What are the key components of the Melbourne Anterior Cruciate Ligament (ACL) protocol?

Key Components of the Melbourne ACL Protocol

The Melbourne ACL protocol is a comprehensive rehabilitation framework that emphasizes exercise interventions as the mainstay of ACL reconstruction rehabilitation, with progressive phases based on objective criteria rather than strict time frames. 1

Early Phase (Weeks 1-2)

• Immediate knee mobilization within the first week to increase range of motion and prevent extension deficit
• Pain management with cryotherapy to control pain and swelling
• Isometric quadriceps exercises beginning in the first postoperative week when pain-free
• Weight bearing as tolerated if correct gait pattern can be maintained
• Physical therapy modalities as adjuncts to allow earlier pain-free exercise rehabilitation

Progressive Strengthening Phase (Weeks 2-4)

• Closed kinetic chain (CKC) exercises beginning from week 2, including partial weight-bearing squats and step-ups
• Progressive strengthening transitioning from isometric to concentric and eccentric exercises when:
  • Quadriceps is reactivated
  • No pain or effusion present
  • No increase in temperature
• Neuromuscular training combined with strength training
• Balance and proprioception exercises to improve neuromuscular control

Advanced Rehabilitation Phase (Weeks 4-8)

• Open kinetic chain (OKC) exercises starting from week 4 with restricted ROM:
  • Week 4: 90°-45°
  • Week 5: 90°-30°
  • Week 6: 90°-20°
  • Week 7: 90°-10°
  • Week 8: Full ROM
• Eccentric training for greater strength gains and muscle hypertrophy
• Core stability exercises to improve gait and knee function
• Plyometric and agility training to improve subjective function and functional activities

Return to Running Phase

• Minimum timeframe of 12 weeks post-surgery (with some protocols suggesting 8 or 16 weeks)
• Combined criteria approach using:
  • Time-based criteria
  • Clinical assessment
  • Functional performance measures

Return to Sport Criteria

• No pain or swelling
• Full knee range of motion
• Limb Symmetry Index (LSI) >90% for strength and hop tests
• Stable knee on clinical examination
• Normalized patient-reported outcomes
• Psychological readiness assessment for return to sport

Key Principles of the Protocol

1. Quality of movement is monitored during all exercises
2. Progression occurs only when exercises do not provoke:
   • Pain
   • Effusion
   • Increase in temperature
3. Objective criteria rather than time alone determine progression
4. Exercise interventions are the cornerstone of rehabilitation
5. Individualized progression based on functional milestones

Common Pitfalls to Avoid

• Delaying mobilization can lead to extension deficit and osteoarthritis development
• Neglecting quadriceps strengthening results in significant negative long-term outcomes (deficits >20% have major impact)
• Focusing only on strength without neuromuscular control leads to poor movement patterns and increased reinjury risk
• Inadequate graft conditioning can cause graft elongation and instability 2
• Premature return to sport without meeting objective criteria increases reinjury risk

The Melbourne ACL protocol represents a shift from conservative, standardized length protocols to more accelerated, individualized approaches based on patient-specific findings and functional milestones 3. This approach has shown superior outcomes in improving knee function in athletes following ACL reconstruction 4.