Page 28 - ISAKOS 2019 Newsletter Vol II

CURRENT CONCEPTS
Technical Tips for Simultaneous ACL Surgery with HTO
Graft Harvest
A 3-cm longitudinal incision is made medial to tibial tubercle, midway between the tubercle and the posteromedial cortex of the tibia. The sartorius fascia is incised, and the semitendinosus and gracilis tendons are identified. Only the semitendinosus tendon is harvested with a tendon stripper because an all-inside ACL reconstruction will be performed with a quadrupled tendon. The harvested tendon graft is prepared on the back table by an assistant. A graft diameter of at least 9 mm is expected.
Arthroscopy
Arthroscopy is performed through standard anteromedial and anterolateral portals. The medial and lateral compartments, the patellofemoral joint, the suprapatellar region, and the intercondylar notch are examined. Any concomitant chondral or meniscal injury is addressed before femoral tunnel drilling. The remaining femoral and tibial stumps of the ACL are removed, the ACL footprints on either side are marked, and the medial wall of lateral femoral condyle is debrided.
Femoral Tunnel
A femoral tunnel guide is placed with its tip on the femoral footprint of the ACL, and a reverse reamer is placed in an outside-in manner until it exits from the medial wall of lateral femoral condyle. Next, a tunnel with a length of 25 mm and the same diameter as the tendon autograft is created with retrograde drilling. A shuttle suture is passed through the tunnel and into the joint and is left in place.
Medial Opening-Wedge Tibial Osteotomy
For the osteotomy, the leg is brought into full extension and is put on a Mayo table. The incision that was made for the graft harvest is extended 10 cm distally. The superficial medial collateral ligament (MCL) attachment on the tibia is released subperiosteally to prevent overloading of the medial compartment after osteotomy. Posteromedial soft- tissue structures and the patellar tendon are protected with retractors. A Kirschner wire (K-wire) is advanced from the medial tibial cortex under fluoroscopic guidance, starting 4 – 5 cm distal to the joint line and aiming for fibular head. A second K-wire is placed 15 mm apart, parallel to the first K-wire. The line connecting the two K-wire insertions on the medial tibial cortex should be parallel to the posterior tibial slope in the sagittal plane. The osteotomy is performed distal to the K-wires, staying parallel to the wires in the coronal and sagittal planes. The osteotomy is started with a thin and wide oscillating saw and is continued with an osteotome. The medial, anterior, and posterior cortices are osteotomized, but the lateral cortex is left intact, with the saw cut stopping 1 cm short from the lateral cortex. A gentle valgus stress is applied to the tibia, using the intact lateral cortex as a hinge.
Stacked osteotomes can be used to gradually open the osteotomy site. Once adequate opening is obtained, a bone spreader is placed into the osteotomy site. The proximal and distal fragments are gradually spread with the bone spreader according to the preoperative plan until the mechanical axis is corrected as desired. To check the alignment, a radiopaque alignment rod is placed over the center of the femoral head and the midpoint of the ankle joint. The position of the rod, and hence the mechanical axis, is checked with the fluoroscope. Once the alignment is correct, a bone wedge allograft is placed into the osteotomy site. This wedge should be placed in the posterior part of the osteotomy site to create a trapezoidal opening (i.e., more opening in the posterior part and less opening in the anterior part). This shape is important in order to avoid increasing the posterior tibial slope, a common occurrence in opening-wedge tibial osteotomies. The bone allograft should fill the osteotomy site but should be below the level of medial cortex so that cortical healing will be possible on the medial side. The bone spreader is removed, and preliminary fixation of the osteotomy site is performed.
We prefer to use a long titanium locking osteotomy plate for fixation. The plate is applied over the medial cortex, with care being taken to leave enough space anterior to the plate for the tibial ACL tunnel. Preliminary fixation is achieved after the placement of all proximal and distal locking screws except for the proximal anterior screw, which will be placed after tibial tunnel drilling.
Tibial Tunnel
A tibial tunnel guide is placed anterior to the plate on the proximal part of the medial tibial cortex, with its tip exiting in the tibial footprint of ACL. A retrograde tunnel with a length of 25 mm and the same diameter as the tendon autograft is created. A shuttle suture is passed through the tibial tunnel and into the joint and is left in place. In order to prevent convergence of the proximal anterior screw with the tibial tunnel, a drill bit is left in the hole that was drilled for the proximal anterior screw.
Graft Passage
The shuttle sutures in the femoral and tibial tunnels are taken out of the joint through the anteromedial portal. The femoral shuttle suture is attached to one of the button fixation devices, which are located on each end of the tendon autograft. The tendon graft is pulled into the joint and femoral tunnel through the anteromedial portal. The adjustable- loop fixation device is tightened and is fixed on the femoral cortex. The suture and button on the distal end of the graft are attached to the tibial shuttle suture, and the graft is pulled into the joint and tibial tunnel.
26 ISAKOS NEWSLETTER 2019: VOLUME II