A Comparative Study Of Two Methods Of Joint Line Measurement After Total Knee Arthroplasty

Objective: The correlation between Total knee arthroplasty(TKA)and knee function was evaluated by comparing the changes of Joint line(JL)measured by two different methods.Methods: A retrospective analysis was performed on 70 patients who underwent TKA surgery in the department of articulation,The Third Hospital of Hebei Medical University from September 2017 to October 2018.Changes in JL were measured at the outermost point of the fibula head and the insertion point of the adductor femur respectively.Western Ontario and Mc Master Universities Osteoarthritis Index(WOMAC)score,Range of motion(ROM)and Feller's patella score were evaluated before and 12 months after surgery.The correlation between the changes of JL under two different reference points and the changes of WOMAC score,ROM score and Feller's patella score was tested.Results: Compared with the preoperative results,the postoperative WOMAC score was significantly decreased(P<0.05),and the scores of ROM and Feller's patella were significantly increased(P<0.05).Twelve months after the operation,there was a weak positive correlation between the changes of JL measured at the outermost point of the fibula head and the changes of WOMAC score,ROM score and Feller's patella score 12 months after the operation of TKA.The changes of JL measured at the femoral adductor insertion point were negatively correlated with the changes of WOMAC score(Spearman correlation coefficient r=-0.778,P<0.01),ROM(Spearman correlation coefficient r=-0.896,P<0.01),and Feller's patella score(Spearman correlation coefficient r=-0.864,P<0.01)12 months after TKA.Conclusions: The changes of JL measured at the insertion point of the adductor femur were negatively correlated with the changes of WOMAC score,ROM score and Feller's patella score after TKA.There was a weak positive correlation between the change of joint line and the change of score.Measuring the change of JL with the femoral adductor stop as the reference point can better evaluate the clinical function of knee joint after TKA.