PURPOSE Changes in tendon structure are commonly seen in patients with unilateral achilles (AT) or patellar (PT) tendinopathy but might also be present on the asymptomatic side, indicating a higher risk for developing symptoms. The aim of this study is to compare tendon structure of the symptomatic side with the asymptomatic side in AT and PT patients and control subjects. METHODS A total of 46 patients with unilateral AT (16 insertional and 30 midportion) and 38 with unilateral PT were included. For the control group, a total of 18 Achilles tendons and 25 patellar tendons were scanned. Tendon structure was assessed using ultrasound tissue characterisation (UTC), which quantifies tendon organisation dividing the structure into four different echo types (I-IV). RESULTS There were significant differences in echo types I, III, and IV between symptomatic and asymptomatic sides and controls. Additionally, there was a significant difference between the symptomatic and the asymptomatic side for all tendinopathy locations. In the insertional AT tendon portion, the symptomatic side showed a higher percentage of echo type III. For the midportion AT, the symptomatic side showed a lower percentage of echo type I and a higher percentage of echo types III and IV. For the patellar tendon, the symptomatic side showed a higher percentage of echo types III and IV. All differences were higher than the minimal detectable changes. CONCLUSION Although patients have symptoms unilaterally, the tendon structures are compromised on both sides. These results stress the importance of monitoring both symptomatic and asymptomatic tendon structures and in addition highlight that the asymptomatic side should not be used as reference in clinical practice. LEVEL OF EVIDENCE III.

中文翻译：

---

诊断为单侧插入或中部跟腱病或髌腱病的患者的双侧肌腱结构变化。


目的肌腱结构的变化常见于单侧跟腱 (AT) 或髌骨 (PT) 肌腱病患者，但也可能出现在无症状一侧，表明出现症状的风险较高。本研究的目的是比较 AT 和 PT 患者以及对照受试者有症状侧与无症状侧的肌腱结构。方法 共纳入 46 例单侧 AT 患者（16 例插入型，30 例中部型）和 38 例单侧 PT 患者。对于对照组，总共扫描了 18 根跟腱和 25 根髌腱。使用超声组织表征 (UTC) 评估肌腱结构，该技术可量化肌腱组织，将结构分为四种不同的回声类型 (I-IV)。结果 有症状侧、无症状侧和对照组之间 I、III 和 IV 型回声存在显着差异。此外，所有肌腱病部位的有症状侧和无症状侧之间存在显着差异。在插入 AT 肌腱部分，有症状的一侧显示出较高比例的 III 型回声。对于中部 AT，有症状的一侧显示 I 型回声百分比较低，III 型和 IV 型回声百分比较高。对于髌腱，有症状一侧显示 III 型和 IV 型回声比例较高。所有差异均高于最小可检测变化。结论 虽然患者单侧有症状，但两侧肌腱结构均受损。这些结果强调了监测有症状和无症状肌腱结构的重要性，此外还强调了无症状侧不应在临床实践中用作参考。证据水平 III.