Patient Selection and Study Design
Data were retrospectively collected from 28 patients who underwent PCL reconstruction from February 2018 to July 2020 locating the tibia tunnel by the path under-the-ACL(under-the-ACL group). Data were also retrospectively collected from 22 patients who underwent PCL reconstruction from August 2016 to January 2018 locating the tibia tunnel by the path over-the-ACL(over-the-ACL group). Greater than 2 years of follow-up was necessary. All patients in both groups were included :1. a diagnosis of acute or chronic tear of PCL with signs of functional deficit, pain, or instability of grade 2 or higher (based on the posterior drawer test) and had a displacement of more than 8mm on stress x-ray [9]; 2. To ensure the effectiveness of the technique of localization, all cases of patients underwent a primary PCL reconstruction and excluded surgically required ACL injury.
The preoperative demographic characteristics of the 2 groups were similar (Table 1). All procedures were performed by a single surgeon (D-W.ZL.). The study was approved by the institutional review board of our institution. All patients who underwent PCL reconstruction underwent postoperative 3D-CT .
Table 1
Demographic and Clinical Characteristics of Patients Included in This Study.
Data |
Parameter | Under-the-ACL | Over-the-ACL | P value |
NO. | 28 | 22 | |
Male:female | 18:10 | 14:8 | 0.962 |
Age,yr | 37.46 ± 11.27 | 36.45 ± 14.01 | 0.779 |
Body mass index, kg/m2 | 25.10 ± 3.61 | 23.59 ± 1.99 | 0.086 |
Time from injury to operation (we) | 14.04 ± 21.57 | 10.77 ± 16.17 | 0.558 |
NOTE. Data are mean ± standard deviation unless noted otherwise.
Surgical Technique
A modified technique for PCL reconstruction with remnant preservation was used wherein a inferolateral tibial tunnel was created and a single hamstring tendon autograft bundle was used in all of patients above. Tibial tunnel placement located 15–20mm inferior and 5–10mm lateral to the posterior cruciate ligament anatomical insertion site in the inferior lateral part of the anatomical footprint (Fanelli area[26]).
The patient was positioned on the operating table in the supine position, and the surgical and nonsurgical knees were examined under general or regional anesthesia. A tourniquet was applied to the operative extremity and the surgical leg prepped and draped in a sterile fashion.
Graft Preparation
A hamstring tendon autograft (gracilis tendon and semitendinosus tendon) longer than 26 cm was harvested. Each graft was folded into a 12 cm, diameter was 8 to 10 mm ,four-strand tendon graft. No. 5 Ethibond (Ethicon, Somerville, NJ) was sutured to the whip-stitched two side of each tendon.
Establishment of the under-the- ACL Path
Surgery began by construction of a high anterolateral portal and a low anteromedial portal followed by the posteromedial portal. A shaver was inserted through the posteromedial portal to excise posterior septum medially to the posterolateral compartment. And then, the arthroscope was inserted through the anteromedial portal, a shaver was inserted through the anterolateral portal, reaching the posterolateral compartment through the under-the-ACL path(between the ACL and lateral femoral condyle) to remove the lateral wall of the posterior septum and fatty tissues behind the PCL remnant and viewing the PCL tibial footprint.
Establishment of the over-the- ACL Path
The same arthroscopic portals were conducted. A shaver was inserted to remove the septum between the ACL and PCL remnant and the posterior septum and fatty tissues through the over-the- ACL Path (between the ACL and PCL remnant) (Fig. 1).
Tibial Tunnel Preparation
The tibial tunnel was performed with the use of Acufex PCL guides (Acufex, Andover, MA) form anteromedial portal. The tibial guide inserted the under-the-ACL path to locate the PCL tunnel from the lateral of PCL at the position of 45° Knee varus flexion. The tip of the guide pin should be carefully protected with a curved curette to prevent injury to the neurovascular structures when it exited posteriorly and the arthroscope was monitoring through the posteromedial portal at the same time. The transtibial PCL tunnel was drilled from the anteromedial aspect of the proximal tibia 1 cm below the tibial tubercle and exits posteriorly at the inferior lateral aspect of the PCL anatomic insertion site. On the basis of measurements provided by graft sizers, an 8- to 10-mm-diameter tunnel was constructed for the graft(Fig. 2).
Femoral Tunnel Preparation
The arthroscope was in the anterolateral portal with the knee flexed approximately 90°. The femoral tunnel was created using a low anterolateral arthroscopic portal through which a guide pin was placed. A femoral guide pin was placed 6 to 7 mm posterior to the distal border of the articular cartilage of the medial femoral condyle and should encompass the anterolateral fibers of the footprint. Overdrilling was performed with a 8- to 10-mm reamer according to the prepared graft diameter to inside-out the medial femoral condyle.
Graft preparation, passage, and fixation
The graft was passed through the posterior compartment, and taken out through the accessory anterolateral portal to the femoral tunnel by the No. 5 Ethibond loop. The remnant of the PCL was retained ,both for femoral and tibial attachment. The graft material was fixed to the femoral side using a endobutton and was then fixed to the tibial tunnel with a bioabsorbable interference screw. An additional post-tie with cortical screw was made for firm fixation of the distal hamstring tendon.
Postoperative Rehabilitation
The knee was maintained in full extension for 3 weeks nonweight bearing. Progressive range of motion occurs during postoperative 3 weeks through 10 weeks. Progressive weight bearing occurs at the beginning of postoperative 8 weeks. Progressive closed kinetic chain strength training, proprioceptive training, and continued motion exercises were initiated very slowly beginning at postoperative 12th weeks. The long leg range of motion brace was discontinued after the 10th week. Return to sports and heavy labor occured after the 16th postoperative month when sufficient strength, range of motion, and proprioceptive skills have returned.
Evaluation
Quantitative tunnel position Measurements on 3D-CT.All measurements were performed using the ruler tool contained in Picture Archiving and Communication System(PACS) software. Three-dimensional surface models were produced using 64-slice multidetector CT. The centers of the tibial tunnel were defined as the centroids of their areas, and the positions of the tibial tunnels were defined in the medial to lateral and proximal to distal directions of the proximal tibia. In the medial to lateral directions, the absolute distance was measured from the medial margin of the tibial plateau to the center of the tibial tunnel aperture. Similarly, the tunnel position in the proximal to distal direction of the proximal tibia was measured as the absolute distance of the posterior slope, which was depicted as a cortical line obliquely oriented to the tibial plateaus. To standardize measurements of different-sized knees, the relative percentages were calculated, with the absolute medial to center of the tunnel distance divided by the proximal tibial plateau width and the absolute proximal to distal distance divided by the posterior slope length of the tibial plateaus.
Posterior Tibial Translation Under Stress Radiography: Posterior stress radiographs were obtained on the day before surgery, 24 months after surgery. Posterior laxity was assessed by posterior force (150 N) applied to the anterior aspect of the tibia, simulating a posterior drawer test, and the knees flexed to 90 , as described by DePhillipo et al[9].
Statistical Analysis
All data were presented as means and standard deviations. Demographic characteristics and the absolute values and relative percentages of tibial tunnel position in the medial to lateral and proximal to distal dimensions were compared in the 2 groups using the Fisher exact test for categorical values, the Student t test for parametric data, and the Mann-Whitney U test for nonparametric data. All statistical analyses were performed using IBM SPSS Statistics, version 26.0, software(SPSS, Chicago, IL), with P < 0 .05 considered statistically significant.