What is the recommended overview, pre‑operative preparation, surgical technique, postoperative care, potential complications, and alternative options for distal femur replacement in patients over 65 with unreconstructable distal femoral pathology?

Distal Femur Replacement: Clinical Overview and Management Protocol

Primary Indication and Patient Selection

Distal femoral replacement (DFR) is the preferred treatment for comminuted intra-articular distal femoral fractures in elderly patients (>65 years) with poor bone quality and unreconstructable fracture patterns, particularly when open reduction internal fixation (ORIF) would provide inadequate fixation. 1, 2

Specific Indications for DFR:

• Comminuted AO/OTA 33C distal femur fractures with intra-articular involvement in low-demand elderly patients 1, 3
• Periprosthetic fractures around total knee arthroplasty with loose femoral components or inadequate fixation potential 2
• Failed osteosynthesis or fracture nonunions in osteoporotic bone 2, 4
• Massive bone destruction where reconstruction is not feasible 4

Key Patient Factors:

• Age typically >70 years with poor bone stock 3
• Low functional demand patients 1
• High comorbidity burden where early mobilization is critical 2

Preoperative Preparation

Medical Optimization:

• Adequate pain management with multimodal analgesia incorporating preoperative nerve blocks 5
• Correction of nutritional deficiencies, particularly calcium and vitamin D 5
• Assessment of cognitive function, renal function, and pressure sore risk 5, 6
• Antibiotic prophylaxis planning 5, 6

Surgical Planning:

• Two-stage procedure required if implant-associated infection is present 4
• Thorough preoperative planning is essential given the 50% complication rate requiring surgical intervention 4
• Consider lateral versus medial arthrotomy approach based on fracture pattern and soft tissue condition 4

Surgical Technique

Approach Selection:

• Lateral approach or medial arthrotomy depending on fracture configuration and prior surgical history 4
• Modular distal femoral replacement systems allow for customization to bone defect size 2, 4

Technical Execution:

• Cemented fixation of femoral and tibial components is standard 2
• Only modular components require exchange if complications occur; cemented nonmodular components are retained 2
• Ensure adequate soft tissue coverage and wound closure to minimize healing complications 4

Postoperative Care Protocol

Immediate Postoperative Management:

• Immediate weight-bearing as tolerated is permitted in 88% of cases, which is the primary advantage over ORIF 2
• Multimodal pain management with continuation of nerve blocks 5
• Tranexamic acid administration to reduce blood loss and transfusion requirements 5
• Correction of postoperative anemia 5, 6

Early Mobilization Strategy:

• Early mobilization is essential to prevent pneumonia, deep vein thrombosis, and pressure ulcers 6
• Physical therapy should begin on postoperative day 1 with weight-bearing as tolerated 2
• At final follow-up (mean 24 months), only 10% of patients remain wheelchair-dependent compared to 23% with ORIF 2, 3

Ongoing Monitoring:

• Regular assessment of wound healing, cognitive function, nutritional status, and renal function 5, 6
• Assessment and regulation of bowel and bladder function 5
• Monitor for early signs of complications requiring prompt intervention 4

Expected Functional Outcomes

Range of Motion:

• Average arc of motion at final follow-up is 95 degrees 2
• Knee Society Score improves significantly from median 20 points preoperatively to 80 points at follow-up 4

Ambulatory Status:

• All DFR patients maintain ambulatory status at 1 year versus 75% with ORIF 3
• Most elderly patients regain ambulatory ability 4

Potential Complications and Management

Common Complications (8-10% implant-related):

• Periprosthetic fractures are the most common complication (occurring in 4-5% of cases) 2, 4
• Deep infection requiring two-stage revision (2% of cases) 2
• Component loosening (rare, <2%) 2, 4
• Wound healing disorders and superficial infections requiring surgical intervention 4
• Arthrofibrosis requiring manipulation 2
• Patellar tendon rupture 4

Critical Pitfall to Avoid:

• The overall complication rate requiring surgical intervention approaches 50% in some series, demanding very thorough preoperative planning and prompt recognition of adverse events 4
• However, when complications occur, only modular components typically require exchange, preserving the cemented femoral and tibial stems 2

Alternative Treatment Options

Open Reduction Internal Fixation (ORIF):

• ORIF results in 18% nonunion rate in patients >70 years with AO/OTA 33C fractures 3
• Average time to fracture union is 24 weeks when successful 3
• 23% of ORIF patients become wheelchair-dependent at 1 year 3
• Reoperation rates are similar between ORIF (11%) and DFR (10%) 3

When ORIF May Be Considered:

• Younger patients with better bone quality 1
• Less comminuted fracture patterns with adequate fixation potential 1
• Higher-demand patients where preservation of native anatomy is prioritized 1

Secondary Fracture Prevention

Systematic Evaluation:

• All patients ≥50 years with fractures require systematic evaluation for subsequent fracture risk 5, 6
• Fracture Liaison Service implementation is the most effective organizational structure 6

Pharmacological Management:

• Use medications demonstrated to reduce vertebral, non-vertebral, and hip fracture risk 5, 6
• Ensure adequate calcium and vitamin D intake 5
• Regular monitoring for medication tolerance and adherence 5, 6
• Smoking cessation and alcohol limitation 5

Interdisciplinary Care Requirements

Interdisciplinary care programs should be used to decrease complications and improve outcomes 5, 6

Essential Team Components:

• Orthogeriatric comanagement for all elderly patients to improve functional outcomes, reduce hospital stay, and decrease mortality 6
• Physical therapy for early mobilization and long-term balance training 6
• Nutritional support services 5, 6
• Pain management specialists 5, 6