Anatomic ACL reconstruction using hamstring tendons ( Linvatec graft tensioner)

An above knee tourniquet is used and the leg exsanguinated. An Alvarado leg holder is used with a lateral support. This allows the knee to be held firmly at 90 degrees flexion and in hyper flexion.

Harvesting of the hamstring grafts is usually performed first but if the EUA is inconclusive than a diagnostic arthroscopy is performed first. The knee is flexed to 90 degrees and the hamstrings are identified 5 cmm or two finger breadths below the medial joint line.

A four centimetre transverse incision is made around one centimetre medial to the tibial tuberosity. Dissection is then performed until the subsartorius fat is identified being careful not to go too medially to avoid damage to the saphenous nerve.

The Gracilis and Semitendinsis tendons can be felt and an oblique incision is made above them. Lifting the sabstaorius fascia identifies the tendons on it’s undersurface.

The tendon is delivered through the wound and the adhering bands are exposed and divided. These are attached inferiorly and medially distal to the calf. Pulling on the tendon produces dimpling of the skin can be used to check the tendon is free.

A closed loop tendon stripper is then used to harvest the graft. Keep the tendon under tension and aim for the ischial tuberosity. The tendon stripper has three settings (open, lock and cut), as the tendon is put in it is moved into the lock position. The stripper is pushed forward with little resistance and the tendon cut once around 25cm of length is achieved.

The tendon is delivered through the wound and detached from the tibia avoiding damage to the MCL.The procedure is then repeated for the Semitendinosis tendon.

Each end is whip stitched using a non absorbable braided suture for around 4 cm.

The tendon is then prepared, stripping of the muscle using a blunt ruler.

The tendons are folded over to produce a quadruple graft. This is compressed using sizing rings.

The graft is pretensioned at 15N to reduce the creep and 20mm is marked. the graft is covered with a Vancomycin soaked swab to reduce the infection risk.

A complete diagnostic arthroscopy is performed next in a standard fashion. Any associated pathology is identified and treated.

The ACL stump can be seen detached from the femur and stuck down to the PCL.

The ACL stump to freed from the PCL trying to retain the footprint. This will help preserve proprioception and the tibial seal.

The ACL stump is free and mobile without disturbing the footprint.

The tibial jig is set to 45 degrees and inserted through the medial portal while viewing through the lateral.

The K wire is sited 2/3 along a line drawn between the tibial spine and posterior edge of the anterior horn of the lateral meniscus.

The point of exit of the wire is checked with a probe as it is often hidden by the retained stump.

After appropriate guid wire placement, the tibial tunnel is drilled with a cannulated drill then dilated to the diameter of the harvested graft. Avoid damage to the retained stump by only just penetrating the cortex.

Next is the preparation of the femoral tunnel. The knee is fixed at 90 degrees and a second high infra patella portal is made. The superior one is used as a viewing portal and the inferior for instramentation.

Soft tissue is removed to expose the medial wall of the lateral femoral condyle. Make sure the knee is flexed to 90 degrees and the posterior edge is accurately identified. Try to identify the lateral intercondylar and lateral bifurcate ridges.

A ruler is used to measure midway between the anterior and posterior edge of the femoral condyle, this is marked using a pic.

The mark should lie midway between the intercondylar ridge and posterior border of the lateral femoral condyle. The lateral bifurcate ridge lies between the AM and PL femoral attachment of the ACL. The mark should lie either on the ridge or just behind the ridge.

The knee is then hyper flexed maintaing the view of the mark on the femoral condyle. View through the high medial portal while instrumenting through the inferior medial portal.

The mark on the femoral wall should be identified in hyper flexion and a guid wire is drilled through the inferior medial portal.

The femoral tunnel is then reamed to 40mm depth being careful not to penetrate the outer femoral cortex, followed by the 4.5mm canunlated endobutton drill.

The guidwire is then removed passing a looped suture through the femoral tunnel.

A straight bird beak retriever is then used through the tibial tunnel to perforate the retained ACL stump and retrieve the suture.

The suture is passing through the tibial tunnel and the stump, through the femoral tunnel and exiting the lateral thigh.

In order to achieve appropriate graft tension intra-operatively the Linvotec SE graft tensioner is used. The guide pins are inserted.

A 20mm closed loop endobutton is used and the sutures are pulled through the tunnels.

The graft is then pulled into place making sure to maintain tension. The endotton is flipped and counter traction is applied to seat the button.

The tendon sutures are tied over the Linvotec tensioner and the appropriate tension is applied.

The knee is cycled 15 times and isometry of the graft is checked. The graft is then re-tensioned to get rid of any slack or remaining creep.

The tensioner is left in place, keeping the tendons separated and under appropriate tension while a intrafix sheath and screw is placed in the middle of the four tendons of the graft.

Maintain the tension while the screw is inserted.

The graft can be seen passing through the stump while maintaining the footprint.

Check for notch impingement in flexion and extension.

The tensioner pins are removed and the sutures cut prior to wound closure. Check that there is a full range of movements especially hyperextension compared with the contralateral knee.