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Traumatic incidences of subtalar joint dislocations are rare, occurring in approximately less than 1% of all traumatic dislocations. These injuries, however, often require prompt treatment due to involvement of skin tenting, open injury, and/or neurovascular compromise. Additionally, functional outcomes may be hampered by high rates of post-traumatic osteoarthritis. Due to the rarity of subtalar joint dislocations, cases are not often reported. A total of 6 acute traumatic subtalar joint dislocations over a 5-year period were included in this case series. Four were caused by high-energy trauma, and two were due to ground level falls. Five (5/6) were medial dislocations and one (1/6) lateral. Three patients had concomitant injuries: one had a posterior process fracture of the talus and two had distal fibular fractures. All six patients had a closed reduction in the operating room under monitored anesthesia care with a standardized post-operative protocol. Three patients were male. Mean patient age, body mass-index, and follow-up was 40.5 years (STD ± 18.7), 32.6 (STD ± 7.6), and 17.7 months (STD ± 9.7), respectively. Average hospital stay was 10.3 days (STD ± 7.9). Five post-operative complications were encountered in 4 patients (66.7%), including post-traumatic arthritis of the subtalar joint in half of the patients (3/6), talonavicular joint arthritis in one patient, and deep wound dehiscence with infection in another patient. All returned to their pre-injury level of work and reactional activity without functional limitations. The recent literature was also reviewed, further emphasizing the lack of data in circulation.
The etiology of these injuries are most commonly high energy trauma, such as motor vehicle accidents or falls from height. Low energy etiologies are less common, but they can occur with sports, ground level falls, or other eversion/inversion injuries of the foot.
Malgaigne and Buerger expanded on Broca's classification and emphasized four types of STJ dislocations based on the position of the foot relative to the talus. A medial dislocation is the most common, occurring at a rate of 80-85% of all cases, while lateral dislocations account for 15-20%.
The severity of these injuries and their deleterious effects are a cause for concern in management . Additionally, functional outcomes may be hampered by high rates of post-traumatic osteoarthritis (OA).
Due to the rarity of the pathology, cases of subtalar joint dislocations are not often reported. Hence, the question remains whether modern complication rates are as great as those reported historically. The aim of the present study was to evaluate the epidemiology and complication rates of STJ dislocations over a 5-year period in order to determine if current treatment techniques are viable as well as to improve discussion with patients regarding expectations.
Institutional review board approval was obtained, and retrospective chart review was undertaken. Inclusion criteria included patients who sustained a STJ dislocation with or without polytrauma, being greater than 18 years of age, and presentation between April 1, 2017 to April 1, 2022. Exclusion criteria included vulnerable patient populations (i.e. prisoners), those who sustained a concomitant talar neck or body fracture, those with a concomitant ankle joint dislocation, and those with less than 9 months of follow up. We identified 9 cases of STJ dislocations at our two Level 1 Trauma Centers (Scripps Healthcare, San Diego, CA) through current procedural terminology (CPT) coding (28435 and 28445). Among the 9 cases of isolated acute traumatic STJ dislocations, 6 patients met both inclusion and exclusion criteria.
Patient demographic information was collected and plain film radiographs were reviewed. On chart review, International Classification of Diseases (ICD) 9 or 10 codes were used for diagnosis of complications. Radiographic OA was further evaluated according to the classification of Kellgren-Lawrence (Table 2).
Radiographic outcome was recorded at latest follow up, as was potential return to pre-injury recreational activities and work status. Need for surgical intervention status post dislocation was also recorded.
All 6 patients had a closed reduction in the operating room under general anesthesia. This was after at least two failures of closed reduction in the Emergency Department. Reduction technique was identical to that as previously described.
First, the knee is flexed to diminish the strain from the gastrocnemius-soleus complex. Secondly, for lateral dislocations, the foot is brought into dorsiflexion and eversion. Conversely, the foot is placed in plantarflexion and inversion for medial dislocations. Next, the foot is pulled distally to aid in release of the talar head and navicular. One hand is then placed on the heel, and the other hand on the tibia for counter pressure. For lateral dislocations, a plantar flexion and inversion force is applied alongside medial stress on the talar head. Inversely for medial dislocations, a dorsiflexion and eversion force are aggressively applied alongside lateral stress to the talar head. Post reduction position is demonstrated in Fig. 1. One patient required the use of percutaneous pinning. All were placed in a posterior leg splint with stirrups for 2-4 weeks, followed by a short leg cast for 4 weeks. After the short leg cast, the 3 patients with isolated STJ dislocations were placed in a controlled ankle motion boot and the 3 patients with concomitant injuries were placed in a walking cast for 4 weeks.
Nine cases of STJ dislocations were identified between 2017 and 2021. Three patients were lost to follow-up, leaving 6 acute traumatic subtalar joint dislocations for analysis, which are illustrated in Table 1. Five (5/6) were medial dislocations and one (1/6) lateral. Four were caused by high-energy trauma, and two were due to ground-level falls. Three patients had associated concomitant injuries: one patient had a posterior process talar fracture, and two experienced ankle fractures. Two were open dislocations. Computed tomography (CT) scans were not obtained in two dislocations.
