Remember the Cross Bracing Protocol (CBP)? These are patients who are managed conservatively without surgery, they are put in a brace to allow ACL healing to occur.The injured knee is kept at 90 degrees of knee flexion to reduce the gap between the ruptured ACL remnants. Research shows that 90 percent people regain continuity of the fibers after 3 months of treatment in the CBP.
Yes, the torn ACL can heal when both ruptured ends attached to each other while the knee is in a bent position. However, more severe ruptures are the least likely to achieve optimal healing.
Not all ACL's that heal (or regain continuity of fibers) in studies had a normal appearance on MRI. 50 percent of subjects in the KANON trial had a normal appearance ACL, the other 50 percent had a thinner/ elongated continuous ligament (Filbay et al, 2023).
56 percent of those with a continuous ligament 3 months post CBP treatment had a thick ligament with normal course. The other 44 percent had a thinned/ elongated continuous ligament.
In this currrent study, subjects with a thick ACL with normal course at 3 months had better 12 month outcomes when it came to knee function, quality of life and return to sport.
In addition, the following characteristics may affect the likelihood of achieving an optimal healing outcome. Patients with partial avulsion of ACL tissue from the femoral attachment are more likely to have a suboptimal healing or even no healing compared to those with the femoral origin intact (pictured above).
Displacement of the ACL ligament outside the intercondylar notch is also associated with suboptimal healing when managed with CBP. This may be due to a significant disruption to the synovial sheath that encapsulates the ACL. Disruption of this sheath negatively impacts healing potential.
If the distance of the gap between the 2 ends of the ruptured ACL is too wide (assessed by measuring the largest distance between the torn ends of the ACL), optimal healing is less likely to occur. Among the first 80 people in this study, 7 out of 40 (18 percent) patients achieved a thick/ taut ligament healing had a gap of ≥7mm on MRI.19 out of 32 (59 percent) had a thinned/ elongated ligament while 7 out of 8 (88%) had no ACL healing at 3 months.
When one or both ends of the ACL stumps appear rounded or retracted, also know as ACL involution, it is usually the early stages of a 'non-heal' and may correspond to poor or no healing. This is observed commonly in patients who present for MRI more than 3 weeks post ACL tear.
Besides the above, meniscal injuries, another ligament injury, articular cartilage damage, osteoarthritic features, bone bruising and joint swelling may also affect the likelihood of achieving optimal healing.
The authors concluded that with further research they may be able to assist people in making an informed treatment decision of the likelihood of individuals achieving optimal healing with nonsurgical management.
Reference
Filbay S, Dowsett M, van Haeringen M et al (2025). A New Way Of Grading Severity Of ACL Rupture On Acute MRI To Consider Potential For Noin- Surgical Healing With Cross Bracing Protocol: ACL Acvute Rupture Characteristics For Healing (ACL-ARCH) MRI Criteria. J Sci Med Sp. 29: 145-148. https://www.jsams.org/article/S1440-2440(25)00411-6/fulltext
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