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In new drug development, cells or animals are treated with the selected candidate compound to confirm its efficacy and safety in nonclinical studies. Clinical laboratory tests are carried out using samples from experimental animals in these studies. The clinical laboratory test method validation in nonclinical fields should be conducted keeping in mind that the circumstances differ from those in clinical settings. However, the validation procedures have not been systematically integrated into any standard. The considerations in this paper set out systematically practical guidance for the validation of quantitative analytical methods for fluid samples collected from animal studies, for the purpose of ensuring that laboratory test method validation is conducted in nonclinical fields at an enough level.

Background The treatment of meniscus injuries combined with anterior cruciate ligament (ACL) reconstruction would be important to improve outcomes after ACL reconstruction. However, the effects of treatment methods for meniscus after ACL reconstruction have not been thoroughly investigated. The objective of this study was to investigate the effects of treatment methods for meniscus on clinical and radiological outcomes at 2 years after ACL reconstruction. Methods Three-hundred and eighteen patients with primary ACL reconstruction using autologous hamstring tendon registered in our multicenter study database and who were followed up for 2 years were included. They were then divided into 3 groups, the no meniscal lesion/untreated group (n = 149), the meniscal repair group (n = 139), and the meniscal resection group (n = 30). Patient-based subjective evaluations (Lysholm score, Knee injury and Osteoarthritis Outcome score and International Knee Documentation Committee subjective score), objective evaluations (Lachman test, pivot shift test and KT measurement), and radiological measurements (medial and lateral joint space width) were compared among the 3 groups preoperatively and at 2 years follow-up. Results All subjective scores and objective evaluations significantly improved in all groups without significant differences among the groups postoperatively. Regarding radiological findings, the medial joint space width significantly decreased only in the resection group during the 2-year period, and the medial joint space width in the resection group was significantly smaller than that of the other groups at the 2-year follow-up. Moreover, the medial joint space width significantly decreased during the 2-year period when MM was resected. Conclusions In radiological findings, medial meniscus resection decreased medial joint space width two years after ACL reconstruction. On the other hand, treatment methods for meniscus neither significantly affected subjective nor objective findings until the 2-year follow-up. Level of evidence Ⅱ, Cohort study.

A better understanding of the etiology of persistent pain after total knee arthroplasty (TKA) is required to prevent unfavorable outcomes. The purpose of this study was to investigate the association of persistent pain after TKA, patient characteristics, and the remaining pain ratio per the preoperative intra-articular anesthetic test.This study included 89 patients who underwent TKA and underwent an intra-articular anesthetic test preoperatively. The remaining pain ratio out of 100 percent 30 min after intra-articular anesthetic injection and demographic data were also evaluated preoperatively. Numerical rating scale (NRS) scores for pain during movement (Q1), at rest (Q2), at first movement in the morning (Q3), and during climbing up and down stairs (Q4) were evaluated 1 year after TKA. Multiple linear regression analysis was performed to assess the impact of independent variables on the NRS score for questionnaire No.4. and the remaining pain ratio per the intra-articular anesthetic.The mean remaining pain ratio per the preoperative intra-articular anesthetic test was 29.3%. The NRS score for Q4 was significantly higher than those for any of the other NRS questionnaires administered 1 year after TKA (Q1-Q4, Q2-Q4, P 0.001; Q3-Q4, P 0.05). The analysis found the weak correlation between the pain ratio of anesthetic test and the NRS score for Q4 after TKA (R = 0.28, P = 0.018). BMI and preoperative FTA were the major predictors of remaining pain ratio per the intra-articular anesthetic test (R = 0.40, P = 0.002).This study revealed that the remaining pain ratio per the preoperative intra-articular anesthetic test was weakly correlated with persistent pain during climbing up and down stairs 1 year after TKA. In addition, BMI and preoperative FTA were associated with the remaining pain ratio per the preoperative intra-articular anesthetic test.

