Hiroki Katagiri

Transplantation of aggregates of synovial mesenchymal stem cells regenerates meniscus more effectively in a rat massive meniscal defect.

Transplantation of mesenchymal stem cells (MSCs) derived from synovium is a possible therapy for meniscus regeneration. We have previously reported that intraarticular injection of 5 million synovial MSCs promoted meniscal regeneration in rat meniscal defects. However, if a similar cell number per body weight were required, preparation of required human MSCs would not be practical in a clinical situation. The use of aggregates of MSCs may be one of the solutions. Here, we investigated whether the use of aggregates of synovial MSCs regenerated meniscus more effectively in a rat meniscectomized model. The total number of synovial MSCs was adjusted to 25,000 cells, and aggregates consisting of MSCs or 25,000 MSCs suspended in PBS were placed on the meniscal defects. Five million MSCs suspended in PBS were also used as another control. For the regenerated menisci, the area was larger and the histological findings were closer to that of the normal meniscus in the aggregate groups than to that in the suspension groups at 4 weeks. The effects of transplantation of aggregates were still observed at 12 weeks. Luminescence intensity remained higher at 3 weeks and thereafter in the aggregate group than in the suspension group when the same number of luciferase expressing MSCs were transplanted. We confirmed that MSCs transplanted as aggregates existed in the regenerated meniscus focally and partially. Transplantation of aggregates of synovial MSCs regenerated meniscus more effectively in a rat massive meniscal defect.

Transplantation of Achilles Tendon Treated With Bone Morphogenetic Protein 7 Promotes Meniscus Regeneration in a Rat Model of Massive Meniscal Defect

Objective This study was undertaken to examine whether bone morphogenetic protein 7 (BMP-7) induces ectopic cartilage formation in the rat tendon, and whether transplantation of tendon treated with BMP-7 promotes meniscal regeneration. Additionally, we analyzed the relative contributions of host and donor cells on the healing process after tendon transplantation in a rat model. Methods BMP-7 was injected in situ into the Achilles tendon of rats, and the histologic findings and gene profile were evaluated. Achilles tendon injected with 1 μg of BMP-7 was transplanted into a meniscal defect in rats. The regenerated meniscus and articular cartilage were evaluated at 4, 8, and 12 weeks. Achilles tendon from LacZ-transgenic rats was transplanted into the meniscal defect in wild-type rats, and vice versa. Results Injection of BMP-7 into the rat Achilles tendon induced the fibrochondrocyte differentiation of tendon cells and changed the collagen gene profile of tendon tissue to more closely approximate meniscal tissue. Transplantation of the rat Achilles tendon into a meniscal defect increased meniscal size. The rats that received the tendon treated with BMP-7 had a meniscus matrix that exhibited increased Safranin O and type II collagen staining, and showed a delay in articular cartilage degradation. Using LacZ-transgenic rats, we determined that the regeneration of the meniscus resulted from contribution from both donor and host cells. Conclusion Our findings indicate that BMP-7 induces ectopic cartilage formation in rat tendons. Transplantation of Achilles tendon treated with BMP-7 promotes meniscus regeneration and prevents cartilage degeneration in a rat model of massive meniscal defect. Native cells in the rat Achilles tendon contribute to meniscal regeneration.

Lateral meniscus posterior root tear contributes to anterolateral rotational instability and meniscus extrusion in anterior cruciate ligament-injured patients

PurposeThe purposes of this study were to investigate (1) meniscus status and clinical findings in anterior cruciate ligament (ACL)-injured patients to clarify associations between the meniscus posterior root tear (PRT) and knee instability, and (2) magnetic resonance imaging (MRI) findings of the PRT to clarify sensitivity and specificity of MRI and prevalence of meniscus extrusion.MethodsThree hundred and seventeen patients with primary ACL reconstruction were included. PRTs for both medial and lateral sides were confirmed by reviewing surgical records. Preoperative MRI was reviewed to evaluate sensitivity and specificity of the PRT and meniscus extrusion width (MEW). Clinical information regarding the number of giving-way episodes, preoperative KT-1000 measurements and preoperative pivot shift was also assessed.ResultsThirty-nine patients had a lateral meniscus (LM) PRT, whereas only four patients had a medial meniscus PRT. One hundred and seventeen patients had no meniscus tear (control). Twenty-eight patients (71.8%) showed positive signs of the LMPRT based on at least one view of MR images, with the coronal view showing the highest sensitivity. MEW in the LMPRT group was significantly larger than that in the control group. The preoperative pivot shift test grade in the LMPRT group was significantly greater than that in the control group. There were no significant differences in other parameters.ConclusionsIn ACL-injured patients, the LMPRT was associated with ALRI as well as with meniscus extrusion. The coronal view of MRI was useful in identifying the LMPRT, although its sensitivity was not high. Therefore, surgeons should prepare to repair PRTs at the time of ACL reconstruction regardless of MRI findings, and they should make every effort to repair the LMPRT.Level of evidenceIII.

