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Editorial Commentary: Efforts to Heal Meniscal Radial Tears Are Ongoing

      Abstract

      Meniscal radial tears are equivalent to the meniscectomized state. However, successful healing rates by current repair methods for meniscal radial tears are still not satisfactory. Several suture configurations that could approximate the tear gap and stabilize meniscal tissue have been developed to overcome the shortcomings of simple horizontal stitches and cross stitches. The hybrid stitch method, composed of horizontal stitches and vertical stitches, has been introduced. This method can provide stable fixation because the vertical stitches suture the bundle of circumferential fibers, and the vertical stitches act as rip stops for the horizontal stitches. However, it is still challenging to heal meniscal radial tears in avascular areas or complex tears. In treating radial tears, it is important not only to improve suture mechanics but also to promote biologic healing potential.
      Radial tears are known to be more detrimental in knee biomechanics than other types of tear, because they decrease contact area and increase contact pressure.
      • Mononen M.E.
      • Jurvelin J.S.
      • Korhonen R.K.
      Effects of radial tears and partial meniscectomy of lateral meniscus on the knee joint mechanics during the stance phase of the gait cycle—A 3D finite element study.
      ,
      • Ode G.E.
      • Van Thiel G.S.
      • McArthur S.A.
      • et al.
      Effects of serial sectioning and repair of radial tears in the lateral meniscus.
      The reason why radial tears have clinical significance is that these ruptures completely disrupt the circumferential fibers, thereby destroying the hoop tension function and rapidly progressing the progression of osteoarthritis.
      • Kim J.G.
      • Lee Y.S.
      • Bae T.S.
      • et al.
      Tibiofemoral contact mechanics following posterior root of medial meniscus tear, repair, meniscectomy, and allograft transplantation.
      ,
      • Lee D.W.
      • Ha J.K.
      • Kim J.G.
      Medial meniscus posterior root tear: A comprehensive review.
      The trend toward meniscal radial tears have been shifting to repair instead of subtotal meniscectomy, although the repair technique is technically demanding. Previous studies have shown that radial tears are difficult to heal since they include injuries of white–white and white–red zones, which are in the avascular area.
      • Barber-Westin S.D.
      • Noyes F.R.
      Clinical healing rates of meniscus repairs of tears in the central-third (red-white) zone.
      It is still challenging to heal radial tears, and consequently efforts to enhance successful healing are ongoing globally. Hybrid stitch methods have been developed with the aim of reinforcing the repair site to protect repaired tissue and allow for healing.
      • Massey P.
      • McClary K.
      • Parker D.
      • Barton R.S.
      • Solitro G.
      The rebar repair for radial meniscus tears: A biomechanical comparison of a reinforced suture repair versus parallel and cross-stitch techniques.
      ,
      • Nakanishi Y.
      • Hoshino Y.
      • Nagamune K.
      • et al.
      Radial meniscal tears are best repaired by a modified "cross" tie-grip suture based on a biomechanical comparison of 4 repair techniques in a porcine model.
      In our opinion, the study by Zhang, Zhou, Li, Luo, Wu, Jiang, Chen, Hou, Yang, Song, and Zhang, “Tibiofemoral Contact Mechanics After Horizontal or Ripstop Suture in Inside-Out and Transtibial Repair for Meniscus Radial Tears in a Porcine Model,”
      • Zhang H.Z.
      • Zhou Y.F.
      • Li W.P.
      • et al.
      Tibiofemoral contact mechanics after horizontal or ripstop suture sin inside-out and transtibial repair for meniscus radial tears in a porcine model.
      provides excellent insight for clinicians to determine the appropriate surgical technique for meniscal radial tears. The authors compared tibiofemoral contact mechanics after horizontal or ripstop (horizontal plus vertical) sutures in inside-out and transtibial repair for meniscal radial tears with 10 porcine knees for each group. They concluded that (1) radial tears of the meniscus in a porcine model significantly decreased medial contact area and increased mean and peak contact pressure; and (2) both inside-out and transtibial ripstop repairs for radial tears aided in restoring intact tibiofemoral contact mechanics at all assessed knee flexion angles. However, the horizontal sutures alone failed to do so for contact pressures at 60° and 90° and for contact areas at all flexion angles.
      Theoretically, hybrid stitch methods such as the ripstop method have a greater load to failure than simple stitches alone could effectively distribute axial loading and lead to lower rates of suture cutout through the meniscal tissue. Our study group developed the modified Mason–Allen repair for medial meniscal root tear since 2012, because this suture method has been known to show better biomechanical properties for rotator cuff tears of the shoulder than other simple stitches.
