| Purpose: To investigate the factors affecting the aseptic loosening of the distal femoral prosthesis and the clinical value of single photon emission computed tomography(SPECT)in the diagnosis of prosthetic aseptic loosening,and to summarize the characteristics of curved medullary needle prosthesis in revision surgery.Methods: We retrospectively analyzed 20 cases who underwent revision surgery for aseptic loosening of prosthesis in the distal femur from October 2011 to December 2018 in our hospital.We analyzed the effect of prosthetic needle bias,femoral osteotomy length and its proportion on the aseptic loosening of prosthesis.We summarized the clinical characteristics of single photon emission computed tomography(SPECT)in identifying the aseptic loosening of prosthesis;We summarized the characteristics of these kinds of revision options and the features of prosthetic design.Results: The average length of femoral osteotomy was 96.92mm(43.00-142.00 mm)in the initial operation of 20 patients,and the average osteotomy ratio was 0.32(0.13-0.63).The femoral lateral plainsshowed the bias angle between prosthetic needle line and femur averaged 3.21°(0.50°-9.70°)and the bias angle on anteroposterior position averaged 4.25°(0.50°-20.27°).The SPECT three-phase performance showed no abnormal radioactivity concentration in the blood flow phase and blood pool phase around femoral prosthesis.However,the delayed phase showed abnormal radioactivity concentration,indicating the bone metabolism was active.Five patients adopted “Cable”to reinforce femurs,and two patients adopted curved medullary needles,and the remaining 18 patients adopted straight medullary needles.Conclusions: The aseptic loosening of prosthesis in the distal femur is related to femoral osteotomy length and its proportion in the primory knee prosthesis replacement.The bias angle between prosthetic needle and femur can increase.SPECT can be considered as a priority tool to eveluate the aseptic loosening of prosthesis.The revision for aseptic loosening in the distal femur should comply with the priciple of individualization.The curved medullary needle prosthesis is more concordant with the femoral physiological curvature. |
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