In sports such as football and basketball, ankles injuries are quite common due to the continuous sprinting and jumping involved [1
]. Furthermore, in the case of a high energy trauma, a subtalar joint dislocation (STJD) can occur, which consists of the displacement of two joints, namely, the talocalcaneal and the talonavicular. This rare condition represents <1%–2% of all large joint dislocations and approximately 15% of all talar injuries and was first described by DuFaurest and Judcy in 1811 [2
]. Usually, this kind of injury affects young male patients [1
] with a male-female ratio of about 3:1 [4
]. The medial dislocation is the most common one, representing about 80% of the isolated dislocation (without fracture) due to its intrinsic instability in inversion. When high energy is applied, forcing supination in a blocked foot, the ligaments that ensure the stability of the STJ break in a specific order: first the dorsal talonavicular ligament, then the interosseous talocalcaneal ligament and finally the calcaneofibular ligament [5
]. This injury can be caused by repetitive low energy traumas (repetitive jumps and landings [1
], hence its vulgar name “basketball foot” due to how prevalent those actions are in that sport) or a single high energy trauma (like a motorcycle crash or falling from heights).
In case of suspected STJD, the first step is to obtain a thorough clinical history: what is the kind of trauma, what is the activity that caused the trauma, timing of the injury, and history of previous ankle trauma or surgery.
The second step is a thorough physical examination: the clinical presentation of a STJD can help with the diagnosis, with a visible deformity of the affected ankle, where the calcaneus is displaced medially, and the talar head is prominent dorsolaterally and associated cutaneous tension of the lateral side of the foot, (Figure 1
). Further, it is not unusual to have an open wound associated with the dislocation. In some cases, however, the dislocation reduces spontaneously, leaving a swollen ankle with ecchymosis [1
The third and last step is to obtain appropriate imaging: radiological images are important for the diagnosis of STJD: standard antero-posterior and lateral radiographic views can show rotational defects or any relics of lateral displacement. An oblique radiographic projection with an internally rotated foot in order to verify the integrity of the tibiotalar articulation is also suggested. Magnetic resonance imaging (MRI) can be used to evaluate the condition of the ligaments. It is mandatory to always evaluate the neurovascular state of the affected foot and the soft tissue condition [15
]; to this end, it is necessary to palpate the posterior tibial pulse and the dorsalis pedis pulse accurately and, comparing the pulse strength between the feet, exclude vascular lesions.
Once all these aspects have been examined, if the dislocation did not reduce spontaneously, the next action is to reduce the displacement; this can be carefully done in the ER with some local anaesthesia, and the knee flexed 90° to reduce tension from the gastrocnemius [16
]. It is usually possible to perform a closed reduction in the acute dislocation; however, if the manoeuvre is impossible to perform or there is still some instability, it can be done in an open manner. After obtaining a good reduction, the joint is immobilised, and a CT scan is done to check for hidden fractures. As of now, there is no “gold standard” method to immobilise the affected ankle. The most used is the classic below-knee cast, either open or closed depending on the skin and soft tissue conditions. The duration of the immobilisation can vary depending on the patient’s general condition, age and type of trauma. Usually, the time is about four to six weeks; however, a study by Dr. Lasanianos [17
] showed that two to three weeks of cast immobilisation followed by partial bearing on the affected limb and specific physiotherapy could improve the outcome of these patients. While the patient can usually obtain a good recovery, complications must not be underestimated. They can generally be divided into acute and chronic. The first complications are caused by damage to the neurovascular bundle and the soft tissues, while the latter are avascular necrosis of the tarsal bone and osteoarthritis. Due to the rarity of an isolated STJD, there is a paucity of data regarding the best way to treat patients affected by this injury. Hence, the purpose of this systematic review was to compile the current literature about isolated medial STJD occurring in athletes during sports activities to compare the effectiveness of the different conservative types of treatment available and potentially find key factors that could play a role in their outcomes.
