Jhurani Anoop, Lavaniya Sanchay, Ardawatia Gaurav, Agarwal Piyush, Dwivedi Abhishek, Srivastava Mudit
Department of Robotic Joint Replacement Surgery Unit, Fortis Escorts Hospital, Jaipur, Rajasthan, India.
Department of Clinical Research, Fortis Escorts Hospital, Jaipur, Rajasthan, India.
J Robot Surg. 2025 Dec 26;20(1):120. doi: 10.1007/s11701-025-03072-z.
Accurate assessment of coronal alignment is essential for total knee arthroplasty (TKA) planning. The Coronal Plane Alignment of the Knee (CPAK) classification integrates mechanical alignment and joint line obliquity into nine phenotypes, but its reliability depends on measurement accuracy. This study aimed to compare the accuracy and reliability of CPAK classification and coronal alignment parameters obtained from computed tomography (CT) and long-leg standing radiographs. A prospective comparative study was conducted on 100 patients undergoing primary TKA for degenerative arthritis. Each patient underwent standardized long-leg standing radiographs and full-limb CT scans using MAKO robotic planning software. Measurements included the arithmetic hip-knee-ankle (aHKA) angle, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and joint line obliquity (JLO). CPAK classification was determined from aHKA and JLO values. Two independent observers recorded all parameters. Inter-modality differences were analyzed using paired t-tests, and reliability was assessed using intraclass correlation coefficients (ICC) and Cohen's kappa. A total of 100 patients were analyzed, with complete datasets for 86 patients. CT consistently produced different values for HKA, LDFA, and MPTA compared with radiographs (p < 0.001), while aHKA, JLO and CPAK classifications showed no significant difference. Both modalities demonstrated excellent interobserver reliability (ICC > 0.88) and near-perfect CPAK agreement (κ = 0.86-0.88) measurement without altering overall CPAK phenotype classification. CT-based measurements provide greater precision and reproducibility for coronal alignment parameters compared with radiographs. However, CPAK classification remains largely consistent between modalities, validating its robustness across imaging techniques. CT offers precise value for preoperative planning, particularly in robotic-assisted workflows or complex deformities, while radiographs remain adequate for routine phenotyping. Level II - Prospective comparative study.
准确评估冠状位对线对于全膝关节置换术（TKA）规划至关重要。膝关节冠状面排列（CPAK）分类将机械对线和关节线倾斜度整合为九种表型，但其可靠性取决于测量准确性。本研究旨在比较CPAK分类以及从计算机断层扫描（CT）和长腿站立位X线片获得的冠状位对线参数的准确性和可靠性。对100例因退行性关节炎接受初次TKA的患者进行了一项前瞻性比较研究。每位患者均接受了标准化的长腿站立位X线片检查，并使用MAKO机器人规划软件进行了全下肢CT扫描。测量指标包括算术髋-膝-踝（aHKA）角、股骨远端外侧角（LDFA）、胫骨近端内侧角（MPTA）和关节线倾斜度（JLO）。根据aHKA和JLO值确定CPAK分类。两名独立观察者记录所有参数。使用配对t检验分析不同检查方式之间的差异，并使用组内相关系数（ICC）和科恩kappa系数评估可靠性。共分析了100例患者，其中86例患者有完整数据集。与X线片相比，CT得出的HKA、LDFA和MPTA值始终不同（p < 0.001），而aHKA、JLO和CPAK分类无显著差异。两种检查方式均显示出极好的观察者间可靠性（ICC > 0.88）和近乎完美的CPAK一致性（κ = 0.86 - 0.88）测量结果，且未改变总体CPAK表型分类。与X线片相比，基于CT的测量为冠状位对线参数提供了更高的精度和可重复性。然而，CPAK分类在不同检查方式之间基本保持一致，验证了其在各种成像技术中的稳健性。CT为术前规划提供了精确数值，尤其是在机器人辅助工作流程或复杂畸形的情况下，而X线片对于常规表型分析仍然足够。二级 - 前瞻性比较研究。
