(CCRPs) for posterior wall acetabulum fracture treatment.METHODS Twelve pelvis models were created for testing plate treatment of fracture in the posterior wall of the acetabulum. These 12 pelvis models were used to create 24 hemipelvis models(experimental) by cutting from the sagittal plane and passing over the center of gravity, after which the posterior wall acetabular fractures(of similar type and size) were created. In these experimental models, the right acetabulum was fixed with a 5-hole CCRP, while the left was fixed with a precontoured anatomic buttress plate(PABP). Samples were placed through thetest device and were subjected to static load testing, with a constant testing velocity of 2 mm/min until the load reached 2.3 kN or the acetabular fixation failed. Dynamic tests were also performed with sinusoidal wave load, with a maximal load of 2.3 kN and a load ratio of 0.1.RESULTS The average stiffness values were 460.83 ± 95.47 N/mm for the PABP and 291.99± 118.58 N/mm for the 5-hole CCRP. The precontoured anatomic acetabulum buttress plates had significantly higher rigidity than the CCRPs(P = 0.022). There was a statistically significant difference between the unloaded and 2.3 kN-loaded values of AL(posterosuperior fracture line vertical to the ground surface) and CL(posteroinferior fracture line vertical to the ground surface) parameters for both th
文摘AIM: To determine whether use of a precontoured olecranon plate provides adequate fixation to withstand supraphysiologic force in a comminuted olecranon fracture model.METHODS: Five samples of fourth generation composite bones and five samples of fresh frozen human cadaveric left ulnae were utilized for this study. The cadaveric specimens underwent dual-energy X-ray absorptiometry(DEXA) scanning to quantify the bone quality. The composite and cadaveric bones were prepared by creating a comminuted olecranon fracture and fixed with a pre-contoured olecranon plate with locking screws. Construct stiffness and failure load were measured by subjecting specimens to cantilever bending moments until failure. Fracture site motion was measured with differential variable resistance transducer spanning the fracture. Statistical analysis was performed with two-tailed Mann-Whitney-U test with Monte Carlo Exact test.RESULTS: There was a significant difference in fixation stiffness and strength between the composite bones and human cadaver bones. Failure modes differed in cadaveric and composite specimens. The load to failure for the composite bones(n = 5) and human cadaver bones(n = 5) specimens were 10.67 nm(range 9.40-11.91 nm) and 13.05 nm(range 12.59-15.38 nm) respectively. This difference was statistically significant(P ? 0.007, 97% power). Median stiffness for composite bones and human cadaver bones specimens were 5.69 nm/mm(range 4.69-6.80 nm/mm) and 7.55 nm/mm(range 6.31-7.72 nm/mm). There was a significant difference for stiffness(P ? 0.033, 79% power) between composite bones and cadaveric bones. No correlation was found between the DEXA results and stiffness. All cadaveric specimens withstood the physiologic load anticipated postoperatively. Catastrophic failure occurred in all composite specimens. All failures resulted from composite bone failure at the distal screw site and not hardware failure. There were no catastrophic fracture failures in the cadaveric specimens. Failure of 4/5 cadaveric specimens was defined whe
