The Cross Bracing Protocol: How Top Physios Are Healing ACLs Without Surgery.
Key insights: 60-second read
- ACLs may have greater healing potential than previously believed - The Cross Bracing Protocol (CBP) aims to hold the torn ligament ends together during early healing.
- 90% of patients showed MRI evidence of ACL healing - A 2023 study of 80 patients found that 90% had a continuous ACL at 3 months.
- Strict protocol required - Knee locked at 90° flexion for 4 weeks, worn 24/7. No knee extension allowed during this phase.
- Not suitable for everyone - Patient selection is critical. Acute injuries, early presentation, and high compliance are key factors.
- Rehabilitation continues throughout - While the knee is immobilised, physiotherapy focuses on maintaining muscle and function.
For decades, a complete ACL rupture was seen as a one-way ticket to surgery. The assumption was simple: the ACL cannot heal as its two ends will have separated and retracted, so surgical reconstruction has always been the primary option.
But what if this assumption was wrong?
Emerging evidence suggests that the ACL may have an underappreciated capacity to heal - if the torn ends are held close together during the early inflammatory phase. The Cross Bracing Protocol (CBP) was developed to create exactly these conditions.
This article is a comprehensive guide to the CBP. Drawing on insights from leading experts including Dr Tom Cross (who developed the protocol), Geoff Ford, Dr Steven Duhig, Dr Kieran Richardson, and A/Prof Steph Filbay, we'll explore what the protocol involves, who it's suitable for, and what the evidence says.
"ACLs appear to have greater healing potential than previously believed. Careful patient selection is essential." - Dr Steven Duhig
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What is the Cross Bracing Protocol?
The Cross Bracing Protocol is a structured, non-surgical treatment pathway designed to promote biological healing of the ACL following an acute rupture.
It was developed by Dr Tom Cross and Dr Merv Cross in Sydney, Australia, based on a simple anatomical observation: at approximately 90° of knee flexion, the distance between the ACL's femoral and tibial attachment sites is shortest.
By immobilising the knee at this angle for the first four weeks after injury, the protocol aims to bring the torn ligament ends close together, allowing clot formation and tissue bridging to occur.
The Core Principle
Rather than assuming the ACL cannot heal, the CBP attempts to recreate the conditions under which other ligaments naturally heal. The knee is held in a position that reduces tension on the ACL and supports the healing process.
The Evidence: What the Research Shows
A landmark 2023 study published in the British Journal of Sports Medicine evaluated the outcomes of 80 consecutive patients with acute ACL rupture managed with the CBP. The findings were striking:
Key Findings from the 2023 Study
- 90% healing rate: 72 of 80 patients (90%) had evidence of ACL healing (a continuous ACL) on 3-month MRI.
- Better outcomes with more healing: Patients with the highest grade of healing reported better knee function and quality of life compared to those with lower-grade healing.
- Higher return to sport: 92% of those with the highest grade of healing returned to pre-injury sport, compared to 64% with lower healing grades.
- Excellent functional outcomes: Patients with higher healing grades reported better than average functional scores reported after ACL reconstruction.
The researchers concluded: "After management of acute ACL rupture with a novel bracing protocol, 90% of patients had evidence of ACL healing on a 3-month MRI. More ACL healing was associated with better knee function and QOL, less passive knee laxity and a higher return-to-sport rate".
It is important to note that this was a case series, not a randomised controlled trial. The findings are promising but still in their infancy. As Dr Tom Cross himself emphasises, larger comparative studies are still needed before the protocol can be considered standard care.
The Protocol: Step-by-Step
Timing is Everything
In a recent podcast, Geoff Ford stresses that the protocol is extremely time-sensitive. Ideally, patients should be assessed within the first week after injury.
Immediately after rupture, bleeding fills the injured area, inflammatory healing begins, and the ligament ends remain relatively mobile. If several weeks pass, scar tissue develops, the ligament ends retract, and union becomes far less likely.
The general cut-off is about three weeks after injury.
