Current Concepts on Subtalar Instability

Subtalar instability remains a topic of debate, and its precise cause is still unknown. The mechanism of injury and clinical symptoms of ankle and subtalar instabilities largely overlap, resulting in many cases of isolated or combined subtalar instability that are often misdiagnosed. Neglecting the subtalar instability may lead to failure of conservative or surgical treatment and result in chronic ankle instability. Understanding the accurate anatomy and biomechanics of the subtalar joint, their interplay, and the contributions of the different subtalar soft tissue structures is fundamental to correctly diagnose and manage subtalar instability. An accurate diagnosis is crucial to correctly identify those patients with instability who may require conservative or surgical treatment. Many different nonsurgical and surgical approaches have been proposed to manage combined or isolated subtalar instability, and the clinician should be aware of available treatment options to make an informed decision. In this current concepts narrative review, we provide a comprehensive overview of the current knowledge on the anatomy, biomechanics, clinical and imaging diagnosis, nonsurgical and surgical treatment options, and outcomes after subtalar instability treatment.

Biomechanical comparison of tenodesis reconstruction for subtalar instability: a finite element analysis

Background There are several types of tenodesis reconstruction designed for subtalar instability. However, no comprehensive comparison has been conducted among these procedures in terms of their correcting power so far. The objective of this study is to evaluate the biomechanical behaviors of 5 representative procedures through finite element analysis. Methods Finite element models were established and validated based on one of our previous studies. The Pisani interosseous talocalcaneal ligament (ITCL) reconstruction, Schon cervical ligament (CL) reconstruction and Choisne calcaneofibular ligament (CFL) reconstruction were compared on the model with the CFL, ITCL and CL sectioned. The Schon triligamentous reconstruction and Mann triligamentous reconstruction were compared on the model with the CFL, ITCL and CL, as well as the ATFL sectioned. The inversion and external/internal rotation were quantified at different ankle positions based on the rotational moment. Then, the stress in ligaments and reconstructed grafts and the contact characteristics of the subtalar joint under inversional stress test were calculated and compared accordingly. Results For single ligament reconstruction, the Choisne CFL reconstruction provided the greatest degree of correction for subtalar instability, followed by the Schon CL reconstruction and then the Pisani ITCL reconstruction. For triligamentous reconstruction, the Mann procedure outperformed the Schon procedure in alleviating the subtalar instability. Conclusion The finite element analysis showed that the Choisne CFL reconstruction and Mann triligamentous reconstruction provided the greatest degree of immediate postoperative subtalar stability. However, both procedures could not restore the biomechanical behaviors of the subtalar joint to normal. The long-term efficacy of these procedures warrants further investigation using a substantially larger sample of clinical cases.

Chronic Lateral Ankle Instability with Subtalar Instability: Does Lateral Ligaments Reconstruction Reliable?

Category: Ankle; Arthroscopy; Sports Introduction/Purpose: To evaluate the functional outcomes of arthroscopic anatomical reconstruction of anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) in the treatment of chronic lateral ankle instability with subtalar instability during short term follow-up Methods: We retrospectively analyzed data in 8 patients (5 males, 3 females; 2 left ankles, 6 right ankles) aged between 21 and 49 years, with an average age of 31.74 +- 8.48 years presenting with CLAI with subtalar instability from Auguse 2015 to October 2018. The duration of the symptoms lasted for 12 to 43 months, with an average of 24.26 +- 10.17 months. All patients underwent arthroscopic anatomical reconstruction of ATFL and CFL. Pre- and postoperative visual analogue scales (VAS), the American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score (AOFAS) and the Karlsson Ankle Functional Score (KAFS) were compared to evaluate the curative effect of the operation Results: After surgery, all incisions healed in stage I and there were no complications. All patients were followed for 12 to 36 months, averaging 26.15 +- 9.34 months. At the final follow-up, the ankle varus stress test and ankle anterior drawer test were both negative. Range of joint motion was good. There was no lateral instability of the ankle and subtalar, and all patients returned to normal gait. The mean VAS score decreased to 1.06 +- 0.27, the AOFAS score increased to 93.16 +- 5.26 and the KAFS score increased to 92.01 +- 6.73. All the follow-up indexes were significantly different from those before surgery Conclusion: Arthroscopic anatomical reconstruction of ATFL and CFL in the treatment of chronic lateral ankle instability with subtalar instability is reliable in short term