Table 1Patient demographics, complications, and radiographic outcomes.
Three patients were male. Mean patient age, body mass index, and follow-up was 40.5 years (STD ± 18.7), 32.6 kg/m (STD ± 7.6), and 16.2 months (STD ± 11.0, range 9-35), respectively. Average hospital stay was 10.3 days (STD ± 7.9). Five complications were encountered in 4 patients (66.7%), including post-traumatic arthritis of the subtalar joint in half of the patients (3/6), one including the talonavicular joint arthritis, and another suffering a deep wound dehiscence with infection. The latter wound, occuring in an open injury and seen in Fig. 2, healed after 6 weeks of intravenous antibiotics and further surgery. Of patients with radiographic OA, none reported pain at the most recent follow up. Two patients reported stiffness. Range of motion of the STJ at last follow-up was within 80% of the contralateral limb in all patients.
Discussion and literature review
Despite reviewing cases at two level 1 trauma centers, only 9 cases of subtalar joint dislocations were identified without talar neck or body fracutures. This underscores the scarcity of STJ dislocations and the need for studies to evaluate treatment protocols and outcomes. Furthermore, no anterior or posterior dislocations were identified. Anterior and posterior STJ dislocations continue to be demonstrated on a case report level.
With 25 cases, they were capable of correlating injury characteristics to clinical and radiographic outcomes at a mean follow up of 5 years. They illustrated 89% rate of radiographic changes to the STJ, and 88% of cases with concomitant injury. Interestingly, this group reported symptomatic OA of the STJ to be less than one-third of the total prevalence of radiographic OA. Previously, the same group had emphasized the importance of CT imaging to uncover concomitant occult injuries.
With a mean follow up of 6 years, they noted a 46.1% and 23.1% rate of OA of the STJ and TNJ, respectively. Patients with conserved STJ range of motion (ROM) were associated with improved AOFAS scores. However, they did not grade or quantify the OA, which could preclude the greater rates of OA seen in our data despite the considerably shorter follow up. Another contributor is our inclusion of Kellgren-Lawrence Grade 1 as significant STJ OA.
In 2019, a group in Italy discussed 3 cases of closed medial dislocations in volleyball players. With 4 weeks of immobilization and early physical rehabilitation, they demonstrated impressive AOFAS scores of 96.6 at 48 months of follow up.
This series included a total of 13 cases and a follow up of 76 months.
Presently, we found that all STJ dislocations were irreducible at bedside in the emergency room, including at least one attempt under conscious sedation without paralytics. Two of these patients' first reductions were at a rural medical center prior to transfer to our facility. This highlights the difficulty in reducing STJ dislocation patterns. Also, this may emphasize the need for urgent treatment in the operating room in favor of putting a patient through multiple reduction attempts. Such protocol may decrease risk of ischemic damage due to skin tenting at the prominence of the talar head.
There are various limitations to this study. For one, there are the limitations inherent to its retrospective case study-based nature, including the absence of clinical or patient reported outcomes. Although, clinical outcome has been associated negatively to the level of osteoarthritis.
The short-term follow up is also a cause for concern, and may be a primary reason why subtalar joint motion was preserved and maintained at least 80% of the STJ motion of the contralateral limb in all patients. Two patients reported stiffness and exhibited less STJ range of motion than the contralateral limb. Also, occult injuries were likely missed in patients who did not obtain CT imaging.
Nevertheless, all patients reported returning to their activities at pre-injury levels. Namely, all returned to manual labor and recreational activities without pain or loss of function, although two patients complained of general stiffness. One novel discovery was the greater progression of OA in the patient who underwent closed reduction and percutaneous pinning, which includes the only case of talonavicular OA. The authors surmise that additional injury to the STJ cartilage may have occurred with the 2.0 mm Steinmann pins in addition to the confounding factor of a more severe injury necessitating pin placement to hold the reduction.
The authors do recommend taking STJ dislocations to the operating room with general anesthesia. Given that all 6 cases, as well as the other 3 without adequate follow-up, were not reducible with conscious sedation in the emergency department. This method may be judicious to expedite reduction with less chance of iatrogenic cartilaginous or neurovascular damage. Overall, the small number of patients and short term follow up does not allow us to draw any conclusions. The amount of case series in the literature is limited, demonstrating the need for further study.
Author contribution statement
The authors confirm contribution to the paper as follows: study conception and design: Ramez Sakkab. Data collection: Ramez Sakkab, Anne He. Analysis and interpretation of results: Ramez Sakkab, Stephanie Dal Porto-Kujanpaa, Brittany Rice. Draft manuscript preparation: Ramez Sakkab, Stephanie Dal Porto-Kujanpaa, Anne He, Brittany Rice. All authors reviewed the results and approved the final version of the manuscript.
Informed patient consent
The authors declare that informed patient consent was not provided for the following reason Institutional Review Board approval was obtained, and informed patient consent was waived.
Declaration of Competing Interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper
This research was supported in part by the National Center for Advancing Translational Sciences of the National Institutes of Health under Award number UL1TR002550. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
The authors would like to thank Donald Green, DPM, FACFAS for their help with the scientific research process.