ACL Cross Bracing Protocol: A Guide to a Non-Surgical Management Option

An anterior cruciate ligament (ACL) rupture has traditionally been viewed as an injury that almost always requires surgery. However, growing evidence now supports that, for selected individuals, the ACL has the capacity to heal (without surgery). One structured approach that aims to support this process is the ACL Cross Bracing Protocol.

As physiotherapists, our role is to help patients understand all evidence-based options available to them. This blog post aims to explain what the ACL Cross Bracing Protocol is, how it works, who it may suit and what rehabilitation is typically involved.

What is the ACL Cross Bracing Protocol?

The ACL Cross Bracing Protocol is a non-surgical management approach developed by Dr Mervyn Cross and Dr Tom Cross. It combines strict knee bracing with a graduated rehabilitation program designed to support healing of a ruptured ACL.

The core principles are simple:

• By positioning the knee flexion (a bent knee) during the early healing phase, tension on the torn ACL is reduced. This allows the ligament ends to begin to bind, which benefits tendon remodelling over time.
• MRI studies have shown high rates of ACL healing at 12 weeks, when the protocol is followed closely, particularly in appropriately selected patients who are highly compliant.

How Does the Protocol Work?

The strict phase of the protocol typically runs for 12 weeks of structured bracing, followed by a progressive strengthening and rehabilitation phase.

In the early weeks:

• The knee is braced in a fixed, bent position (most often at 90 degrees)
• Weight bearing is restricted
• Exercises focus on maintaining muscle activity without stressing the healing ligament

As healing progresses:

• The brace is gradually opened to allow increasing range of motion
• Exercises progress from isometric (static) to isotonic (movement-based)
• Weight bearing is re-introduced in a graded way

This staged approach allows the ACL to be exposed to progressive load, which is important for ligament remodelling, fibre alignment and strength development. Strict compliance with the brace is essential and this can often be one of the main challenges for patients following the protocol.

What Does Rehabilitation Involve?

Rehabilitation during the Cross Bracing Protocol is active, but carefully controlled and monitored. A physiotherapist will monitor and prescribe:

• Maintenance of quadriceps, hamstring, hip and calf strength
• Whole body exercise and strength to limit de-conditioning
• Gradual exposure to knee movement as the brace settings change
• Education around activity modification, sleep positioning and expectations

As patients transition out of the brace, rehabilitation focuses on:

• Restoring single leg strength, especially as compared to the non-injured side
• Neuromuscular control and balance
• Running, jumping and change of direction mechanics
• Sport and/or work-specific conditioning

Return to sport or high-demand work is guided by functional testing, imaging (MRI at 12 months to check ensure appropriate ACL healing), individual goals and confidence, rather than time alone.

Who Might be Suitable for the ACL Cross Bracing Protocol? 

The Cross Bracing Protocol is not appropriate for everyone. It may be considered when:

• The ACL rupture is recent (not chronic)
• There is minimal associated meniscal or cartilage damage
• The individual is motivated and able to comply with strict bracing
• Shared decision-making has occurred with the broader health team

Importantly, the outcomes are best when patients understand that this approach still requires significant commitment, structured rehabilitation and ongoing loading beyond confirmation of healing.

Key Takeaways

• ACL healing is possible without surgery, in selected cases
• The Cross Bracing Protocol provides a structured and evidence-based framework to support healing
• Compliance with bracing is critical, especially in the first 12 weeks
• Rehabilitation does not stop once healing is seen on MRI

If you’ve sustained an ACL injury and want to understand whether non-surgical management may be appropriate for you, a physiotherapist experienced in ACL rehabilitation can guide you through the decision-making process. The team at Inner Strength Bayside are happy to help!

Written by Louisa Clarke, Physiotherapist.

References

• Filbay SR et al. Healing of acute anterior cruciate ligament rupture on MRI following non-surgical management with the Cross Bracing Protocol. Br J Sports Med. 2023.
• Filbay SR et al. Evidence of ACL healing on MRI following rehabilitation alone and associations with patient-reported outcomes: KANON trial secondary analysis. Br J Sports Med. 2023.
• Frobell RB et al. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med. 2010.
• Frobell RB et al. Treatment for acute ACL tear: five-year outcome of a randomized trial. BMJ. 2013.
• Filbay SR et al. Evidence-based recommendations for the management of ACL injuries. Br J Sports Med. 2023.
• Delincé P, Ghafil D. Anterior cruciate ligament tears: conservative or surgical treatment? Knee Surg Sports Traumatol Arthrosc. 2012.
• Fältström A et al. Patient-reported outcomes after ACL reconstruction versus non-surgical management. Br J Sports Med. 2021.