Ishii Yoshinori, Noguchi Hideo, Sato Junko, Takahashi Ikuko, Ishii Hana, Ishii Ryo, Ishii Kei, Toyabe Shin-Ichi
Ishii Orthopaedic & Rehabilitation Clinic, Gyoda, Saitama, Japan.
Kanazawa Medical University, School of Plastic Surgery, Ishikawa, Japan.
Arthroplast Today. 2022 Sep 19;17:137-141. doi: 10.1016/j.artd.2022.06.015. eCollection 2022 Oct.
The posterior tibial slope angle (PTS) is crucial for sagittal alignment after total knee arthroplasty (TKA). This study aimed to determine which PTS based on the lateral view of standard knee radiographs (LSKRs; 36 × 43 cm) reflects the PTS based on a full-length lateral tibial radiograph (FLTR).
A total of 290 patients (355 knees) who underwent primary TKA were retrospectively recruited. Cross-sectional views from the 3-dimensional digital model of the tibial prosthesis and bone complex in the sagittal plane were used as FLTRs and LSKRs. Considering the region 21.5 cm proximal to the site of FLTR as the spot for LSKR to determine the 5 tibial diaphyseal axes, the axis that simulates the PTS as determined by the tibial mechanical axis between the center of the tibial component and the ankle plafond in LSKR was determined and compared.
PTS (α) defined by the line connecting the midpoints of tibial width between the region 10-cm distal to the knee joint and the distal end of the tibia based on LSKR revealed the least mean difference (0.13° ± 1.00°) and the strongest correlation ( < .001, r = 0.948) with PTS based on FLTR (α). The number of knees in α, indicating a difference of <2° from α, was 333 of 355 (93.8%). The equivalence test results indicated that α and α were statistically equivalent within a difference of 2° ( < .001).
PTS (α) can be used as a clinically reliable substitution of the true PTS on an FLTR for evaluating sagittal alignment after TKA.
胫骨后倾角度（PTS）对于全膝关节置换术（TKA）后的矢状位对线至关重要。本研究旨在确定基于标准膝关节X线片（LSKRs；36×43 cm）侧位片的哪种PTS能反映基于胫骨全长侧位X线片（FLTR）的PTS。
回顾性纳入290例行初次TKA的患者（355膝）。将胫骨假体与骨复合体矢状面的三维数字模型的横断面视图用作FLTRs和LSKRs。将FLTR部位近端21.5 cm处视为LSKR确定5条胫骨干轴线的位置，确定并比较LSKR中模拟由胫骨组件中心与踝关节面之间的胫骨机械轴所确定的PTS的轴线。
基于LSKR，通过连接膝关节远端10 cm处至胫骨远端之间胫骨宽度中点的线所定义的PTS（α）与基于FLTR的PTS（α）相比，平均差异最小（0.13°±1.00°），相关性最强（<0.001，r = 0.948）。α中与α相差<2°的膝关节数量为355个中的333个（93.8%）。等效性检验结果表明，α与α在相差2°范围内具有统计学等效性（<0.001）。
PTS（α）可作为临床上评估TKA后矢状位对线时FLTR上真实PTS的可靠替代指标。
