Background

Chronic idiopathic patellofemoral pain is associated with patellar maltracking in both adolescents and adults. To accurately target the underlying, patient-specific etiology, it is crucial we understand if age-of-pain-onset influences maltracking.

Methods

Twenty adolescents (13.9 ± 1.4 years) and 20 adults (28.1 ± 4.9 years) female patients with idiopathic patellofemoral pain (age-of-pain-onset: < 14 and > 18 years of age, respectively) formed the patient cohort. Twenty adolescents and 20 adults (matched for gender, age, and body mass index) formed the control cohort. We captured three-dimensional patellofemoral kinematics during knee flexion-extension using dynamic MRI. Patellar maltracking (deviation in patient-specific patellofemoral kinematics, relative to their respective age-controlled mean values) was the primary outcome measure, which was compared between individuals with adolescent-onset and adult-onset patellofemoral pain using ANOVA and discriminant analysis.

Findings

The female adolescent-onset patellofemoral pain cohort demonstrated increased lateral (P = 0.032), superior (P = 0.007), and posterior (P < 0.001) maltracking, with increased patellar flexion (P < 0.001) and medial spin (P = 0.002), relative to the adult-onset patellofemoral pain cohort. Post-hoc analyses revealed increased lateral shift [mean difference ± 95% confidence interval = −2.9 ± 2.1 mm at 10° knee angle], posterior shift [−2.8 ± 2.1 mm, −3.3 ± 2.3 mm & -3.1 ± 2.4 mm at 10°, 20°& 30°], with greater patellar flexion [3.8 ± 2.6 mm & 5.0 ± 2.8 mm, at 20°& 30°] and medial spin [−2.2 ± 1.7 mm & -3.4 ± 2.3 mm at 20°& 30°]. Axial-plane maltracking accurately differentiated the patient age-of-pain-onset (60–75%, P < 0.001).

Interpretation

Age-of-pain-onset influences the maltracking patterns seen in patients with patellofemoral pain; with all, but 1, degree of freedom being unique in the adolescent-onset-patellofemoral pain cohort. Clinical awareness of this distinction is crucial for correctly diagnosing a patient's pain etiology and optimizing interventional strategies.

中文翻译：

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患有髌股疼痛的青少年和成人表现出明显的髌骨轨迹不良模式

背景

慢性特发性髌股疼痛与青少年和成人的髌骨运动轨迹不良有关。为了准确定位潜在的、患者特异性的病因，我们必须了解疼痛发作年龄是否会影响追踪不良。

方法

20 名患有特发性髌股疼痛的青少年（13.9 ± 1.4 岁）和 20 名成人（28.1 ± 4.9 岁）女性患者（疼痛发病年龄分别为 < 14 岁和 > 18 岁）组成了患者队列。20 名青少年和 20 名成年人（性别、年龄和体重指数相匹配）组成了对照组。我们使用动态 MRI 捕获了膝关节屈伸过程中的三维髌股运动学。髌骨轨迹不良（患者特异性髌股运动学相对于各自年龄控制平均值的偏差）是主要结果指标，使用方差分析和判别分析对青少年发病和成人发病的髌股疼痛个体进行比较。

发现

女性青少年发病的髌股疼痛队列表现出外侧 ( P  = 0.032)、上侧 ( P  = 0.007) 和后侧 ( P  < 0.001) 跟踪不良增加，髌骨屈曲 ( P  < 0.001) 和内侧旋转 ( P = 0.002），相对于成人发病的髌股疼痛队列。事后分析显示横向移位增加[平均差±95%置信区间=-2.9±2.1毫米在10°膝角]，后移[-2.8±2.1毫米，-3.3±2.3毫米和-3.1±2.4毫米在10°膝角] 10°、20°和30°]，具有更大的髌骨屈曲[3.8 ± 2.6 mm和5.0 ± 2.8 mm，在20°和30°]和内侧旋转[−2.2 ± 1.7 mm和-3.4 ± 2.3 mm在20° & 30°]。轴平面追踪不良准确地区分了患者的疼痛发作年龄（60-75%，P  < 0.001）。

解释

疼痛发作年龄影响髌股疼痛患者的轨迹失调模式；除 1 外，所有的自由度在青少年发作的髌股疼痛队列中都是独一无二的。临床对这种区别的认识对于正确诊断患者的疼痛病因和优化介入策略至关重要。