Quantitative CT Bone Density Measurement of Tibia to Predict Knee Prosthesis Looseness

Deng Gang; Wang Zhishan; Song Wei; Qin Xiaofeng; Lv Delin; Zhai Kun; Liu Bin

Abstract：Objective To investigate the effect of quantitative CT bone mineral density measurement of tibia on the prediction of knee prosthesis loosening.Methods A retrospective analysis was performed on 102 patients who underwent knee arthroplasty in the Department of Orthopaedicss of the 63650 Army Hospital of the People's Liberation Army from January 2019 to January 2021.45 males and 57 females were included.The average age range was(68.90±7.67)years,ranging from 57 to 78 years.There were 40 cases of left knee and 62 cases of right knee.The body mass index(BMI)ranged from 21.26 to 30.01 kg/m2,with an average of(26.35±3.64)kg/m2.The 102 patients were divided into the loose group and the non-loose group according to whether the prosthesis was loose or not.The bone mineral density of femur and proximal tibia was measured by dualenergy X-ray absorptiometry(DXA)and quantitative computed tomography(QCT)during preoperative and postoperative follow-up.Osteoporosis was diagnosed according to T value.The general data of the two groups of patients were analyzed,and the difference of bone mineral density between the two groups before surgery was observed.Reliability analysis was used to observe the internal and inter-measurement consistency of QCT detection.The changes of bone mineral density before and after operation were observed,and the diagnostic accuracy of DXA and QCT were analyzed.Results All patients were followed up for 12～24 months,with an average of(12.53±2.28)months.The number of osteoporosis cases in all patients after TKA was significantly increased.The results of QCT and DXA before TKA showed that the osteoporosis in the loose group was significantly higher than that in the non-loose group(P＜0.05).The diagnosis rate of tibia and proximal femur with QCT before and after operation was higher than that with DXA(P＜0.05).The observer consistency evaluation showed that the measurement results of different observers were highly consistent and the overall subjective error was small.Conclusion QCT bone mineral density measurement is accurate and reliable.The measurement of bone mineral density of proximal tibia before total knee arthroplasty can predict the prosthesis loosening to some extent.