Background Previous studies have shown a wide range of anatomical classifications of the subtalar joint (STJ) in the population and this is related to the different force line structures of the foot. Different subtalar articular surface morphology may affect the occurrence and development of flat foot deformity, and there are fewer studies in this area. The main objective of our study was to determine the association of different subtalar articular surface with the occurrence and severity of flat foot deformity. Methods We analyzed the imaging data of 289 cases of STJ. The articular surface area, Gissane’s angle and Bohler’s angle of subtalar articular surface of different types were counted. The occurrence and severity of flat foot deformity in different subtalar articular surface were judged by measuring the Meary angle of foot. Results We classified 289 cases of subtalar articular surface into five types according to the morphology. According to Meary angle, the flat foot deformity of Type I and Type IV are significantly severer than Type II (P < 0.05). Type II (7.65 ± 1.38 cm2) was significantly smaller than Type I (8.40 ± 1.79 cm2) in the total joint facet area(P < 0.05). Type III (9.15 ± 1.92 cm2) was smaller than Type I (8.40 ± 1.79 cm2), II (7.65 ± 1.38 cm2) and IV (7.81 ± 1.74 cm2) (P < 0.05). Type II (28.81 ± 7.44∘) was significantly smaller than Type I (30.80 ± 4.61 degrees), and IV (32.25 ± 5.02 degrees) in the Bohler’s angle (P < 0.05). Type II (128.49 ± 6.74 degrees) was smaller than Type I (131.58 ± 7.32 degrees), and IV (131.94 ± 5.80 degrees) in the Gissane’s angle (P < 0.05). Conclusions After being compared and analyzed the measurement of morphological parameters, joint facet area and fusion of subtalar articular surface were closely related to the severity of flat foot deformity and Type I and IV were more likely to develop severer flat foot deformity. Level of evidence Level III, retrospective comparative study.

Objective: Due to the different force exerted during the posterior malleolus fracture (PMF), the difference in sagittal angle (SA) between the fracture fragments may affect ankle stability. But this aspect is less well studied and the aim of this study was to investigate the relationship between SA and the stability of PMF. Methods:The imaging data of 120 patients with PMFs from January 2014 to November 2022 were collected retrospectively and reconstructed. We first measured SA, posterior fragment area (PFA) and fragment area ratio (FAR), reanalyzing the correlation of SA with PFA and FAR, respectively. To better describe the morphological characteristics of the fracture fragments, we further measured the fragment width diameter ratio (FWR), the fragment length ratio (FLR), fragment height (FH), contact area (CA), and finally carried these data into the regression model of SA versus FAR to conduct the intermediary role.Results: SA was negatively correlated with PFA(s) (r = À0.583, P < 0.001), with regression equation s = À0.063SA + 3.066; SA was negatively correlated with FAR (r = À0.204, P < 0.05), with regression equation FAR = À0.002SA + 0.198; A significant correlation was found between FWR, FLR, FH, CA and SA (P < 0.05), as well as between FWR, FLR, FH and FAR (P < 0.05); Further intermediary role analysis showed that FWR, FLR, FH had a partial intermediary role between SA and FAR. Conclusions:As SA increased, PFA and FAR decreased, so the larger the SA was due to the effect of vertical shear force, reflecting higher ankle stability, meanwhile, FWR, FLR and FH should also be considered on the fixation method of fracture fragments.

Background: The function of the distal tibiofibular ligament on the ankle in the occurrence of high ankle sprain (HAS) has been widely studied. Then, in different genders, the effect of the anatomical morphology of fibular notch (FN) on HAS is unclear. Therefore, on the basis of excluding the anatomical differences caused by gender, we explore the impact of different types of FN on the severity of HAS.Methods: We selected 120 patients and further classified these 120 patients into four HAS groups according to FN depth with deep concave type FN ≥ four mm and shallow flat type FN < four mm. A further 120 normal individuals were served as a control group. FN morphological indicators, tibiofibular distance (TFD), and ankle mortise indexes were measured and compared between patients and control groups.Results: In males with shallow flat type, the Anterior tibiofibular distance (aTFD), Middle tibiofibular distance (mTFD), Posterior tibiofibular distance (pTFD), Front tibial width (FTiW), Middle tibial width (MTiW), Posterior tibial width (PTiW) and Depth of ankle mortise (DOAM) of HAS group were higher than those in normal group (P < 0.05). In males with deep concave type, the aTFD, mTFD and DOAM of patients were significantly higher (P < 0.05). Among females with shallow flat type, the aTFD, mTFD, pTFD, FTiW and MTiW in HAS group were greater than those in normal group (P < 0.05). Among the females with deep concave type, the mTFD and pTFD of patients were higher (P < 0.05).Conclusions: After analyzing the morphological indicators of FN, it is found that in both males and females, HAS patients have significant differences in TFD and certain ankle mortise indexes compared with normal people. But more importantly, the above abnormalities are often more common in HAS patients with shallow flat FN, indicating that shallow flat FN may be related to more serious distal tibiofibular ligament injury and ankle mortise widening, resulting in a worse prognosis.Level of evidence: Level III, retrospective comparative study.

