Genu valgus is one of the most common limb deformities in hereditary multiple exostoses (HME). However, it is easily concealed and may account for subsequent osteoarthritis of the knee. The knees of 56 patients (33 men and 23 women) with HME were investigated bilaterally. Knee valgus was described by the mechanical axis deviation (MAD), mechanical lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA). We investigated sex, age, BMI, total number of palpable osteochondromas, number of radiographic osteochondromas around the knee, forearm deformities, morphology and distribution of lesions, and correlations between these factors and genu valgus. The measurement of LDFA and MPTA was performed to identify the sources of genu valgus deformity. Based on the measurement of the mechanical axis, limbs were classified as genu valgus (n = 22) or normal mechanical axis groups (n = 90). The different severities of the genu valgus patients were classified by MAD. By bivariate logistic regression, genu valgus was significantly associated with more sessile and flared metaphyseal lesions. However, only the number of flared metaphyseal lesions had a significant influence on the severity of genu valgus. By analyzing the LDFA and MPTA, it was found that abnormalities of both proximal tibia and distal femur play important roles in genu valgus. Early detection of sessile and flared metaphyseal knee lesions in patients with HME can contribute to early intervention of genu valgus. Level of relevance: Level 2.

膝外翻是遗传性多发性外生骨疣 (HME) 中最常见的肢体畸形之一。然而，它很容易被隐藏，并可能导致随后的膝关节骨关节炎。对 56 名 HME 患者（33 名男性和 23 名女性）的膝关节进行了双侧调查。膝外翻由机械轴偏差 (MAD)、机械外侧股骨远端角 (LDFA) 和内侧近端胫骨角 (MPTA) 描述。我们调查了性别、年龄、BMI、可触及骨软骨瘤的总数、膝关节周围的放射学骨软骨瘤数量、前臂畸形、病变的形态和分布，以及这些因素与膝外翻之间的相关性。进行 LDFA 和 MPTA 的测量以确定膝外翻畸形的来源。根据机械轴的测量，肢体被分类为膝外翻（n = 22) 或普通机械轴组 ( n = 90)。根据 MA​​D 对膝外翻患者的不​​同严重程度进行分类。通过双变量逻辑回归，膝外翻与更多无柄和张开的干骺端病变显着相关。然而，只有爆发性干骺端病变的数量对膝外翻的严重程度有显着影响。通过对LDFA和MPTA的分析，发现胫骨近端和股骨远端的异常在膝外翻中起重要作用。早期发现 HME 患者的无蒂和外翻性膝关节干骺端病变有助于膝外翻的早期干预。相关性级别：2 级。