Talar fractures are uncommon injuries, often occurring after a high energy trauma associated with forced ankle dorsiflexion and axial load [1]. It has been documented that talar fractures represent about 2.5% of all fractures seen in Emergency departments, the most commonly site involved being the talar neck (almost 50% of all cases), followed by talar body [2]; despite being a rare condition, the treatment is always challenging: conservative approach by bracing is possible only in case of undisplaced fractures, whereas in the majority of cases it is required surgical intervention to reduce and stabilize the fracture [3]. In most cases, this kind of injuries are associated to poor clinical outcome, with a high rate of serious post-op. complications. The most feared of them is avascular osteonecrosis (ON), whose onset is related to the vascular damage following displaced fracture [2, 4, 5]. Talar vascular supply is provided by branches from tibialis anterior, tibialis posterior and peroneal arteries [6] and high energy trauma is responsible for a severe impairment of talar vascularization: Leland G. Hawkins in 1970 originally estimated a rate of avascular ON of 42% in Type II talar neck fracture, with an increase up to 91% in case of Type III fractures [4]. Currently, there are available only a few clinical trials describing the clinical outcome and the complications’ rate following surgical treatment of displaced talar fracture, and the overall findings suggest that early and delayed sequelae seems almost unavoidable [7]. In particular the clinical relevance of ON is peculiar, since it is responsible for severe functional limitation and often requires more sacrificing procedures such joint fusion [8]. However, the limited number of trials published up to now, often with a small number of patients, demands for further data to confirm these highly unfavorable complications rate. The aims of the present manuscript are: 1) to review the available evidence concerning the risk of post-op complications that should be realistically expected following reduction and internal fixation of these challenging fracture; 2) to describe the clinical outcome and the rate of post-op complications in a series of homogenous patients treated surgically after talar neck fracture-dislocations (Hawkins grade II-IV), comparing the results obtained with those documented in the available literature.

The Database search identified 2191 reports on the Pubmed, 963 on Embase, and 1322 on Web of Science. After title screening and duplicates removal, abstracts were checked and selected according to the aforementioned inclusion/exclusion criteria. As shown in Fig. (1), a total of 34 full-text articles were assessed for eligibility. Twenty-one articles did not fulfill the inclusion criteria and were further excluded and three studies were included after reference screening, thus leading to a total of 16 studies considered in the final analysis [10, 12-26]. All the trials were analyzed for relevant outcomes and data were summarized in Table 2, with a particular attention on reporting the percentage of the common early and delayed complications after surgical treatment of talar neck fracture. As evident by the table, the majority of the trials (15 out of 16) included were retrospective case series with a small number of patients evaluated (<50 patients in 12 out 16 studies), mainly at middle term follow-up (< 5 years in 11 out of 16 trials). Looking at specific complication rates, an overlook at the data extracted from clinical trials revealed that the most common complication was osteoarthritis (both subtalar and tibio-talar), followed by osteonecrosis and then mal-union. The mean percentage of subtalar and tibio-talar OA onset following surgical treatment of talar fracture were 53.2% (ranging from 27% to 87%) and 33.7% (ranging from 8% to 76%) respectively. The rate of ON onset varies from 11% to 59%, with a mean value of 30.2%. The third most common complication is malunion, which, despite not being documented by all authors, reaches an average 24.7% of patients (Table 2).

The main finding of the present study is that full recovery after a displaced talar fracture is extremely hard to achieve and, in the vast majority of cases, patients have to face some grade of functional impairment and pain limiting physical activities up to middle term evaluation. There is a large range of potential complications following surgical treatment, and the most common of them are peritalar osteoarthritis and osteonecrosis: In the present case series, the authors documented 51.9% of post-traumatic OA and 25.9% of osteonecrosis, in line with the data emerged from the analysis of the available evidence.

Talar fractures are uncommon injuries, often consequence of high energy trauma, which is responsible of different fracture patterns with different prognosis in terms of clinical outcome. The most challenging conditions are those characterized by a fracture of talar neck (the most common fracture site) and/or talar body, with “peritalar” displacement (tibio-talar, subtalar and/or naviculo-talar displacement) [27, 28]. The peculiar anatomical features of talar vascularization, characterized by vessels entering from the talar neck and supplying the talar body in a retrograde manner, explain the high risk of post-traumatic osteonecrosis, that has been deemed as the most common and dramatic consequence following a displaced fracture [29]. Since the first reports on the management of talar fractures, authored by Hawkings [4], the threat of ON has always been impending, and looking at the data emerging from “early” literature, the percentage of ON was in most cases more than 50%. Despite several decades have passed, with inherent progress in surgical techniques, equipment and management of soft tissue injuries, the rate of post-traumatic ON is still considerable, as proven by the data emerged from the present review, which focused on clinical trials published in the last 30 years. Anyway, a recent meta-analysis has suggested that surgical managament of talar fractures, which became routine only after 1990, has contributed to reduce the rate of ON, especially in Hawkins II and III neck fractures [30]. Surprisingly, the present review found a large variability among studies regarding the incidence of post-traumatic ON, with some trials reporting values as low as 10% and others presenting higher incidence, up to 50% of cases. The aforementioned meta-analysis found an overall incidence of ON at about 30%. Anyway, this variability in results among trials may be explained by the overall poor quality of the studies published up to now, which are mainly retrospective with a low number of patients included and follow-ups restricted to mid-term evaluation at variable intervals. Furthermore, due to the intrinsic rarity of talar fractures, studies always included different fracture patterns, thus increasing the number of variables to consider and limiting the possibility of generalizing results to clearly understand the impact of post-traumatic ON. Despite the lack of high level trials with inherent bias in terms of homogeneity of patients and evaluations, a thorough overlook on the complications’ rate is fundamental to provide reliable information to patients suffering from such injuries.

