Objective: The modified advanced core decompression (mACD) combines the advantages of a low invasive core decompression with maximal removal of osteonecrotic bone and a biologic reconstruction of the resulting bone defect.
Indications: Avascular (atraumatic) osteonecrosis of the femoral head (ARCO stage II).
Contraindications: Subchondral fractures (ARCO stage III); advanced osteoarthritis (e.g., ACRO stage IV); persisting risk factors such as high-dose corticoid therapy, chemotherapy, alcohol abuse; open growth plates; history of side effects or intolerance to components of the applied bone substitute; lack of patient compliance; osteomyelitis or other septic conditions.
Surgical technique: Supine positioning on the operation table, skin disinfection, and sterile draping. Skin incision and core decompression using a 3.2 mm guide wire. Removal of a bone cylinder from a nonaffected area of the femoral neck using a hollow trephine. Drilling of the osteonecrotic area over the applied wire up to 5 mm to the subchondral bone under fluoroscopy, insertion of an expandable bone knife and removal of the osteonecrotic bone supported by a curette. Bone grafting of the autologous bone into the subchondral defect zone and filling of the drill canal by resorbable bone substitute.
Postoperative management: Bed rest for 24 h, then partial weight bearing (20 kg) on crutches for 2-6 weeks depending on the bone quality in the defect zone and the applied bone substitute.
Results: Midterm superiority (2 years) in hip survival of the mACD over advanced core depression and core depression, especially in ARCO stage II.
Keywords: Core decompression; Femoral head; Joint preservation; Minimally invasive surgical procedures; Osteonecrosis.