      • Lee D.W.
      • Jang S.H.
      • Ha J.K.
      • Kim J.G.
      • Ahn J.H.
      Meniscus root refixation technique using a modified Mason-Allen stitch.
      Our recent biomechanical study revealed that the modified Mason–Allen repair had similar or better biomechanical properties compared with all other suture methods, in terms of maximum failure load and stiffness.
      • Chung K.S.
      • Choi C.H.
      • Bae T.S.
      • et al.
      Comparison of tibiofemoral contact mechanics after various transtibial and all-inside fixation techniques for medial meniscus posterior root radial tears in a porcine model.
      Lee et al.
      • Lee D.W.
      • Jang S.H.
      • Ha J.K.
      • Kim J.G.
      • Ahn J.H.
      Meniscus root refixation technique using a modified Mason-Allen stitch.
      suggested that the modified Mason–Allen stitch, which consists of a simple vertical and a simple horizontal stitch, reproduces the locking mechanism through a rip stop effect of the horizontal loop. Our clinical research showed that modified Mason–Allen stitch was associated with better reduction of meniscal extrusion than simple stitches, and we supposed that the modified Mason–Allen repair could lead to less arthritic changes and result in favorable clinical outcomes than simple stitches.
      • Lee D.W.
      • Kim M.K.
      • Jang H.S.
      • Ha J.K.
      • Kim J.G.
      Clinical and radiologic evaluation of arthroscopic medial meniscus root tear refixation: Comparison of the modified Mason-Allen stitch and simple stitches.
      Similar to our modified Mason–Allen stitch in medial meniscal root tears, Zhang et al. have used ripstop stitches with inside-out or transtibial method for medial meniscal radial tears. In ripstop stitches, the simple vertical mattress suture bundles the circumferential fibers and 2 vertical mattress play as rip stops for 2 horizontal loops. Massey et al.
      • Massey P.
      • McClary K.
      • Parker D.
      • Barton R.S.
      • Solitro G.
      The rebar repair for radial meniscus tears: A biomechanical comparison of a reinforced suture repair versus parallel and cross-stitch techniques.
      reported that Rebar repair for radial tears had a greater load to failure and a lower rate of suture cutout via the meniscal tissue, compared with the simple horizontal stitches and cross-stitch method in cadaveric study. In their study, Rebar means a reinforced suture bar (vertical mattress) in ripstop stitches.
      However, we have several concerns about the ripstop stitches. First of all, in vitro biomechanical experiments tend to be zero-time study, so interpretation from this may implicitly ignore the role of biology, for instance, the status of healing tissue, or normal hoop tension. In addition, biomechanical studies can’t reproduce the complex real situation including distraction, compression, and shear. Hence, further clinical studies are necessary to determine the effect of reinforced suture bar on healing or radial tear.
      The ripstop suture was first described in Japan by Nakata et al.
      • Nakata K.
      • Shino K.
      • Kanamoto T.
      • et al.
      New technique of arthroscopic meniscus repair in radial tears.
      in 2012, which was called the “tie-grip suture” for repair of radial meniscal tears that involved hybrid fixation, consisting of a configuration of vertical and horizontal mattress sutures across the radial tear site. The addition of the vertical mattress sutures to act as a ripstop suture is effective in preventing meniscal cut-out of the meniscus and it may be used in poor-quality tissue. However, Tsujii et al.
      • Tsujii A.
      • Amano H.
      • Tanaka Y.
      • Kita K.
      • Uchida R.
      • Shiozaki Y.
      • Horibe S.
      Second look arthroscopic evaluation of repaired radial/oblique tears of the midbody of the lateral meniscus in stable knees.
      evaluated arthroscopic findings after inside-out “tie-grip suture” repair for radial/oblique tears of the meniscus midbody. They showed that inside-out repair using the tie-grip suture technique for isolated radial/oblique tears of the meniscus mid-body achieved complete or partial healing only in 61% of patients. In particular, all patients with partial oblique tears were considered failure. Satisfactory results were obtained, especially in patients with tears extending to the vascular zone, whereas those with tears in the avascular zone failed to achieve healing.
      During the ripstop procedure, 2 vertical mattress can make a gap at the inner margin of the radial tear, and it leads to failure of healing. Nakanishi et al.
      • Nakanishi Y.
      • Hoshino Y.
      • Nagamune K.
      • et al.
