Patients were placed in supine position under general anesthesia.
1) Routine arthroscopy
Standard anteromedial and anterolateral portals were created. The condition of the cartilage, particularly that of the PF joint, was evaluated, and lateral release was performed as needed.
2) Skin incision
A longitudinal 8-cm incision was made between the tibial tubercle and posteromedial tibial cortex.
3) Graft preparation
The gracilis (GC) and semitendinosus (ST) were harvested with an open-ended tendon stripper. In general, grafts for the anteromedial bundle (AMB) and the posterolateral bundle (PLB) were created with a four- or double-fold ST and four- or double-fold GC, respectively. EndoButton (Smith & Nephew Endoscopy, Andover MA) was used for fixation on the femoral side. The other end of the grafts was stitched with a 2.5-mm Telos artificial ligament (Aimedic MMT, Tokyo, Japan) for fixation on the tibial side.
4) Creation of the femoral and tibial tunnels
In addition, the distal anteromedial portal was created 2 cm medial from the anteromedial portal, and the femur tunnels were established independently using the transportal technique. The tibial tunnels for the AMB and PLB, with an angle of 50° and 55°, respectively, were created in the anatomical ACL footprint using the ACUFEX Anatomic ACL Guide (Smith & Nephew Endoscopy, Andover MA). Then, dilators were used to smoothen the tunnels (Figs. 1A, B).
OWDTO was performed according to the procedure of Gaasbeek 13). The superficial medial collateral ligament (sMCL) was released completely at the distal attachment to the tibial cortex, and a retractor was inserted behind the proximal tibia to protect the neurovascular structures.
The initial oblique osteotomy was initiated at the medial cortex 4 cm distal from the medial tibia plateau and was terminated at the lateral hinge point (5 mm medial from the lateral cortex and at the level of the proximal tibiofibular joint) using a bone saw. The second descending osteotomy of the tibial tubercle was performed distally, leaving the tuberosity in the proximal fragment. The angle between the descending and oblique planes was 90°, and the thickness and length of the distally osteotomized tibial tubercle were 7–10 and 40 mm, respectively. The distal end was cut to form a tapered shape (Fig. 1C).
The oblique osteotomy site was gradually opened using a bone spreader while the knees were extended, and the lower extremity alignment was confirmed. The postoperative weight-bearing line was targeted to pass 57–67% from the medial edge of the medial plateau (based on the severity of cartilage damage). Next, the OSferion ® (β-tri-calcium phosphate; Olympus Terumo Biomaterials, Tokyo, Japan) blocks, which were cut to size, were placed in the opened space 14). The released sMCL was sutured using 0-Vicril, and the OSferion ® blocks were covered.
To fix the distal part of the tibial tubercle to the distal fragment of the tibia, a 5.0–6.0-mm cannulated cancellous screw (Meira, Nagoya, Japan) was inserted in an anterior–posterior direction using a flat washer.
6) Plate fixation
The Tris plate® (Olympus Terumo Biomaterials, Tokyo, Japan) was set at the optimum position in the medial cortex of the tibia, and the dilators were inserted again into the tibial tunnels. The locking screws for plate fixations were sequentially inserted. When the screw was drilled in the proximal front-hole of the plate, interference was confirmed with a dilator in the PLB. Therefore, a short screw was inserted (Figs. 1D, E, and F).
7) Graft passage and fixation
Graft passage and EndoButton flipping in the lateral femoral cortex were performed in the PLB and then the AMB. The latter was fixed with a force of 30 N and the former with a force of 20 N using three M4 staples ® (Meira, Nagoya, Japan) in the anterior tibial cortex with a knee flexion angle of 20° while axial pressure was applied (Figs. 1G). To fix the grafts, three staples were inserted into the distal fragment of the tibia while preventing interference with the plate screws (Figs. 2A, B).
Knee range-of-motion and exercises were started 1 day after surgery. Patients could walk with full weight-bearing 2–3 weeks after surgery. Then, the protocol for normal ACLR alone was followed; patients could jog 4 months after surgery, and they resumed sports activities after 8–9 months. Gap filling at the osteotomy site was almost achieved 3–4 months after surgery. Second-look arthroscopy and implant removal were performed 1 year after surgery (Fig. 3).