An intact medial meniscus (MM) shows minimal posteromedial shift during knee flexion as its posterior root serves as an anchor to limit shifting during joint movements and load-bearing.1 An MM posterior root tear (PRT) causes abnormal tibiofemoral joint biomechanics and inability to convert axial load into hoop stress.2,3 Furthermore, the function of the MM as a joint stabilizer is lost, leading to severe medial and posterior MM extrusion beyond the medial tibial plateau.4

Transtibial pullout repair of MMPRTs decreases the posteromedial extrusion/extra-articular volume of the MM postoperatively,5,6 restores physiological rotation during knee flexion, and reduces the mean tibiofemoral contact pressure by increasing the contact area.7,8 Favorable clinical outcomes have been reported previously,9 and pullout repair has become the gold standard in the treatment of MMPRT.

Several techniques have recently been developed for MMPRT repair.10,11 However, MM medial extrusion in the coronal plane does not always improve postoperatively,12 and patients with increased extrusion after repair have low functional scores.13 Although techniques such as anatomic bone tunnel creation,14 additional bone tunnel creation at the posteromedial corner,15 and combination with MM centralization 16 are available to reduce MM extrusion combined with pullout, MM posteromedial extrusion in the knee flexion persists in some patients after pullout repair, and an optimal root repair method has yet to be found. Here, we describe a novel posterior anchoring technique that may help reduce the MM posteromedial extrusion postoperatively.

MATERIALS AND METHODS

The study was approved by our Institutional Review Board and performed in adherence to the Declaration of Helsinki. All patients provided informed consent.

Indication

We defined MMPRTs as avulsion injuries of the MM posterior root or as complete radial tears within 1 cm from the posterior bony insertion of the MM.17Pullout repair of MMPRTs was performed in patients who have body mass index <35 kg/m2, femorotibial angle <180 degrees, mild cartilage lesions (Outerbridge grade 0 to II), and Kellgren-Lawrence grade 0 to II confirmed by preoperative radiography and magnetic resonance imaging (MRI). From October 2020 to March 2021, 41 patients (10 males, 31 females) underwent MMPRT pullout repair using this technique.

Diagnostic Arthroscopy

Consecutive arthroscopic findings and schematic illustrations are shown in Figures 1 and 2. A standard arthroscopic examination was performed using a 4-mm-diameter 30 degrees arthroscope (Smith & Nephew, London, UK). A probe was introduced through the anteromedial portal to confirm the MMPRT (Fig. 1A). In cases with tight medial compartments, we used outside-in pie-crusting of the medial collateral ligament with a standard 18-gauge (1.2×40 mm) hypodermic needle (Terumo Corporation, Tokyo, Japan).18 The surrounding synovium was debrided by shaving to stimulate capillary bleeding, improve healing, and facilitate the next step.

FIGURE 1:

Arthroscopic images of a novel technique to prevent posteromedial extrusion of the medial meniscus using two cinch sutures and an additional all-inside anchoring suture. A, A complete radial tear of the medial meniscus posterior root. B and C, Two cinch sutures were applied using the Knee Scorpion (Arthrex Inc., Naples, FL) suture passer. D, The tibial tunnel was created using an aiming guide. E, Two cinch sutures were pulled out through the bone tunnel using a suture retriever and 2-0 Nylon. F, Configuration of the two cinch sutures. G and H, Additional bone tunnel was created using an awl and a 2.0-mm Kirschner wire in externally rotated knee flexion. I, An all-inside first suture was inserted into the medial meniscus and posterior meniscocapsular ligament. J, An all-inside second suture was inserted into the bone tunnel in knee flexion. K, Confirmation of adequate tension of the all-inside suture. L, A final appearance following pullout and anchoring repair. MFC indicates medial femoral condyle; MM, medial meniscus; MTP, medial tibial plateau; TCS, two cinch sutures.

FIGURE 2:

Schematic illustrations of a novel technique using two cinch sutures and an additional all-inside anchoring suture. A and B, Two cinch sutures were applied using the Knee Scorpion (Arthrex Inc., Naples, FL) suture passer. C, The tibial tunnel was created using an aiming guide. D, Two cinch sutures were pulled out through the bone tunnel using a suture retriever and 2-0 Nylon. E, Configuration of the two cinch sutures. F, Additional bone tunnel was created using a 2.0-mm Kirschner wire in externally rotated knee flexion. G, An all-inside first suture was inserted through the inferior surface of the medial meniscus posterior horn with tensioning two cinch sutures. H, An all-inside second suture was inserted into the bone tunnel in knee flexion. I, A final appearance following pullout and anchoring repair. MFC indicates medial femoral condyle; MM, medial meniscus; MTP, medial tibial plateau; PCL, posterior cruciate ligament; TCS, two cinch sutures.

