以黏彈生物力學特性量化評估踝關節之穩定性

Abstract

背景：踝關節內翻扭傷(以下簡稱扭傷)是一種運動與日常生活中很常見的傷害。扭傷後，有很大比例的病人會產生長期的後遺症，除了造成患者的困擾，長期就診與治療之下也造成龐大的醫療成本支出與國家的負擔。為了治療、減緩與預防後遺症的發生，在受傷之初施予正確的診斷和治療是很重要的。踝關節前拉測試(以下簡稱前拉測試)是一種常見的臨床診斷技術，目的是用來診斷扭傷造成之踝關節外側韌帶受傷。雖然行之有年，但時至今日它的效用仍然有許多爭議。傳統上，前拉測試的原理是根據韌帶受傷後的彈性變化做為診斷的依據。然而，韌帶等生物組織不只有彈性，而是同時具有黏性和彈性，且根據過去的研究，受傷會使這些黏彈特性產生變化。我們認為藉由前拉測試的概念量測並量化踝關節之黏彈特性，將有潛力發展成一種新的量化評估踝關節外側韌帶受傷的技術。 目的：本研究之目的為：(1)以前拉測試的概念為基礎，發展一套非侵入式量測並量化踝關節黏彈特性的技術；(2)研究此技術的量測重複性和可靠度；(3)研究扭傷與未扭傷之踝關節的黏彈特性差異；(4)研究踝關節黏彈特性和受試者本體之功能穩定性的關係。 方法：15位單一踝關節扭傷的病人與15位近期無任何踝關節傷害與症狀的控制組受試者參與本研究。其中任選三位受試者做可靠度測試。在臨床測試中，每位受試者的兩隻踝關節皆接受量測。我們定義黏性指數以做為量化評估踝關節黏性的指標；黏性指數愈大，黏性愈低。踝關節之彈性以剛性評估。功能穩定性以CAIT量表評估；CAIT分數愈低，功能穩定性愈不好。我們量測受傷和未受傷踝關節的這三個指標，並以統計方法分析它們的差異。斯皮爾曼相關係數用來評估踝關節黏彈特性和功能穩定性的關係。 結果：我們發展的技術呈現良好的可靠度(r > 0.9)。受傷踝關節的黏性指數明顯比未受傷的大(6,351 ± 5,003比上1,163 ± 778; p < 0.001)，表示受傷踝關節的黏性明顯較低。另外受傷踝關節的CAIT分數明顯比未受傷的低(13.3±4.3比上24.9 ± 4.1; p < 0.001)，表示受傷踝關節的功能穩定性明顯較差。我們也發現，黏性指數和CAIT分數呈現中度的負相關性，相關係數為-0.655 (p < 0.001)。在剛性的部分，受傷和未受傷踝關節之間沒有顯著的差異。 結論：我們發現，藉由量化踝關節的黏彈特性並以其做為生物標記，我們可以成功區分受傷和未受傷的踝關節，因為受傷踝關節的黏性比未受傷的明顯低很多。另外，具有較低黏性的受傷腳比起具有較高黏性的未受傷腳，有明顯較差的功能穩定性。我們進一步發現，踝關節黏性和功能穩定性有中度的相關性。根據本研究的發現，我們相信量化踝關節的黏彈特性除了有潛力做為一種新的量化診斷踝關節外側韌帶受傷嚴重程度的技術，也可以做為一種輔助評估病人本體功能穩定性的臨床工具。

Background: Inversion ankle sprain is an important healthy problem. For medical and economic reasons, it is important to correctly evaluate the initial injury to better ensure for the proper diagnosis and treatment, and to help prevent further complications. The anterior drawer test is a common clinical examination to evaluate lateral ankle ligament injures following inversion ankle sprain. However its value is still controversial. Biological tissues such as ligaments exhibit viscoelastic behaviors. Injury to the ligament may induce changes of these viscoelastic properties. We hypothesize that to evaluate the viscoelastic properties of the ankle by the anterior drawer test may raise another way of assessing lateral ankle ligament injuries objectively. Purposes: The purposes of this study are to: (1) develop an instrument to perform the anterior drawer test for noninvasive evaluation of the viscoelastic properties of the ankle quantitatively in vivo; (2) investigate the reliability of the instrument; (3) compare the viscoelastic properties of the ankle between patients suffering from inversion ankle sprain and controls; (4) investigate the relationship between the viscoelastic properties of the ankle and the subjective feelings of the patient. Methods: 15 patients with unilateral inversion ankle sprain and 15 controls participated in this study. The reliability test was performed on three randomly chosen subjects. In patient and control test, both ankles of each subject were tested. The viscoelastic properties of the ankle were measured by the instrument. The viscosity index was defined to evaluate the ankle viscosity; larger the viscosity index was associated with lower ankle viscosity. The stiffness was used to evaluate the ankle elasticity; larger the stiffness was associated with stronger ankle elasticity. The severity of functional ankle instability (FAI) was evaluated by the Cumberland Ankle Instability Tool (CAIT) questionnaire; less the CAIT score was associated with more severe instability. Injured ankles of patients and uninjured ankles of both groups were compared by the Wilcoxon signed-rank test and the Mann-Whitney U test. The spearman’s rank correlation coefficient was applied to determine the relationship between the viscoelastic properties of the ankle and the severity of FAI. Results: The instrument was shown to be reliable (r > 0.9). Injured ankles of patients had significantly larger viscosity index (6,351 ± 5,003 versus 1,163 ± 778; p < 0.001) and less CAIT score (13.3±4.3 versus 24.9 ± 4.1; p < 0.001) compared with uninjured ankles of both groups. There was a moderate relationship between the viscosity index and the CAIT score with a correlation coefficient -0.655 (p < 0.001). No significant difference in the stiffness could be found among all ankles of both groups. Conclusion: In this study, injured ankles were successfully differentiated from uninjured ankles by analyzing the viscoelastic properties of the ankle quantitatively. Specifically, injured ankles exhibited significantly less viscous than uninjured ankles. We believed that the viscoelastic properties of the ankle can serve as sensitive and useful clinical biosignatures to differentiate between injured and uninjured ankles. In addition, injured ankles of patients with less viscosity exhibited significantly more severe FAI than uninjured ankles of both groups with more viscosity. There is a moderate relationship between the ankle viscosity and the severity of FAI. These findings reveal that, the reliable instrument studying the viscoelastic properties of the ankle not only may provide a clinical examination for objectively assessment of the severity of lateral ankle ligament injuries, but also may provide a clinical tool for assisting in quantifying the severity of FAI.