Hallak Amer, Shichman Ittai, Ashkenazi Itay, Khoury Amal, Warschawski Yaniv, Gold Aviram, Snir Nimrod
Tel Aviv Sourasky medical Center, Tel Aviv-Yafo, Israel.
Tel Aviv University, Tel Aviv, Israel.
Arch Orthop Trauma Surg. 2025 Apr 28;145(1):274. doi: 10.1007/s00402-025-05878-w.
The Coronal Plane Alignment of the Knee (CPAK) classification categorizes knee phenotypes based on constitutional limb alignment and joint line obliquity (JLO). Restricted Inverse Kinematic Alignment (RIKA) is a surgical philosophy that incorporates calculated perioperative parameters to achieve patient-specific alignment. This study investigated the reproducibility of restoring preoperative CPAK phenotypes via the tibia-first RIKA concept in total knee arthroplasty (TKA).
This prospective study assessed 129 patients who underwent RIKA TKA using an imageless navigation robotic-assisted arm with a single implant design for primary osteoarthritis between January 2022 and December 2023. Preoperative and postoperative angles for the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were measured from full-length standing anteroposterior X-ray imaging. Arithmetic HKA (aHKA) was defined as MPTA - LDFA, and JLO was outlined as MPTA + LDFA to classify each knee into one of nine CPAK phenotypes. CPAK boundaries for neutral aHKA and JLO were 0° ± 2° and 180° ± 3°, respectively.
The mean pre- and postoperative aHKA were - 2.73° (SD ± 4.9°) vs. -2.83° (SD ± 3.0°), respectively. The most common preoperative CPAK phenotypes were I (n = 74, 42.5%) and II (n = 40, 23.0%). Among patients with preoperative type I phenotype, 39.2% (29/74) preserved their composition postoperatively, while 48.6% (36/74) converted to type IV. Of 40 Type II knees, 65.0% (26/40) preserved alignment, with 25.0% (10/40) shifting to type V. In preoperative types IV and V, 75% (12/16) and 88.5% (23/26) preserved their phenotypes, respectively. Valgus categories (III, VI, IX) were neutralized into types II and V. CPAK types VII, VIII, and IV were rare throughout.
The use of tibia-first RIKA achieved adequate preservation of the native coronal alignment postoperatively. These findings suggest that balancing a knee using tibia-first approach with the use of imageless navigation robotic-assisted systems is a valid tool for surgeons who seek contemplating RIKA TKA.
膝关节冠状面排列（CPAK）分类根据肢体固有排列和关节线倾斜度（JLO）对膝关节表型进行分类。受限逆运动学排列（RIKA）是一种手术理念，它结合计算出的围手术期参数以实现患者特异性排列。本研究调查了在全膝关节置换术（TKA）中通过胫骨优先RIKA概念恢复术前CPAK表型的可重复性。
这项前瞻性研究评估了129例在2022年1月至2023年12月期间使用无图像导航机器人辅助手臂、采用单一植入物设计治疗原发性骨关节炎的接受RIKA TKA的患者。从全长站立前后位X线成像测量术前和术后的外侧股骨远端角（LDFA）和内侧胫骨近端角（MPTA）。算术HKA（aHKA）定义为MPTA - LDFA，JLO定义为MPTA + LDFA，以将每个膝关节分类为九种CPAK表型之一。中性aHKA和JLO的CPAK边界分别为0°±2°和180°±3°。
术前和术后aHKA的平均值分别为-2.73°（标准差±4.9°）和-2.83°（标准差±3.0°）。最常见的术前CPAK表型为I型（n = 74，42.5%）和II型（n = 40，23.0%）。在术前为I型表型的患者中，39.2%（29/74）术后保留了其组成，而48.6%（36/74）转变为IV型。在40例II型膝关节中，65.0%（26/40）保持了排列，25.0%（10/40）转变为V型。在术前IV型和V型中，分别有75%（12/16）和88.5%（23/26）保留了其表型。外翻类别（III、VI、IX）被中和为II型和V型。CPAK VII型、VIII型和IV型在整个过程中都很罕见。
使用胫骨优先RIKA在术后能充分保留天然冠状面排列。这些发现表明，对于考虑进行RIKA TKA的外科医生来说，采用胫骨优先方法并结合无图像导航机器人辅助系统来平衡膝关节是一种有效的工具。
