Medial Displacement Calcaneal Osteotomy and FDL- Transfer - With a Human, Allogeneic Cortical Bone Screw

The goal of this observational study is to compare the use of a screw made of human bone (Shark-Screw®, Surgebright) with the metal/biotenodesis 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/biotenodesis screw?Is the time to union similar between the different screws?Is the complication rate similar between the different screws?Are the activity scores AOFAS, FAOS and FFI after surgery similar in the compared patient groups?Participants will havethe surgeryfollow-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.

Indication for the use of a metal/biotenodesis screw or human bone screw in medializing calcaneus osteotomy with FDL transfer.BMI< 40 kg/m²Exclusion Criteria:Insufficient knowledge of GermanAlcohol and drug abusePregnant woman or nursing motherForeseeable compliance problemsNeoplastic diseases, malignant bone tumors, rheumatoid arthritisActive osteomyelitisHistory of foot surgeryAdvanced osteoarthritis of the lower ankle jointUlcerations in the skin of the surgical areaImmunosuppressive medications that cannot be discontinuedBMI >40