Arthroscopic side-to-side repair for complete radial posterior lateral meniscus root tears

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).

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.

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.

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.

A total of 29 patients met the inclusion criteria and were enrolled in this study. There were 21 males and 8 females with a mean age of 25.41 ± 6.61 years (range, 17–39 years). The mean follow-up period was 26.68 ± 2.91 months (range, 24–36 months). The demographic data of the patients are summarized in Table 1.

During the follow-up, none of the patients complained of locking, catching, giving way or effusion. None of the patients had lateral joint-line tenderness or a positive McMurray test. Thus, the repaired meniscus was considered having a 100% clinical success rate. At the final follow-up, the subjective scores of IKDC, Lysholm, and Tegner improved significantly compared to the preoperative values (Table 2).

The postoperative MRI showed that 28 (96.6%) patients achieved complete healing and 1 patient achieved failure of healing with an abnormal hyperintensity signal in the repair site. Twenty-two patients underwent second-look arthroscopy at mean 13.0 ± 1.31 months (range, 11–16 months) postoperatively. On the second-look arthroscopy, 19 (86.4%) patients showed complete meniscus healing (Fig. 3) and 3 (13.6%) patients showed partial healing. No failure of healing was detected among these 22 patients.

The primary biomechanical function of meniscus is to convert the tibiofemoral axial load into hoop stress during both knee extension and deep flexion [16]. Complete radial PLMRTs disrupt the continuity of the circumferential fibers and lead to loss of hoop stress, causing overload of the lateral compartment and early degenerative changes [1, 3]. A recent biomechanical study by Schillhammer showed that PLMRTs resulted in a significantly increased peak contact pressure (49%) and decreased tibiofemoral contact area (33%) [17]. The posterior lateral meniscus root is also an important secondary restraint to the rotational laxity of the knee joint. To date, several studies have shown that PLMRTs further destabilize the rotational stability of the ACL-deficient knee under a simulated pivot-shift loading [18, 19]. Overall, complete radial PLMRTs have severe biomechanical consequences and are functionally equivalent to a total meniscectomy.

Arthroscopic transtibial pull-out technique and side-to-side repair technique are the 2 most common techniques of surgical repair for complete radial PLMRTs [4‐10]. The former involves a bone tunnel running from the anteromedial aspect of the tibia to the anatomic attachment site of the lateral meniscal root on the tibia. Sutures are then passed through the meniscal root and through the tunnel and secured over the anterior tibia. However, the theoretical disadvantages of this technique include (1) need for a bone tunnel which might interfere with concomitant ligament reconstruction, (2) need for distal fixation which places the sutures at risk for failure, and (3) if the root fragment is large, that the outer part of the meniscus is secured to the original insertion site will cause an increased meniscal tension [20]. In contrast, side-to-side repair belongs to anatomic repair that does not change the native anatomic and physiologic properties of the meniscus.

Recently, posterior lateral meniscus root fixation using suture anchors has also been described [21]. The main concerns about this technique include anchor pullout with subsequent failure of fixation, and technical difficulty [22].

To date, the studies regarding the clinical outcomes after arthroscopic side-to-side repair for treatment of complete radial PLMRTs remain limited. Ahn reported a cohort of 27 patients who underwent arthroscopic side-to-side repair for complete radial PLMRTs [6]. The clinical healing rate of the repaired meniscus was up to 100% at 1 year postoperatively. Eight of the nine patients who underwent second-look arthroscopy showed complete meniscus healing. Anderson retrospectively reviewed 8 patients who underwent arthroscopic side-to-side repair for complete radial PLMRTs [7]. The mean IKDC, Lysholm, and Tegner scores improved significantly at a mean follow-up of 70.5 months. In another study, Song analyzed a small sample of 15 patients with complete radial PLMRTs who underwent arthroscopic side-to-side repair using a Fast-Fix device [8]. At a mean follow-up of 24 months, all the patients showed clinical healing, and 86.6% of the patients showed meniscus healing on the second-look arthroscopy. Similar to these studies, this present study also showed that arthroscopic side-to-side repair could significantly improve both objective and subjective functional outcomes with a high rate of meniscus healing in patients with complete radial PLMRTs.

This study has several limitations. First, this study was a retrospective study with all the inherent limitations of a retrospective study. Second, this study included a limited number of patients. Third, the period of the follow-up was 2 years but still relatively short, and longer-term evaluations are required to evaluate long-term clinical outcomes. Fourth, this study did not involve any control group.