Yuya Kodama

Pullout repair of a medial meniscus posterior root tear using a FasT-Fix ® all-inside suture technique

A medial meniscus posterior root tear (MMPRT) may increase the tibiofemoral contact pressure by decreasing the tibiofemoral contact area. Meniscal dysfunction induced by posterior root injury may lead to the development of osteoarthritic knees. Repair of a MMPRT can restore medial meniscus (MM) function and prevent knee osteoarthritis progression. Several surgical procedures have been reported for treating a MMPRT. However, these procedures are associated with several technical difficulties. Here, we describe a technique to stabilize a torn MM posterior root using the FasT-Fix® all-inside meniscal suture device and a new aiming device. The uncut free-end of the FasT-Fix® suture can be used as a thread for transtibial pullout repair. Our procedure might help overcome the technical difficulties in arthroscopic treatment of a MMPRT.

The anterior cruciate ligament-lateral meniscus complex: A histological study

ABSTRACT The anterior root of the lateral meniscus (LM) dives underneath the tibial attachment of the anterior cruciate ligament (ACL). Although the distinct role of meniscal attachments has been investigated, the relationship between the LM anterior insertion (LMAI) and ACL tibial insertion (ACLTI) remains unclear. This study histologically analyzed the LMAI and ACLTI. Samples were divided into four regions in an anterior-to-posterior direction. Histological measurements of these insertion sites were performed using safranin O-stained coronal sections. Distribution and signal densities of type I and II collagen were quantified. The ACLTI and LMAI formed the ACL–LM complex via fiber connections. The anterior part of the ACLTI had a widespread attachment composed of dense fibers. Attachment fibers of the LMAI became dense and wide gradually at the middle-to-posterior region. The ACL–LM transition zone (ALTZ) was observed between the LMAI and the lateral border of the ACLTI at the middle part of the ACL tibial footprint. Type II collagen density of the LMAI was higher than that of the ACLTI and ALTZ. Our results can help create an accurate tibial bone tunnel within the dense ACL attachment during ACL reconstruction surgery.

Location of the tibial tunnel aperture affects extrusion of the lateral meniscus following reconstruction of the anterior cruciate ligament

The anterior root of the lateral meniscus provides functional stability to the meniscus. In this study, we evaluated the relationship between the position of the tibial tunnel and extrusion of the lateral meniscus after anterior cruciate ligament reconstruction, where extrusion provides a proxy measure of injury to the anterior root. The relationship between extrusion and tibial tunnel location was retrospectively evaluated from computed tomography and magnetic resonance images of 26 reconstructed knees, contributed by 25 patients aged 17–31 years. A measurement grid was used to localize the position of the tibial tunnel based on anatomical landmarks identified from the three‐dimensional reconstruction of axial computed tomography images of the tibial plateaus. The reference point‐to‐tibial tunnel distance (mm) was defined as the distance from the midpoint of the lateral edge of the grid to the posterolateral aspect of the tunnel aperture. The optimal cutoff of this distance to minimize post‐operative extrusion was identified using receiver operating curve analysis. Extrusion of the lateral meniscus was positively correlated to the reference point‐to‐tibial tunnel distance (r 2 = 0.64; p < 0.001), with a cutoff distance of 5 mm having a sensitivity to extrusion of 83% and specificity of 93%. The mean extrusion for a distance >5 mm was 0.40 ± 0.43 mm, compared to 1.40 ± 0.51 mm for a distance ≤5 mm (p < 0.001). Therefore, a posterolateral location of the tibial tunnel aperture within the footprint of the anterior cruciate ligament decreases the reference point‐to‐tibial tunnel distance and increases extrusion of the lateral meniscus post‐reconstruction.