Post-Cam Design and Contact Stress on Tibial Posts in Posterior-Stabilized Total Knee Prostheses: Comparison Between a Rounded and a Squared Design

BACKGROUND The post-cam mechanism in posterior stabilized (PS) prostheses plays an important role in total knee arthroplasty (TKA). The purpose of this study is to clarify the difference of the contact stress on the tibial post between a rounded post-cam design and a squared design during deep knee flexion and at hyperextension using the three-dimensional (3D) finite element models. METHODS We created 2 types of 3D, finite element models of PS prostheses (types A and B), whose surfaces were identical except for the post-cam geometries: type A has a rounded post-cam design, while type B has a squared design. Both types have a similar curved-shape intercondylar notch of the femoral component. Stress distributions, peak contact stresses, and contact areas on the tibial posts at 90°, 120°, and 150° flexion with/without 10° tibial internal rotation and at 10° hyperextension were compared between the 2 models. RESULTS Type B demonstrated more concentrated stress distribution compared to type A. The peak contact stresses were similar in both groups during neutral flexion; however, the stresses were much higher in type B during flexion with 10° rotation and at hyperextension. The higher peak contact stresses corresponded to the smaller contact areas in the tibial post. CONCLUSION A rounded post-cam design demonstrated less stress concentration during flexion with rotation and at hyperextension compared with a squared design. The results would be useful for development of implant designs and prediction of the contact stress on the tibial post in PS total knee arthroplasty.

Bilateral Hypoplasia of Both Medial and Lateral Menisci Partially Fused With the Cartilage Surface of the Tibial Plateau

Hypoplastic meniscus is an extremely rare abnormality. The authors present the first case of meniscal hypoplasia with a partial fusion of meniscus and tibial cartilage. A 22-year-old man underwent surgery for a chronic patellar dislocation. Preoperative magnetic resonance imaging and arthroscopy incidentally revealed hypoplasia of both medial and lateral menisci. Moreover, the posterior horn of the medial meniscus and middle body of the lateral meniscus were fused with the cartilage surface of the tibia. Magnetic resonance imaging of the contralateral knee showed similar meniscal anomalies. This case presents an interesting and extremely rare abnormality of the meniscus. [Orthopedics. 2018; 41(6):e884-e887.].

Review of Shino et al (1984) on anterior cruciate ligament reconstruction using allograft in the dog

This article discusses the original1984 publication of ‘Replacement of the anterior cruciate ligament using an allogeneic tendon graft. An experimental study in the dog’. The original classic study discovered the revascularisation and remodelling of an allograft for anterior cruciate ligament reconstruction (ACLR) using microangiographic, histological and biomechanical methods. The original classic study suggested that a transplanted allogeneic tendon can substitute for an autograft in ACLR. The original classic study suggested this new option to the orthopaedic medical community. Currently, an allograft is one of the main alternatives used for ACLR. This article begins with a detailed summary of the original classic study. Second, this article reviews the historical perspectives, the scientific and societal effect and the effect of the original classic study on present practices. Finally, the ultimate goal of this article is to validate the use of allogeneic tendon grafts in ACLR with the current evidence of clinical studies and animal experiments and to elucidate any remaining questions regarding allogeneic tendon grafts, which could then be resolved through studies in the near future.

