Management of Subtalar Fractures-Dislocations at Ségou Hospital in Mali: A 7 Cases Series

Introduction: Subtalar or peritalian dislocation is rare; it represents 15% of peritalian injuries. The aim of this study was to describe the radioclinical and therapeutic characteristics and to assess the functional result. Patients and Methods: This study is about a continuous descriptive and prospective study over a period of 5 years. It has been conducted from March 2013 to February 2018 at the Ségou Hospital, a second referral hospital in Mali. The functional results were evaluated by the score of the American Orthopedic Foot and Ankle Society (AOFAS). Results: Seven cases of subtalar dislocation fractures were diagnosed in six male patients with an average age of 38 years (36 to 47 years old). In five cases the etiology of the trauma was a motorcycle accident and a fall from height. The lesion was bilateral in one case. The average time to care was 3 hours (1 to 9 hours). There was one case of open dislocation fracture with talus enucleation. The dislocation was medial in 6 cases and lateral in one case. It was pure in three cases. The treatment was orthopedic in 2 cases and surgical in 5 cases. The post-operative complications were complicated by an infection of the operative site in one case. The average length of hospital stay was 4 days. The functional result was excellent in 2 cases; good in 2 cases, fair in 2 cases and poor for 1 case. Conclusion: Subtalar dislocation is a rare and serious lesion of the posterior tarsus. The long-term prognosis depends on the earliness of treatment and the severity of the associated injuries.


Introduction
Subtalar or peritalian dislocations affect the talo-calcaneal and talo-navicular joints; the tibio-talian and calcaneo-cuboid joints being intact [1] [2]. The stability of the subtalar joint is ensured by powerful ligaments. Most of these dislocations occur in a context of high-energy trauma such as falls, sports, motorcycle or automobile accidents [3]. It is rare in routine trauma practice, represents 1% -2% of all dislocations and 15% of peritalian lesions [4]. Ankle deformation related to dislocation is usually obvious. In the context of polytrauma, dislocation can go unnoticed. Computed tomography is of great help, confirms the diagnosis and assesses the associated osteocartilaginous lesions [1] [2] [5] [6].
Pure dislocation reduced and immobilized early has a good prognosis. It is associated with fracture and other peritalian lesions in 60% of cases. Ignorance of these associated lesions can quickly lead to the installation of pain in the peritalian joint [7] [8]. The objective of this work consists in describing the radio-clinical and therapeutic characteristics and in evaluating the result functional of subtalar dislocations.

Patients and Methods
It is a continuous descriptive and prospective study over a period of 5 years extending from March 2013 to February 2018. It was carried out in the orthopedics and traumatology department of the Ségou Hospital which is a 2nd Reference Hospital of Mali. The hospital's medical imaging department does not have a CT scan. The study population involved patients received and treated for dislocation or subtalar fracture-dislocation during the study period. Each patient had a medical file in which the clinical and radiological follow-up was mentioned. The average follow-up was 18 months.
We have adopted the Malgaigne classification [9] which allows us to distinguish 4 varieties of dislocation: -Medial subtalar dislocation: 50% to 90% of subtalar dislocations; -Less frequent lateral subtalar dislocation; -The subtalar dislocations in the anterior and posterior variety are exceptional.

Therapeutic Method
Reduction of the dislocation was done in an emergency. In closed dislocations the reduction, often orthopedic, was carried out under general anesthesia in order to obtain optimal muscle relaxation. The reduction in the medial variety was obtained by plantar flexion of the foot with traction of the forefoot to release the head from the slope, followed by a varus maneuver to raise the foot below the slope. The open reduction had been indicated in irreducible and open dislocations. In these open dislocations antibiotic therapy based on amoxicillin-clavulanic acid was administered upon admission of the patient. At the same time, trimming, reduction of dislocation and skewering were performed. Functional rehabilitation began immediately post-operatively and was continued until the ankle and foot function recovered.

Assessment Method
The results were assessed according to clinical, radiological and functional crite- Depending on the score the result is judged: -Excellent: score between 90 and 100 -Good: score between 80 and 90 -Fair: score between 70 and 80 -Poor: score less than 70

Result
During the study period, we enrolled six patients with seven cases of dislocations beneath the heels. Our patients were all male with an average age of 38 years (range 36 and 47). In five cases, the etiology of the trauma was a motorcycle accident following an attempt to evict an obstacle with the notion of pivoting around a foot placed on the ground. This same mechanism was found in these five patients. In one case the etiology was a fall from height. The lesion was bila-  X-rays of the foot and ankle, front and profile, allowed these dislocations to be broken. It was medial in 6 cases and lateral in one case.
We had observed three cases of pure talar dislocation. In four cases they were associated with bone lesions: talus fracture (2 cases) a medial malleolus fracture (1 case) (Figure 2), a bimaleolar fracture and second metatarsal fracture (1 case), could not be performed in our patients due to its unavailability.
The treatment was orthopedic in 2 cases and surgical in 5 cases. This surgery was indicated after failed attempts to reduce dislocation by external maneuver and in the form associated with a skin opening. In all cases, a plastered boot was made and kept for 6 weeks. In surgical treatment, the ankle approach was anterior ( Figure 3).
The reduction was followed by a racking-in (Figure 4). The post-operative suites were interspersed with superficial suppuration of the operative wound in one case. The pins were removed in the sixth post-operative week. The functional result according to the score of the American Orthopedic Foot and Ankle Society (AOFAS) was excellent in 2 cases; good 2 cases, fair 2 cases an d poor 1 case. The average length of hospital stay was 4 days.