Phase 1: Weeks 0-4 - Complete Immobilisation
The knee is locked at 90° of flexion in a brace.
- The brace is worn 24 hours per day, including during sleep and showering.
- The knee must not be straightened at any point during this phase.
- Patients use crutches or a knee scooter for mobility.
- Weight-bearing is possible in theory, but functionally limited because the knee is locked at 90°.
On a recent Physio Network podcast, Dr Steven Duhig describes this as the hardest phase psychologically. Everyday activities - sleeping, showering, sitting, getting dressed - must all be performed without allowing the knee to extend.
Phase 2: Weeks 5-12 - Progressive Extension
After four weeks, extension is gradually restored.
| Time | Brace Setting |
|---|---|
| Weeks 0-4 | Locked at 90° |
| Week 5 | 60° |
| Week 6 | 45° |
| Week 7 | 30° |
| Week 8 | 20° |
| Week 9 | 10° |
| Weeks 10-12 | Continued progression before brace removal |
Brace removal typically occurs at approximately 12 weeks, although timing may vary according to MRI findings, healing quality and associated injuries.
MRI Assessment at 12 Weeks
One of the key differences from traditional conservative management is that healing is objectively assessed.
Around three months, patients undergo a repeat MRI. The MRI looks for:
- Continuity of the ACL fibres
- Tissue bridging
- Fibre orientation
- Overall appearance of healing
Clinical examination is then combined with MRI findings to determine the next stage of rehabilitation.
Who is Suitable for the Cross Bracing Protocol?
Experts like Geoff Ford repeatedly stress that patient selection is probably the most important factor. Not every ACL rupture can or should undergo the protocol.
Ideal Candidate Characteristics
- Acute injury: Presentation within the first 7-10 days after injury
- Early MRI: Confirmation of ACL rupture and assessment of tear morphology
- Isolated or manageable injury: No unstable bucket-handle meniscal tears or other concurrent knee tissue injuries requiring urgent surgery
- High compliance: Ability to follow the strict protocol without deviation
- Motivated patient: Willingness to accept several months of inconvenience
- Appropriate tear morphology: Proximal tears (where the ligament pulls off the bone) tend to heal better than mid-substance or distal tears
Absolute Contraindications
- Bucket-handle meniscal tears requiring urgent surgery
- Osteochondral loose bodies
- Previous or current deep vein thrombosis (DVT)
- Significant thromboembolic risk
- Presentation too late after injury (commonly >3 weeks)
Relative Contraindications (Require Careful Consideration)
- Poor social support
- Inability to work while braced
- Right-leg injury (driving is generally not possible)
- Mental health concerns
- Anticipated poor adherence
What Dr Tom Cross Looks For
On the British Journal of Sports Medicine (BJSM) podcast, Dr Tom Cross explains that the team developed a grading system to determine which tears have the greatest likelihood of healing. Certain tear locations appear substantially more favourable than others. The key question is: Can these torn fibres be brought together at 90°? This determines suitability more than simply whether the ACL is "completely torn".
Rehabilitation During the Protocol
One of the most important points discussed around non-surgical management is that rehabilitation does not stop just because a person is immobilised.
Rehabilitation Priorities
- Maintain quadriceps activity: This becomes one of the biggest challenges. Because the knee remains fixed in deep flexion, normal strengthening is limited. Focus on quadriceps activation, isometrics where appropriate, and electrical stimulation when indicated.
- Hip and calf strength: Continued training of surrounding muscles.
- Cardiovascular fitness: Arm ergometer, upper-body circuits, later introduction of cycling, and rowing when appropriate.
- Minimise muscle atrophy: Regular, prescribed exercises that do not compromise the healing ligament but still engage and fatigue surrounding muscles.
As Dr Steven Duhig explains, the goal is to "lose as little muscle and function as possible while allowing the ACL the greatest opportunity to heal".
