What is the recommended treatment and management for distal femoral replacement (DFRB)?

Treatment for Distal Femoral Replacement (DFR)

Immediate Surgical Approach

For elderly patients with complex distal femur fractures, comminuted intra-articular fractures, or periprosthetic fractures with poor bone quality, distal femoral replacement should be performed within 24-48 hours to optimize outcomes and allow immediate weight-bearing mobilization. 1, 2

Surgical Technique Selection

• Use a rotating-hinged distal femoral replacement device with modular components to address severe bone loss and instability 3
• Cemented femoral stems are mandatory to improve function, reduce residual pain, and decrease periprosthetic fracture risk, particularly in osteopenic bone 1, 4
• Choose between lateral or medial arthrotomy approach based on soft tissue condition and prior surgical scars 5
• For patients with active infection, perform two-stage procedures with interval antibiotic spacer placement 5

Specific Indications for DFR

• Periprosthetic fractures around total knee arthroplasty with loose femoral components 2, 6
• Comminuted intra-articular distal femoral fractures in low-demand elderly patients with poor bone quality 7, 3
• Failed osteosynthesis with massive bone destruction 5
• Distal femoral nonunion in osteoporotic bone 3
• Revision TKA with severe bone loss exceeding 50% of bone diameter 8, 3

Perioperative Management Protocol

Pre-operative Optimization

• Administer multimodal analgesia with pre-operative nerve blocks to establish optimal pain control 1
• Correct calcium and vitamin D deficiencies in all patients prior to surgery 1
• Assess cognitive function, renal function, and pressure-injury risk systematically 1
• Plan antibiotic prophylaxis according to infection-prevention protocols 1

Intra-operative Measures

• Administer tranexamic acid intra-operatively to reduce blood loss and transfusion requirements 1, 4
• Ensure adequate soft tissue coverage and meticulous hemostasis to prevent wound complications 5

Post-operative Care

• Allow immediate weight-bearing as tolerated in 88% of cases to prevent deconditioning 2
• Continue multimodal pain management with ongoing nerve-block techniques 1
• Address postoperative anemia through appropriate medical management 1, 4

Early Mobilization & Rehabilitation

• Initiate physical therapy on postoperative day 1 focusing on weight-bearing as tolerated and balance training 1
• Implement structured muscle strengthening programs to optimize functional recovery 4
• Monitor for early complications including wound-healing disorders, which occur in approximately 14% of cases 5

Expected Outcomes & Complications

Functional Results

• Knee Society scores improve significantly from preoperative mean of 20-39 points to postoperative 80-87 points 5, 3
• Average arc of motion at final follow-up is 95 degrees 2
• Approximately 90% of patients regain ambulatory ability, with only 10% remaining wheelchair-dependent 2

Complication Rates & Management

The overall complication rate is high at 36-50%, requiring vigilant monitoring and prompt intervention. 5, 6

• Periprosthetic joint infection (PJI) is the most common complication at 17%, particularly in patients with prior infection history 6
• Patients with prior PJI have fourfold increased risk of postoperative infection compared to aseptic cases 6
• Periprosthetic fractures occur in approximately 10-14% of cases and typically require only modular component exchange 5, 2
• Wound-healing disorders and superficial infections necessitate surgical intervention in approximately 14% of cases 5
• Aseptic loosening is rare with modern cemented techniques 3

Implant Survivorship

• Revision-free survivorship: 91.6% at 1 year, 87.9% at 2 years, 82.5% at 5 years, and 73.4% at 10 years 6
• Patients with prior PJI have the lowest survivorship compared to those undergoing DFR for periprosthetic fracture or mechanical loosening 6
• When revision is required, only modular components need exchange while cemented femoral and tibial components are retained 2

Secondary Fracture Prevention

Systematic Evaluation

• All patients aged ≥50 years require systematic evaluation for future fracture risk following DFR 1
• Implement Fracture Liaison Service (FLS) as the most effective organizational model for secondary prevention 1, 4

Pharmacologic Management

• Prescribe anti-osteoporotic therapy proven to reduce vertebral, non-vertebral, and hip fracture risk after addressing secondary hyperparathyroidism 1, 4
• Ensure adequate calcium and vitamin D intake as part of the preventive regimen 1
• Monitor medication tolerance and adherence regularly 1

Lifestyle Modifications

• Advise smoking cessation and alcohol limitation to lower re-fracture risk 1
• Continue long-term balance training to prevent subsequent fractures 4

Interdisciplinary Care Model

• Establish orthogeriatric co-management for elderly patients to improve functional recovery, shorten hospital stay, and decrease mortality 1
• Include nutritional support services to optimize recovery and bone health 1
• Involve pain-management specialists throughout the perioperative period 1
• Monitor wound healing, cognitive function, nutritional status, and renal function regularly 1
• Assess and manage bowel and bladder function proactively 1

Special Considerations for Metastatic Disease

When DFR is indicated for metastatic carcinoma or myeloma:

• Administer bone-modifying agents to reduce incidence of femur fracture regardless of tumor histology 8
• Use radiation therapy to decrease fracture rate in patients at increased risk 8
• Arthroplasty improves patient function and decreases need for postoperative radiation therapy compared to internal fixation alone 8
• Consider patient life expectancy, mental status, mobility status, and metabolic status in surgical planning 8