DA-THA for Protrusio Acetabuli: A Challenging Primary THA Case

Surgical approach: A Direct Anterior Approach (DAA) was used. Pre-operative plan: • Approach: Direct anterior approach • Implant of choice: Primary implant with an ultra-porous coated cup • Backup implant: Modular dual mobility implant • Bone loss management: Bone graft from the femoral head Operative technique summary: • An in-situ femoral neck osteotomy was performed. • A portion of the superolateral acetabular osteophyte was removed to facilitate mobilization and extraction of the femoral head. • Acetabular reaming was performed under fluoroscopic guidance to avoid violating Kohler’s line. • The anterior and posterior columns remained intact and supportive. • A stable press-fit was achieved against the native acetabular rim. • A large medial bone defect remained after preparation. • The medial void was filled using structural/autologous femoral head graft (“shift bone graft”) mixed with fresh reaming bone debris. • The cup position was reassessed with a trial before final implantation. This case demonstrates that primary total hip arthroplasty through the Direct Anterior Approach can be successfully performed in protrusio acetabuli, provided that meticulous pre-operative planning and intra-operative execution are used. Key elements that contributed to success included: • choosing the Direct Anterior Approach for this complex primary THA, • obtaining pre-operative CT for detailed planning, • performing in-situ femoral neck osteotomy, • using fluoroscopy to control reaming and avoid over-medialization beyond Kohler’s line, • preserving the supportive anterior and posterior columns, • achieving rim press-fit fixation, • reconstructing the medial acetabular defect with autologous femoral head graft and reaming debris, • preparing a backup implant strategy in case primary fixation was inadequate.