Optical coherence tomography (OCT) is an attractive tool for evaluating cartilage. We developed an OCT system that reconstructs and analyzes a three-dimensional (3D) OCT image by determining the cartilage surface and cartilage-bone boundary from the image taken with currently available OCT devices. We examined the usefulness of 3D renderings of OCT images. In a rat meniscectomized model, the tibia was harvested after 0, 2, 4, or 8 weeks (n = 6). We scanned 300 slices in the y-plane to cover a 4 × 3 × 6-mm section (x-plane; 10 µm × 400 pixels, y-plane; 10 µm × 300 pixels, z-plane; 12.66 µm × 500 pixels) of the medial tibial cartilage. The cartilage surface line and the cartilage-bone boundary were plotted semi-automatically. Slices from 300 two-dimensional (2D) sequential images were systematically and visually checked and corrected, as necessary. We set a region of interest in the cartilage and quantified the cartilage volume in the 3D image. The Osteoarthritis Research Society International (OARSI) histological score was also obtained. The cartilage volume determined using 3D OCT images was 0.291 ± 0.022 mm3 in the normal, 0.264 ± 0.009 mm3 at 2 weeks, 0.210 ± 0.012 mm3 at 4 weeks, and 0.205 ± 0.011 mm3 at 8 weeks. The cartilage volume significantly decreased at 4 and 8 weeks and was significantly correlated with the OARSI histological score (r = -0.674; P = .002). Although the 3D image information could be obtained from the 2D images, the 3D OCT images provided easier-to-understand information because the 3D reconstructed cartilage provided information about the smoothness of the surface, the area, and depth of the defect at a glance.

Although several factors have been considered to be associated with pivot shift test grade in ACL injured patients, a conclusion regarding which factors contribute to the pivot shift test grade has not been reached. The purpose of this study was to identify factors associated with preoperative pivot shift test grade. Three hundred and sixty-six consecutive patients who underwent ACL reconstruction in our hospital were enrolled in the study. Patients were divided into two groups on the basis of preoperative pivot shift test grade (Mild: grade 0–3, Severe: grade 4–6). First, 13 independent variables (age, gender, period from injury to surgery, hyperextension, KT measurement, contralateral side pivot shift test grade, medial and lateral tibial slope, lateral condyle length, lateral condyle height, distal femoral condyle offset, medial and lateral meniscus tear) were analyzed by one-way ANOVA and Chi-squared test. Binary Logistic regression was then performed based on the results of univariate analyses (independent variables of p

Purpose: Subcutaneous patient-controlled analgesia (PCA) has been widely used for orthopedic surgeries including total knee arthroplasty (TKA). This study aims to clarify the usefulness of subcutaneous PCA in the early phase after TKA. Methods: Our subjects consisted of 88 osteoarthritis knee patients who underwent primary TKA, and were classified into two groups: 42 patients received a subcutaneous PCA (containing fentanyl and droleptan) after operation (PCA group), and 46 patients were managed without a subcutaneous PCA (control group). We compared the incidence of side effects for 3 days postoperatively, measuring the number of times patients used adjuvant analgesia and range of motion on day 7 between the two groups. 34 of 42 patients in the PCA group tolerated PCA use until POD 3 (continuation sub-group), while 8 patients could not continue PCA (interruption sub-group). Demographic data of the two sub-groups were compared. Results: The mean number of times adjunctive analgesics were used by the PCA group (3.7 ± 2.2) was significantly less than in the control group (5.4 ± 2.8) (p = 0.0049). There were no significant differences in the frequency of side effects between the two groups. There was no significant difference in range of motion between the two groups. Comparing the continuation and interruption sub-groups, patients over 80 years old were at risk to discontinue a subcutaneous PCA (p = 0.0319, odds ratio 5.4). Conclusion: These findings demonstrate that subcutaneous PCA would be a safe postoperative pain regimen for TKA patients, but the effect was not enough to promote early functional recovery. Levels of evidence: Therapeutic, Level Ⅱ. Keywords: Subcutaneous patient controlled analgesia (PCA), Total knee arthroplasty (TKA). postoperative pain control

