Toshiyuki Ohara

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.

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.

Hypoxia enhances proliferation through increase of colony formation rate with chondrogenic potential in primary synovial mesenchymal stem cells

Synovial mesenchymal stem cells (MSCs) are an attractive cell source for cartilage and meniscus regeneration. Use of primary MSCs is the preferable because these cells are safer than cells passaged several times in terms of probability of chromosome abnormalities. The effect of hypoxia on the proliferation of MSCs is controversial and remains unknown in primary synovial MSCs. Primary synovial MSCs were cultured at normoxia or hypoxia, and colony number, cell number, surface epitopes, mitochondria activity, TEM finding, and chondrogenic potential were analyzed. To investigate the effect of hypoxia on attachment of synovial MSCs, cells were cultured at hypoxia for the first 3 days, then cultured at normoxia. To investigate the effect of hypoxia on proliferation, cells were also cultured at hypoxia for the last 11 days. Hypoxia increased colony number and cell number per dish in primary synovial MSCs. Hypoxia did not affect cell number per colony, surface epitopes, mitochondria activity, TEM finding or chondrogenic potential. Hypoxia for the first 3 days did not alter colony number per dish or cell number per dish, while hypoxia for the last 11 days increased. Hypoxia enhanced proliferation through increase of colony formation rate with chondrogenic potential in primary synovial MSCs.

Low dosage of monoiodoacetic acid induces arthritis without bone defect in a rat model

Mio Udo, MD, Ichiro Sekiya, phD, MD, Kunikazu Tsuji, PhD, Nobutake Ozeki, phD, MD, Yusuke Nakagawa, MD, Toshiyuki Ohara, MD, Ryusuke Saito, MD, Katsuaki Yanagisawa, MD, Takeshi Muneta, phD, MD. Department of Joint Surgery and Sports Medicine, Tokyo Medical and Dental University, Tokyo, Japan, Center for Stem Cells and Regenerative Medicine, Tokyo Medical and Dental University, Tokyo, Japan, Department of Cartilage Regeneration, Tokyo Medical and Dental University, Tokyo, Japan.