Abstract:Objective To discuss the changes in the absolute length of lower limb after total knee arthroplasty.Methods We prospectively analyzed 56 patients with endstage osteoarthritis who had undergone primary unilateral TKA from January 2014 to December 2017.There were 14 men and 42 women.The age ranged 56 to 82 years,with an average of (71.6±2.4) years.According to the degree of preoperative varus,the patients were divided into two groups,with varus deformity <5° in group A and 10°≥varus deformity≥5 ° in group B.During the operation,marks were made on the anterior side of the femur and the tibia respectively,the distance of marks were measured with the full extension of the knee before osteotomy and after the prosthesis was installed.the difference between the two marks was the change value of the absolute length of the lower limb.The mechanical axis,range of motion,KSS score and functional score of the two groups were recorded before and after the operation.At the same time,the satisfaction rate of the patients after the operation and the perception rate of the changes in limb length were recorded.Results The 56 patients obtained an average follow-up of 18 months(from 6 to 40 months).No postoperative complications like infection or Aseptic loosening.The range of motion was (78.5±30.2)°,KSS was (64.8±11.6),function score was (62.8±9.8),and mechanical axis was (3.8±1.2)°on average in group A before operation.The range of motion was (76.4±31.4)°,KSS was (63.4±10.4),function score was(60.6±9.6),and mechanical axis was (7.4±2.3)°on average in group B before operation.At 6 months postoperation,the range of motion was (96.4±28.4)°,KSS was (86.2±10.4),function score was (83.6±9.6),and mechanical axis was(1.6±1.1)°on average in group A,the difference was significantly compared with preoperative.the range of motion was (94.6±26.6)°,KSS was (84.8±10.2),function score was (86.2±9.2),and mechanical axis was (1.8±1.2)°on average in group B,the difference was significantly compared with preoperative.There was no statistical significance between group A and group B after operation.In general,82.1%(46/56) of the patients had an increase in the absolute length of limbs after operation,of which 71.4%(20/28) in group A and 92.9%(26/28 ) in group B.The difference was significantly between group A and group B.About 50.0%(28/56 ) patients perceived changes in limb length after operation,of which 35.7%(10/28) in group A and 64.3%(18/28)in group B.There is statistical significance.About 24.2% of the patients were dissatisfied with the change in leg length.Half a year after operation,the number of patients who perceived changes in leg length decreased to 14.3%(8/56),of which 10.7%(3/28) in group A and 17.9%(5/28) in group B,There was no statistical significance.The number of patients dissatisfied with changes in limb length decreased to 3.6%(2/56).Conclusion TKA can obviously improve the function,relieve the pain and restore the mechanical axis of the limbs.However,the absolute length of limbs maybe increased after operation,and the change is related to the degree of the preoperative knee varus.After operation,some patients will have obvious perceived the change,thus affecting the overall satisfaction rate of treatment.
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