What is the role of resistive training in offloading for avascular necrosis (AVN) management?

Role of Resistive Training in Offloading for Avascular Necrosis (AVN) Management

Resistive training is recommended as a complementary therapy to offloading in AVN management, with focus on strengthening muscles around affected joints while avoiding direct loading of necrotic areas.

Understanding Offloading in AVN

Avascular necrosis (AVN) occurs due to temporary or permanent loss of blood supply to bone, leading to bone necrosis, with the femoral head being most commonly affected 1. Proper offloading is essential in AVN management to:

• Reduce mechanical stress on affected areas to prevent progression of bone destruction 2
• Prevent collapse of necrotic bone and subsequent joint deformity 3
• Allow for potential healing and revascularization of affected bone 4

Recommended Offloading Approaches

• For early-stage AVN (stages I-II), protected weight bearing is the primary offloading strategy 3
• Total contact casts or non-removable knee-high walkers may be used for effective offloading of lower extremity AVN 2
• Removable devices can be considered when non-removable options are contraindicated, though patient adherence is a concern 2

Role of Resistive Training

Resistive training can play a valuable supportive role in AVN management when properly implemented:

• Strengthens muscles surrounding affected joints to improve functional capacity without directly loading necrotic areas 5
• Increases muscle force and mass, improving ability to perform weight-bearing activities with reduced stress on affected joints 5
• Elicits reduced cardiorespiratory response compared to endurance exercise, making it more tolerable for individuals with limited exercise capacity 5

Optimal Training Parameters for AVN

• Perform 10-15 repetitions at lower resistance levels (40-60% of one-repetition maximum) 5, 6
• Complete 1-3 sets of exercises 2-3 days per week 5
• Focus particularly on strengthening muscles that support affected joints 5
• Avoid heavy isometric repetitive training that might increase loading on affected areas 2
• Use light resistive training with small free weights or repetitive isolated muscle training 2, 6

Implementation Strategies

• For lower extremity AVN (hip, knee, ankle):

  • Focus on quadriceps strengthening as it optimizes performance of tasks like stair-climbing and sit-to-stand movements 5
  • Include leg extensions, leg curls, and leg press exercises with modified positioning to avoid direct loading of affected areas 5

• For upper extremity AVN (shoulder, elbow):

  • Include bench press, lateral pulldowns, biceps curl, and triceps extension with appropriate modifications 5

• Progressive overload should be implemented by:

  • Gradually increasing resistance/weight
  • Increasing repetitions per set
  • Increasing sets per exercise
  • Decreasing rest periods between sets 5

Special Considerations and Precautions

• Avoid direct loading of the affected joint during acute phases of AVN 3, 4
• Modify exercise positions to prevent compression forces on necrotic areas 5
• For hematologic malignancy patients with AVN, consider risk of infection and cytopenia when designing exercise programs 2
• In patients with AVN secondary to steroid use, be aware of potential bone fragility requiring more gradual progression 1

Clinical Monitoring and Follow-up

• Regular assessment of pain during and after exercise sessions 7
• Periodic imaging to evaluate disease progression and response to treatment 7
• Adjustment of exercise program based on disease stage and symptoms 3

Conclusion of Benefits

When properly implemented as part of a comprehensive management plan, resistive training in AVN can:

• Maintain muscle strength and joint function without accelerating disease progression 5
• Improve quality of life by enhancing ability to perform daily activities 5
• Potentially slow progression of functional limitations associated with AVN 3, 4