Two Cinch Sutures (TCS)

We used a Knee Scorpion suture passer (Arthrex Inc., Naples, FL) to pass 2 No. 2 strong sutures vertically through the meniscal tissue. The suture was placed with a safety margin of approximately 10 mm from the edge of the tear to prevent suture cutout and loss of fixation as a first cinch stitch (Figs. 1B, 2A). The first suture was inserted into the inner part of the MM posterior horn, and the second suture was inserted into the outer part, more than 5 mm away from the tear (Figs. 1C, 2B). It is important to keep the first suture under tension through the anteromedial portal to enable easy access while placing the second suture.

Tibial Tunnel Creation and Suture Relay

MM posterior root attachment was confirmed before placing a custom-made posterior root-aiming device (Posterior Root Tear guide, Smith & Nephew; Unicorn Meniscal Root guide, Arthrex Inc.)19 at the anatomic center of the posterior root attachment as described previously (Figs. 1D, 2C, 3).20 A 2.4-mm guide pin was inserted at a 45 degrees angle to the root attachment with the aiming device, and a 4.0-mm cannulated drill was used to overdrill. After removing the inner guide pin alone, 4 TCS were pulled out through the cannulated drill using a suture relay technique (Figs. 1E, 2D). Gentle tension was applied to the sutures until the posterior horn reached its tibial attachment area (Figs. 1F, 2E).

FIGURE 3:

Appearance outside the knee joint (right knee) when a custom-made posterior root-aiming device is placed at the anatomic center of the posterior root attachment. A, Lateral view. B, Superior view.

Creation of Second Tibial Tunnel, All-Inside Suture Anchoring, and Tibial Fixation

In the next step, a further bone tunnel was created using an arthroscopic awl and 2.0-mm Kirschner wire, aiming at the posterior corner of the medial tibial plateau (approximately 15 mm away from the posterior root attachment) in externally rotated knee flexion (Figs. 1G, H, 2F). A flexible reamer for a 1.8 mm Q-Fix anchor (Smith & Nephew) can be used as an alternative to a Kirschner wire. This technique could be performed through a standard anteromedial portal without any accessory portal. The first anchor of the JuggerStitch (Zimmer Biomet, Warsaw, IN) all-inside meniscal repair device was inserted through the inferior surface of the MM posterior horn with tensioning TCS (Figs. 1I, 2G) in knee extension, and the second anchor of the same JuggerStitch repair device was inserted into the second bone tunnel, in knee flexion (Figs. 1J, 2H). Once sufficient tension of the posterior anchoring suture was confirmed (Fig. 1K), the free end of the all-inside suture was cut. Tibial fixation of the pullout sutures was performed using a bioabsorbable screw (5.0 and 6.0-mm diameter for good and poor bone quality, respectively) with an initial tension of 10 N in 30 degrees knee flexion, as previously described (Figs. 1L, 2I).10 Bone tunnels and MM movement could be investigated by computed tomography 1 week postoperatively (Fig. 4) and MRI 1 month postoperatively (Fig. 5). In our case, we found that severe posteromedial extrusion of the MM in knee flexion was decreased postoperatively, whereas MM extrusion in knee extension remained unchanged before and after pullout repair.

FIGURE 4:

Computed tomography images of the right knee. A, Superior view of the 3-dimensional tibial plateau reconstruction showing the main bone tunnel (diameter, 4.0 mm; dotted circle) and the second bone tunnel posteromedially (diameter, 2.0 mm; solid circle). B, Coronal images of the posteromedial bone tunnel (arrow). C, Sagittal images of the posteromedial bone tunnel (arrow). D, Schematic diagram of each anchor (red arrow, the first anchor inserted into medial meniscus; yellow arrow, the second anchor inserted into the posteromedial bone tunnel). LFC indicates lateral femoral condyle; LTP, lateral tibial plateau; MFC, medial femoral condyle; MTP, medial tibial plateau.

