ALL INSIDE ACL RECONSTRUCTION : TECHNIQUE AND ADVANTAGES

ALL INSIDE ACL RECONSTRUCTION : TECHNIQUE AND ADVANTAGES

All inside ACL is an upcoming technique to reconstruct a torn ACL with many potential advantages. Understanding the advantages requires understanding the technique and its principles.

The method involves reconstructing ACL using a SINGLE triple or quadruple semitendinosus tendon

autograft (gracilis is not harvested), in contrast to standard ACL techniques that require SemiT and Gracilis autografts. Bone patellar tendon autograft cannot be employed for this technique. See pics below.

Fig: A showing All Inside ACL reconstruction with sockets cut in femur and tibia instead of complete length tunnels with suspensory fixation used on both ends. Fig B is showing conventional ACL  Reconstruction with suspensory fixation on femoral end and interference screw in tibial tunnel reamed till the cortex to allow screw insertion.

Sockets are cut in femur and tibia (see pic below) rather than full length tunnels. This requires use of special reamers called Flip Cutters which are retro reamers that ream from inside the joint towards outside.

The semitendinosus graft is multi-folded (4 times) to generate a total length no more than 7.5 cm (Preferably < 6.5 cm) as a longer graft might bottom out in the sockets and might not adequately tension.

Fixation on both ends is essentially suspensory using buttons/ loops. Reverse tensioning loops are particularly useful to make tensioning process easier. An interference screw cannot be used as sockets don’t exit on tunnel ends that are not reamed to a diameter large enough to accommodate interference screws.

A particular advantage of the technique is the ease of drilling femoral tunnel which is a major challenge with conventional techniques that require the knee to be flexed post 90 degree to get desired trajectory. Drilling of femoral tunnel in conventional technique is in inside out fashion. Out side in fashion (see pic below) would require reaming from outside in and this would require muscle splitting on lateral thigh.

Fig showing Outside in drilling of femoral tunnel

Now, in All inside technique, drilling is outside in fashion (see pic below). The flipcutter opens on entering the joint and creates a socket moving from inside the joint out. The cutter is closed prior to exiting the cortex (see pic below) and hence no muscle splitting is required. The out side in drilling allows the knee to remain in comfortable 90 degree flexion as one can reliably control the exit point of the femur simultaneously looking at the entry point inside the knee with arthroscope.

Diagram depicting the flipcutter (retrocutter) in closed and open (cutting) position.

A double bundle reconstruction is very much possible as the technique can be very easily adapted  even to suit a double bundle reconstruct using four button construct.

POTENTIAL ADVANTAGES OF THE TECHNIQUE OVER CONVENTIONAL

• Its more bone preserving in nature, as only partial length sockets are cut rather than complete length tunnels as in conventional ACL reconstruction.
• Reduced postoperative pain as there is minimal periosteal disruption at tunnel ends (as ends are not reamed). This allows for a faster Rehabilitation and earlier return to sports for the sportsman.
• Smaller skin incision as only SemiT has to be harvested.
• Since ACL is reconstructed using only Semitendenosus and the spared gracilis tendon (hamstring) leaves the leg with greater hamstring strength shielding the graft
• Visualization during femoral tunnel insertion is easier as one may not need to flex beyond 90 degree to get desired trajectory
• A fibertape can also be used to augment graft (internal brace) as in suspensory fixation differential tensioning of both graft and tape is possible.

Limitations are very few. The technique has a small learning curve. Since there are no tunnels exiting on cortex, graft has to be introduced in sockets by making it enter the knee via Antero medial portal. Hence the portal incision has to be slightly larger to introduce graft (rather a passport cannula should be placed to ascertain smooth passage).

AN ALL INSIDE ACL RECONSTRUCTION USING A SEMITENDENOSUS ALLOGRAFT IS TAKEN AS THE MOST MINIMALLY INVASIVE ACL RECONSTRUCTION SURGERY.