## 1 Introduction  
Proprioception is defined as the ability to sense the position of a joint in space; this skill is one of the most crucial determinants of joint stability, balance, coordination, grace of movement, and injury prevention [1]. The information from the tactile and proprioceptive receptors of the foot soles and ankle flexor muscles work together in a complementary way to maintain the standing stance [2].  
Ankle proprioception is one of the most important components contributing to balance control during walking and sport activities [3]. The information from ankle receptors and the central processing are essential for postural and balance control [4]. In some sports, such as boxing, an increase in proprioceptive function and a decrease in visual dependence on postural control was evidenced [5].  
Due to aging, both static position sense and the movement detection threshold appear to deteriorate. In older adults, this impaired proprioception could result in balance problems, a higher incidence of falls, and compromised quality of life [6, 7].  
Osteoarthritis (OA) affects around 15% of the world's adult population with joint pain and disability; approximately 1-2% is affected by ankle arthrosis [8]. Unlike other lower limb joints, ankle OA is rarely primary; the most common etiology is a previous trauma, and this implies that the patients suffering from this degenerative arthropathy are younger than the ones affected by knee or hip OA [9]. To restore pain-free ankle mobility, Total Ankle Replacement (TAR) is among the most common elective surgical procedures performed nowadays if the conservative treatment does not improve the symptoms [10; 11].  
End-stage osteoarthritis, on the other hand, causes a loss of cartilage and mechanoreceptors, important inflammation leading to reduced proprioception, and postural balance feedback. Abnormal proprioceptive signals not only affect sensory function but also motor control since sensory information is essential for movement programming [12]. The total replacement of the lower limb joints could, in theory, partially restore joint sensation and motion, enhancing motor coordination, functional stability, and proprioception. Knee and hip arthroplasty have been largely studied, and at 1-year follow-up after surgery, patients who have undergone these surgeries showed better unilateral balance than TAR patients [13]. These patients showed a higher dynamic postural alteration of balance, increased use of the hip strategy, and less ankle strategy to maintain their balance [14]. This finding highlights how the ankle is important for balance and how it is important to work to normalize the function of it after the surgery. Sensorimotor and neuromuscular training are programs focused on regaining proprioception and balance control [15].  
The role of proprioception in Total Ankle Replacement (TAR) is a topic of growing interest in the field of orthopedic surgery. Proprioception, the sense of joint position and movement, is crucial for maintaining balance and coordinating movements. Its effects on postural stability can be quantitatively assessed under open and closed eyes conditions using a force platform, electronic mat, or accelerometers, which provide a more objective measurement than clinical scales despite an intra- and inter-subject variability of the computed posturographic parameters reported in previous studies [16; 17].  
In the context of TAR, understanding and optimizing proprioception could potentially enhance post-operative functional outcomes and patient satisfaction. The aim of this study is to evaluate ankle proprioception before and after a Total Ankle Replacement (TAR), implanted using an anterior approach in patients with end-stage degenerative arthropathy, via an instrumental objective assessment.