Study design
From March 2014 to March 2017, the medical records of patients who underwent arthroscopic surgery for PLMRTs at our institution were identified. The inclusion criteria were (1) patients who were diagnosed with complete radial PLMRTs and underwent arthroscopic side-to-side repair, and (2) patients with a minimum 2-year follow-up. The exclusion criteria were (1) age older than 60 years, (2) significant osteoarthritis of the joint (Kellgren-Lawrence grade III or IV), or (3) previous surgery of the same knee. As complete radial PLMRTs occurred frequently associated with anterior cruciate ligament (ACL) injury, so concomitant ACL injury was not an exclusion criterion for this study.
A total of 122 patients (122 knees) who underwent arthroscopic surgery for PLMRTs at our institution were identified (Fig. 1). Of these, 37 patients were diagnosed with complete radial PLMRTs and all these patients underwent arthroscopic side-to-side repair. Among them, one patient was older than 60 years, one patient had significant knee osteoarthritis, one patient had previous surgery for tibial plateau fracture, three patients were lost to follow-up with a follow-up period less than 2 years, and two patients had incomplete clinical functional assessments. Therefor, we studied the remaining 29 patients (29 knees).
This study received approval from our institutional review board. All patients provided signed informed consent to allow their clinical and radiological data to be used for research programs.
Surgical technique
All surgeries were performed under general anesthesia. The patients were placed in a supine position. An arthroscopic evaluation was performed using two standard anterior knee arthroscopy portals. If the ACL was torn, the lateral meniscus was addressed before ligament reconstruction. The knee was placed in the figure-of-4 position. The torn edge of the meniscus was refreshed with a motorized shaver (Fig. 2a). A suture hook loaded with a No. 2 polydioxanone (PDS; Ethicon, Somerville, NJ) suture was introduced through the anterolateral portal and pierced the outer part of the meniscus downward approximately 5 mm away from the torn edge. Then, a suture hook loaded with a lasso loop was introduced through the anteromedial portal and pierced the inner part of the meniscus downward to bring the inferior end of the PDS suture through the inner part of the meniscus upward (Fig. 2b). Next, both of the two free ends of the PDS suture were retrieved and tied with four to five simple knots using the arthroscopic knot pusher (Fig. 2c).
The same procedure was repeated and it required usually 2 or 3 stitches to form a firm repair (Fig. 2d).
Postoperative rehabilitation
Postoperatively, the leg was immobilized with a knee brace in full extension. Quadricep-strengthening exercises were started on the second day. Passive knee flexion was started at 2 weeks postoperatively, while active knee flexion was started at 4 weeks postoperatively. Partial weight bearing was allowed at 6 weeks postoperatively and full weight bearing was allowed at 8 weeks postoperatively. Normal activities were permitted at 6 months postoperatively.
Assessment
Demographic data were collected from the database, including age, sex, side of injury, time from injury to surgery, and concomitant surgical procedures. The patients were assessed preoperatively; at 1, 3, 12, and 24 months postoperatively; and at the final follow-up.
The functional outcomes were assessed by both objective and subjective measures. These measures included (1) the symptoms of meniscus retear, such as locking, catching, giving way and effusion; (2) examinations of joint-line tenderness and McMurray test; and (3) International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner score. According to Barrett’s criteria, a repaired meniscus was considered clinical healing if there was no joint line tenderness, no effusion and a negative McMurray’s test [11].
At the final follow-up, MRI scan (3.0-T MR System, Signa Excite, GE Medical Systems, Waukesha, Wisconsin, USA) was obtained for assessment of the healing status of the repaired meniscus. A repaired meniscus was considered failure of healing if one of following MRI signs was present: (1) “ghost sign”, the absence of an identifiable meniscus on the sagittal sequence or high signal replacing the normal dark meniscus [12]; (2) meniscal extrusion, a meniscal sagittal displacement of > 3 mm at the level of the medial collateral ligament [13]; and (3) abnormal hyperintensity signal, which extended to the articular surface of the meniscus root [14].
For the patients who wanted to remove the implant for ACL reconstruction and agreed to undergo second-look arthroscopy, the healing status of the repaired meniscus was assessed using an arthroscopic probe and classified according to Horibe’s criteria [15]. If there was no visible surface defect with complete synovial coverage, it was defined as complete healing. If there was a small defect with synovial coverage over more than half of the torn area, it was defined as partial healing. If there was a large defect with synovial coverage over less than half of the torn area, it was defined as failure of healing.
Statistical analysis
All statistical analyses were performed using SPSS software (IBM-SPSS statistics 22.0; New York, USA). Continuous variables were presented as the mean and standard deviation. A paired-samples t test was used to determine the differences between preoperative and postoperative quantitative variables. The significance level was set at 0.05.