FIGURE 5:

Three-dimensional magnetic resonance images of the medial meniscus. Gray, proximal tibia; blue, meniscus on the tibial surface; violet, extruded medial meniscus. A, Preoperative image in 10 degrees knee flexion showing medial extrusion of the medial meniscus. B, Preoperative image in 90 degrees knee flexion showing severe posteromedial extrusion of the medial meniscus. C, Postoperative image in 10 degrees knee flexion showing medial extrusion of the medial meniscus. D, Postoperative image in 90 degrees knee flexion showing no apparent change from the status in 10 degrees knee flexion and less posteromedial extrusion of the medial meniscus compared with that before surgery.

Postoperative Protocol

Patients wore a knee immobilizer and did not bear weight for the first week after surgery. Subsequently, partial weight-bearing (20 kg) was permitted with gradual progression (+20 kg/week) to full weight-bearing. Patients were allowed 30 degrees knee flexion after 1 week, and 60, 90, and 120 degrees after 2, 3, and 4 weeks, respectively. Deep knee flexion was only allowed 12 weeks after surgery. Athletic activities (jogging, cycling, and/or golf) were allowed following an evaluation of the repaired MM posterior root with MRI after 12 weeks.

DISCUSSION

Favorable clinical outcomes have been previously described when 2 or 3 simple vertical sutures are used,21 despite their inferior load-to-failure strength.22 The cinch suture has more biomechanical strength than other suture techniques and is advantageous because it causes fewer perforations of the meniscal tissue when using all-inside suture devices.23,24 Furthermore, a simple cinch suture showed less cyclic displacement than a locking loop but a similar ultimate failure load.24 We used cinch sutures in our technique as it appeared to have their advantage of strength, ease of use, and requirement of only 1 perforation of the meniscus, which possibly reduced failure, surgery time, and risk of iatrogenic chondral damage.

Another advantage of our technique is that it allows the creation of additional bone tunnels and “the insertion of” all-inside sutures without the need for any accessory portal because it can be performed through a standard anteromedial portal when manipulating the knee rotation and flexion angles. Furthermore, because the strong posterior meniscocapsular ligament25 is penetrated with the MM posterior segment using an all-inside first suture, the risk of suture loosening or cutout is low. Therefore, we believe that this is a simple, safe, and reproducible technique to perform additional suture anchoring using an all-inside suture device.

Our technique, which uses additional posterior anchoring combined with conventional TCS, can help decrease the MM posteromedial extrusion in knee flexion and might be a good option for arthroscopic repair of MMPRTs. Clinical, biomechanical, and radiologic long-term studies, including second-look arthroscopy and functional scoring in a large number of patients treated with this new technique, are needed for efficacy comparison of our novel technique with that of previously described techniques.

ACKNOWLEDGMENTS

The Authors would like to thank Saori Yoshioka and Masaaki Yokoyama at SYSTEM TIES Co. Ltd (Okayama, Japan; www.system-ties.co.jp/) for illustration creating and Editage (www.editage.com) for English language editing.

