Subtalar fusion is commonly performed in post-traumatic subtalar osteoarthritis, rheumatoid arthritis, posterior tibial tendon dysfunction, tarsal coalition and primary subtalar osteoarthritis. Patients with osteoarthritis or severe dysfunction involving both the ankle and the subtalar joint may benefit from an tibiotalocalcaneal fusion (TTC) or an ankle replacement and subtalar fusion. With the development of new prosthetic designs and of surgical techniques, total ankle replacements (TAR) became a reasonable alternative to fusion with functional and quality of life improvements. A gait analysis of patients that underwent TAR and simultaneous subtalar fusion allows to study with precision and reliability the ankle range of motion (ROM). On the contrary, in healthy subjects or in patients that underwent isolated TAR this is not possible because the ankle ROM is influenced by the ROM of the subtalar joint in such a way that it is not possible to analyze the two joints separately. Also, excluding the role of the subtalar joint, it is possible to accurately analyze and compare the consequences on ankle kinematics of two different prosthetic designs.

Patients who previously have underwent TAR and simultaneous subtalar fusion are retrospectively reviewed. Minimum follow-up after the surgery is 12 months.

Inclusion Criteria:

• Patients who underwent ankle prosthesis (Hintegra ankle system, Zimmer Trabecular Metal Total Ankle) and simultaneous fusion of the subtalar joint with at least 12 months of follow-up willing and capable of adhering to postoperative clinical protocols and functional evaluations and who have signed a specific informed consent form approved by the Ethics Committee
• Males or females aged between 20 and 80 years old.
• Patients with diagnosis of primary not-inflammatory degenerative articular disease

Exclusion Criteria:

• Patients with Body Mass Index (BMI)> 35.
• Patients with active or suspected latent periprosthetic infection
• Patients who underwent revision surgery.
• Prosthesis of the hip, knee or ankle, homolateral or contralateral.
• Fusion failure of subtalar joint.
• Patients with chronic heart failure (NYHA stage> 2)
• Presence of neurological disorders, neuromuscular disorders or other major musculoskeletal pathologies
• Cognitive deficits.
• Impossibility to match questionnaires due to cognitive disorders or language dysfunctional disorders

Patients who underwent simoultanous total ankle replacement and subtalar fusion