Subtalar dislocation is characterized by simultaneous dislocation of the subtalar (talocalcaneal) and talonavicular joints, hence the name talocalcaneonavicular. These lesions can be grouped into four distinct categories: anterior and posterior, which are exceptional, lateral and medial. Medial subtalar dislocations are more frequent, are due to low-energy trauma and generally have good functional results. Anatomical reduction and stabilization of the subtalar joint and optimal management of all associated foot injuries are the key to good results.

OBJECTIVE: In contrast to osteochondral lesion (OCL) of the ankle, OCLs in other joints of the foot, such as subtalar joint, talonavicular joint, calcaneocuboid joint, and the midfoot, are rare conditions, but they can also lead to significant morbidity. The objective of this systematic review was to summarize the clinical evidence for the treatment of OCLs of the subtalar, talonavicular, calcaneocuboid, and the other midfoot joints.
METHODS: A systematic search of the MEDLINE, EMBASE, and Cochrane Library databases was performed in January 2021 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines by 2 independent reviewers. Included studies were evaluated with regard to LOE (level of evidence) and QOE (quality of evidence). Variable reporting outcome data, clinical outcomes, and complications were evaluated.
RESULTS: Seventeen studies with 21 patients were included, all of which were case reports (level 5) without any case series reporting greater than 3 patients. There were 5 patients with OCL in the subtalar joint, 15 patients in the talonavicular joint, and 1 patient in the calcaneocuboid joint. Thirteen case reports (4 subtalar joint, 8 talonavicular joint, and 1 calcaneocuboid joint) reported surgical treatment. Surgical procedures mainly included debridement, bone marrow stimulation, fixation, and bone grafting, through open or arthroscopy, all of which resulted in successful outcomes. Four case reports (1 subtalar joint, 3 talonavicular joint) reported successful conservative treatment. Other 13 case reports reported successful surgery after failed conservative treatment. No complications and reoperations were reported.
CONCLUSIONS: The current systematic review revealed that there is no available evidence to ascertain clinical outcomes of both conservative and surgical treatments for cartilage lesions in the talonavicular joint, subtalar joint, and the midfoot joints, owing to the extreme paucity of literature. Both nonoperative and operative treatments can be considered, but no treatment strategies have been established.

Background and Objectives: Sinus tarsi syndrome (STS) is defined as pain located at the lateral opening of the tarsal sinus. The exact etiology of sinus tarsi syndrome is not completely understood. Some do not believe it to be a true pathology. This review aims to clarify the definition of sinus tarsi syndrome to better understand the underlying pathologies. We further propose an algorithm to evaluate sinus tarsi pain and provide advice for consecutive treatment options. Design: This is a narrative review. By searching PubMed, the available current literature was reviewed. Articles were critically analyzed to determine the pathoanatomy, biomechanics, and etiology of sinus tarsi pain. Algorithms for clinical evaluation, diagnosis, and treatment were also recorded. Finally, the authors approach to evaluating and treating sinus tarsi pain was included in this review. Results: Reviewing the available literature, STS seems to be a catch-all phrase used to describe any pain in this anatomic region. Many causes of sinus tarsi pain were listed, including impingement, subtalar instability, and many other pathologies around the ankle. Conclusions: A thorough evaluation of patients presenting with pain in the sinus tarsi or instability of the hindfoot is essential to determining the underlying cause. When the cause of pain is still not clear after clinical exam and radiologic assessment, subtalar arthroscopy can be helpful as both a diagnostic and treatment tool. We propose that the term of STS should be avoided and that a more accurate diagnosis be used when possible. Once a diagnosis is made, appropriate treatment can be initiated.

The sinus tarsi is a funnel-shaped region at the junction of mid-foot and hind-foot which contains fat, vessels, nerves and ligaments. The ligaments help stabilise the subtalar joint and maintain the longitudinal arch of the foot. The nerve endings contain proprioceptive fibres indicating a role for the sinus tarsi in movement of the foot. Sinus tarsi syndrome is a clinical entity characterised by lateral hind-foot pain with worsening on palpation and weight-bearing, and perceived instability. It is associated with both traumatic and non-traumatic causes. Magnetic resonance imaging is the imaging modality of choice for assessment of the sinus tarsi and sinus tarsi syndrome. In this review article, we review the anatomy and various aetiologies of sinus tarsi syndrome, along with the imaging appearances.