REFERENCES 1. Bhatia S, LaPrade CM, Ellman MB, et al. Meniscal root tears: significance, diagnosis, and treatment. Am J Sports Med. 2014;42:3016–3030. 2. Allaire R, Muriuki M, Gilbertson L, et al. Biomechanical consequences of a tear of the posterior root of the medial meniscus. Similar to total meniscectomy. J Bone Joint Surg Am. 2008;90:1922–1931. 3. Padalecki JR, Jansson KS, Smith SD, et al. Biomechanical consequences of a complete radial tear adjacent to the medial meniscus posterior root attachment site: in situ pull-out repair restores derangement of joint mechanics. Am J Sports Med. 2014;42:699–707. 4. Masuda S, Furumatsu T, Okazaki Y, et al. Medial meniscus posterior root tear induces pathological posterior extrusion of the meniscus in the knee-flexed position: an open magnetic resonance imaging analysis. Orthop Traumatol Surg Res. 2018;104:485–489. 5. Okazaki Y, Furumatsu T, Okazaki Y, et al. Medial meniscus posterior root repair decreases posteromedial extrusion of the medial meniscus during knee flexion. Knee. 2020;27:132–139. 6. Okazaki Y, Furumatsu T, Yamauchi T, et al. Medial meniscus posterior root repair restores the intra-articular volume of the medial meniscus by decreasing posteromedial extrusion at knee flexion. Knee Surg Sports Traumatol Arthrosc. 2020;28:3435–3442. 7. Okazaki Y, Furumatsu T, Kodama Y, et al. Transtibial pullout repair of medial meniscus posterior root tear restores physiological rotation of the tibia in the knee-flexed position. Orthop Traumatol Surg Res. 2019;105:113–117. 8. LaPrade CM, Foad A, Smith SD, et al. Biomechanical consequences of a nonanatomic posterior medial meniscal root repair. Am J Sports Med. 2015;43:912–920. 9. Chung KS, Ha JK, Ra HJ, et al. A meta-analysis of clinical and radiographic outcomes of posterior horn medial meniscus root repairs. Knee Surg Sports Traumatol Arthrosc. 2016;24:1455–1468. 10. Okazaki Y, Furumatsu T, Kodama Y, et al. Description of a surgical technique of medial meniscus root repair: a fixation technique with two simple stiches under an expected initial tension. Eur J Orthop Surg Traumatol. 2019;29:705–709. 11. Okazaki Y, Furumatsu T, Miyazawa S, et al. A novel suture technique to reduce the meniscus extrusion in the pullout repair for medial meniscus posterior root tears. Eur J Orthop Surg Traumatol. 2019;29:1805–1809. 12. Kaplan DJ, Alaia EF, Dold AP, et al. Increased extrusion and ICRS grades at 2-year follow-up following transtibial medial meniscal root repair evaluated by MRI. Knee Surg Sports Traumatol Arthrosc. 2018;26:2826–2834. 13. Chung KS, Ha JK, Ra HJ, et al. Pullout fixation of posterior medial meniscus root tears: correlation between meniscus extrusion and midterm clinical results. Am J Sports Med. 2017;45:42–49. 14. Starke C, Kopf S, Grobel KH, et al. The effect of a nonanatomic repair of the meniscal horn attachment on meniscal tension: a biomechanical study. Arthroscopy. 2010;26:358–365. 15. Dean RS, DePhillipo NN, Monson JK, et al. Peripheral stabilization suture to address meniscal extrusion in a revision meniscal root repair: surgical technique and rehabilitation protocol. Arthrosc Tech. 2020;9:e1211–e1218. 16. Koga H, Watanabe T, Horie M, et al. Augmentation of the pullout repair of a medial meniscus posterior root tear by arthroscopic centralization. Arthrosc Tech. 2017;6:e1335–e1339. 17. Feucht MJ, Salzmann GM, Bode G, et al. Posterior root tears of the lateral meniscus. Knee Surg Sports Traumatol Arthrosc. 2015;23:119–125. 18. Todor A, Caterev S, Nistor DV. Outside-in deep medial collateral ligament release during arthroscopic medial meniscus surgery. Arthrosc Tech. 2016;5:e781–e785. 19. Furumatsu T, Okazaki Y, Kodama Y, et al. The accuracy of a newly developed guide system in medial meniscus posterior root repair: a comparison between two aiming guides. Knee Surg Relat Res. 2019;31:7. 20. Hiranaka T, Furumatsu T, Kamatsuki Y, et al. The distance between the tibial tunnel aperture and meniscal root attachment is correlated with meniscal healing status following transtibial pullout repair for medial meniscus posterior root tear. Knee. 2020;27:899–905. 21. Chung KS, Noh JM, Ha JK, et al. Survivorship analysis and clinical outcomes of transtibial pullout repair for medial meniscus posterior root tears: a 5- to 10-year follow-up study. Arthroscopy. 2018;34:530–535. 22. Fujii M, Furumatsu T, Xue H, et al. Tensile strength of the pullout repair technique for the medial meniscus posterior root tear: a porcine study. Int Orthop. 2017;41:2113–2118. 23. Anz AW, Branch EA, Saliman JD. Biomechanical comparison of arthroscopic repair constructs for meniscal root tears. Am J Sports Med. 2014;42:2699–2706. 24. Krych AJ, Johnson NR, Wu IT, et al. A simple cinch is superior to a locking loop for meniscus root repair: a human biomechanical comparison of suture constructs in a transtibial pull-out model. Knee Surg Sports Traumatol Arthrosc. 2018;26:2239–2244. 25. DePhillipo NN, Moatshe G, Chahla J, et al. Quantitative and qualitative assessment of the posterior medial meniscus anatomy: defining meniscal ramp lesions. Am J Sports Med. 2019;47:372–378.