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Author Topic: what is a failed ACL  (Read 822 times)

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Offline billythehamster

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what is a failed ACL
« on: January 01, 2008, 07:53:40 PM »
I am two weeks post op and I have heard it said that an ACL recon can fail. What does this mean and are there any signs early on that you can look out for?

Offline ATsoccergirl

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Re: what is a failed ACL
« Reply #1 on: January 01, 2008, 08:14:17 PM »
Main Causes of Failure can be listed as:
1. Drill hole placement in a non-anatomic location.
2. Failure of Fixation
3. Graft impingement
4. Intrinsic graft failure
5. Arthrofibrosis
6. Trauma

1. Placement of the graft is the single most difficult aspect of ACL surgery. Tunnels are drilled into both the femur and tibia in order to secure the graft. Precise placement and orientation of these tunnels to achieve the exact anatomic location of the normal ACL are important for success. Slight variations in placement produce abnormal stresses and lengthen the graft. Improper alignment can result in impingement, which can sacrifice the integrity of the graft. It can also result in excessive laxity, or decreased range of motion, both of which produce unsatisfactory results. Experience of the surgeon matters the most. Newer computer guided systems may help less experienced surgeons improve their accuracy.

2. The weakest link in the reconstruction is the point of attachment. The goals of fixation are to achieve sufficient strength and stiffness, and avoid further complications such as inflammatory response or degradation over time. The fixation technique will initially need to secure the graft tissue in place, while the graft incorporates into the bone tissue, which is the ultimate goal of the reconstruction. Of the many options for graft fixation, our preference has been to use bone patellar tendon bone grafts with interference fit screws. Generally, the fixation choice depends primarily on the type of graft material used. With patellar tendon grafts, interference screws, either metal or bioabsorbable, are used to secure the bony attachments on either end. With hamstring tendons, which require securing soft tissue to bone, a variety of methods are used including cross pin, endobutton, screw and post, or belt-buckle staple technique each can produce favorable results.

3. Graft impingement occurs from entrapment of the graft in the intercondylar notch. This can occur from graft placement, variations in notch shape and size and from graft hypertrophy. If the graft is impinged then wear increases, length can increase, and failure occur. Most commonly decreased range of motion is noted. The treatment involves surgical debridement or graft re-positioning.

4. Intrinsic failure of the graft can occur from graft impingement or trauma. Recent reports have noted atraumatic rupture rate of autogenous ACL reconstruction of 2% and an allograft rupture rate of 15%.  In the case of allografts a low level of immunologic reaction can weaken the graft and cause early failure as well.

5. Arthrofibrosis occurs in up to 10% of ACL reconstructions. The fibrosis is the formation of scar tissue after injury or surgery leading to decreased range of motion in the knee. This can be diminished by early and full range of motion exercises both before and immediately after surgery. Some people will develop the fibrosis no matter what procedures are followed. Generally arthroscopic surgical debridement with a careful rehabilitation program will result in a successful outcome.

6. Trauma can cause excessive force on the graft during the healing process before it has reached full strength. In addition, significant trauma after the full healing of the graft can cause rupture of the graft similar to it would cause rupture of the original ACL.

Other than the surgeon noticing excessive laxity, generally failures are not recognized until later in the recovery period during which higher levels of stress are placed on the graft. 
1999 LR, 2002 ACL/PLC recon, reversal of LR, 2004 ACL revision, 2006 Car accident torn PCL and small fractures resulting in bone chips in my knee.  Torn MCL 3 times.  Wicked screws under IT band and Pes Anserine.  June 2008-Hip Arthroscopy.

Offline billythehamster

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Re: what is a failed ACL
« Reply #2 on: January 01, 2008, 08:34:59 PM »
wowser - thanks for the explaination