Analysis of Coronal Plane Alignment Distribution Characteristics and Gender/Body Mass Index Differences in Patients with Knee Osteoarthritis in Northwest China

Ma Chengyuan; Wang Jianpeng; Zhao Guanghui; Ma Jianbin

Abstract：Objective To analyze the distribution characteristics of the coronal plane alignment of the knee(CPAK)classification in patients with knee osteoarthritis in Northwest China,and to provide a theoretical basis for the selection of alignment in total knee arthroplasty.Methods A retrospective analysis was conducted on 282 knee osteoarthritis patients(involving 500 knees)at Honghui Hospital Affiliated to Xi'an Jiaotong University from August 2024 to September 2024.Among them,there were 92 male patients and 190 female patients,with ages ranging from 46 to 83 years and an average age of(67.2±6.4)years.The body mass index(BMI)ranged from 16.2 to 37.0 kg/m2,with an average of(25.5±3.5)kg/m2.CPAK classification was performed based on the preoperative medial proximal tibial angle(MPTA),lateral distal femoral angle(LDFA),arithmetic hip-knee-ankle angle(aHKA),and joint line obliquity(JLO)of the patients.Patients were grouped by gender and BMI:170 knees in the male group and 330 knees in the female group;228 knees in the normal BMI group(BMI＜25 kg/m2)and 272 knees in the overweight/obese group(BMI≥25 kg/m2).Subgrouping based on gender within BMI groups showed 85 knees in males and 143 knees in females in the normal BMI group,while 85 knees in males and 187 knees in females in the overweight/obese group.The CPAK classification patterns were compared among different groups.Results Among all patients,the distribution of CPAK classifications was as follows:Type Ⅰ accounted for 42.2％(211 knees),Type Ⅳ for 25.4％(127 knees),TypeⅡ for 11.4％(57 knees),Type Ⅴ for 8.0％(40 knees),Type Ⅲ for 5.2％(26 knees),Type Ⅵ for 3.8％(19 knees),Type Ⅶ for 3.0％(15 knees),Type Ⅸ for 0.8％(4 knees),and Type Ⅷ for 0.2％(1 knee).Type Ⅰ accounted for the highest proportion in both male and female groups,which were 47.1％(80 knees)and 39.7％(131 knees)respectively.Similarly,Type Ⅰ also had the highest proportion in both the normal BMI group and the overweight/obese group,accounting for 42.1％(96 knees)and 42.3％(115 knees)respectively.In the normal BMI group,Type Ⅰ was the most prevalent classification in both males and females,accounting for 48.2％(41 knees)and 38.5％(55 knees)respectively.In the overweight/obese BMI group,Type Ⅰ also ranked first in both genders,with proportions of 45.9％(39 knees)in malesand 40.6％(76 knees)in females.Conclusion Type Ⅰ is the most common CPAK classification in knee osteoarthritis patients in Northwest China,followed by Type Ⅳ and Type Ⅱ.Type Ⅰ remains the dominant classification among patients with different genders and BMI levels.This study provides a reliable theoretical basis for the selection of TKA alignment in knee osteoarthritis patients in Northwest China.