Department of Orthopaedic Surgery, National University Health System, Singapore.
Phys Sportsmed. 2024 Oct;52(5):492-496. doi: 10.1080/00913847.2024.2315012. Epub 2024 Feb 9.
The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT).
A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a 'J-sign' evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour's classification, femoral sulcus angle, trochlear groove depth, and Wiberg's classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination.
Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign ( = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign ( = 0.01).
Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.
J 征是一种评估髌骨外侧移位的临床评估工具，如果在伸展时观察到髌骨的外侧平移呈倒置 J 形，则认为其为阳性。本研究旨在确定临床 J 征与动态运动学计算机断层扫描（DKCT）上观察到的影像学特征之间的关联。
通过回顾 2005 年 1 月 1 日至 2016 年 12 月 31 日在一家机构进行 CT 髌骨轨迹扫描的所有 18 岁或以下患者的临床记录，进行了回顾性研究。纳入了评估临床 J 征阳性或阴性的患者。使用轴位切片评估的影像学参数包括髌骨倾斜角、髌骨吻合角、Dejour 分类、股骨滑车沟角、滑车沟深度和 Wiberg 分类。然后根据临床检查中 J 征的存在与否将患者分为两组。然后分析放射学测量值与临床检查中 J 征的存在与否的相关性。
与临床检查中 J 征阴性的患者（分别为 18.3°±10.8°和 32.1°±20.8°）相比，J 征阳性患者的髌骨倾斜角为 23.3°±14.2°，髌骨吻合角为 47.1°±28.5°。（ = 0.024 和 0.004）。在膝关节完全伸展和 20°屈曲时比较吻合角的变化，也显示 J 征阳性患者的变化明显更高，为 28.0°±20.4°，而 J 征阴性患者的变化为 11.9°±17.5°。J 征阳性患者的 TT-TG 距离也增加到 17.6 ± 5.6 mm，而 J 征阴性患者的 TT-TG 距离为 14.7 ± 6.9 mm（ = 0.01）。
在伸展时测量时，J 征阳性患者的髌骨倾斜度和髌骨吻合角增加。TT-TG 距离的增加也与 J 征阳性显著相关。在膝关节完全伸展和 20°屈曲时测量时，J 征阳性患者的髌骨吻合角变化也更大。
