Yang Minzhi, Kong Xiangpeng, Song Ping, Cao Zheng, Chai Wei
Chinese PLA Medical School, Beijing, China.
Senior Department of Orthopedics, The Fourth Medical Center of Chinese PLA General Hospital, Beijing, China.
Orthop Surg. 2025 Aug;17(8):2281-2290. doi: 10.1111/os.70091. Epub 2025 Jun 14.
Conflicting evidence exists regarding the impact of total hip arthroplasty (THA) on valgus knee deformities in patients with developmental dysplasia of the hip (DDH). The aim of this retrospective study was to identify the factors potentially contributing to the worsening of valgus knee deformities in DDH patients after THA.
This retrospective case-control study included 51 patients (69 hips) with Crowe type IV DDH who underwent primary THA between January 2018 and January 2020. The anatomic lateral distal femoral angle (aLDFA), mechanical lateral distal femoral angle (mLDFA), anatomic medial proximal tibial angle (MPTA), hip-knee-ankle (HKA) angle, anatomic tibiofemoral angle (TFA), joint line convergence angle (JLCA), tibial joint line angle (TJLA), femoral offset (FO), acetabular offset (AO), global offset (GO), and extent of leg lengthening were measured before and after THA. The case group comprised patients who complained that their valgus knee deformity worsened after THA, and the control group comprised those who did not. Hip-level data were compared using generalized linear mixed effects models for proportions/rates and linear mixed models for means.
The case group has 19 hips, and the control group has 50 hips. Both groups showed improvement in the HKA after THA (p < 0.05), but the case group presented with a smaller HKA (177.4 ± 2.4 vs. 175.2 ± 2.7, p < 0.001) and greater AO (5.8 ± 1.0 vs. 5.0 ± 1.0, p = 0.011) and GO (7.9 ± 0.7 vs. 7.0 ± 1.1, p = 0.003) values before THA. After THA, GO decreased in both groups, and the TJLA increased in the case group (0.6 ± 2.6 to 2.3 ± 3.5, p = 0.011).
THA improved the HKA in DDH patients. However, a decrease in GO could lead to an increase in the TJLA, suggesting pseudoprogression of the valgus knee deformity and therefore lead to complaints of worsening of valgus knee deformities. GO restoration during surgery may reduce the impact on the TJLA.
关于全髋关节置换术（THA）对发育性髋关节发育不良（DDH）患者膝外翻畸形的影响，存在相互矛盾的证据。这项回顾性研究的目的是确定可能导致DDH患者THA后膝外翻畸形加重的因素。
这项回顾性病例对照研究纳入了2018年1月至2020年1月期间接受初次THA的51例（69髋）Crowe IV型DDH患者。测量THA前后的解剖学外侧股骨远端角（aLDFA）、机械性外侧股骨远端角（mLDFA）、解剖学内侧胫骨近端角（MPTA）、髋-膝-踝（HKA）角、解剖学胫股角（TFA）、关节线汇聚角（JLCA）、胫骨关节线角（TJLA）、股骨偏移（FO）、髋臼偏移（AO）、整体偏移（GO）以及肢体延长程度。病例组包括那些抱怨THA后膝外翻畸形加重的患者，对照组包括那些没有这种情况的患者。使用广义线性混合效应模型对比例/率进行髋部水平数据比较，使用线性混合模型对均值进行比较。
病例组有19髋，对照组有50髋。两组在THA后HKA均有改善（p < 0.05），但病例组THA前的HKA较小（177.4±2.4 vs. 175.2±2.7，p < 0.001），AO（5.8±1.0 vs. 5.0±1.0，p = 0.011）和GO（7.9±0.7 vs. 7.0±1.1，p = 0.003）值更高。THA后，两组的GO均降低，病例组的TJLA升高（0.6±2.6至2.3±3.5，p = 0.011）。
THA改善了DDH患者的HKA。然而，GO的降低可能导致TJLA升高，提示膝外翻畸形假性进展，从而导致膝外翻畸形加重的主诉。手术中恢复GO可能会减少对TJLA的影响。
