Revolutionary new management of ACL Ruptures?

Exploring the Cross Bracing Protocol (CBP): A Conservative Approach to ACL Healing

Anterior cruciate ligament (ACL) ruptures are often regarded as one of the most challenging injuries for athletes and active individuals. Traditionally, ACL reconstruction surgery has been the go-to solution, largely due to the belief that the ACL lacks the capacity to heal on its own. However, this assumption is now being questioned as new conservative approaches, such as the Cross Bracing Protocol (CBP), are gaining traction.

Emerging evidence suggests that the ACL may have more healing potential than previously thought, with the CBP showing promising results in clinical studies. The CBP focuses on immobilizing the knee in a flexed position immediately after injury, potentially facilitating natural ligament healing. So, how effective is this novel approach, and could it be a viable alternative to ACL reconstruction?

The Science Behind the Cross Bracing Protocol

The CBP is a structured, non-surgical treatment plan where the knee is immobilized at 90 degrees of flexion for the first four weeks following an ACL rupture. This immobilization gradually progressed to full range of motion by week ten. The primary goal is to reduce the gap between the torn ends of the ACL, creating a more favorable environment for the ligament to heal naturally.

A recent study investigated the effectiveness of this protocol by evaluating MRI evidence of ACL healing at three months post-injury. The findings were compelling—90% of participants showed signs of ACL healing, a significant improvement compared to only 30% in non-CBP studies. Half of these participants (50%) exhibited grade 1 healing, which indicates a thickened and continuous ACL on the MRI.

MRI Monitoring and Long-Term Outcomes

MRI technology plays a crucial role in monitoring ACL healing during the CBP. In the study, the healing grades at the three-month mark were strong indicators of long-term outcomes. Participants with grade 1 healing reported better knee stability, less laxity, and a higher rate of returning to sports (RTS), with 92% of them successfully resuming activity compared to 62% of those with lower healing grades.

While the majority of participants maintained their healing grade from three to six months, four of five patients with grade 1 healing improved further to grade 0, indicating complete recovery. However, re-injuries occurred in 14% of participants, mainly in those who had grade 2 or 3 healing at the three-month mark.

ACL Healing: A Paradigm Shift?

The promising results of the CBP challenge long-held beliefs about the ACL’s inability to heal naturally. From a biological standpoint, the ACL has a rich vascular supply, allowing it to undergo typical phases of healing after injury, which is contrary to the notion that ACL injuries require surgical intervention.

Though more research is needed, the CBP could shift the way clinicians approach ACL injuries. Conservative management such as Physiotherapy guided rehabilitation might become a more attractive option, especially for patients who prefer to avoid surgery and the associated risks of graft harvesting and fixation.

Limitations and Future Directions

While the CBP shows promise, it’s not without limitations. The study mentioned had a pragmatic design, lacking a control group, which makes it harder to generalize the findings. Additionally, departures from the protocol, as well as re-injuries occurring before the recommended return-to-sport timeline, highlight the need for more structured studies.

There is also room for improvement in identifying patients who are more likely to benefit from conservative management. For example, MRI findings such as partial femoral avulsions or displacement of the ACL tissue outside of the intercondylar notch were predictive of poorer healing outcomes. This insight could lead to the development of clinical prediction tools, helping doctors identify which patients are ideal candidates for the CBP early on.

Furthermore, combining the CBP with other innovative techniques like bridge-enhanced ACL restoration (BEAR) or the Fertilized ACL procedure could improve outcomes for patients with lower healing grades. These procedures use biological scaffolds to promote ACL healing without requiring grafts, potentially offering a middle ground between conservative and surgical treatments.

Another limitation is the need for a multidisciplinary team to manage rehabilitation as blood thinners are required to reduce the risk of the formation of a D.V.T due to the prolonged immobilization. 

Clinical Implications

While ACL reconstruction has been the dominant approach for decades, many patients experience poor long-term outcomes, including reduced participation in sports, lingering pain, and the early onset of osteoarthritis. The high rate of re-injury after surgery further raises questions about the long-term success of surgical management.

Momentum is building for conservative approaches like the CBP, which offers an alternative by promoting natural healing. Early MRI assessments, especially at the three-month mark, could play a pivotal role in determining whether surgery is necessary, or if the ACL is on the path to recovery without it.

Although challenges remain, the CBP is an exciting step forward in ACL treatment, and ongoing research will help refine this protocol. With further validation, the CBP could revolutionize the way ACL injuries are managed, reducing the need for invasive surgeries and improving the long-term quality of life for patients.

Reference

Fibay S et al. (2023) Healing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the cross bracing protocol. British Journal of Sports Medicine