Effect Of Different Directions Of Sagittal Osteotomy On Tibial Component Position And Knee Joint Function In UKA

ObjectiveThe ideal reference landmark for sagittal osteotomy has not yet been determined in unicompartmental knee arthroplasty(UKA).The purpose of this study was to evaluate the effect of different sagittal osteotomy directions on the position of the tibial component and to analyze the correlation between the position and the postoperative clinical effect.MethodA total of 50 patients(50 knees)who underwent UKA for knee osteoarthritis in the Guangdong hospital of traditional Chinese medicine from June 2019 to March 2020 were randomly selected,and the mean follow-up period was 5.34 months.All patients were randomly divided into two groups according to different reference marks during osteotomy.The text group was the center of femoral head(CFH)group and the control group was the anterior superior iliac spine(ASIS)group.The prosthesis used in this study was Oxford phase III.Computerized tomography(CT)of the knee joints of the patients was performed to evaluate the rotation angle of the tibial component by measuring the angle(a)between the tangent of the lateral wall of the tibial component and the Akagi’ s line.The prosthesis is externally rotated.A positive value of the tibial component relative to each reference line was considered external rotation,whereas itis internal rotation.Patient-derived clinical scores using the WOMAC score,KSS score and the range of knee motion were assessed preoperatively,and the last follow-up following surgery.The effects of tibial component rotation on the WOMAC,KSS,body mass index(BMI)and the ROM were analyzed using linear regression analysis.ResultsTotal 50 patients(50 knees)were included in this study,of which 25 were in the CFH group(25 knees),including 5 males and 20 females.The average age was 65.56 years(58-73 years),and the average BMI was 24.73kg/m2(20.4-27.9),the average tibial component rotation angle was 6.03°(-3.3-11.6。);25 cases(25 knees)in the ASIS group,8 in males and 17 in females,with an average age of 63.88 years(57-71 years),the average BMI was 23.88(18.1-30.8),and the average rotation angle of postoperative tibial prosthesis was 4.86°(-2.6-9.8°).The postoperative KSS score and WOMAC score of the two groups were better than those before surgery,and the differences were statistically significant(P<0.05).There was no significant difference between the CFH group and AS IS group in the tibial component rotation angle and knee function scores(P>0.05).Linear regression analysis showed no significant correlation between the rotation angle and body mass index,postoperative KSS score,WOMAC score,and knee ROM(P>0.05).ConclusionShort-term results after unicompartmental knee arthroplasty are good.The reference mark suchas CFH or ASIS for sagittal tibial osteotomy may cause the component rotation in the axial plane with different degrees,almostwere external.The angle of external rotation has no significant correlation with the preoperative BMI of the patients and the postoperative knee function score.However,the rotation angle of the prosthesis measured in this study does not affect the early clinical effects of UKA,further research into the long-term effects is needed.