Rethinking ACL Injury Management: The Science Behind the Cross Bracing Protocol
Anterior cruciate ligament (ACL) injuries are common, particularly in athletes, and have traditionally been managed with surgery due to the belief that the ACL has limited healing potential. However, recent evidence is challenging this long-standing approach. The Cross Bracing Protocol has emerged as a promising non-surgical option. This blog post explores the scientific foundation, key components, and clinical outcomes of the Cross Bracing Protocol.
What is the Cross Bracing Protocol?
The Cross Bracing Protocol is a structured, non-surgical rehabilitation approach aimed at supporting the healing of acute ACL ruptures. Developed by Drs Mervyn and Tom Cross, the protocol involves immobilising the knee at 90 degrees of flexion for four weeks. This is followed by a gradual progression in range of motion and supervised physiotherapy.
Rationale and Mechanism
The protocol is based on the concept of "closed reduction", where positioning the knee in 90 degrees of flexion helps bring the torn ends of the ACL closer together. This may allow a connective tissue bridge to form and promote ligament healing.
This period of immobilisation aligns with established orthopaedic principles of reduction and stabilisation to optimise tissue repair.
Protocol Details
Initial Phase (Weeks 1 to 4):
Knee is immobilised at 90 degrees of flexion in a brace, worn at all times.
Non-weight bearing using crutches or a knee scooter.
Anticoagulation medication is commonly prescribed to reduce the risk of deep vein thrombosis (DVT).
Progressive Range of Motion Phase (Weeks 5 to 12):
Week 5: Brace adjusted to allow 60 to 90 degrees of flexion.
Week 6: 45 to 90 degrees flexion.
Week 7: 30 to 120 degrees flexion, weight bearing as tolerated with crutches.
Week 8: 20 to 120 degrees flexion, weight bearing without crutches if able; anticoagulation is usually discontinued.
Week 9: 10 to 120 degrees flexion.
Week 10: Brace use becomes unrestricted and can be removed for sleep.
Week 12: Brace is removed entirely; MRI and clinical review follow.
Rehabilitation
Rehabilitation is supervised by a physiotherapist and focuses on:
Maintaining muscle strength
Controlling swelling
Gradually restoring functional movement
Exercises are tailored to target the quadriceps, hamstrings, gluteals and core muscles, progressing as ROM improves.
Return to Sport
Straight-line running typically begins around week 16 or 17.
Return to full training and sport is individualised and usually occurs after 9 to 12 months, following clinical review and repeat MRI.
Scientific Evidence and Outcomes
ACL Healing Rates and MRI Findings:
A prospective study involving 80 patients found that 90% had MRI evidence of ACL healing at three months following the CBP, compared to just 30% in a group managed without it.
Half of the CBP group achieved grade 1 healing, which indicates full continuity of the ACL.
Functional Outcomes:
Patients with better MRI healing (ACLOAS grade 1) reported higher Lysholm and ACL Quality of Life (ACLQOL) scores at one year post-injury.
Lower knee laxity and improved return-to-sport outcomes were seen in those with higher healing grades.
Clinical Implications:
The CBP challenges the long-held belief that the ACL cannot heal without surgery.
It presents a viable, non-surgical alternative for some patients with acute ACL ruptures.
Patient selection and adherence to the protocol are key to achieving good outcomes.
Conclusion
The Cross Bracing Protocol marks a significant shift in how ACL injuries may be managed. It provides a non-surgical, scientifically supported pathway to ligament healing and functional recovery. While more research is underway, current findings suggest that for carefully selected patients, outcomes with the CBP may be comparable to those seen after surgery.
If you’ve recently sustained an ACL injury and want to explore whether the Cross Bracing Protocol might be right for you, book in for an assessment at SurfEdge Sports Physiotherapy. We’ll work with you to develop a personalised plan based on the latest evidence and your individual goals.
👉 Book online at www.surfedge.physio/book-now
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