Distal spiral TSFs are a unique type of TSF that are considered caused by indirect rotational forces and are associated with ankle fractures [4, 5]. Most previous studies have focused on the association between PMFs and TSFs. In 1988, Bostman first reported 5 cases of PMFs among a cohort of 527 patients with TSFs on the basis of radiographs [2]. Subsequent investigations have focused on the association between PMF and TSF, revealing a significant correlation between PMF and distal spiral TSF [7, 8, 15, 25]. Concurrently, the utilization of advanced CT scans and even additional MRI for ankle fracture evaluation has led to an increase in the detection of occult PMFs [4, 9, 17, 26, 27]. A systemic review conducted by Wang et al. reported that the incidence of PMF in TSF patients was 25.5% (range 7.2–47.9%), whereas the incidence of PMF in patients with distal spiral tibial fractures was 70.4% (range 35.7–92.3%) [14]. In our study, the incidence of PMFs in patients with distal spiral TSFs was 70.3%, which is comparable to that reported in previous studies. We further found that 71.1% of PMFs were Bartonicek type 4 fractures, suggesting an axial loading force in the occurrence of PMF in patients with distal spiral TSFs in addition to an indirect rotational force [4, 11, 15, 26].

In addition to PMFs, distal spiral tibial fractures can be associated with other malleolar fractures, including LMFs, MMFs, and AITFL avulsion fractures [28]. The incidence of concomitant malleolar fractures in patients with distal spiral TSFs ranges from 69% to 89.1% [13, 16, 17]. Reports on the specific incidence and combination types of concomitant malleolar fractures in patients with distal spiral TSFs are still lacking [4, 11, 15, 16]. Jung reported 47 ankle injuries among 71 TSFs, which could have comprised any combination of PMFs, AITFL avulsion fractures, and LMFs, and observed only one atypical MMF in combination with a PMF; however, such incidence and combination types were not reported in patients with distal spiral TSFs [16]. Stuermer reported 47 coinjuries of the ankle joint among 38 distal spiral TSFs, but the combination types were not reported [15]. Warner reported 11 cases of ankle injuries in patients with distal spiral TSFs on the basis of MRI; these injuries included PMFs, MMFs, and AITFL avulsion fractures, but LMF was not included in the analysis [17]. Suzuki also reported the incidence and features of concomitant ankle fractures in in patients distal spiral TSFs but performed a separate analysis of LMFs [4]. As the lateral malleolus is involved in the stability of the ankle joint, we considered it necessary to include LMFs and comprehensively analyse the incidence and combination types of concomitant malleolar fractures in patients with distal spiral tibial fractures. We found that the incidence of malleolar fractures in patients with distal spiral TSFs was 89.1%, and these fractures may have involved one site (50%) or multiple sites (39.1%). Among the 25 patients with multiple fractures, 8 patients had PMFs, LMFs, and AITFL avulsion fractures, and one patient had a quandrimalleolar fracture in which the stability of the ankle joint was almost destroyed (Figure 1) [29]. These findings suggest that the concomitant malleolar fractures are complex in patients with distal spiral TSFs. Moreover, the high incidence of Weber C LMFs, Bartonicek type 4 PMFs and Rammelt II AITFL avulsion fractures suggested that the ankle stability was compromised. These results emphasize the importance of thoroughly evaluating the ankle joint in patients with distal spiral TSFs to avoid misdiagnosis of the contaminant fractures.

Wang et al. evaluated risk factors for PMFs in patients with distal spiral tibial fractures and reported that age, external rotation of the proximal tibia and spiral fibula fractures were independent risk factors, whereas osteoporosis was an independent protective factor in multivariate analysis [20]. To our knowledge, there is currently no research on the risk factors for concomitant malleolar fractures in individuals with distal spiral tibial fractures. We found that age was associated with the number of concomitant malleolar fracture sites and was particularly associated with LMFs and AITFL avulsion fractures. In addition, proximal fibula fractures are considered associated with ankle fractures in cases of TSF [5, 12]. However, despite the high incidence of proximal fibula fractures, these injuries were not associated with any malleolar fractures. This may have been because our study population was limited to patients with distal spiral TSFs, not TSFs. We found that fibula fractures at the same level were associated with more severe tibial spiral fractures, suggesting that direct trauma may be associated with these distal spiral TSFs.

This study has several limitations. First, the sample size was relatively small. This is partly due to the selection of distal spiral tibial fractures for investigation; therefore, patients with TSFs caused by direct trauma were excluded. Future studies should increase the sample size to improve the reliability and applicability of the present findings. Second, the analysis was based on CT scans, whereas MRI was not routinely performed in these cases. As CT scans have limitations in assessing soft tissue injury, the use of MRI may allow for a more precise evaluation of soft tissue injuries such as those of the deltoid ligament. Finally, we did not comprehensively investigate the risk factors for concomitant malleolar fractures in patients with distal spiral TSFs. Further study should consider a broader range of potential risk factors, such as personal habits, lifestyle, and level of physical activity of the patients, to facilitate a more thorough assessment for risk factors.

In conclusion, we found that distal spiral TSFs are strongly associated with malleolar fractures. Concomitant malleolar fractures can be complex, and these patients often exhibit compromised ankle stability. Therefore, a comprehensive evaluation of the ankle joint is important when treating individuals with distal spiral TSFs. A CT scan of the ankle joint is crucial for avoiding misdiagnosis of concomitant malleolar fractures and the potential need for additional fixation of these fractures. Elderly patients are at increased risk for sustaining multiple malleolar fractures, and special attention should be given not only to PMFs but also to LMFs and AITFL avulsion fractures.