To evaluate the biomechanical action of lateral malleolar’s anatomical hook-plate in treatingWeber A-type ankle fracture. Methods Forty-eight cadaveric specimens of adult’s inferior extremities from June 2005to October 2006 were observed, consisting of 26 males and 22 females and aged 18-55 years. The external malleolus of the specimens were transected by using a wire saw at the ankle joint level, and then were divided into 4 groups randomly (groups A, B, C and D). Four distinct internal fixation instruments were used: lateral malleolar’s anatomical hook-plate in group A, general screws in group B , 1/3 tubular plate in group C and standard tension band in group D. Each group was further divided into 2 subgroups, A1-D1 and A2-D2. A1-D1 groups underwent anti-pressure and A2-D2 groups underwent anti-torsion biomechanically comparative analysis. Results The peak values of anti-pressure experiments in groups A1-D1 were (799.83 ± 105.47), (699.17 ± 63.81), (598.83 ± 123.14) and (453.00 ± 111.67) N respectively, group A1 was significantly higher than groups B1, C1 and D1 (P lt; 0.01); meanwhile, the peak values of anti-torsion experiments in groups A2-D2 were (37.17 ± 1.81), (30.33 ± 2.22), (20.50 ± 2.92), (24.83 ± 3.47) Nm respectively, group A2 was significantly higher than groups B2, C2 and D2 (P lt; 0.01). Conclusion The lateral malleolar’s anatomical hook-plate represents a definite biomechanical superiority, when compared with other 3 internal fixation instruments in treating fracture of external mlleolus.
Objective To investigate the advance in surgical treatment of inferior pole fracture of patella and to explore the existing problems and further research directions. Methods Domestic and foreign l iterature in recent years on patella fracture was extensively reviewed, the surgical treatment of inferior pole fracture of patella was summarized by combining the research findings with cl inical experience. Results The surgical treatment of inferior pole of patella fractures included retaining the integrity of the patella and partial patellectomy of inferior pole of patella and extending knee installationreconstruction. There were kinds of ways to retain the integrity of the patella, such as circular wire fixation, tension bandfixation, NiTi-patella concentrotor fixation, basket plate fixation, reforming McLaughl in way and polydioxanone suture netfixation; the latter category is partial patellectomy and extensor device reconstruction. Every surgical way had its advantages and l imitations. Conclusion Most studies tend to retain the integrity of the patella, but some researches have shown that partial resection of inferior pole of patella had no significant effect on knee function. It is important to obtain the security excisional range and elongation range postoperative by experiment for regulating the treatment of comminuted fractures of inferior pole of patella.
Objective To explore the effects of changes in the length of the patella on patellofemoral contact areas and pressures, to provide a theoretical foundation for treatment of lower pole of patella fracture. Methods Using homemadeloadingequipment, pressure sensitive films of 100 mm × 100 mm in size were placed on the force platform, vertically downwardload (0-19.6 N) was given. The pressure-sensitive response curve was obtained by computer image analysis of the pressuresensitive tablets and calculation. Six male left fresh knee specimens from voluntary donation were placed in homemade-test fixed load device, and the double-layer pressure sensitive film was placed on the patellofemoral joint surface; under loading of 196 N at flexion of 0, 15, 30, 45, 60, 75, 90, 105, 120, and 135° for 2 minutes, respectively, the pressure sensitive film was removed as the control group. Patellas were transected cut and in situ fixed by Kirschner wire and steel-wire as in situ fixation group. Bone fragments obtained from the corresponding 1/6 and 2/6 of contralateral patella, were embedded in the interspace between osteotomy with internal fixation with Kirschner wire and steel-wire respectively as lengthening group. Followed by the amputating patella length of 1/6, 2/6, 3/6 from proximal to distal and internal fixation with Kirschner wire and steel wire by turns as a shortening group. Repeat the above steps of each experiment. By image analysis the pressure sensitive film, the patella joint contact area were measured, and patellar contact pressure (including the peak pressure and average pressure) was calculated according to pressure-sensitive response curve. Results The actural contact area were significantly smaller in the shortening groups than in the control group at flexion of 30-135° (P lt; 0.05); the pressure was significantly bigger in shortening 1/6 group at flexion of 0, 15, 60, and 75°, in shortening 2/6 group at flexion of 0° and 75-135°, and in shortening 3/6 group at flexion of 0-30°and 75-135° than in the control group (P lt; 0.05); the peak pressure was significantly bigger in shortening 1/6 group at flexion of0, 15, and 60-105°, in shortening 2/6 group at flexion of 0, 15, and 75-105°, and in shortening 3/6 group at flexion of 0, 30, and 60-135° than in the control group (P lt; 0.05). The actural contact area was significantly smaller in the lengthening groups than in the control group at flexion of 15, 60, and 90°, and it was bigger at flexion of 105, 135° in lengthening 2/6 group than in the control group (P lt; 0.05); the pressure was significantly bigger in the lengthening groups at flexion of 15-75° than in the control group and it was smaller in the lengthening groups at flexion of 105, 135°, and smaller in lengthening 2/6 group at flexion of 120° (P lt; 0.05); the peak pressure was significantly smaller in lengthening 1/6 group than in the control group at flexion of 0, 90, and 105° and smaller in lengthening 2/6 group at flexion of 0° (P lt; 0.05). The actural contact area was significantly bigger in all lengthening groups than in all shortening groups at flexion of 30, 45, and 75-135° (P lt; 0.05). The pressure was significantly bigger in shortening 1/6 group than in lengthening groups at flexion of 0, 60, and 90° (P lt; 0.05), in shortening 2/6 group at flexion of 0, 60, and 90-120° (P lt; 0.05), in shortening 3/6 group at flexion of 0-135° (P lt; 0.05). The peak pressure was bigger in shortening groups than in lengthening 1/6 group at flexion of 0, 90, and 105° (P lt; 0.05), bigger than lengthening 2/6 group at flexion of 0° (P lt;0.05余请见正文.....