Sunday, June 25, 2023

Healing with CBP After ACL Tear

Previous common belief among clinicians and researchers was that after tearing your anterior cruciate ligament (ACL), chances are you will need reconstuctive surgery. Especially if it affects your activities of daily living like climbing stairs, squatting etc. More so if you wish to return to sports.

Well, latest research shows that one may not need surgical intervention to achieve healing after all. The following paper (Filbay et al, 2023) showed excellent results with the Cross Bracing Protocol (CBP) in patients who tore their ACL. 72 out of 80 participants (90 percent) with a total tear of their ACL at baseline had MRI signs of ACL healing (a continuous ACL) after only 3 months.

Of the 8 participants whose ACL's did not heal, 6 had attached to the lateral wall ± PCL (post cruciate ligament), with MRI evidence after 3 months.

The subjects studied were between 10-58 years old who saw a sports doctor in private practice in Sydney, Australia and followed up from 2016-2021 with MRI confirming acute ACL rupture. They were all managed with the CBP.

The CBP aims to reduce the gap distance between the torn ACL remnants by immobilizing the knee at 90 degrees flexion (or bending) for 4 weeks in a knee brace after acute rupture. This to facilitate bridging of tissue and healing between the torn/ ruptured bits. The subjects also used crutches (or wheelchair, i-walker etc) for up to 8 weeks. After 4 weeks the range of motion is increased weekly whilst the subjects underwent physiotherapist-supervised rehabilitation

Previous published research by Filbay et al (2023) support current findings. The KANON (Knee Anterior Cruciate Nonsurgical versus Surgical treatment) trial found at least 30 percent of participants (16 out of 54 participants) with ACL ruptures had signs of  healing (shown on MRI) with conservative management. (Note:  In the KANON trial, subjects with ACL tears had better outcomes when randomized to rehabilitation and optional delayed ACL reconstruction or early surgery and rehabilitation).

The high rate of healing observed after 3 months on MRI suggests that this CRP can be conducive to ACL healing. It is also heartening to note that patients with other associated injuries at baseline became asymptomatic after the CBP.

But it is not known whether a continous ACL observed on MRI demonstrates restoration of pre injury ACL function. 14 percent (11 patients) had re-ruptured their ACL at time of follow up. This rate of reinjury is comparable with re-injury rates following ACL surgery. 90 percent of these re-ruptures occur after return to high risk sports.

Note that data from this study was collected in the course of clinical practice rather than in a research setting so some adaptations were made to the CBP over time. The study design also did not allow comparison of outcomes with people managed with surgery or rehabilitation alone. 

Looking at the protocol in detail (supplementary detail in appendix 1), one would need to wear a knee brace for 12 weeks while using crutches for up to 10 weeks. Some would definitely choose that considering the potential for positive outcomes. 

Results from the KANON trial and the CBP clearly suggest that there may be more ACL healing than what was commonly known. I would add that larger randomized cohorts with longer follow up duration will add more weight to this protocol. Take collagen at the same time to help with further healing.


Filbay SR, Roemer FW, Lohmander LS et al (2023). Evidence Of ACL Healing On MRI Following ACL Rupture Treated With Rehabilitation Alone May Be Associated With Better Patient-Reported Outcomes: A Secondary Analysis Fom The KANON Trial. BJSM. 57: 91-99. DOI: 10.1136/bjsports-2022-105473. *

Filbay SR, Dowsett M, Chaket JM et al (2023). Healing Of Acute Anterior Cruciate Ligament Rupture On MRI And Outcomes Following Non-Surgical Management With The Cross Bracing protocol. DOI: 10.1136/bjsports-2023-106931

*Some of the authors from this study like Frobell and Roemer first investigated ACL healing with papers published back in 2013. You can read more from our other blog.

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