SELF-HEALING POTENTIAL OF THE ACL
                     SELF-HEALING 
POTENTIAL OF 
THE ACL
http://www.virtualphysicaltherapists.com/
A twist, a pop, a fall to the ground, pain, and immediate swelling…unfortunately, 
this experience is too common in our young athletes. 
Anterior Cruciate Ligament (ACL) ruptures cause instability and potentially end 
sports activity and careers, causing long-term physical and psychological 
consequences.  Is surgery the best option, or is there a self-healing potential for 
the ACL?
ACL Injury Stats:
More than 200 000 ACL injuries occur in the United 
States each year. Most occur during athletic activity 
involving pivoting and cutting sports affecting high 
school females 4-6x more often than their male 
counterparts. Most injuries result from non-contact 
and not a collision with another player. Change of 
direction (COD) has been identified as the leading 
cause of ACL tears. A quick turn adds a high load 
when the knee is flexed, rotated, and abducted. 
When the foot is planted on the ground, this quick 
change of direction causes stress on the ACL, and 
the addition of high-level force can be disastrous. 
**The position of the knee during a change of 
direction is the key to reducing ACL trauma.**
Surgery is Currently the Most Common 
Treatment:
Approximately 90% of Americans who tear their 
ACL eventually have surgery, replacing the ACL 
with a cadaver or using a piece of their 
infrapatellar or hamstring tendon.
The ACL is the main stabilizer of the knee. An 
intact ACL is considered essential for athletic 
activity, especially sports that require pivoting and 
cutting. It is also thought that the ACL is incapable 
of healing because of inadequate blood supply.
Therefore surgical repair is essential to return to playing high-level sports, and 
opting not to repair will lead to meniscal tears and early osteoarthritis. Searching 
the internet will produce site after site that the ACL does NOT have blood supply 
because the fluid in the knee that allows smooth movement blocks clotting, thus 
preventing the ability of the ACL to connect and heal. ACL repair is sold as the gold 
standard enabling the return to play and preventing further meniscal damage and 
osteoarthritis. 
**Research has shown that the outcomes of ACL reconstruction are not as great 
as we are told, with the increased risk of re-injury and future risk of 
osteoarthritis.**
Less Commonly Known ACL Surgical Outcomes:
• Only 65% of those who underwent ACL reconstruction returned 
to their preinjury level. (1,2,3)
• Only 55% of individuals return to competitive sports following 
surgery. (1,2,3)
• There is a high rate (15x) of retearing the repaired ACL (9%) or 
the contra ACL (20.5%) within 2 years following ACL 
reconstruction.
• 25% of athletes (under 25 years of age) who return to high-risk 
sports go on to have a second ACL injury. 
• Expectations for returning to the preinjury sport are often not 
met. 
• High rates of reinjury suggest that there is 
insufficient neuromuscular training during rehab following ACL 
reconstruction.
• A 20-year follow-up study on ACL tears found no difference in the amount of 
osteoarthritis in surgical repairs vs. rehab only.
• Potential surgery side effects: infection, scar tissue, blood clots, kneecap pain, 
pain/weakness/tendonitis at the graft site (hamstring or patellar tendon), 
reaction to anesthesia
• Surgical outcomes have shown poor odds of returning to play and high 
incidences of retear.
There is a FALSE ACL surgical narrative….. we need a Paradigm shift & Rethink a 
rush to ACL Reconstruction.
Non-surgical Outcomes Following a Complete ACL Tear:
Surprisingly 2 and 5 years after an ACL injury, the research found 
no significant differences in outcomes of ACL surgery versus those that completed 
a structured rehab program instead of surgical repair. Even more surprising, a 
twenty-year study found no difference in arthritis between those getting surgery 
and those doing conservative care.
The anterior cruciate ligament has healing capabilities, and conservative 
management may provide some athletes with optimal functional outcomes. 
Unfortunately, very few studies compare surgical reconstruction to rehab alone for 
ACL tears. The studies did show that long-term results were much better in non-
surgical patients.