Background Synovial mesenchymal stem cells (MSCs) are an attractive cell source for cartilage and meniscus regeneration. The optimum cryopreservation medium has not been determined, but dimethylsulfoxide (DMSO) should be excluded, if possible, because of its toxicity. The purposes of our study were to examine the possible benefits of higher concentrations of serum and the effectiveness of 100% serum (without DMSO) for the cryopreservation of synovial MSCs. Methods Human synovium was harvested from the knees of four donors with osteoarthritis during total knee arthroplasty. Synovial MSCs (8 × 105 cells) were suspended in 400 μL medium and used as a Time 0 control. The same number of synovial MSCs was also suspended in 400 μL α-MEM medium containing 10% fetal bovine serum (FBS) (5% DMSO, and 1% antibiotic), 95% FBS (and 5% DMSO), or 100% FBS (no DMSO) and cryopreserved at − 80 °C for 7 days. After thawing, the cell suspensions (1.5 μL; 3 × 103 cells) were cultured in 60 cm2 dishes for 14 days for colony formation assays. Additional 62.5 μL samples of cell suspensions (1.25 × 105 cells) were added to tubes and cultured for 21 days for chondrogenesis assays. Results Colony numbers were significantly higher in the Time 0 and 95% FBS groups than in the 10% FBS group (n = 24). Colony numbers were much lower in the 100% FBS group than in the other three groups. The cell numbers per dish reflected the colony numbers. Cartilage pellet weights were significantly heavier in the 95% FBS group than in the 10% FBS group, whereas no difference was observed between the Time 0 and the 95% FBS groups (n = 24). No cartilage pellets formed at all in the 100% FBS group. Conclusion Synovial MSCs cryopreserved in 95% FBS with 5% DMSO maintained their colony formation and chondrogenic abilities to the same levels as observed in the cells before cryopreservation. Synovial MSCs cryopreserved in 100% FBS lost their colony formation and chondrogenic abilities. Electronic supplementary material The online version of this article (10.1186/s12891-019-2700-3) contains supplementary material, which is available to authorized users.

The meniscus functions as a load distributor and secondary stabilizer in the knee, and the loss of the meniscus increases the risk of osteoarthritis. Freeze-thawed menisci are used in clinical practice to replace defective menisci; however, the disadvantages of freeze-thawed tissues include disease transmission and immune rejection. In this study, we decellularized menisci using high hydrostatic pressure (HHP) and compared the decellularized menisci with freeze-thawed menisci. Porcine menisci were either pressurized at 1,000 MPa for 10 min and then washed with DNase solution or frozen at -80°C for 2 days and thawed. These menisci then underwent in vitro histological, biochemical, and biomechanical comparisons with native menisci. The HHP-treated and freeze-thawed menisci were also subcutaneously implanted in a pig, and later harvested for histological analysis. The numbers of histologically detected cells were significantly lower and the amount of biochemically detected DNA was approximately 100-fold lower in HHP-treated than in native and freeze-thawed menisci. The compression strength of the HHP-decellularized menisci was decreased after 1 and 50 cycles at 20% strain but was unchanged in the freeze-thawed menisci. After implantation, the numbers of multinucleated giant cells were significantly lower around the HHP-treated menisci than around the freeze-thawed menisci. Recellularization of the HHP-decellularized menisci was confirmed. Thus, although the HHP-decellularized menisci were mechanically inferior to the freeze-thawed meniscus in vitro, they were immunologically superior. Our study is the first to demonstrate the use of HHP for decellularization of the meniscus. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2466-2475, 2019.

Background:Several types of anterolateral structure (ALS) augmentation procedures in anterior cruciate ligament (ACL) reconstruction have been reported. However, information is limited regarding the effect of additional ALS augmentation on rotatory stability in a clinical setting.Purpose/Hypothesis:This study aimed to investigate the contribution of additional ALS augmentation in ACL reconstruction in cases with a high risk of residual pivot shift. The 2 hypotheses were as follows. First, additional ALS augmentation would improve rotatory stability as compared with solely reconstructing the ACL. Second, graft tension changes would be different between the ACL and ALS during knee range of motion and against anterior or rotatory loads.Study Design:Controlled laboratory study.Methods:Fifteen patients who met at least 1 of the following criteria were included: (1) revision ACL reconstruction, (2) preoperative high-grade pivot shift, or (3) hyperextended knee. The pivot-shift test was performed preoperatively and during surgery after ACL reconstruction and after additional ALS augmentation with acceleration measurements from a triaxial accelerometer. The tension changes of the ACL and ALS grafts were also measured during knee range of motion and against manual maximum anterior tibial translation, internal rotation, and external rotation.Results:After ACL reconstruction, the pivot-shift acceleration was still greater than that of the uninjured knee. However, additional ALS augmentation further reduced acceleration when compared with ACL reconstruction alone in both primary and revision cases ( P < .05 vs preoperative, P < .05 vs ACL). During knee flexion-extension, the tension of the ACL increased as the knee was extended, whereas that of the ALS did not change. Graft tension of the ACL and ALS became higher with internal rotation and lower with external rotation as compared with the neutral position. Tension of the ACL was significantly increased against anterior tibial translational loads, whereas that of the ALS was not.Conclusion:Additional ALS augmentation further improved the rotatory stability during ACL reconstruction in patients with a high risk of residual pivot shift at the time of surgery. Significant differences in graft tension changes were also observed between the ACL and ALS against different loads. Additional ALS augmentation may be considered to eliminate the pivot shift in patients with a high risk of residual pivot shift.