Biomechanical comparison of tenodesis reconstruction for subtalar instability: a finite element analysis

Background: There are several types of tenodesis reconstruction designed for subtalar instability. However, no comprehensive comparison has been conducted among these procedures in terms of their correcting power so far. The objective of this study is to evaluate the biomechanical behaviors of 5 representative procedures through finite element analysis.Methods: A finite element model was established and validated based on one of our previous studies. The Pisani interosseous talocalcaneal ligament(ITCL) reconstruction, Schon cervical ligament(CL) reconstruction and Choisne calcaneofibular ligament(CFL)reconstruction were compared on a model with the CFL, ITCL and CL sectioned. The Schon triligamentous reconstruction and Mann triligamentous reconstruction were compared on a model with the CFL, ITCL and CL, as well as the anterior talofibular ligament (ATFL) sectioned. The inversion and external/internal rotation were quantified in different ankle positions with rotational moment.Results: For single ligament reconstruction, the Choisne CFL reconstruction provided the greatest degree of correction for subtalar instability, followed by the Schon CL reconstruction and then the Pisani ITCL reconstruction. For triligamentous reconstruction, the Mann procedure outperformed the Schon procedure in alleviating the subtalar instability.Conclusion: The finite element analysis showed that the Choisne CFL reconstruction and Mann triligamentous reconstruction provided the greatest degree of immediate postoperative subtalar stability. However, both procedures could not restore the biomechanical behaviors of the subtalar joint to normal. The long-term efficacy of these procedures warrants further investigation using a substantially larger sample of clinical cases.

The Interosseous Talocalcaneal Ligament Injury Findings in Lateral Ankle Instability with Sinus Tarsi Pain

Category: Ankle, Arthroscopy, Sports Introduction/Purpose: Lateral ankle instability (LAI) with concomitant sinus tarsi pain is a quite common finding. However, there has been few studies evaluating the subtalar arthroscopic findings for LAI with sinus tarsi pain. The purpose of the study is to evaluate the ST arthroscopic findings of chronic ankle instability with sinus tarsi syndrome. We hypothesized that chronic ankle instability with sinus tarsi pain is highly associated with interosseous talocalcaneal ligament (ITCL) tear which may be the cause for subtalar instability (STI). Methods: The study is based on 104 LAI with sinus tarsi pain ankles who had performed lateral ankle ligament stabilization. i.e. Modified Brostrum procedure (MBP), lateral ankle reconstruction (LAR) or subtalar ligament reconstruction (STR) with subtalar arthroscopic (STA) examinations from 2007 to 2018. The STA has been mainly focused on the ITCL injury and debridement of the ITCL tears and synovitis were performed when present. VAS pain score, AOFAS, Karlsson-Peterson functional score were evaluated. Results: According to the ST arthrosopic findings, ITCL tears were present in 94% (98/104) of the ankles. Lateral ankle instability (LAI), subtalar instability (STI), and LAI and STI combined were 32%, 30% and 38% respectively. MBP, LAR and STR were performed in 23%, 22% and 56% respectively. VAS pain score was improved from 5.3 to 1.9 (p<0.05). AOFAS score was improved from 67 to 89 (p<0.05), while K-P score improved from 50 to 83 (p<0.05). Sinus tarsi pain was relieved in 65% of the patients. Conclusion: We found the high incidence of the ITCL tears (98%) in LAI with sinus tarsi pain, and also diagnosed the STI in 68% of the ankles. We believe that in case of LAI with sinus tarsi pain, ST arthroscopic evaluation for ITCL tears is necessary and the possibility