The aim of the study is to investigate the effect of subtalar extra-articular calcaneo-stop screw on the proprioceptive and nociceptive pathways of the ankle before and after implantation. The hypothesis of the study is that an increased number of receptors related to proprioception will be detected in the sinus tarsi.

Inclusion Criteria:

Study Group:

• Patients aged 14 years old and above that will remove the calcaneo stop screw, in place for at least 3 years after the implant, will be recruited
• Patients willing and able to give informed consent for the participation in the study. For underage patients, a parent/legal representative will give consent for the participation in the study.
• Male and female patients in fertile age can be recruited.

Control Group:

• Syndromic patients
• Previous foot malformation (synostosis, congenital clubfoot)
• Female participant who is pregnant, lactating or planning pregnancy during the course of the study.

Exclusion Criteria:

Control Group:

• Syndromic patients
• Previous foot malformation (synostosis, congenital clubfoot)
• Female participant who is pregnant, lactating or planning pregnancy during the course of the study.

Study Group:

• Patients suffering from post-operative complications
• Syndromic patients
• Previous foot malformation (synostosis, congenital clubfoot)
• Female participant who is pregnant, lactating or planning pregnancy during the course of the study.

Patients with subtalar extraarticular screw arthroereisis, gender male and female, no comorbidities.

Control group are patients that will insert the calcaneo-stop screw (age between 10 and 14 years old).

Study group are patient that remove the calcaneo-stop screw (age from 14 years old)