Distal Skin Ulceration Associated With an Absent Farabeuf's Angle in a Transtibial Amputee: A Case Report on the Importance of Socket Assessment

Transtibial amputation is frequently performed in patients with diabetes mellitus complicated by peripheral vascular and infectious diseases of the foot, and successful prosthetic rehabilitation depends as much on surgical technique as on the subsequent quality of socket fitting.Anterior beveling of the distal tibia, classically referred to as Farabeuf's angle, is intended to blunt the prominent anterior tibial crest and create a smooth, well-padded residual-limb tip capable of tolerating axial and shear loading within a prosthetic socket.We report the case of a 56-year-old man with insulin-treated type 2 diabetes mellitus who had undergone a left transtibial amputation for diabetic foot disease two years earlier and was fitted with a definitive prosthesis four months before presentation.He developed a small, clean, superficial wound at the tip of the residual limb; although he was advised to discontinue prosthesis use until complete healing, he continued to bear weight on the limb.Three months later, he presented with a 1-cm ulcer extending into the subcutaneous plane, with perilesional necrosis and local inflammatory changes but no purulent discharge, malodor, or fever.Neurovascular examination of the residual limb was preserved, and plain radiographs demonstrated a squared, non-beveled anterior margin of the distal tibial cut, consistent with an absent Farabeuf's angle.Management consisted of complete offloading of the prosthesis, local wound care, and refashioning of the socket to accommodate the prominent bony margin.This case illustrates that distal residual-limb ulceration in a transtibial amputee, even with preserved sensation, should prompt evaluation of both the skeletal anatomy created at amputation and the biomechanical fit of the prosthetic socket, and supports routine, structured socket assessment during prosthetic follow-up, particularly in patients with diabetes.