Relationship of leg length discrepancy with knee osteoarthritis and its skeletal imaging characteristics
Min Hongwei, Liu Kemin, Qi Pan, Qu Tiebing
School of Rehabilitation, Capital Medical University, Arthropathy Disagnosis and Treatment Center, Beijing Bo'ai Hospital, China Rehabilitation Research Center, Beijing 100068, China
Abstract：Objective This work aims to explore the relationship between leg length discrepancy (LLD) and the onset and imaging features of primary knee osteoarthritis (KOA) to provide a theoretical basis for the prevention and treatment of this disease.Methods Clinical and imaging data of 141 patients with primary KOA who underwent total knee arthroplasty (TKA) were analyzed retrospectively from June 2017 to August 2019 in Beijing Bo'ai Hospital. Among these patients, 19 were males and 122 were females with an average age of(67.8±9.4)years and body mass index (BMI) of (26.8±2.9) kg/m2. Prior to the operation, the whole legs were examined by CT, and bilateral leg length, anatomical femoral-tibial angle (AFTA), and pelvic tilt angle (PTA) were measured by Webviewer software. The K-L grade of KOA severity was evaluated using weight-bearing X-ray. The patients were categorized into LLD (LLD>5 mm) and control groups (LLD<5 mm) according to the magnitude of LLD. The LLD group was further divided into long and short leg sides according to lower limb length. The incidence of LLD in patients with KOA was evaluated, and the differences in sex, age, BMI, and PTA were compared between the two groups. In the LLD group, the association of LLD with age, BMI, and PTA was evaluated by Spearman correlation analysis, and the differences of AFTA, K-L grade, and TKA operation location (long or short leg side) were compared.Results Among the 141 patients with KOA, 68 patients presented as LLD with incidence rate of 48.2%. The PTA (3.93°±3.13°) of LLD group was higher than that of control group (2.31°±2.06°), and the difference was statistically significant (t=3.654, P<0.05). In the LLD group, the AFTA of the short leg side (4.74°±7.02°) was larger than that of the long leg side (2.0°±5.69°), and the difference was statistically significant (χ2=2.554, P<0.05). The operation rate of TKA in the short leg side was 89.7% (61/68), which was significantly higher than that in the long leg side at 57.4% (39/68), and the difference was statistically significant (χ2=16.753, P<0.05). No statistically significant difference in K-L grade was observed between the short and long leg sides (P>0.05). In the LLD group, Spearman correlation analysis showed that LLD was positively correlated with PTA, and the difference was statistically significant (rs=0.547, P<0.01). No correlation was observed among LLD, BMI, and age (rs=0.082, 0.075, all P values>0.05).Conclusions LLD has high incidence in patients with primary KOA and usually occurs on the short leg side and may lead to pelvic tilt. When the magnitude of LLD is high, the deformity becomes severe. Early active intervention may be important in the prevention of KOA.
闵红巍, 刘克敏, 亓攀, 曲铁兵. 双下肢不等长与原发性膝骨关节炎的关系及影像学特点的相关性研究[J]. 中华解剖与临床杂志, 2020, 25(5): 466-471.
Min Hongwei, Liu Kemin, Qi Pan, Qu Tiebing. Relationship of leg length discrepancy with knee osteoarthritis and its skeletal imaging characteristics. Chinese Journal of Anatomy and Clinics, 2020, 25(5): 466-471.
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