A new aiming guide can create the tibial tunnel at favorable position in transtibial pullout repair for the medial meniscus posterior root tear

INTRODUCTION Injuries to the medial meniscus (MM) posterior root lead to accelerated cartilage degeneration of the knee. An anatomic placement of the MM posterior root attachment is considered to be critical in transtibial pullout repair of the medial meniscus posterior root tear (MMPRT). However, tibial tunnel creation at the anatomic attachment of the MM posterior root is technically difficult using a conventional aiming device. The aim of this study was to compare two aiming guides. We hypothesized that a newly-developed guide, specifically designed, creates the tibial tunnel at an adequate position rather than a conventional device. MATERIALS AND METHODS Twenty-six patients underwent transtibial pullout repairs. Tibial tunnel creation was performed using the Multi-use guide (8 cases) or the PRT guide that had a narrow twisting/curving shape (18 cases). Three-dimensional computed tomography images of the tibial surface were evaluated using the Tsukadas measurement method postoperatively. Expected anatomic center of the MM posterior root attachment and tibial tunnel center were evaluated using the percentage-based posterolateral location on the tibial surface. Percentage distance between anatomic center and tunnel center was calculated. RESULTS Anatomic center of the MM posterior root footprint located at a position of 78.5% posterior and 39.4% lateral. Both tunnels were anteromedial but tibial tunnel center located at a more favorable position in the PRT group: percentage distance was significantly smaller in the PRT guide group (8.7%) than in the Multi-use guide group (13.1%). DISCUSSION The PRT guide may have great advantage to achieve a more anatomic location of the tibial tunnel in MMPRT pullout repair. LEVEL OF EVIDENCE III.

Meniscal Extrusion Progresses Shortly after the Medial Meniscus Posterior Root Tear

Purpose Medial meniscus posterior root tears (MMPRT) induce medial meniscus extrusion (MME). However, the time-dependent extent of MME in patients suffering from the MMPRT remains unclear. This study evaluated the extent of MME after painful popping events that occurred at the onset of the MMPRT. Materials and Methods Thirty-five patients who had an episode of posteromedial painful popping were investigated. All the patients were diagnosed as having an MMPRT by magnetic resonance imaging (MRI) within 12 months after painful popping. Medial meniscus body width (MMBW), absolute MME, and relative MME (100×absolute MME/MMBW) were assessed among three groups divided according to the time after painful popping events: early period (<1 month), subacute period (1–3 months), and chronic period (4–12 months). Results In the early period, absolute and relative MMEs were 3.0 mm and 32.7%, respectively. Absolute MME increased up to 4.2 mm and 5.8 mm during the subacute and chronic periods, respectively. Relative MME also progressed to 49.2% and 60.3% in the subacute and chronic periods, respectively. Conclusions This study demonstrated that absolute and relative MMEs increased progressively within the short period after the onset of symptomatic MMPRT. Our results suggest that early diagnosis of an MMPRT may be important to prevent progression of MME following the MMPRT.

Medial meniscus posterior root tear induces pathological posterior extrusion of the meniscus in the knee-flexed position: An open magnetic resonance imaging analysis

BACKGROUND A medial meniscus posterior root tear (MMPRT) is defined as an injury to the posterior meniscal insertion on the tibia. In MMPRT, the medial meniscus (MM) hoop function is damaged, and the MM undergoes a medial extrusion into the interior from the superior articular surface of the tibia. However, the details of MM position and movement during knee joint movement are unclear in MMPRT cases. The present study aims to evaluate MM position and movement via magnetic resonance imaging (MRI) examination of the MM posterior extrusion (MMPE) at knee flexion angles of 10° and 90°. We hypothesized that, during knee flexion, the MM will shift to the posterior and the posterior extrusion will increase compared to that when the knee is extended. MATERIALS AND METHODS Twenty-four patients were diagnosed with symptomatic MMPRT on open MRI examination. Preoperative MMPE, anteroposterior interval (API) of the MM, and MM medial extrusion (MMME) at knee flexion angles of 10° and 90° were measured. RESULTS For patients with MMPRT, the MMPE increased from -4.77±1.43mm to 3.79±1.17mm (p<0.001) when the knee flexion angle increased from 10° to 90°. Further, flexing the knee from 10° to 90° decreased the API of the MM from 20.19±4.22mm to 16.41±5.14mm (p<0.001). MMME showed no significant change between knee flexion angles of 10° and 90°. DISCUSSION This study demonstrated that, in cases of MMPRT, the MMPE clearly increases when the knee is flexed to 90°, while MMME does not change. Our results suggest that open MRI examination can be used to evaluate the dynamic position of the posterior MM by scanning the knee as it flexes to 90°. LEVEL OF EVIDENCE IV: retrospective cohort study.

