From January 2018 to December 2021, patients who underwent ACL reconstruction combined slope and varus correction ACWTO at the orthopedic department of our hospital were prospectively enrolled. Our surgical indication of ACL reconstruction combined slope and varus correction ACWTO were as follows: (1) ACL injury is associated with severe anterior tibial instability and is required ACL reconstruction; (2) PTS＞13°（According to julliard et al. 's measurement） (3) varus deformity (more than 5°); (4) medial meniscal posterior root tears (MMPRT) confirmed by preoperative MRI and arthroscopic exploration.
The inclusion criteria were as follows: (1) aged over 16 years; (2) complete ACL rupture confirmed by arthroscopic exploration; (3) a minimum 2-year follow-up;(4) unilateral ACL injury. The exclusion criteria were as follows: (1) first or second ACL revision; (2) combined other ligamentous laxities; (3) high-grade positive pivot shift test result (＞grade 3, gross), and need for lateral extra-articular tenodesis (5) generalized joint laxity (Beighton score＞5); (6) presence of radiological signs of arthritis on plain radiographs of the lateral compartment according to the Kellgren-Lawrence classification13. This study was approved by the Institutional review board.
Radiological Assessment For PTS
All included patients underwent anteroposterior and lateral weightbearing whole leg radiographs (Figure 1). PTS is calculated from lateral radiographic image according to a previously established measurement technique12. The PTS was defined as the angle between a line drawn along the anatomic axis of the medial tibial plateau and the perpendicular line of the mechanical axis of the lower leg. In addition, the measurement of the femoral tibial angle (FTA) on coronal plane and presence of radiological signs of arthritis according to the Kellgren-Lawrence classification also can be obtained from whole-leg radiographs. All measurements were made by two independent senior radiologists.
All surgical procedures were performed by 2 senior surgeons (JC.L. and Z.L.). Surgery was performed with the patient under general anesthesia with a femoral nerve block. The patient was positioned supine on a radiolucent table with a narrow cuff tourniquet at the root of the thigh and a lateral post at the level of the tourniquet.
Knee arthroscopic evaluation was firstly performed through standard anteromedial and anterolateral portals and all intra-articular structures of the knee were examined. Hamstring (gracilis and semitendinosus) tendons were harvested through a 3 cm incision on anteromedial surface of the proximal tibia at the level of tibial tubercle. The diameter of the graft must be at least 8mm. Two-tunnel transtibial pull-out MMPRT repair was performed using the PDS suture (Deputy) (Figure 2). Two sutures were placed in a vertical, simple suture configuration. Thereafter, two tibial tunnels were created using an anterior cruciate ligament reconstruction tibial tunnel guide (Smith & Nephew), with its tip in contact with the attachment site of the posterior root. Stitched sutures were passed through the Epidural needle through the tibial tunnel and then pulled out through the tibial tunnel entry.
With arthroscopic assistance, femoral tunnel was prepared through the anteromedial portal at the midpoint between anteromedial and posterolateral bundle by using the standard inside-out technique. The tibial guide was placed at 55°and taken from the external cortex into the center of the ACL tibial footprint, and a guide K-wire was inserted. And then, slope and varus correction ACWTO was performed though 2cm medial to the tibial tuberosity with a 10-15 cm anterior longitudinal incision. With the fluoroscopic guidance, two parallel 2.0-mm K-wires are obliquely inserted from both side of the distal patellar tendon toward the posterior tibial cortex, aiming for the insertion site of the posterior cruciate ligament. These two parallel Kirschner wires formed the first plane of the osteotomy. Based on preoperative measurements, the second distal osteotomy line on tibial was marked to ensure achieve proper correction. Next, two 2.0-mm K-wires were placed distal to the previously mentioned placed pins with aim of converging the pins just anterior to the posterior cortex. These two additional Kirschner wires formed the second plane of the osteotomy. These 4 pins consisting of two osteotomy planes ensures that the osteotomy bone is wedge-shaped on both the sagittal and coronal planes, and will serve as the guide for the bone cuts for the closing wedge osteotomy (Figure 2). After the anterior bony segment was resected, the anterior fracture was closed and temporarily fixed with two 2.0-mm K-wires. And then, the fluoroscopy was performed to measure corrected PTS and mechanical axis. When the desired correction was achieved, fixation was performed using the TomoFix instrumentation system, and ensure that the TomoFix plate did not interfere with tibial tunnel (Figure 2). The tibial tunnel was sequentially reamed the same size as the 4-strand hamstring tendon autografts. The Rigidfix cross pin system (DePuty) was used foremoral-side fixation. The ACL graft was tensioned while the knee was moved through full range of motion for 20 cycles. Then tibial fixation was performed with Intrafix interference screw system (DePuty) at 30° knee flexion. Finally, the previously stitched sutures were manually tensioned and tied using a surgeon’s knot at 30° knee flexion.
The rehabilitation protocol was identical for all patients. All patients were to remain non-weightbearing for 6 weeks and in a dynamic knee hinged knee brace. Isometric quadriceps exercise, ankle pump, straight leg exercise was started as soon as possible. Early rehabilitation is focused on pain and swelling control, knee range of motion (ROM) training, quadriceps control. ROM exercises aimed at obtaining full extension in early stage, and obtaining at least 90° flexion at fourth weeks. After the sixth week, the goals were to regain full ROM and muscle function. Partial weight-bearing allowed after the 4 postoperative weeks, and full weight bearing is allowed after 8 weeks, depending on results of radiological confirmed bony consolidation. Another goal was for patients to start non-pivoting sports at 4 months, and to return preinjury level of sports activities at 9 months to 12 months.
For radiologic evaluation, preoperative and at the final follow-up PTS and mechanical axis were assessed with weightbearing lateral radiographs of the whole lower extremity using the method as previously mentioned.
Knee stability evaluation consisted of side-to-side difference in anterior tibial translation (ATT), the grade of Lachman test and pivot-shift test at preoperative and final follow-up. ATT was measured using the KT-1000 arthrometer with the knee in 20° of flexion. The Lachman test was graded as 0 (0–2 mm), 1 (3–5 mm), 2 (6–10 mm), or 3 (>10 mm). The pivot shift test was graded as 0 (absent), 1 (glide), 2 (clunk), 3 (gross). The grade of Lachman test and pivot-shift test were independently determined with two experienced knee surgeons (JC.L. and Z.L.).
Kee functional measures included patient reported outcomes (Lysholm knee score16, IKDC subjective knee score8, Tegner Activity Level Scale26).
Statistical analysis was performed using SPSS 20.0 software (IBM). Preoperative and final follow-up outcome measures were compared. The paired Student t test or Wilcoxon signed-rank test was used to compare continuous variables according to the assumption of normality and homoscedasticity. A P value < 0.05 was considered statistically significant.