This is an interesting case of ACL repair in a 27 year old soldier.
This gentleman had a football injury and presented five weeks after the injury to an Accident & Emergency department. He was unhappy with his knee because of continuing swelling and instability. When examined, he was found to be ACL deficient with a positive Lachman and Anterior drawer test.
An MRI was performed and the ACL was seen to be abnormal with a wavy appearance suggestive of the ligament having been torn away from its origin on the femur. The decision was made to continue to a surgical arthroscopy procedure to see what could be done.
Image 1 - Pre-operative MRI scan
At arthroscopy you can see that the tissue of the ACL itself looks 'healthy' in all the pictures that were taken.
Image 2 - Only the expert eye would detect a problem
Image 3 - Probing reveals that the ACL has torn off above and then stuck to the PCL.
Image 4 - Scissors being used to separate the attachment between ACL and PCL
On initial observation [image 2], one could be forgiven for thinking that there is nothing wrong with the ligament. As soon as it is probed however [image 3], it is clear that something is wrong. Although the ligament covering is still intact, the skinny upper part reveals that the ligament has torn off from its attachment at the top, and then has joined onto the PCL (or posterior cruciate ligament) behind it. Actually, attachment to the PCL like this is not uncommon, and the reason that the ACL tissue looks so healthy is because it has obtained some blood supply from the blood vessels of the PCL.
In order to mobilise it so that it can be pulled up into the correct position again, the surgeon uses scissors [image 4] to dissect it off from the PCL.
Image 5 - FiberLink sutures are passed around the ACL
Image 6 - 2.4 mm drill passing into the notch via from outside the femur
Image 7 - the sutures retrieved through the tunnel, ready to pull the ACL back up
The surgeon passes FibreLink sutures around the ACL [image 5], in order to pull the ligament back onto the origin on the femur. In order to do this, a 2.4 mm tunnel is made in the femur from the outside of the bone into the notch of the femur [image 6] - the drill tip is on the left and the larger instrument is a positioning guide. The FibreLink suture is retrieved through this tunnel [image 7], ready to pull the ACL back up to its pre-injury position
Now the surgeon gets ready to add the internal brace, which comes into the joint from the tibia side. A guide is placed in the middle of the lower end of the ACL [image 8], and a 2.4 mm tunnel is drilled up from the tibia into the joint.
Image 8 - A drill guide is positioned on the tibia at the lower end of the ligament
Image 9 - A 2.44 mm tunnel is drilled up from the tibia and an instrument pulls a suture down from the femur, through the joint into the tibial tunnel.
Image 10 - This suture is attached to the FiberTape internal brace which will be pulled down through the tunnel in the tibia, and out of the bone to be fixed in position with a Swivelock plastic screw.
A 2.4 mm wire is passed through the tunnel to facilitate the passing of a suture [image 9], which is retrieved, ready to feed down the tibial tunnel. The suture leads the FibreTape internal brace down [image 10] and eventually it will be fed down the tibial tunnel and out, to be fixed into the tibia bone with a plastic Swivelock screw..
Image 11 - the ACL ligament just before being pulled up and tensioned
Image 12 - the ACL ligament pulled into position and tensioned. You cannot see the internal brace as it is obscured by the ACL
Finally, the two constructs will be pulled up into the femur and the ligament correctly tensioned before both of them are fixed in place.
Image 13 - Front (AP) view X-ray showing the tiny button on the femur and the tiny screwhole on the femur which contains the radio-translucent SwiveLock fixation.
Image 14 - Side view (lateral) X-ray giving you a better idea of the situation of the two fixation devices. The tunnels in both these pictures are not showing as their diameter is so small.
The X-rays reveal only the tiny button on the femur, securing the FiberTape internal brace at that end, while a tiny circle on the tibia shows the position of the SwiveLock, which is the plastic screw to hold it on the tibial end. You cannot see the device as the X-rays just pass through plastic, so you can only see its screwhole. Let's take a look now at the 'before' and 'after' MRI scans...
Image 15 - The 'before' MRI with the wavy ACL
Image 16 - See how the ACL has been re-tensioned. You can make out some of the tunnel.
Image 17 - a different MRI slice to show the tunnel in the tibia
What is very exciting are the MRI scan images. The pre-op image [image 15] we have already seen you will remember the wavy appearance of the incompetent ACL stuck to the PCL. In first post-operative MRI image [image 16] you can see that the ACL is now tensioned and cleared distinguishable from the PCL. At its lower end in the tibia you can make out the tunnel, which we could not see on the X-ray because MRI is better at highlighting it. In this view the tunnel does not seem to go right through - but that is just because each view is effectively a 3 mm 'slice' through the joint and of course we are drilling obliquely so we don't see the tunnel completely. The hole for the plastic SwiveLock is evident a little way below the tunnel exit. The next 'slice' is a slightly different contrast and shows the tibial tunnel a bit better, although you cannot see the femoral tunnel as it is shorter and oblique to the view.
The scars, as you can see, are trivial.
At three months this soldier had a full range of motion - no pain, he was clinically stable and despite the surgeon's advice he had gone back to running and had gone back to football!
ACL injuries are usefully classified using the Sherman system:
Type I's are the type of tears that do best with a repair. The ideal patient has a femoral detachment with a good quality ACL remnant, and it is a fairly acute injury (less than 6 weeks or a healthy stump if stuck to the PCL).