Imageological Study Of Rotational Alignment Reference Landmarks Of The Tibial In Unicompartmental Knee Arthroplasty

Background: Due to the prolonged life expectancy of the population,the incidence of knee osteoarthritis(KOA)increased gradually,which has a great impact on the quality of life of the elderly.With the development of joint surgery techniques,unicompartmental knee arthroplasty(UKA)has a significant effect on unilateral compartmental osteoarthritis.The rotation of femoral and tibial component is an important problem to be considered during operation.For the reference of external rotation of femoral component,the surgical epicondylar axis is generally chosen,but the rotation of tibial component has not been agreedObjective: Through the measurement of the anatomical landmark of the tibia on the MRI of the knee joint,aiming to provide a reference for the rotation of the tibial component in the UKA.Methods:This study included 22 patients who underwent knee arthroplasty in our hospital,including 6 males and 16 females,with an average age of 59.7 years(45-80 years).MRI scan was performed in the medial position of knee extension.The angles between the surgical epicondylar axis(SEA)and the medial intercondylar ridge(MIR),the substitute AP(s AP)line connecting the medial border of the patellar tendon at the articular surface level and the medial tubercle,and the tibial anteroposterior(AP)were measured,respectively.Then,when the virtual sagittal osteotomy was performed parallel to the MIR line,the s AP line and the AP line,the maximum width and length(m/ l)ratio of the tibial cut surface was measured.Results: The MIR was 95.8°±3.5°(88.7°-102.6°)relative to the external rotation of SEA,the s AP line was 90.6° ± 3.4°(83.4°-95.5°)relative to the external rotation of SEA,the AP line was 90.3° ±3.4°(83.0°-95.4°)relative to the external rotation of SEA.MIR was externally rotated by approximately 5.8° relative to the AP line of the tibia(P < 0.001).There was no difference in the average rotation angle of the tibia AP line and the s AP line relative to the SEA(P=0.747).The sagittal osteotomy m/l ratio parallel to MIR was 0.50 ± 0.023(0.44-0.55),the m/l ratio of the sagittal osteotomy parallel to the s AP line was 0.53 ± 0.025(0.46-0.58),the m/l ratio of the sagittal osteotomy parallel to the AP line was 0.53±0.027(0.46-0.58).The m/l ratio parallel to the s AP line and the AP line is closer to the m/ l ratio of the components.Conclusion: Obtaining AP orientation of the tibia is equally important in total knee arthroplasty and UKA.In sagittal osteotomy of the tibia,the reference MIR line may lead to external rotation of the tibial components,and s AP line is almost parallel to the AP line.It can be used as a reference axis for rotation orientation of the tibial components in UKA.