Digennaro V, Cecchin D, Villari E, Panciera A, Ferri R, Benvenuti L, Faldini C
1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, Via G.C. Pupilli 1, 40136 Bologna, Italy.
1st Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, Via G.C. Pupilli 1, 40136 Bologna, Italy.
Knee. 2025 Oct;56:276-284. doi: 10.1016/j.knee.2025.05.035. Epub 2025 Jun 10.
The CPAK classification categorizes coronal knee alignment matching the arithmetic hip-knee-ankle angle and joint line obliquity. While several studies have evaluated alignment variability in different populations, no data exist for the Italian population. This study aims to assess the distribution of CPAK classification in Italian patients undergoing TKA for osteoarthritis, with secondary objectives exploring gender differences and correlations with anthropometric parameters.
A retrospective analysis was conducted on 978 consecutive patients who underwent total knee arthroplasty or unicompartmental knee arthroplasty between May 2016 and April 2024. After excluding 284 patients, 620 patients were included in the study. Mechanical hip-knee-angle, Lateral Distal Femur Ange and Medial Proximal Tibial Angle were measured on long leg radiograph. Arithmetic HKA and Joint Line Obliquity were than calculated and patients were divided into the 9 phenotypes of the CPAK classification.
A total of 620 patients were evaluated: The mean age was 69.3 years. The mean BMI was 28.51. The mean mHKA was -4,63 (SD = 8,19) while the mean aHKA was -0.84° (SD = 5). The mean JLO was 174,18° (SD = 4.58). The three most frequent CPAK phenotypes were I (186; 30%), II (147; 23,7%), and III (126; 20,3%), indicating a prevalence of apex distal joint line obliquity. The most common alignment was varus. Female patients showed a greater tendency for valgus alignment (24,4%) compared to males (13%). No correlation was found between anthropometric parameters and alignment.
The CPAK classification distribution in the Italian osteoarthritic population is consistent to that reported in the literature. Level of evidence Level III.
CPAK分类对与算术髋-膝-踝角和关节线倾斜度相匹配的膝关节冠状位对线进行分类。虽然有几项研究评估了不同人群中的对线变异性，但意大利人群的数据尚不存在。本研究旨在评估接受全膝关节置换术（TKA）治疗骨关节炎的意大利患者中CPAK分类的分布情况，次要目标是探讨性别差异以及与人体测量参数的相关性。
对2016年5月至2024年4月期间连续接受全膝关节置换术或单髁膝关节置换术的978例患者进行回顾性分析。排除284例患者后，620例患者纳入研究。在长腿X线片上测量机械性髋-膝角、股骨远端外侧角和胫骨近端内侧角。然后计算算术髋-膝角（aHKA）和关节线倾斜度（JLO），并将患者分为CPAK分类的9种表型。
共评估620例患者：平均年龄69.3岁。平均体重指数（BMI）为28.51。平均机械性髋-膝角（mHKA）为-4.63（标准差=8.19），而平均算术髋-膝角（aHKA）为-0.84°（标准差=5）。平均关节线倾斜度（JLO）为174.18°（标准差=4.58）。三种最常见的CPAK表型为I（186例；30%）、II（147例；23.7%）和III（126例；20.3%），表明顶点远端关节线倾斜度占优势。最常见的对线是内翻。女性患者与男性患者（13%）相比，外翻对线倾向更大（24.4%）。未发现人体测量参数与对线之间存在相关性。
意大利骨关节炎人群中CPAK分类分布与文献报道一致。证据级别：III级。