Background To search for a method of accurate transosseous tunnel drilling for the distal tibiofibular syndesmosis based on three-dimensional (3D) printing technology to design a guide design and to assess its veracity. Methods CT scan and MRI data of 150 patients with distal tibiofibular syndesmosis injury in the Affiliated Hospital of traditional Chinese medicine of Southwest Medical University were selected. Using Mimics software to reconstruct inferior tibiofibular syndesmosis CT data. Design 2 The non-collinear tunnel is superimposed on the three-dimensional model, and a virtual drilling is performed between the tibia and the fibula using a double inner gusset. Then, in the Geomagic Studio software model, an elliptical plane is calculated and extracted as a guide design for precise drilling. Then put the design and the 3D inferior tibiofibular syndesmosis model together for 3D printing. 8 parameters were measured, and the effects of the virtual model and the actual model and the guide rail design were compared. Results We compared 8 parameters of the 3D virtual model and actual model successfully. No differences were significantly found between the real and virtual bone tunnels in measurements. (P > 0.05). Conclusions The veracity of transosseous tunnel placement for distal tibiofibular syndesmosis reconstruction combined with 3D printing guide design technology in the distal tibiofibular syndesmosis is reliable.

Background Previous studies have shown a wide range of anatomical classifications of the subtalar joint (STJ) in the population and this is related to the different force line structures of the foot. Different subtalar articular surface morphology may affect the occurrence and development of flat foot deformity, and there are fewer studies in this area. The main objective of our study was to determine the association of different subtalar articular surface with the occurrence and severity of flat foot deformity. Methods We analyzed the imaging data of 289 cases of STJ. The articular surface area, Gissane's angle and Bohler's angle of subtalar articular surface of different types were counted. The occurrence and severity of flat foot deformity in different subtalar articular surface were judged by measuring the Meary angle of foot. Results We classified 289 cases of subtalar articular surface into five types according to the morphology. According to Meary angle, the flat foot deformity of Type Ⅰ and Type Ⅳ are significantly severer than Type Ⅱ (P < 0.05). Type II (7.65 ± 1.38 cm2) was significantly smaller than Type I (8.40 ± 1.79 cm2) in the total joint facet area(P < 0.05). Type III (9.15 ± 1.92 cm2) was smaller than Type I (8.40 ± 1.79 cm2), II(7.65 ± 1.38 cm2) and Ⅳ(7.81 ± 1.74 cm2 ) (P < 0.05).Type II (28.81 ± 7.44∘) was significantly smaller than Type I (30.80 ± 4.61 degrees), and IV (32.25 ± 5.02 degrees) in the Bohler’s angle (P < 0.05). Type II (128.49 ± 6.74 degrees) was smaller than Type I (131.58 ± 7.32 degrees), and IV (131.94 ± 5.80 degrees) in the Gissane’s angle (P < 0.05). Conclusions After being compared and analyzed the measurement of morphological parameters, joint facet area and fusion of subtalar articular surface were closely related to the severity of flat foot deformity and Type I and IV were more likely to develop severer flat foot deformity. Level of evidence: Level III, retrospective comparative study.

ObjectivesThe 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.MethodsOne 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.ResultsIn 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).ConclusionsIn 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.

BackgroundPrevious studies have studied more factors on the ankle stability of the posterior ankle fracture, which is related to a stereostructure of the fracture fragment. Previous studies have shown that the ankle stability may be affected by the sagittal surface of the fracture block, with less research in this field. The aim of this study was to explore the influence of the sagittal angle(SA) on ankle joint stability by scanning and reconstructing three types of posterior malleolus fractures(PMFs) with different sagittal angle (SA).MethodsThe CT data of 87 patients with PMFs were collected retrospectively and reconstructed. PMFs were divided into three types: posterolateral-oblique type (type I), medial-extension type (type II) and small-shell type (type III).The collected sagittal angle data were statistically analyzed with the posterior fragment area, fragment area ratio (FAR), fragment transverse diameter ratio (FWR), fragment length ratio (FLR), fragment height (FH), and contact area (CA).Results(1)SA was positively correlated with posterior fragment area(r = 0.804,P < 0.01),with regression equation s = 0.085*SA + 0.34;(2)SA was positively correlated with FAR(r = 0.392,P < 0.01),with regression equation FAR = 0.004*SA + 0.092;(3)SA was positively correlated with FWR(r = 0.261,P < 0.05), with regression equation FWR = 0.03*SA + 0.4624;(4)SA was positively correlated with FLR(r = 0.481,P < 0.01), with regression equation FLR = 0.05*SA + 0.209;(5) SA was positively correlated with CA (r = 0.474, P < 0.01),with regression equation CA = 7.942*SA + 160.866;(6)SA was positively correlated with FH(r = 0.474,P < 0.01), with regression equation FH = 0.046*SA + 1.406.ConclusionThe sagittal angle was positively correlated with posterolateral-oblique type (type I) of Posterior malleolus fractures, and SA could be considered to reflect the ankle joint stability of PMFs.Level of evidence: Level III, retrospective comparative study.