**1. Introduction**

Rare primary arthroses of the ankle joint account for less than ten percent of all cases. Additionally, traffic accidents and sports injuries lead to serious fractures of the ankle joint with posttraumatic osteoarthritis [1]. However, chronic instabilities due to insufficiency of the inner and outer ligaments of the upper ankle joint, as well as acute and chronic syndesmosis injuries with resultant chronic instability, are also possible causes, and habitual malpositions with an axial deviation of the hindfoot or entire leg axis also favor such signs of wear and tear [2]. If non-surgical therapy, such as adjustment of footwear, nonsteroidal anti-inflammatory drugs, and physiotherapy, fails, and joint preservation is no longer possible, the indication for arthrodesis of the ankle joint arises.

In this context, it is known that a subsequent conversion of a total ankle replacement into a tibiotalar arthrodesis is inferior to a primary fusion [3,4]. The idea that previously mild osteoarthritis of the subtalar joint may develop into severe osteoarthritis leads to a discussion of early indications for tibiotalocalcaneal arthrodesis (TTCA).

Regardless of the radiological findings, complaints of pain surrounding the subtalar joint cannot always be reliably differentiated when tibiotalar arthrodesis (TTA) is indicated.

**Citation:** Sell, R.; Meinert, M.; Herrmann, E.; Gramlich, Y.; Klug, A.; Neun, O.; Hoffmann, R.; Fischer, S. Preservation of the Subtalar Joint Determines Outcomes in a 10-Year Evaluation of Ankle Arthrodesis. *J. Clin. Med.* **2023**, *12*, 3123. https:// doi.org/10.3390/jcm12093123

Academic Editor: Christian Carulli

Received: 31 March 2023 Revised: 13 April 2023 Accepted: 23 April 2023 Published: 25 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

The indication for TTA or TTCA then depends primarily on the experience of the treating surgeon, in addition to the patient's disability and pain.

The outcomes of TTA and TTCA are sometimes unsatisfactory and are associated with low score values due to the associated restriction of movement and the long duration of pain and suffering [5,6]. We aimed to compare the clinical outcomes of TTCA and TTA in a direct comparison using a demographically comparable and large patient population.
