| 제목 |
Comparison of stress methods for the ultrasonographic assessment of ATFL laxity in CAI patients |
| 소속 |
Korea University Guro Hospital, Department of Rehabilitation Medicine1 |
| 저자 |
Sang Rok Woo1*, Hyeok Sung Choi1, Byung Heon Kang1, Hyun Jin Park1, Seok Kang1, Joon Shik Yoon1† |
Background
Anterior talofibular ligament (ATFL) is the most frequently damaged structure in ankle sprains. Injured ATFL often results in chronic ankle instability (CAI) and causes mechanical instability and persistent pain. Several studies have addressed the usefulness of stress ultrasound (US) for the detection of ATFL laxity in CAI patients. However, standard method to apply a stress have not been established yet.
Methods
Ten patients with unilateral CAI were recruited. Inclusion criteria was: (1) recurrent sprain and residual symptoms of pain, instability and giving way for at least 6 months after the first ankle sprain, (2) ankle instability instrument (AII) score ≥ 5/9, (3) no history of ankle injury on the other side. ATFL length was defined as the distance between the bony landmarks of lateral malleolus and talus while identifying the fibrillar pattern of the ligament (Fig. 1a). The US measurement was repeated 3 times for each methods in the following order: (1) neutral; 10’ plantarflexion and 0’ inversion/eversion, (2) manual stress; maximal manual talar tilt to the end-feel, (3) device-parallel; inversion stress via device parallel to the bimalleolar axis, (4) device-rotation; inversion stress via device with leg 45° externally rotated. 125N of force via Telos stress device was applied. The 3 pressure points were at the middle fibula, fifth metatarsal head and the midpoint of them. (Fig. 1b)
Results
The ATFL lengths and ATFL ratio are demonstrated on table 1. In Wilcoxon signed-rank test, ATFL ratio showed significant difference between affected and unaffected side in all the stress methods, but ATFL length showed no statistically significant difference in any position. Analyzed in repeated measures ANOVA, the ATFL lengths and ratio measured in the device-rotation method were significantly greater than the other test conditions in both affected and unaffected sides. The intraclass correlation coefficient (ICC) of single measures were shown on table 2. The intra-rater reliability was higher with stress device compared to the the manual maneuver.
Conclusion
Increased ATFL laxity on the affected side was more clearly identified when the lengths were compared in proportion than in difference. Using the stress device showed more effective ligament elongation and higher intra-rater reliability compared to the manual talar tilting maneuver. Furthermore, the device-rotation position stretched the ligament more than the device-parallel position.
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Table 1. ATFL lengths and ATFL ratio by different methods
Table 2. The intraclass correlation coefficient (ICC) of single measures
Figure 1a (upper). Different positions for US imaging. A: neutral, B: manual stress, C: device-parallel, D: device-rotation. Figure 2b (lower). ATFL length measurement, between the bony prominence of the talus (left) and the lateral malleolus (right)
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