Discussion
Our patients were young adult males who were victims of a traffic accident. This epidemiological profile can be superimposed on that of the literature [11] [12]. In our series, medical dislocation was the most common (6 cases). This variety is the most frequent and the most described in the literature [1] [12]. In 80% -85% of cases, the foot moves medially, bringing with it the calcaneus. The head of the slope remains prominent on the dorsolateral face. The lateral form is less frequent and represents 15% -20% of cases [13] [14]. It is important to distinguish the two forms because the causal mechanism, the reduction method and the long-term prognosis are different [13] [14]. The inversion of the foot is at the origin of the medial luxation while the eversion produces the lateral form. The powerful calcaneal-navicular ligament resists the inversion or eversion force which dissipates through the weak talo-navicular and talo-calcaneal. The rupture of these two ligaments promotes the displacement of the calcaneus, the navicular bone and the entire distal part of the bones of the foot either medially or laterally [14] [15] ( Figure 5). [18] [19]. They witness the violence of the trauma. We had observed only one open dislocation case. These subtalar dislocations are associated with a skin opening in 10% to 40% of cases [20]. These skin openings are more frequent in lateral forms and in trauma with high velocity [20].
No vascular-nerve damage was detected. Monson and Ryan [21] reported a case with involvement of the posterior tibial artery and bruising of the nerve.
Ischemia of the foot is more common in lateral dislocation because the posterior tibial artery is eased at the level of the talus [22]. Compression, stretching, or rupture of a vascular-nerve bundle can lead to abolition of the posterior and/or tibial pulse, and sensitivity disturbances.
Standard x-rays of the foot and ankle confirmed our diagnoses of dislocation and objectified associated bone lesions which were present in 5 cases. Associated osteocartilaginous lesions are frequently described in the literature, especially in lateral dislocations [19] [22]. They were not found in our series during intraoperative exploration due to the unavailability of CT scans.
We were able to urgently reduce 2 cases of medial variety by external maneuver.
The other 5 cases, including a lateral form following the failure of your reduction attempt or skin opening, required a reduction in the sky. Several authors recommend the reduction of this dislocation in an emergency, which makes it possible to avoid necrosis of the underlying skin, to reduce the risk of irreducibility and to obtain a better functional result [12] [18] [21]. The keystone of treatment is rapid and gentle reduction under general or locoregional anesthesia [23].
Approximately 10% of medial dislocations and 15% to 20% of lateral forms cannot be reduced by external maneuver. The interposition of tissue (posterior tibial, long flexor of the hallux) and bone fragments have been identified as factors preventing reduction [14]. Reduction must always be followed by radiological monitoring to see the accuracy of reduction, look for associated fractures and exclude a diastasis between the medial malleolus and the talus, witness to damage to the deltoid ligament.
Like some authors, we had plastered for 6 weeks. For surgically reduced forms, pin stabilization was associated. This method is suspected of stiffening but is a guarantee against instability [22]. In our series we observed a case of superficial  [24].
The 2 cases of excellent result concerned the pure forms reduced by external maneuver and immobilized by plastered boot. The high frequency of associated fractures in our series (5 cases), the irreducibility in some cases by external maneuver and the suppuration of the operating site would be our elements of poor prognosis. These different factors could explain our good, fair and poor results.
Indeed the prognosis is good in simple dislocations without associated fracture and easily reduced by external maneuver [1]. According to Lancaster et al., the prognosis is poor when dislocation is associated with soft tissue damage, skin opening, extra-articular or joint fractures, infections, lateral dislocation, neglected dislocation and osteonecrosis [23].
In our series we noted 3 cases of osteoarthritis (2 subtalar cases and one talo-crural case). Ankle stiffness was observed in 3 patients. In fact, osteoarthritis, very common in certain series (25% to 60% d), affects both the subtalar joint and that of Chopart, even the talo-crural joint [9] [16] [22]. According to Rammelt S [9] the presence of osteoarthritis could be explained by cartilaginous contusion, subchondral ischemia and mechanical dysfunction by injury of the ligament in hedge. However, stiffness and osteoarthritis predominate at the subtalar joint [9] [12] [24].

Conclusion
Subtalar dislocation is a rare and serious lesion of the posterior tarsus. Its diagnosis is guided by clinical and imagery which identifies the associated osteocartilaginous lesions. Its management is done urgently and consists of a reduction in dislocation followed by a plastered compression. The prognosis depends on the speed of treatment and the severity of the associated lesions.