Open in situ subtalar arthrodesis (ISTA) has been a standard procedure for treating subtalar arthritis for varied etiologies with good outcomes. There has been a paradigm shift from ISTA to arthroscopic subtalar arthrodesis (ASTA) over the past two decades due to increase in number of surgeons performing arthroscopy worldwide. However, there is only limited evidence in the existing literature to substantiate the benefit of this change with regards to patient benefit. To our knowledge, there are also no systematic reviews comparing the results of the two techniques for subtalar arthrodesis (STA).
Our systematic review aims to determine the superior technique for performing STA by comparing the outcomes, union rates, and complications between open and arthroscopic approach for in situ STA. We hypothesised that both procedures would have similar outcomes, union rates, time to union, and complication rate for in-situ STA.
Three databases, MEDLINE/PubMed, the Cochrane Library, and Google Scholar, were searched using predefined inclusion and exclusion criteria to compare the two procedures. Risk of bias assessment was done using The Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I) tool for assessing the risk of bias in the included studies. Weighted mean averages were computed for all parameters and tabulated separately for ASTA and ISTA.
We included a total of 22 studies with a total of 978 (ASTA-310, ISTA-668) patients in the review. The most common indication for both techniques was post traumatic subtalar arthritis due to malunited calcaneal fracture in both groups (54.5%). The American Orthopaedic Foot & Ankle Society score was better in the ASTA group with a weighted average improvement of 43.4, while the weighted average improvement was 31.1 in the ISTA group, respectively. Patients undergoing ASTA had a weighted average union rate of 95.5% (standard deviation [SD]-3.6) with a weighted average time to union of 12.2 weeks (SD-2.4) while the ISTA group reported 90.7% (SD-6) union rate with a weighted average time to union of 15.5 weeks (SD-8.4). The weighted overall average complication rate was 13.1% (SD-8.9) in ASTA group and 20.3% (SD-16.2) in the ISTA group with hardware-related complications being the most common in both the groups.
From the existing literature, our review suggests that both ASTA and ISTA techniques are effective procedures for STA. However, there is no conclusive evidence to recommend one technique over another. High quality randomised studies may be further required to clearly define the superiority of one technique over another LEVEL OF EVIDENCE: level III.

Articular facet morphology plays a fundamental role in subtalar joint biomechanics and stability, and likely influences the development of hindfoot osteoarthritis. While multiple anatomical studies have shown wide variation in articular facet configuration, the clinico-radiological findings are rarely presented. We illustrate a case of bilateral subtalar joint middle facet agenesis in a 45-year-old woman, which was missed despite several presentations. We demonstrate the imaging findings to enable clinicians to distinguish this from the more common middle facet coalition. We summarise the developmental anatomy and discuss the potential implications on biomechanical function. Recognition of middle facet agenesis within the complex subtalar joint is important to prevent misdiagnosis and unnecessary surgery.

The dominant characteristics of the human foot are its shock-absorbing capability during walking or gait cycle and its adaptation to uneven surfaces. On the stance phase of the gait, the foot has to be flexible at first for shock absorption and adapt to the terrain; whereas, during the propulsive phase, it has to be dynamically rigid to function as a lever. Foot flexibility and rigidity are mainly controlled at the subtalar and midtarsal joints by tendons and ligaments. The subtalar joint is part of the longitudinal arch, but the midtarsal joint along with the tarsometatarsal joint are components of the transverse arch. However, the existence and functional role of transverse arch in human was challenged by some authors. But recent studies have revealed that the transverse arch has a predominant role in midfoot stiffness (Venkadeshan et al., 2020, & Holowoka et al., 2017). This midfoot stiffness allows the human foot to store elastic energy at the time of heel strike, which is utilized during the push-off mechanism for propulsion, thus making bipedalism more energy-efficient. Moreover, the transverse arch allows the longitudinal arch to be flexible like a lever and, at the same time, makes the arch of the foot rigid to behave like a stiff spring lever. Understanding the role of the transverse arch is obligatory to study the biomechanics of foot injuries and Charcot or diabetic foot. Studies on diabetic foot have shown that the modulation of transverse arch biomechanics and off-loading modalities would improve outcomes in the form of wound-healing and prevention of re-ulceration.