A novel suture technique using the FasT-Fix combined with Ultrabraid for pullout repair of the medial meniscus posterior root tear

Medial meniscus posterior root has an important role in the maintenance of knee articular cartilage. Although pullout repair of the medial meniscus posterior root tear has become a gold standard, it has several difficulties for suturing. We have developed a modified Mason–Allen suture technique using the FasT-Fix all-inside suture device combined with Ultrabraid. The present suture technique allows a strong grasping of the medial meniscus posterior horn for arthroscopic pullout repair.

Hyaluronan stimulates chondrogenic gene expression in human meniscus cells

ABSTRACT Purpose/Aim of the Study: Inner meniscus cells have a chondrocytic phenotype, whereas outer meniscus cells have a fibroblastic phenotype. In this study, we examined the effect of hyaluronan on chondrocytic gene expression in human meniscus cells. Materials and Methods: Human meniscus cells were prepared from macroscopically intact lateral meniscus. Inner and outer meniscus cells were obtained from the inner and outer halves of the meniscus. The cells were stimulated with hyaluronan diluted in Dulbecco’s modified Eagle’s medium without serum to the desired concentration (0, 10, 100, and 1000 μg/mL) for 2–7 days. Cellular proliferation, migration, and polymerase chain reaction analyses were performed for the inner and outer cells separately. Meniscal samples perforated by a 2 mm diameter punch were maintained for 3 weeks in hyaluronan-supplemented medium and evaluated by histological analyses. Results: Hyaluronan increased the proliferation and migration of both meniscus cell types. Moreover, cellular counts at the surface of both meniscal tissue perforations were increased by hyaluronan treatments. In addition, hyaluronan stimulated α1(II) collagen expression in inner meniscus cells. Accumulation of type II collagen at the perforated surface of both meniscal samples was induced by hyaluronan treatment. Hyaluronan did not induce type I collagen accumulation around the injured site of the meniscus. Conclusion: Hyaluronan stimulated the proliferation and migration of meniscus cells. Our results suggest that hyaluronan may promote the healing potential of meniscus cells in damaged meniscal tissues.

Complete tear of the lateral meniscus posterior root is associated with meniscal extrusion in anterior cruciate ligament deficient knees: POSTERIOR ROOT TEAR CAUSES LATERAL MENISCAL EXTRUSION

This study aimed to evaluate the relationship between preoperative lateral meniscal extrusion (LME) and arthroscopic findings of lateral meniscus posterior root tear (LMPRT) in knees with anterior cruciate ligament (ACL) tear. Thirty‐five knees that had LMPRTs with concomitant ACL tears on arthroscopy were evaluated. Patients were divided into two groups, partial and complete root tears, via arthroscopic findings at the time of ACL reconstruction. For comparison, we added two groups, using the same database; 20 normal knees (normal group) and 20 ACL‐injured knees without LM injury (intact LM group). We retrospectively measured preoperative LMEs using magnetic resonance imaging (MRI). Twenty‐three knees had partial LMPRTs. Complete LMPRTs were observed in 12 knees. The average LME was −0.1 ± 0.4 mm in the normal group, 0.2 ± 0.5 mm in the intact LM group, 0.4 ± 0.8 mm in the partial LMPRT group, and 2.0 ± 0.6 mm in the complete LMPRT group. A significant difference in preoperative LMEs was observed between the complete LMPRT group and the other groups (p < 0.001). The receiver operating curve analysis, which distinguishes a partial tear from a complete tear, identified an optimal cut‐off point of 1.1 mm for preoperative LME. This LME cut‐off had a sensitivity of 100% and specificity of 83% for complete LMPRT. We found that preoperative LMEs were larger in complete LMPRTs associated with ACL injuries than in partial LMPRTs. Our results suggest that preoperative MRI‐detected LME may be a useful indicator for estimating LMPRT severity in ACL‐injured knees. Level of evidence: Retrospective comparative study level IV.

Formation of ring-shaped lateral meniscus following anterior cruciate ligament reconstruction: A case report

Highlights • There were no meniscal anomalies such as discoid meniscus and ring-shaped meniscus at the first surgery.• Postoperative MRI showed a ring-shaped lateral meniscus.• On second-look arthroscopy, there was a meniscus-like tissue formation that connected the anterior horn to the posterior horn of the lateral meniscus at the lateral intercondylar tubercle.• The ring-shaped meniscus-like tissue was spontaneously formed after ACL reconstruction.