Deformity, Foot

The study in question is a post market clinical follow up (PMCF) study to evaluate the safety and performance of bioabsorbable headless compression screw Inion CompressOn in selected fracture, osteotomy and arthrodeses operations of the foot and ankle. The study recruits 125 adult patients who meet the acceptance criteria. The follow-up time for each study patient is 4 years. The study is a single center single group study which is conducted in Tampere University Hospital (TAYS) in Finland. The main focus of the study in terms of performance is to evaluate the bone healing/ossification of operated areas. The main focus of the study in terms of safety is to evaluate the occurrence of adverse events and required revision surgeries that are or might be related to the study device.

The goal of this observational study is to compare the use of a screw made of human bone (Shark-Screw®, Surgebright-GmbH) with the metal/Bio-Tenodesis screw (Arthrex) in the treatment of the symptomatic flatfoot using the medializing calcaneus osteotomy with flexor digitorum longus transfer (FDL) in adult patients. The advantage of the human bone screw is that after surgery no hardware removal is necessary. The screw is transformed from the body to normal bone. The main questions it aims to answer are: * Can the human bone screw achieve union rates like the metal/Bio-Tenodesis screw? * Is the time to union similar between the different screws? * Is the complication rate similar between the different screws? * Are the activity scores American Orthopaedic Foot and Ankle Society (AOFAS), Foot and Ankle Outcome Score (FAOS) and Foot Function Index (FFI) after surgery similar in the compared patient groups? Participants will have * the surgery * follow-ups at 6 weeks, 6 months, 1 and 2 years. * X-rays are performed at each follow up. * CT-scans are performed after 6 months. * activity scores are collected at the follow up after 6 months, 1 year and 2 years.