Question - Hamstring Autograft Strength

by Kyle
(North East, England)

Me

Me

I've read many different articles about the strength difference between the original ACL, the patellar tendon autograft and the hamstring autograft.


Some say the patellar tendon is the gold standard because it is the strongest, whereas others say the hamstring autograft is twice as strong as the original acl and 1.3 times (or something) as strong as the patellar tendon.

I don't know what to believe. I recently read an article referring to the capability of withstanding force measured in newtons and it said

"Recalling that a normal ACL fails under a load of 1725 Newtons and a patellar-tendon replacement gives up the ghost at about 2900 Newtons, you will be appalled to learn that a semitendinosis graft substitute for the ACL falls apart at just 1200 Newtons, and the gracilis goes to pieces at a paltry load of only 860 Newtons".

So does this mean that if the tendon is reconstructed from the hamstring and gracilis it would have the tensile strength of 1200 (hamstring) plus 860 (gracilis) equaling 2060N and therefore stronger than the original ACL?

What is your opinion on the whole strength of grafts issue? I recently have had an ACL reconstruction and there fore am very interested.

I have created a story on this website detailing my injury.

Please reply. Thanks

Kyle

Comments for Question - Hamstring Autograft Strength

Average Rating starstarstarstarstar

Click here to add your own comments

Aug 13, 2013
Rating
starstarstarstarstar
ACL Graft Healing NEW
by: Anonymous

A normal ACL has a tensile strenth between 1800 to 2200 Newtons. Your patella autograph would measure around 2950 Newtons, and your Hamstring autograph would measure in at 4500 Newtons for tensile strenth. However, that's tensile strength, not shear. A shearing force is the most common way to rupture your ACL, the plant and twist (Derrick Rose, Tiger Woods, Adrian Peterson, RG3, for example). ACL fail at 200 to 500 Newtons of shear force.

Your body has to revasularize and fixate your grafts, whcih take 8 to 12 weeks. The most important part of ACL surgery is the location, location, location. Even if the graft is .5 mm off and you're at a much higher rate for graft failure. Follow that up with a good rehab program will be your most important thing to returning to play reguardless of graft type.

Just from my experience in sports medicine and sports rehabilitation. Athletes tend to have less problems with hamstring grafts than patellar grafts when it comes to rehab. Patellar tendon grafts will lose about 20% force from the quadriceps, and the hamsting graft will lose about 7% force from the hamstring. And, in the end the strength of the autograph will be roughly the same, which either way will be less than your original ACL.

Aug 13, 2013
Rating
starstarstarstarstar
ACL Graft Healing NEW
by: Anonymous

A normal ACL has a tensile strenth between 1800 to 2200 Newtons. Your patella autograph would measure around 2950 Newtons, and your Hamstring autograph would measure in at 4500 Newtons for tensile strenth. However, that's tensile strength, not shear. A shearing force is the most common way to rupture your ACL, the plant and twist (Derrick Rose, Tiger Woods, Adrian Peterson, RG3, for example). ACL fail at 200 to 500 Newtons of shear force.

Your body has to revasularize and fixate your grafts, whcih take 8 to 12 weeks. The most important part of ACL surgery is the location, location, location. Even if the graft is .5 mm off and you're at a much higher rate for graft failure. Follow that up with a good rehab program will be your most important thing to returning to play reguardless of graft type.

Just from my experience in sports medicine and sports rehabilitation. Athletes tend to have less problems with hamstring grafts than patellar grafts when it comes to rehab. Patellar tendon grafts will lose about 20% force from the quadriceps, and the hamsting graft will lose about 7% force from the hamstring. And, in the end the strength of the autograph will be roughly the same, which either way will be less than your original ACLm

Jun 16, 2009
Rating
starstarstarstarstar
Graft Failure - second Surgery
by: Anonymous

I had ACL surgery in Sept 2007 - Hamstring Tendon Graft - and waited 13 months before returning to soccer and sports. I was fine up until recently where I started to swell up after games and the swelling and discomfort would stay for long periods of time despite icing and physio. I saw my surgeon last night and he confirm I tore the ACL again and will need a second surgery. The surgeon is recommending using the hamstring tendon from my right knee to repair the left for the second time (since the left hamstring tendon was already used in the first surgery). Any guidance or advice on going that route. It makes me nervous to have to go into my good knee to have a second surgery.

Jun 22, 2008
Rating
starstarstarstarstar
Strength vs. fixation
by: Bart - SII

There is a lot of literature out there regarding the tensile strengths of the ACL and the various types of graft tissues used. I don't know exact numbers, however, I believe that the more important issue is the way the graft is fixed into the bone tunnels during the surgery.

Ultimately, the most common reason for graft failure is not because of the strength of the graft, but the success of placing the graft in the correct position and that the graft does not migrate after surgery. My opinion is that the best graft choice is one that utilizes bone plugs on each end - so a patellar tendon allograft or autograft. The use of the bone plugs allows the graft to heal into the femur and tibia and provide excellent fixation - keeping the graft from migrating or stretching out.

When it comes to graft strength, any tissue used is able to withstand normal daily stresses - in fact the stress placed on the ACL with normal sports activities is well below the tensile limit.

I hope this makes sense - focus on your rehab and regaining your strength - if you do that and get your muscular stabilizers back on track, your graft strength should be fine.


Click here to add your own comments

Return to Sports Injury Answers - Knee Ligaments.