Objective To evaluate the selection of the type of prosthesis in revision hip arthroplasty. Methods There were 33 hips in our study,male in 7 hips and female in 26 hips.The average age of the patients were 59 years.The reasons ofthe revision included aseptic loosing in 22 hips, infection in 8 hips(2 infection hips with discharging sinuses),and acetabular erosion in 3 hips.The operationsfor revision were 13 cemented and 12 cementless acetabular prosthesis with autograft inmorselized form;the femoral revision were all selected in cemented prosthesis.The revision for infection hip were all cemented prosthesis of extensively porouse-coated. Results The average follow-up duartion was 3.9 years and 11 months.There was a radiolucency but no clinical instability accompanied in 2 hips and remaining moderate pain in4 hips.No dislocation and fracture were seen in the series.Harris score were improved to 82.4(68.88). Conclusion The commonest reason of revision hip arthroplasty was aseptic loosing.The acetabular prosthesis in revision could select cemented or cementless components and femoral prosthesis could select extensively coated stem.The cemented components could yield good results in infection hips revision.
Objective To analyze the biomechanical changes of the adjacent cervical facet joints when the angled cervical prosthesis is replaced. Methods A total of 400 northwestern people were involved, with an age of 40 years or older.The cervical vertebra lateral X-ray films were taken, and the cervical angles were measured by professional computer aided design software, then the cervical intervertebral disc prosthesis with 10° angle was designed. The finite element models of C4，5and C4-6 segments with intact cervical discs were developed; the C4，5 disc was replaced by the cervical prosthesis with 0° and 10° angle respectively; and then all models were subjected to axial loading, flexion/extension, lateral bending, and torsion loading conditions; the stress effects on adjacent facet joints after replacement were observed by comparing with that of the intact model. Results The cervical angles were (9.97 ± 3.64)° in C3，4, (9.95 ± 4.34)° in C4，5, (8.59 ± 3.75)° in C5，6, and (8.49 ± 3.39)° in C6，7, showing no significant difference between C3，4 and C4，5, C5，6 and C6，7 (P gt; 0.05) and showing significant differences between the other cervical angles (P lt; 0.05). When C4，5 model was axially loaded, no significant difference in equivalent shearing stress were observed in intact, 0°, and 10° groups; at flexion/extension loading, the stress was biggest in intact group, and was smallest in 10° group; at lateral bending, the stress got the high rank in intact group, and was minimum in 10° group; at torsion loading, the stress state of 10° group approached to the intact one condition. When C4-6 model was loaded, the facet joint stress of the replaced segment (C4，5) decreased significantly at axial loading, flexion/extension, and lateral bending; while no obvious decrease was observed at torsion loading; the stress of the adjacent inferior disc (C5，6) decreased significantly at axial loadingand lateral bending condition, while less decrease was observed at torsion loading, no significant change at flexion/extension condition, it approached to that of the intact one. Conclusion The finite element analysis reveals that the biomechanical properties of 10° designed prosthesis is approximate to that of the intact cervical disc, thus the 10° designed prosthesis can meet the requirements of biomechanical function reconstruction of the cervical spine.