"The brace itself doesn't heal the ACL. The brace simply creates an environment that may allow the body's own healing response to occur." - Geoff Ford
Common Misconceptions
A/Prof Steph Filbay and Dr Kieran Richardson challenge several longstanding beliefs about ACL injuries in their discussions on non-operative approaches:
- ❌ Every ACL rupture requires surgery. - Many patients function well without reconstruction; some ACLs demonstrate biological healing.
- ❌ A ruptured ACL can't reconnect on its. - The evidence increasingly shows that ACLs can heal under the right mechanical conditions.
- ❌ Reconstruction prevents osteoarthritis. - ACL injury itself substantially increases OA risk, and reconstruction does not appear to eliminate this increased risk.
- ❌ MRI findings alone determine treatment. - MRI findings should always be interpreted alongside symptoms, examination, and patient goals.
The Bottom Line
The Cross Bracing Protocol represents a significant shift in how we think about ACL injuries. Rather than assuming that every complete ACL rupture requires reconstruction, the protocol offers a structured pathway that may allow the body's own healing mechanisms to restore continuity to the ligament.
In the first 80 patients managed with the protocol, 90% showed MRI evidence of ACL healing at 3 months, and those with better healing reported excellent knee function and high return-to-sport rates.
However, this is not a one-size-fits-all solution. Only certain ACL injuries are eligible and the process is not for everyone. The protocol is restrictive, time-sensitive, and requires excellent compliance. Eventual surgery is still an option for everyone is the protocol isn't successful.
If you have sustained an acute ACL rupture, the most important step is to seek early assessment and discuss all your management options - surgery, exercise-based rehabilitation, and the Cross Bracing Protocol - with a clinician who can help you make an informed decision based on your injury, goals, and circumstances.
I hope this article has provided a clear, practical overview of the Cross Bracing Protocol. If you have questions about your ACL injury or want to discuss which management pathway might be right for you, I'm here to help.
- Grant
Frequently Asked Questions
How long does the Cross Bracing Protocol take?
The brace is worn for approximately 12 weeks, followed by a progressive rehabilitation program. Return to sport is not recommended until 9-12 months post-injury, depending on functional recovery and strength testing.
Does a healed ACL on MRI mean a normal ACL?
No. As Dr Tom Cross explains, healing does not necessarily mean identical collagen structure, identical biomechanics, or identical injury risk. The goal is achieving continuity, stability, and acceptable function to return to activity without reconstruction where appropriate.
What if the protocol doesn't work?
Some patients fail to heal, remain unstable, or sustain associated injuries and ultimately proceed to ACL reconstruction. An important advantage highlighted by Dr Steven Duhig is that traditional ACL surgery is still a viable option for many if healing has been unsuccessful.
Is the Cross Bracing Protocol suitable for everyone?
No. Patient selection is critical. The protocol is most suitable for acute injuries presenting within 7-10 days, with appropriate tear morphology and motivated patients who can comply with the strict protocol. It is not recommended for those with unstable meniscal tears requiring surgery, DVT risk, or late presentations.
Does the CBP work for mid-substance ACL tears?
Current evidence suggests the protocol may be most effective for proximal tears (where the ligament pulls off the bone). Mid-substance and distal tears may have a lower likelihood of healing, though further research is needed to determine which tear patterns are most suitable.
What is the role of anticoagulation in the CBP?
Because prolonged immobilisation increases the risk of venous thromboembolism, patients undergoing the original protocol are typically prescribed anticoagulants after consultation with their treating medical team. In the 2023 study, DVT screening and anticoagulation were added to the protocol.
One key insight
"A 2023 study found that 90% of patients managed with the Cross Bracing Protocol had MRI evidence of ACL healing at 3 months. Those with better healing reported excellent knee function and a 92% return-to-sport rate - exceeding outcomes typically reported after ACL reconstruction."
Living With a Knee Injury?
If you've sustained an ACL injury or are unsure about your management options, a thorough assessment can help. Learn more about our knee pain physiotherapy services in Port Macquarie.
Want personalised guidance?
If you'd like help making sense of your knee injury or any other persistent issue, you can book with Grant either in Port Macquarie or via an online telehealth consultation.