Both coronal and sagittal laxity of well-functioning knees after total knee arthroplasty (TKA) was examined, and the correlations between the joint laxity and the clinical outcomes were analyzed to clarify the adequate joint laxity for the prosthesis, and the relationship between the laxity and the outcomes.Forty well-functioning TKA knees with a high-flexion posterior-stabilized (PS) prosthesis were studied. All patients were diagnosed as having osteoarthritis with varus deformity and were followed up for 2 years or more. The coronal and sagittal laxity was assessed at extension and flexion, and the correlations between the joint laxity and the clinical outcomes were evaluated.The varus and valgus laxity averaged 5.6 ± 1.8° and 3.6 ± 1.2° at 10° knee flexion, and 7.4 ± 5.1° and 3.6 ± 2.7° at 80° knee flexion, respectively, and the AP laxity at 30° and 75° knee flexion averaged 8.7 ± 3.6 mm and 6.6 ± 2.3 mm, respectively. Knee flexion angle correlated with the joint laxity, while the other outcomes including patient-reported pain and instability were adversely affected by the greater laxity.This study exhibited the importance of consistent medial laxity both at extension and flexion, which averaged 3.6°. Care should be taken to maintain the medial stability and to obtain adequate laxity both at extension and flexion during surgery. A few degrees of medial tightness can be allowed to achieve excellent clinical results after TKA for preoperative varus knees.Therapeutic study, Level III.

Background It is still controversial whether which femoral tunnel creation technique is best during anterior cruciate ligament reconstruction (ACLR). We aimed to clarify the features of three different techniques based on the femoral tunnel position created with the same tunnel-creating concept and the measurement data. Methods The femoral tunnel of double-bundle (DB) ACLR was created using the behind-remnant approach in a remnant preserved manner following the policy of our institute. The trans-tibial approach (TT) was applied for all primary ACL injured cases until December 2012. The trans-portal approach (TP) was applied from January to September 2013, and the outside-in approach (OI) was indicated from October 2013 to March 2014. We compared the femoral tunnel aperture positions with the postoperative three-dimensional computed tomography (3D-CT). Additionally, the femoral tunnel length and the septum distance of each anteromedial (AM) and posterolateral (PL) tunnel were analyzed. Results The AM tunnel aperture position of TT was significantly higher and shallower than that of TP in knee flexion position. The femoral tunnel length of TP was significantly shorter than that of TT and OI. The septum between each tunnel of OI trended wider than that of TT and TP. Conclusions The AM tunnel aperture position of TT runs the risk of a high and shallow position. TP runs the risk of insufficiently short tunnel length. It is important to apply each method flexibly to each case because no single best approach was found.

BACKGROUND The purpose of this study was to compare arthroscopic findings of a degenerative flap and radial tear of the medial meniscus (MM) before and one year after treatment by meniscus repair and synovial mesenchymal stem cell (MSC) transplantation. METHODS Patients with a degenerative flap and radial MM tear that would generally be treated by meniscectomy were included. The patients ranged in age from 45 to 62 years and all underwent meniscus repair and synovium harvest at time 0. The digested synovium was cultured with autologous serum for 12 days, and an average of 4 × 107 MSCs were transplanted at two weeks. A second-look arthroscopy was performed at 52 weeks (n = 6). The average duration of symptoms was 24 months. For flap tears, arthroscopic findings were quantified in terms of the presence, stability, and smoothness of the meniscus at each zone and area. The Lysholm score was evaluated throughout the 52 week follow-up. RESULTS Four patients with MM flap tears showed deficiencies in the central area at the posterior junctional zone before treatment, but this zone was completely restored to a stable and smooth condition in two patients and partially restored in the other two patients. The arthroscopy score for a flap tear at the central area of the posterior junctional zone was 0.3 ± 0.5 before treatment and 4.3 ± 2.1 after treatment. The score was significantly higher after treatment (p