Return to Play with Complete ACL Tear & NO surgical Repair
But there are instances when a complete ACL tear athletes have returned to play 
without surgery.
McDaniel and Dameron in 1983, found that after14-years 76% of untreated patients 
with ACL ruptures returned to strenuous sports. They all had reduced incidences of 
giving way but continued high rotary instability.
Despite What is Commonly Believed, the ACL 
has Self-Healing Potential!
Over the years, a few cases of spontaneous healing of 
complete ACL tears have been reported, but this has 
not received as much attention as profitable surgery.
Over 50% of ACL tears can heal by themselves with no 
focused treatment. Research has found that 
56% of tears spontaneously heal at 2 years and 58% at
 5 years
.
Instead of rushing to surgery, the focus should be on 
the self-healing potential of the ACL!  
A fracture requires 6-8 weeks to heal. We have only begun researching ACL healing, so 
we do not know the amount of time needed and the best position, diet, exercise, etc., 
that will promote this process. Unfortunately, very few studies have been done, and 
little is known about what facilitates and what stressors reduce ACL healing other than 
our plasma is involved.
If over 50% can heal without targeted treatment, then significantly more with improve 
with proper care. We do not have a protocol for large double-blinded studies. Still, we 
do have smaller studies and case reports on individuals that were able to return to 
higher level sport activity without surgery. Initially, the focus is on stabilizing the knee 
to avoid additional trauma and rotary stress on the injured ligament. This is usually 
done by bracing and self-awareness by avoiding movements or activities that may 
harm a newly injured knee. As the weeks pass, the individual will gain confidence and 
can wean from bracing. We also know that weight bearing is critical for ligamentous 
healing and maintaining knee integrity. Physical loadings provide an important stimulus 
for maintaining ligament tissue’s normal structure and function. 
Research of Spontaneous ACL Healing
1. 1996 Ihara et al. analyzed 50 athletes with acute ACL ruptures treated without 
surgery using a specially designed brace. Eleven months later, 29 patients 
showed a continuous ACL on MRI.
2. 1996 50 cases of complete rupture after only 3 months of early protected 
motion 74% of ACL tears showed healing. 
3. Two case studies were reported (1998) of spontaneous ACL healing.  It was 
found that proximal injuries close to the bone should enhance the healing 
capability.
4.  2001 case study of spontaneous healing of a complete ACL tear after one 
year.
5.  2002 Fujimoto et al. followed 31 patients using an extension block soft     
brace x2-      3 months. All patients showed healing, 74% were stable at 16 
months, and only 8 required surgery because of instability 
6.  2012 Costa-Paz et al. followed complete ACL tears with no bracing or 
specific rehab program. They found after 30 months no instability and MRIs, 
showed end-to-end ACLs, and were able to return to their previous sports 
activity without bracing and specific rehab parameters.
• Surgery: Instead of Replacing – Enhance ACL 
Healing 
• There have been exciting new developments in ACL 
restoration. Unlike ACL reconstruction, which replaces the 
torn ACL with a graft from the patient or donor, a bridge-
enhancer known as BEAR reportedly can heal a torn 
ligament. The procedure uses an implant containing bovine 
collagen and the patient’s blood to fill the gap between the 
torn ends of the ACL to promote healing.
• BEAR (Bridge-Enhanced ACL Restoration) procedure uses a 
new device called the BEAR® Implant, made from purified 
bovine (cow) collagen, to bridge the ACL stump to the bone 
using stitches to stimulate restoration. Instead of replacing 
the torn ligament, this new technique helps the ACL grow 
back together. Bear is a new procedure and is currently 
being studied across the nation. 
ACL Reconstruction does have a place after all conservative care has 
failed…BUT, we hope that the promotion of the self-healing potential 
of the ACL becomes the new gold standard of care instead of ACL 
replacement.
VIRTUAL 
PHYSICAL 
THERAPISTS
[email protected]
HTTP://WWW.VIRTUALPHYSICALTHERAPISTS.COM/
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