In Different Gender Groups, What Is the Impact of the Fibular Notch on the Severity of High Ankle Sprain: A Retrospective Study of 360 Cases

Abstract

Objectives: The role of the distal tibiofibular ligament in the occurrence of high ankle sprain (HAS) has been widely studied. But previous studies have overlooked the physiological and anatomical differences between males and females and have not further refined gender. Therefore, the impact of the anatomical morphology of fibular notch (FN) on HAS in different genders is still unclear. This study aimed to explore the impact of different types of FN on the severity of HAS and to estimate the prognosis of patients with HAS while excluding anatomical differences caused by gender.

Methods: One hundred and eighty patients with HAS were included in this study as the experimental group (i.e., HAS group). They were further divided into four groups according to gender and FN depth, with deep concave FN ≥ 4 mm and shallow flat FN < 4 mm. Another 180 normal individuals were set as the control group. The FN morphological indicators, tibiofibular distance (TFD), and ankle mortise indexes were measured and compared with those in HAS group. The independent t-test was used to compare continuous variables between groups, the intraclass correlation coefficient (ICC) was used to analyze the reliability of intra-observer measurement, and the Pearson correlation coefficient was used to verify the correlation between FN and the severity of HAS.

Results: In males with shallow flat type, the measurements of anterior tibiofibular distance (aTFD), middle tibiofibular distance (mTFD), posterior tibiofibular distance (pTFD), front ankle mortise width (fAMW), middle ankle mortise width (mAMW), posterior ankle mortise width (pAMW), and depth of ankle mortise (DOAM) in HAS group were significantly larger than those in normal group (p < 0.05). In male patients with deep concave type, the measurements of aTFD, mTFD, fAMW, mAMW, and DOAM were significantly larger than those in normal group (p < 0.05). Among female patients with shallow flat type, the measurements of aTFD, mTFD, pTFD, fAMW, mAMW, pAMW, and DOAM were found to be significantly larger than those in normal group (p < 0.05). Among female patients with deep concave type, the measurements of mTFD, pTFD, fAMW, mAMW, and DOAM were found to be significantly larger than those of the normal group (p < 0.05). The depth of FN was negatively correlated with TFD, and the AOFAS score of patients with shallow flat type was significantly lower than that of patients with deep concave type after treatment (p < 0.05).

Conclusions: In different gender groups, compared with the normal controls, the TFD and partial ankle mortise indices were significantly different in HAS patients. Moreover, FN depth was negatively correlated with TFD, and the AOFAS score of shallow flat patients was significantly lower than that of deep concave patients. These suggested that shallow flat FN may be associated with more severe distal tibiofibular ligament injury and ankle mortise widening, leading to poorer prognosis. This should be taken seriously in clinical practice.

Keywords: Ankle Mortise; Distal Tibiofibular Syndesmosis; Fibular Notch; High Ankle Sprain; Tibiofibular Distance.

FIGURE 1

Measurement of fibular notch (FN)‐related morphological parameters. (A) Axial CT section proximal to the 10 mm above the tibial plafond. (B) The deep concave type of FN. A, the deepest point at the FN; FN Depth: Distance from the point A to the nearest point on the tangent between the tip of the anterior tibial tubercle and the tip of the posterior tibial tubercle. (C) The shallow flat type of FN. (D) tibiofibular distance (TFD): Anterior tibiofibular distance (aTFD): A, the anterior border of the fibula; the distance between the point A and the nearest perpendicular point from point A on anterior tibial tubercle. Middle tibiofibular distance (mTFD): B, the deepest point at the incisura, the distance between the point B and the nearest point from point B on the fibula. Posterior tibiofibular distance (pTFD): C, the medial border of the fibula; the distance between the point C and the nearest perpendicular point from point C on the lateral border of the posterior tibial tubercle.

FIGURE 2

Measurement of ankle mortise indexes. (A) Depth of ankle mortise (DOAM): The distance between the anterior and posterior malleolus in the sagittal plane. Ankle mortise width (AMW): (B) Axial CT section proximal to the tangential plane to both dome of the talus. (C) A, the middle points of the medial malleoli; B, the middle points of the lateral malleoli; Front ankle mortise width (fAMW): Draw a tangent line (A) of medial malleolus through point A and a tangent line (B) of lateral malleolus through point B; Draw a tangent of tibia parallel to AB and intersect with tangents a and b at two points C and D, and CD is fAMW. Middle ankle mortise width (mAMW): between point A and point B. Posterior ankle mortise width (pAMW): Draw a tangent line of the posterior ankle parallel to AB, intersect with tangent lines a and b at two points E and F, and EF is the pAMW.