      Radial meniscal tears are best repaired by a modified "cross" tie-grip suture based on a biomechanical comparison of 4 repair techniques in a porcine model.
      modified the ripstop stitches, and they crossed the 2 vertical mattress to avoid a gap at the inner margin. They showed that the cross tie-grip suture (modified ripstop stitches) resulted in less displacement at repair site compared with the tie-grip stitches, double horizontal stitches, and cross stitches, and consequently they assumed that the cross tip-grip suture may be advantageous in healing for radial meniscal tears.
      In 2015, James et al.
      • James E.W.
      • Laprade C.M.
      • Feagin J.A.
      • Laprade R.F.
      Repair of a complete radial tear in the midbody of the medial meniscus using a novel crisscross suture transtibial tunnel surgical technique: A case report.
      described the transtibial pull-out repair technique using two 5-mm transtibial tunnels for repair of radial tears in the meniscus midbody. However, there are concerns regarding limitation of meniscus motion after healing, since this technique firmly fixated the meniscus to the tibial plateau with sutures through transtibial tunnels. Although the transtibial technique may reproduce the capsular attachment such as coronary ligament, Zhang et al. did not show differences between inside-out and transtibial methods. We think that the transtibial repair technique is more technically challenging, more time consuming, and there is a possibility of increased morbidity, than inside-out methods.
      Our group strongly believes that restoration and preservation of hoop tension is the key objective we should pursue in meniscus repair. Although not yet satisfactory enough, numerous surgical techniques have been developed to achieve stability of torn and displaced menisci, and certain degree of global consensus has been reached so far. Under the premise that reasonable stability of menisci can be routinely achieved, the future of meniscus repair seems to lie in biological healing adjuvants such as fibrin clot, collagen-wrapping techniques, bone marrow stimulation, and stem cells, etc.
      We introduced meniscus repair with fibrin clot in 2012.
      • Ra H.J.
      • Ha J.K.
      • Jang S.H.
      • Lee D.W.
      • Kim J.G.
      Arthroscopic inside-out repair of complete radial tears of the meniscus with a fibrin clot.
      We drew 20 to 30 mL of peripheral blood from the patient and extracted fibrin clot, and it was placed in the defect in the meniscus and secured by fastening the sutures outside the joint. Twelve patients with complete radial tears of the meniscus were treated by arthroscopic inside-out repair with fibrin clots. At a mean of 30 ± 4 postoperative months, 11 of 12 cases showed complete healing on follow-up magnetic resonance imaging. Six of 7 patients undergoing a second-look arthroscopic examination had healed completely. Since then, we have continued to perform this procedure routinely and achieved numerous favorable results.
      Meanwhile, Piontek et al. introduced the “all-inside” meniscus repair combined with collagen matrix wrapping and bone marrow injection in 2012 and serially reported 2-year and 5-year clinical follow-up.
      • Piontek T.
      • Ciemniewska-Gorzela K.
      • Szulc A.
      • Słomczykowski M.
      • Jakob R.
      All-arthroscopic technique of biological meniscal tear therapy with collagen matrix.
      • Piontek T.
      • Ciemniewska-Gorzela K.
      • Naczk J.
      • et al.
      Complex meniscus tears treated with collagen matrix wrapping and bone marrow blood injection: A 2-year clinical follow-up.
      • Ciemniewska-Gorzela K.
      • Bąkowski P.
      • Naczk J.
      • Jakob R.
      • Piontek T.
      Complex meniscus tears treated with collagen matrix wrapping and bone marrow blood injection: Clinical effectiveness and survivorship after a minimum of 5 years' follow-up.
      Fifty-four consecutive patients with complex meniscal tears were treated with the aforementioned technique and recently reported to have very good mid-term clinical and magnetic resonance imaging–based outcomes as well as a favorable survival rate.
      In a recent review article on stem cell therapies on meniscus repair, Jacob et al.
      • Jacob G.
      • Shimomura K.
      • Krych A.J.
      • Nakamura N.
      The meniscus tear: A review of stem cell therapies.
      concluded that mesenchymal stem cells appear to be safe and effective in producing superior-quality meniscal repairs. However, presently there is no consensus on the ideal cell source and scaffold for meniscus regeneration. The solution to meniscal tissue regeneration is a particularly elusive one and appears far more complex than that of cartilage regeneration due to the complex phenotype and function of meniscal tissue. The authors anticipate that stem cell therapies will become more effective in the near future to aid meniscal repair modalities, thereby adding another weapon to retard dreaded osteoarthritis progression in the knee.

      Supplementary Data

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