Purpose

To evaluate the effect of joint line obliquity of the knee on intrasubstance degeneration of isolated medial meniscus horizontal cleavage tear (HCT) in young patients.

Methods

Sixty knees of 50 patients aged < 40 years (mean age, 33.3 ± 5.5 years old), who underwent arthroscopic partial meniscectomy (APM) for HCT, were retrospectively reviewed. The radiologic parameters of alignment, including mechanical hip-knee-ankle (mHKA) angle, posterior tibial slope, and joint line obliquity, were measured on preoperative long-standing whole-leg radiographs. The patients were classified into two groups, simple horizontal type (type 1) and complicated type (type 2), according to the presence of diffuse intrasubstance degeneration of the meniscus on preoperative magnetic resonance imaging. The risk factors for intrasubstance degeneration of HCT were analyzed using multiple logistic regression analysis. Medial joint space width (JSW) on weight-bearing 45° flexion posteroanterior radiographs and the mHKA were measured to evaluate the radiographic outcomes. The clinical outcomes were evaluated using the modified Lysholm score. Among patients followed-up for > 5 years, the clinical and radiologic outcomes were compared between the two groups.

Results

The joint line obliquity was significantly greater in the type 2 group than in the type 1 group (2.9 ± 1.3 vs. 0.9 ± 1.4, P < 0.001), and a significant risk factor for diffuse intrasubstance degeneration (P < 0.001; odds ratio, 2.88; 95% confidence interval, 1.27–6.54). The relative changes in the JSW in the type 2 group were greater than those in the type 1 group during the mean follow-up period of 7.9 ± 2.5 years (26% vs 10%, P = 0.045). The modified Lysholm score was not significantly different between the two groups (n.s).

Conclusion

The diffuse intrasubstance degeneration of medial meniscus HCTs in young patients is associated with increased joint line obliquity of the knee joints. The radiologic outcomes after APM were inferior in the patients with diffuse intrasubstance degeneration. However, the clinical outcomes were not different during the mid-term follow-up.

Level of evidence

Level III.

中文翻译：

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青年患者内侧半月板水平劈裂撕裂的物质内变性与膝冠状面关节线倾斜度增加有关。

目的

为了评估膝关节倾斜度对年轻患者中分离的内侧半月板水平劈裂撕裂（HCT）物质内变性的影响。

方法

回顾性分析了50例年龄<40岁（平均年龄，33.3±5.5岁）的患者，他们接受了关节镜下部分半月板切除术（APM）进行的HCT检查。在术前长期站立的全腿X线片上测量了放射学参数，包括机械性髋膝膝踝（mHKA）角，胫骨后斜度和关节斜度。根据术前磁共振成像中弯液面弥散性物质内变性的存在，将患者分为简单水平型（1型）和复杂水平型（2型）两类。使用多元逻辑回归分析分析了HCT体内物质变性的危险因素。承重45°屈曲后前X线片和mHKA的内侧关节间隙宽度（JSW）被测量以评估X线片的结果。使用改良的Lysholm评分评估临床结局。在随访超过5年的患者中，比较了两组的临床和影像学结果。

结果

2型组的关节斜度明显高于1型组（2.9±1.3 vs. 0.9±1.4，P  <0.001），并且是弥散性物质内变性的重要危险因素（P  <0.001;优势比， 2.88； 95％置信区间1.27-6.54）。在7.9±2.5年的平均随访期内，2型组JSW的相对变化大于1型组（26％比10％，P  = 0.045）。修改后的Lysholm评分在两组之间无显着差异（ns）。

结论

年轻患者内侧半月板HCT的弥散性物质内变性与膝关节的关节线倾斜度增加有关。弥散性物质内变性患者的APM放射学结果较差。但是，中期随访期间的临床结局没有差异。

证据水平

第三级。