Isolated medial STJD is a rare and complex injury whose most common cause is a fall from height as a result of jumping [32
]. In our review, the most represented causes of STJD were basketball (12 cases), soccer (six cases), volleyball (three cases) and one case for other causes (tennis, climbing, baseball, military drills, and long jump). Dislocation of this joint is usually caused by the application of a high-energy force that causes the rupture of the strong joint capsule and ligaments, such as the deltoid complex, which plays an important role as a stabiliser of the head of the talus and the SBJ with the tibionavicular section of the tibiocalcaneonavicular ligament. As a result, it represents a rare injury in low- or medium-energy trauma, such as sports injuries, whereas it is more common following motor vehicle accidents [23
In the literature, the medial STJD is described as a rare condition, representing <1%–2% of all foot dislocations [2
]. Due to this fact, there is a lack of a gold standard conservative treatment; in the present study, outcomes with different types of conservative treatment and time of immobilisation were compared to highlight the best conservative treatment. The incidence is typically higher in males than in females, in particular in young men, with an estimated ratio reported of 6–9:1 [33
]. However, a recent review performed by Hoexum and Heetveld in 2014 [8
] reported a male-female ratio of 3:1. In our review, the incidence of STJD was in line with this latter ratio, being as expected considerably higher in young male patients than female patients, but not as high as the 6–9:1 ratio reported in the other studies [33
]. The mean age of the patients was 32.54 years, and out of 26 patients, there were 20 males and six females (with a male-female ratio of 3.3: 1); of 26 patients, all of the patients were athletes, but a higher number of patients were recreational athletes (23 patients) compared to professional ones (three patients).
High-energy mechanisms are often associated with open dislocations, although Bibbo et al. [36
] did not find this more frequent with medial or lateral dislocation. Goldner et al. [37
] reported that open dislocations tended to occur more commonly with the lateral STJD pattern. Surprisingly, no case of open dislocation during sports activities was found in this literature review, and only in one was an open reduction described. Several indicators of prognosis have been defined in the literature, mostly regarding the type of treatment and duration of immobilisation [16
]. Different treatment for the management of the isolated medial STJD was also identified in this study, especially concerning the method and time of immobilisation. However, immediate reduction of the STJD was performed in all cases, either in a closed or open way. An emergency reduction is essential to avoid the risk of secondary cutaneous necrosis by ischemia over the prominence of the talar head [38
]. All patients included in this study underwent emergency closed reduction, except one patient in the study by Jungbluth et al. [33
] who was treated with open reduction and external fixation. An External Fixator was also used in the patient in the study by Wang et al. [22
] after immobilisation in a short leg cast for two weeks. The method of immobilisation that was most used in this review was a below-knee cast, used by six authors to treat 19 patients. The posterior splint combined with the short leg cast was the second most frequent method of immobilisation, used by three authors to treat three patients. All of the patients (100%) treated with immobilisation with posterior splint and cast achieved good results after the treatment, whereas a satisfactory result was achieved by 61.11% of patients immobilised in a short leg cast only. Both methods appear to be valid, but they are not comparable due to the very limited data available, so it was not possible to find a statistically significant difference between the two treatments. As shown in Figure 3
of our review, the patients that complained of worsening of ROM of the STJ or presented some degree of osteoarthritis after the injury were all treated with just casting. Out of a total of 18 patients, 11 had good results; one complained of occasional pain; two showed reduced ROM of the STJ; four presented subtalar or talonavicular joint osteoarthritis. This evidence is probably linked to the greater number of patients that belong to this category, but our data suggest that another method of immobilisation should be used.
Regarding immobilisation length, some authors [16
] state that decreasing immobilisation time also decreases the incidence of joint stiffness after treatment. This was confirmed by the data we provided in Table 5
, where we show the meta-regression of the independent variables present in the studies. As can be seen in Table 5
, we obtained a coefficient of −5.56 regarding the immobilisation length, meaning that longer immobilisation corresponded with worse outcomes. Thus, short immobilisation (4 weeks or less) seems to be preferred. None of the studies reviewed had an immobilisation time of fewer than four weeks, so it is not possible to recommend immobilisation of fewer than four weeks based on this review of the literature. Most patients in our review regained normal ROM of the STJ after six weeks of immobilisation; that was also the most common immobilisation time, with a total of 14 patients. However, as shown in Figure 4
, out of those patients, 2 showed reduced ROM of the STJ, and four patients showed some degree of osteoarthritis of the subtalar or talonavicular joint. Meanwhile, out of the eight patients who were immobilised for fewer than six weeks, all had good outcomes except one who complained of occasional pain.
This review is limited by the level of evidence of the studies included, consequently presenting some drawbacks: firstly, the studies included are not homogenous for the outcome scores. The poor homogeneity of clinical evaluation scores has played an important role, lowering the possibility of obtaining a precise comparison between the different conservative treatments available. Also, the quality of the included studies made it difficult to undertake a full and statistically reliable comparison of the published data. Unfortunately, our selection included mainly case reports and case series, with a small sample size, lack of control groups, and restricted statistical comparison. Hence, all studies in the series had low levels of evidence (IV). Due to these different aspects, there is a risk of reporting bias in the present study. Finally, additional Randomised Controlled Trials (RCT) are needed to definitively determine the most beneficial method of immobilisation. Duration of immobilisation has been shown to be pivotal in prognosis [16
], so it deserves further study to delineate the best course of action in professional and recreational athletes affected by isolated medial STJD.