Anterior cruciate ligament injuries result in a larger functional deficit in fighting sport athletes: comparison of functional status among different sport types

Objectives To compare the effects of anterior cruciate ligament (ACL) injuries and the preoperative period on functional status in different sports using preoperative patient data from the Multicenter Arthroscopic Knee Surgery (MAKS) study, a multicentre prospective cohort study of patients who underwent ACL reconstructions and meniscal surgeries conducted in 2013. Methods Of the 1648 patients registered in the MAKS study cohort, 826 underwent unilateral primary ACL reconstruction. These patients were divided into three groups based on sports activity type: contact, fighting and non-contact. The patients were further divided into two subgroups according to preoperative period data: acute (≤3 months) and chronic (>3 months). We standardised the preoperative evaluation items (Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) subjective form, and Lysholm score) and surgical records. Results The mean Lysholm score in the non-contact group was statistically significantly better than that in the fighting group. The two KOOS subcategories were statistically significantly superior in the non-contact group than in the fighting group. In the contact group, acute cases showed statistically significantly lower IKDC subjective scores and lower scores in two KOOS subcategories than the chronic cases. In the fighting group, chronic cases showed better IKDC subjective scores and scores for three KOOS subcategories than the acute cases. In the non-contact group, chronic cases showed better IKDC subjective scores and scores for all KOOS subcategories than the acute cases. Conclusion When athletes with ACL injuries are divided by sport type into fighting, contact and non-contact groups, the functional status of fighting sport athletes was more negatively influenced by ACL injury than those of non-contact sport athletes. When divided into acute and chronic phases, overall acute cases showed lower scores than the chronic cases in all sport types. In acute cases, the functional status of fighting sport athletes was more negatively influenced than non-contact sport athletes, whereas in chronic cases, there were no differences among the different sport types. The sport types and postinjury period should be considered for decision-making on therapeutic measures of patients with ACL injuries. Level of evidence Level II.

Posteriorly inserted anterior cruciate ligament in knees with discoid lateral meniscus corresponding to bony morphological characteristics of femoral lateral condyle

PURPOSE Discoid meniscus often causes mechanical problems and needs surgical treatment at an early age. However, many aspects of its morphological development and changes remain unknown. The purpose of this study was to investigate the insertion of the femoral anterior cruciate ligament (ACL) via the behind-ACL approach and the morphology of the lateral femoral condyle to which the ACL attaches to clarify the morphological characteristics of the knee with discoid lateral meniscus (DLM). METHOD Sixty-six patients with meniscus injury who underwent arthroscopic surgery were retrospectively reviewed. Preoperative plane radiographs were reviewed. To evaluate the shape of the femoral condyle, the ratio of the medial and lateral condyles, obliquity of the inter-epicondylar line, and the prominence ratio were assessed. From the arthroscopic observation using the behind-ACL approach, the insertion of the femoral ACL was classified as low, middle, and high based on the height from the deepest area of the articular surface to the direct insertion, including fibrous extension from the joint surface at 90° flexion. RESULTS Twenty-nine patients had DLM (DLM group), and 37 patients had a semilunar meniscal injury (non-DLM group). The ratio of the lateral femoral condyle, obliquity of the inter-epicondylar line, and prominence ratio in the DLM group were significantly smaller than those in the non-DLM group. On the other hand, no significant difference in the ratio of the medial femoral condyle was observed. Arthroscopic evaluation revealed that the femoral ACL was significantly inserted lower in the DLM group than in the non-DLM group. CONCLUSION The femoral ACL with DLM was inserted close to the femoral joint surface with morphological abnormality in the knees with DLM related to hypoplasic of the lateral femoral condyle.

Augmentation of the Pullout Repair of a Medial Meniscus Posterior Root Tear by Arthroscopic Centralization

The meniscus roots are critical for meniscus function in preserving correct knee kinematics and avoiding meniscus extrusion and, consequently, in the progression of osteoarthritis. Several techniques exist for medial meniscus posterior root tear repair; however, current surgical techniques have been proved to fail to reduce meniscus extrusion, which has been shown to be associated with development of osteoarthritis, although significant improvements in the postoperative clinical findings have been achieved. This Technical Note describes an arthroscopic technique for the medial meniscus posterior root tear in which a pullout repair is augmented by a centralization technique to restore and maintain the medial meniscus function by efficiently reducing meniscus extrusion.