The analysis of literature has also revealed several shadows on the prognostic factors of displaced talar fractures, thus fostering further studies in this particular topic of traumatology: For example, it is generally assumed that timing of fixation (early vs delayed) do not correlate with the risk of ON, but actually just a few studies have enquired this specific aspect and, therefore, this issue should not be considered as definitive [31, 32]. There is no clear evidence whether a fixation technique (screws vs plate vs K wires) is better than the other, nor if there are surgical tricks (e.g. screws placed anterior to posterior rather than posterior to anterior) that could improve clinical outcome [30]. Similarly, the use of a double surgical approach does not seem to increase the risk of ON with respect to the single access [10]. Therefore, the onset of ON should not be regarded as the major fear, and also taking into account other more common traumatic injuries, such as displaced proximal humerus and proximal femur fractures, even in this cases the reports suggest that incidence of ON is not negligigle and not particularly lower with respect to talar fracture [33, 34]. The key element is fracture displacement in a small bone with a vulnerable vascularization: even in case of a good reduction (which is often a challenge, especially in comminuted fractures), ON should be expected in the follow-up.

In spite of all these open questions, the real “villain” when dealing with displaced talar fractures is post-traumatic osteoarthritis, which can be regarded as the main responsible for the poor clinical outcome in most of the cases. Even on this aspect, reports suggests a very variable range in the rate of OA onset, but the reasons may be the same of those mentioned for ON. Anyway, a large number of trials show very high percentage of post-traumatic OA, with peak values of more than 70% [12, 14]. This should be also related to the remarkable rate of mal-union, particularly varus mal-alignment, that appears to be the third most frequent complication following surgical treatment of talar displaced fractures. Furthermore, it shoud be noted that the majority of trials investigated the clinical outcome up to mid term evaluation, so a higher incindence of peritalar OA at longer follow-up [17] must be expected. Based on these findings, the role of post traumatic arthropathy seems central in determining the unsatisfactory clinical outcome. In the present case series, we reported an incidence of 51.9% of post-traumatic OA, followed by 25.9% of ON, 18.5% of mal-union, and then lower figures regarding wound complications and surgical site infection. These findings stimulated us to look at the literature to understand the role of complications after surgical treatment of displaced talar fractures. We were able to find a correspondence between our data and those reported by other clinical trials published in the last three decades: our hypothesis was that ON was not the major candidate for poor outcome, which should instead be ascribed to OA, and literature supports this proposition. Moreover, the presence of radiografic ON can be clinically silent or pauci-symptomatic, whereas OA has a tendency to be more clinically aggressive and limiting for the patients. Based on these premises, the clinicians should be aware of the necessity of properly inform patients about the high risk of complications’ onset, especially post-traumatic OA, that could require further surgery (in our series 4 patients – 15% of total – underwent fusion procedures before the final evaluation). Under a surgical point of view, when approaching a displaced talar fracture, it is of utmost importance to achieve an optimal reduction, which is not always possible due to the presence of comminution or concurrent severe soft tissue injuries. By the way, even in case of a technically satisfactory surgery, significant complications may occurr: overall, displaced talar fractures represent a complex scenery, requiring careful monitoring during following years [35].

Our clinical trial is affected by major flaws, that are also quite common in the rest of available literature: the retrospective design, the small number of patients included, the middle term evaluation and the lack of seriated sequential imaging. This limitations foster high quality further research in the field of talar fracture: the main goal of the present study, which includes our clinical experience and a survey of the published evidence, was to raise awareness on what to expect by surgeons and patients following a displaced talar fractures. Future well- designed, prospective trials should aim at identifying potential prognostic factors that could be addressed to reduce the rate of post-op complications.

The present retrospective trial highlighted that displaced talar neck fractures are challenging to treat and the outcomes at middle term are poorly satisfactory. Patients should be properly informed about the risk of serious early and delayed complications, that could compromise clinical results. With regards to complications’ rates, data from our case series and the evidence coming from the available literature (16 clinical trials) were comparable, and confirmed that the most common complication at middle term evaluation was by far osteoarthritis, followed by avascular osteonecrosis.