The subtalar joint has a complex anatomic function that includes inversion and eversion of the hindfoot, assisting in walking on uneven surfaces. Arthritis is the most common pathological condition affecting this joint and can require fusion. The surgery can be performed open or with arthroscopic assistance. This systematic review assesses articles written on the safety and efficacy of isolated arthroscopic subtalar fusion.
Using MEDLINE and Embase, we systematically reviewed articles published before May 21, 2020.
Of 395 articles, 17 on a total of 395 patients (409 operations) were included in the review. The average duration of follow-up was 40.0 months (range, 3 to 105 months). Radiographic evidence of union was reported for 95.8% of cases at an average of 11.9 weeks (range, 6 to 56 weeks) postoperatively. Delayed union was reported in 1.0% of patients and nonunion, in 4.3% of patients. In the articles reporting patient satisfaction, including pain relief, 95.4% of patients had positive outcomes. Postoperative complications were reported in 64 patients (16.2%), including 37 (9.4%) with symptomatic implants, 11 (2.8%) with dysesthesia or neuropathic pain, and 3 (0.8%) with postoperative infection.
Arthroscopic subtalar fusion is a safe and effective alternative to open subtalar arthrodesis, with high patient satisfaction rates, high union rates at similar follow-up intervals, and low complication rates. The aim of future research should be to determine the ideal cases for this approach as well as the most efficient arthroscopic surgical technique and postoperative rehabilitation to optimize function and union as seen on radiographs.
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

To assess the complication rate of hindfoot nailing of acute fractures involving the tibiotalar joint, and mortality, patient-reported outcome measures, and return to preinjury activities.
MEDLINE; EMBASE.
A systematic literature search for articles in English was completed using MEDLINE and EMBASE databases on April 23, 2020. Original research articles that assessed patients with acute intra-articular fractures of the ankle joint (malleolar ankle fractures and/or pilon fractures) that were treated with a locked hindfoot intramedullary nail, inserted retrograde through the plantar surface of the foot, were selected for inclusion. Case reports (≤4 patients), studies with nonlocked implants, and non-English studies were excluded.
A validated data extraction form was used, which included study demographics (authors, journal, date of publication, and study design), patient characteristics, implant type, and reported outcomes. Risk of bias for each included study was evaluated using the Institute of Health Economics Quality Appraisal Checklist for case series and the Risk of Bias in randomized trials tool, where appropriate. The best evidence was summarized and weighted mean values were provided when appropriate.
Ten case series and one randomized controlled trial were included. The overall quality of studies was poor with considerable bias. The majority of studies included elderly patients (weighted mean age 75.5 years) with diabetes (42% of patients). Overall complication rate was 16% with an 8% major complication rate (deep infection, malunion, nonunion, implant failure) and an overall infection rate of 6.2%. Pooled mortality rate was 27% with fracture union rates from 88% to 100%. Mean proportion of patients able to return to preinjury level of activity was 85%.
Hindfoot nailing of acute ankle and pilon fractures in elderly patients and patients with diabetes is associated with complication rates comparable with other methods of fixation. Issues with elimination of subtalar joint motion and implant complications secondary to poor implant fixation persist. The literature to date has composed of primarily Level IV studies with considerable bias. Further research is necessary to clarify the role of hindfoot nailing of acute ankle and pilon fractures.
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The aim of the present systematic literature review was to determine results and complications in subtalar arthroereisis for stage-2 adult-acquired flatfoot.
A search of the PubMed, Medline, CINAHL, Cochrane and Embase databases used MeSH terms \"arthroereisis\" AND \"flatfoot\" OR \"adult-acquired flatfoot\" OR \"pes planovalgus\" OR \"pes planus\". Two of the authors analyzed 125 articles. After reading titles and Abstracts, 105 articles were read in full text and their references were analyzed. Finally, 12 articles were selected and divided into 2 groups: isolated and associated arthroereisis.
Improvement in functional scores was greater in associated arthroereisis. Whether isolated or associated, arthroereisis achieved radiologic correction. However, the rate of complications was high, mainly concerning tarsal sinus pain.
Subtalar arthroereisis for stage-2 adult-acquired flatfoot is rarely performed in isolation. When it is associated to other procedures, good radiologic and clinical results can be expected.
IV.