Radiographic evaluation of mechanically tested cemented total hip arthroplasty femoral components retrieved post-mortem

Guidelines for assessing total hip arthroplasty (THA) radiographs for femoral implant stability have not been published; therefore, often the determination is subjective. The aim of this study was to identify radiographic criteria for veterinary clinicians to use when evaluating radiographs for femoral implant stability. Specific objectives were to: identify radiographic features associated with canine THA femoral implant loosening, evaluate whether technical recommendations for human femoral component implantation apply to dogs, and evaluate the effectiveness of radiographs for identifying canine THA implant loosening. Post-operative, follow-up, and post-mortem contact radiographs of canine implanted femora retrieved postmortem and mechanically tested for implant stability were evaluated. Based on the results, radiographic evaluation is not an effective means of assessing canine femoral implant stability; however, certain radiographic findings including implant retroversion, cement mantle cracks, or the appearance of cement-metal interface radiolucencies, may be indicative of implant loosening. It was also found that femoral implants completely surrounded by cement mantle of any thickness were less likely to loosen than those with an area lacking cement between the implant and bone. There was also a trend suggesting an association between inferior cement mantle quality and femoral implant loosening. In order to improve cement mantle quality and ensure that implants are completely surrounded by cement mantle, the use of modern cementing techniques is recommended.