DeAngelis Joseph P, Anderson Richard, DeAngelis Nicola A
University of Connecticut, Department of Orthopaedic Surgery, MARB, 4th Floor, Farmington, CT 06032, USA.
Foot Ankle Int. 2007 Apr;28(4):490-3. doi: 10.3113/FAI.2007.0490.
The width of the medial clear space often is used to determine the integrity of the deltoid ligament, the primary medial stabilizer of the ankle joint. The normal clinical relationship of the superior clear space to the medial clear space is not well described. This investigation sought to determine if the superior clear space constitutes an accurate point of comparison for the medial clear space and a means for assessing ligamentous stability in an adult ankle.
A retrospective review of consecutive ankle radiographs for a 4-month period of time was completed using a university-based radiology database. Using a digitally calibrated ruler, the widths of the medial and superior clear spaces were measured on the mortise view. These values were compared using a Student's t-test.
Digital radiographs of 564 consecutive ankles were reviewed retrospectively and 94 cases were without evidence of trauma, surgery, or degenerative disease. The medial and superior clear spaces were measured on the mortise view and found to be 2.7 mm (standard deviation 0.5; range 1.3 mm to 4.3 mm; 95% confidence interval 1.7 mm to 3.8 mm) and 3.6 mm (standard deviation 0.6; 2.0 to 5.3; CI 2.4 mm to 4.7 mm), respectively. The average absolute difference was 0.9 mm (standard deviation 0.5; -0.7 to 1.5; CI -0.1 mm to 1.8 mm) and in 92 of 94 ankles (98%), the superior clear space was greater than or equal to the medial clear space.
Understanding the normal radiographic relationship of the superior and medial clear spaces may help in the diagnosis of ligamentous instability in the ankle and may obviate the need for additional diagnostic tests.
内侧间隙的宽度常被用于确定三角韧带（踝关节主要的内侧稳定结构）的完整性。关于上间隙与内侧间隙的正常临床关系，目前尚无详尽描述。本研究旨在确定上间隙是否可作为内侧间隙的准确对照点，以及是否可作为评估成人踝关节韧带稳定性的一种方法。
利用大学放射科数据库，对连续4个月的踝关节X线片进行回顾性研究。在踝关节正位片上，使用数字校准尺测量内侧间隙和上间隙的宽度。采用学生t检验对这些数值进行比较。
回顾性分析了564例连续踝关节的数字X线片，其中94例无创伤、手术或退行性疾病的证据。在踝关节正位片上测量内侧间隙和上间隙，结果分别为2.7毫米（标准差0.5；范围1.3毫米至4.3毫米；95%置信区间1.7毫米至3.8毫米）和3.6毫米（标准差0.6；2.0至5.3；置信区间2.4毫米至4.7毫米）。平均绝对差值为0.9毫米（标准差0.5；-0.7至1.5；置信区间-0.1毫米至1.8毫米），在94例踝关节中的92例（98%）中，上间隙大于或等于内侧间隙。
了解上间隙和内侧间隙的正常影像学关系，可能有助于踝关节韧带不稳定的诊断，并可能无需进行额外的诊断检查。
