Advanced HTO and DFO Osteotomy

High tibial osteotomy (HTO) and distal femoral osteotomy (DFO) are joint-sparing reconstructive procedures that correct lower limb malalignment to redistribute mechanical load across the knee. Indications include young to middle-aged active patients (typically 40-60 years) with symptomatic unicompartmental osteoarthritis (medial compartment with varus alignment for HTO; lateral compartment with valgus alignment for DFO), focal chondral defects with associated malalignment, posttraumatic deformity, and meniscal deficiency or transplantation cases.

HTO surgical techniques: opening-wedge medial HTO (most common today—allows precise correction with proximal medial tibial plate fixation, requires bone graft for opening, allows multiplanar correction), closing-wedge lateral HTO (older technique, faster healing but causes limb shortening, fibular osteotomy required), and dome osteotomy (less common, allows correction without length change). DFO techniques: opening-wedge medial DFO and closing-wedge lateral DFO for valgus deformity correction. Double-level osteotomy combines tibial and femoral procedures for combined deformity and is increasingly recognized as superior to single-level when both joint sides contribute to malalignment.

Surgical planning involves detailed preoperative assessment with weight-bearing long-leg radiographs to determine mechanical axis (Mikulicz line) and origin of deformity (intra-articular vs femoral vs tibial), CT for 3D understanding, and computer-assisted planning or patient-specific instrumentation for precise execution. Target alignment for HTO is typically 62.5% Fujisawa point on tibial plateau (lateralization of mechanical axis), achieving 3-6° valgus from neutral mechanical axis. Modern fixation includes locking plates with rigid internal fixation, allowing partial weight-bearing at 6 weeks and full at 12 weeks. Outcomes: 10-year survival before conversion to TKA is 75-85%, best in young patients with high BMI <30, intact ACL, no patellofemoral disease, and adequate technical correction. Complications include nonunion (5-10%), hinge fracture in opening-wedge, deep vein thrombosis, infection, and progression of OA in opposite compartment. Recent innovations include patient-specific 3D-printed cutting guides, computer-assisted navigation, and biological augmentation with cell therapy or scaffolds for combined cartilage repair.