Anatomic Double Bundle ACL Reconstruction - A Mistake?

[abknee]

After reading about this online and that Tiger Woods had this procedure performed it got me thinking. The new acl is constructed from 2 double looped hamstring tendons. This requires 4 holes to be drilled for the two new grafts to be placed.

Now lets assume that the grafts heal properly and everything is fine. What you now have is 2 grafts that are each half as stiff as a single quadruple bundled hamstring graft. This to many may seem an equivalent but the way I see it (and I might be totally wrong) that the 2 grafts are weaker.

Lets says it takes a force of 1000N to rupture the quadruple bundle. Now assume it takes a force of 500N each to rupture either of the 2 grafts in a double bundle technique. If a force of 500N is applied to the quadruple bundle there may be a tearing of the acl but as only force of 50% of its maximum force to failure there may not be. But if the force is applies to the double bundle acl we know that the 500n will not be spread equally across the double bundle this would result in a force of over 50% of the maximum force to failure being applied to one of the two grafts resulting in damage that taken as a whole more serious than for the quadruple bundle.

In essence the double bundle tendon is more susceptible to lower forces causing more damage than the quadruple tendon.

Well that's my understanding - I may be totally wrong but hey then again I might be right!

[crumpet]

Abknee:

This is interesting! You are certainly proving some food for thought on these boards!

I think the "theory" behind the double bundle is that some-times both take the force, at different angles -- which would be superior to one bundle. According to the DB advocates...they say this is exactly what your native ACL would do.

~C:)

[drmark]

The developer of this operation reports a 17% failure rate. Compare this to the 5% failure rate of the single bundle auto patella tendon repair.

Some ideas, like this one, seem to work better on cadavers than live people.

[digginit]

Would the double bundle, despite a higher failure rate, offer better knee mechanics?

~dig

[drmark]

Not when you consider the failure rate.

People come to my clinic all the time and complain or recurrent instability of the knee.
No one ever complains of bad, or boasts of good mechanics.

Results are for humans
Mechanics are for the laboratory.

Dichotomies like this is why "evidenced based" or "outcome based" research has become the standard in the industry.

That is not to say that more research should't be done. I just wouldn't want to be a subject in the next several studies.

[digginit]

Well, not knowing all that much about golf (and how much his knee problems would affect his golf game), I can see that someone like Tiger Woods might choose the procedure that would leave him with a more naturally-functioning knee, even if there was a higher risk of failure.

Was wondering if the double bundle would make any significant difference in a real live person.

[drmark]

The clinical results published by the originator of the procedure were not so special.
Despite the importance of Tiger Woods to golf, I think its doubtful that any special though went into deciding what procedure Tiger had. That is the operation that his doc always does. Tiger choose the doc, and the doc chose the procedure.

[abknee]

http://www.bloomberg.com/apps/news?pid= ... 1SQZgFacBU

Mr Rosenberg is Tiger Surgeon. I suspect there may be an increase of people asking for double bundle ACL operations post Tiger. The point that needs to be made is Tiger was winning tournaments with a torn cruciate so as long as his rehab goes ok he will continue winning tournaments with his "new cruciate". The problem is people will add his surgery choice to his success and equate that its the best way to go and perhaps force poor surgeons to start performing a very risky double bundle operation.

I see the number of revision surgeries increasing which is what my Knee Surgeon mentioned - he is doing a lot more acl revisions.

[drmark]

Agreed. 1000%

[feeny]

Im an engineer type fellow - and the engineer in me likes fewer holes, fewer moving parts, fewer things to do.

That whole thing sounds like more of everything...
...and to me that means more to go wrong...!


PS: I still want to know what difference any particular graft type makes after a few years in any event....is all this discussion about graft type to do with the initial period after surgery - or does it have any real impact two years down the track? ...assuming fixation, tunnels etc are placed competently and proper rehab following appropriate protocol - does graft type really make a difference to the patient in the long term? [other than issues associated with harvest site]

[drmark]

The double bundle operation is the absoute opposite of the K.I.S.S. principle.
Everytime I didn't follow the pirnciple, I got into major trouble.

[abknee]

Let me see if I can deduce graft choice. It's a bit long winded so please bear with me.

1) Graft choice
2) Graft modality - single, double etc.
3) fixation method
4) tunnel placement
5) any other damage to knee
6) Surgeon competency
7) Age of patient
Rehab schedule of patient (how well patient sticks to activities)
9) Rehab protocol
10) Patient requirements post op - does he she want to return to active sports and when
11) Luck - you could do everything right and then trip, stumble and snap your cruciate

For any given patient issues are, in no particular order, the list may not be exhaustive so please anyone add to it. So when statistics are mentioned in studies only a few key variables are assessed. So if we cannot assess accurately all of the variables we should develop a model that mimics the behaviour most of time. So based on this we can consider a subset of variables and based on these variables make an assessment of one graft choice vs another if that is what we are testing.

Then I would say the variables that need to be considered are modality, fixation method, tunnel placement, Surgeon competency. If we study one Surgeon and consider them to be competent based on their outcomes then we can discount the all variables (modality, fixation method, tunnel placement, Surgeon competency) because we know they have no bearing on the outcome for the Surgeon as they are equal for each patient, which leaves just one - graft choice which the Surgeon makes. Which concurs with drMark assessment that if a Surgeon cannot choose the graft choice for you then he should not be in Surgery.

As a patient you choose the Surgeon and he chooses the Graft. This is based on the patient somehow verifying the Surgeons competency. So graft choice should not be a concern of the patient even though it does become a concern (it did for me).

[crumpet]

This may sound like a silly question but...since we are on the subject of graft choice....

Can you get a graft harvested out of a live person. Like...say for instance I wanted a bone to bone patella tendon out of my brother. Could he donate his to me?

~C:)

[abknee]

NOOOOOOOOOOOOOOOOO

That would be saying lets fix this broken leg on this table by breaking the other table leg - two broken legs better than one.

[ATsoccergirl]

Theoretically I guess you could harvest a graft from someone else, but what surgeon would do it. You can take the graft from uninjured side which is known as a contralateral graft.