Relationship between lower limb alignment distribution and short-term clinical results after primary total knee arthroplasty in patients with varying degrees of knee varus

Abstract

To analyze the relationship between the distribution of lower limb alignment and short term clinical efficacy in patients with varus-type osteoarthritis after primary total knee arthroplasty (TKA). From December 2016 to March 2018, 87 patients (101 knees) with knee osteoarthritis were treated with the first total knee arthroplasty by the same medical group, including 21 males(25 knees) and 66 females(76 knees), ranging in age from 51 to 85 years old, with a mean of (67.6±7.0) years old. According to the difference of hip knee ankle angle (HKA) after total knee arthroplasty, the patients were divided into 4 groups:neutral position group (group A), -3°≤HKA≤3°, 50 knees;slight varus group (group B), 3°< HKA<6°, 20 knees;severe varus group (group C), HKA≥6°, 20 knees;valgus group (group D), HKA<- 3°, 11 knees. The preoperative sex, age, body mass index, operative side, preoperative and postoperative knee joint activity, HSS score, KSS clinical and functional score were compared among the 4 groups, and the relationship between the force line distribution of femoral and tibial prosthesis and the recent clinical effect was compared. All the patients were followed up with a mean duration of(18.4±4.0) months. The range of motion of knee joint, HSS and KSS scores at the latest follow-up after operation in the 4 groups were higher than those before operation, and the difference was statistically significant (P<0.001). There were significant differences in HSS and KSS scores among the 4 groups at the latest follow up (P<0.05);and the results in group A were better than those in group C and group D (P<0.05);the results in group B were better than those in group C and group D (P< 0.05);there was no significant difference between group A and group B or group C and group D(P>0.05). There was no significant difference in knee joint activity among the 4 groups. The score of femoral prosthesis force line within ±3°was better than that of the other group (P<0.05), and the score of tibia prosthesis force line had no significant difference between within ±3° group and other group (P>0.05). The short term clinical efficacy of patients with knee varus osteoarthritis after primary total knee arthroplasty is related to the distribution of lower limbs alignment. The short-term clinical efficacy of slight inversion position can be similar to that of neutral position. The force line distribution of femoral prosthesis is related to the short term clinical efficacy after primary knee arthroplasty.