Purpose To improve long-term outcomes of open-wedge high tibial osteotomy (OWHTO), procedures combining OWHTO aimed at neutral alignment and arthroscopic centralization for meniscal extrusion have been introduced. The purpose of the present study was to compare short-term clinical and radiological outcomes of medial joint space width (JSW) after the OWHTO aimed at neutral alignment with and without arthroscopic centralization for an extruded medial meniscus. Methods A retrospective review of 50 primary OWHTO patients was conducted. Thirty-five patients included for analysis after exclusion criteria was applied. Twenty-one knee osteoarthritis patients, who underwent the OWHTO with arthroscopic meniscal centralization, were included in the centralization group. Fourteen patients, who underwent solely OWHTO, were included in the control group. Lysholm knee scale, International Knee Documentation Committee (IKDC) subjective score, Knee Osteoarthritis Outcome Score (KOOS), and patient subjective satisfaction scores were recorded at the final follow-up. Radiographic changes of JSW and joint line congruence angle (JLCA) were measured 2 years postoperatively. Patient demographic data were also reviewed. Results IKDC subjective scores, KOOS subgroup scores, patient subjective satisfaction scores, and Lysholm score did not show significant differences between the two groups at the final follow-up. Change of the JSW in the centralization group was significantly greater than that in the control group 2 years postoperatively (Control group: -0.1 mm, Centralization group: 0.8 mm P =0.03). Conclusion Change of JSW after OWHTO aimed at neutral alignment with arthroscopic centralization for extruded medial meniscus was greater than solely OWHTO, and there was no significant difference in the short-term clinical outcomes between the 2 procedures at the final follow-up.

Synovial mesenchymal stem cells (MSCs) are an attractive cell source for transplantation because of their high chondrogenic potential, especially in areas like the meniscus of the knee. A synovial MSC suspension placed onto the meniscus for 10 min promoted healing of repaired meniscal tears that generally do not heal. Here, we quantified the proportion of human synovial MSCs that adhered to a porcine abraded meniscus, clarified their morphological changes, and revealed the mechanism by which the synovial MSCs adhered to the meniscus. The numbers of adhering cells at immediately after 10, 60 min and 6, 24 h after suspension placement were calculated. The meniscus surface was examined by scanning electron microscopy, and 50 cells were randomly selected at each time period, classified, and quantified for each of the six donors. Approximately 28% of the synovial MSCs immediately adhered to the meniscus after placement and the proportion of adhered cells increased further with time. All cells maintained a round shape for 60 min, and then transformed to a mixture of round and semi-flattened cells. By 24 h, flattened cells covered the meniscus. Microspikes were observed in 36% of the floating synovial MSCs and in 76% of the cells on the meniscus shortly after placement on the meniscus, then the proportion of cells with pseudopodia increased. The bleb-dominant cell proportion significantly decreased, and the smooth-dominant cell proportion increased within 60 min. Microspikes or the bodies of synovial MSCs were trapped by meniscal fibers immediately after placement. The proportion of adhered cells increased with time, and the cell morphology changed dynamically for 24 h as the synovial MSCs adhered to the meniscus. The MSCs in the round morphological state had a heterogeneous morphology. The microspikes, and the subsequent development of pseudopodia, may play an important role in adhesion onto the meniscus. Synovial mesenchymal stem cells (MSCs) are an attractive cell source for transplantation in the meniscus of the knee because of their high chondrogenic potential. This study describes the morphological features of synovial MSC adhesion to the meniscus and provides ways to increase the number of adherent MSCs so that clinical outcomes can be improved.

Background Meniscus surgery is the most commonly performed orthopedic surgery, and despite recent emphasis on saving the meniscus, the current status of meniscus surgeries is little known in many countries, including Japan. The National Database of Health Insurance Claims and Specific Health Checkups of Japan and the Statistics of Medical Care Activities in Public Health Insurance track meniscus surgeries through health insurance claims. The National Database provides the numbers for 2014 and 2015, and the Statistics of Medical Care Activities provides the numbers from June 2011 to June 2016. Our aim was to analyze isolated meniscus surgery numbers and meniscus repair ratios by age group based on the National Database and evaluate trends of meniscus repair ratios for the latest six years from the Statistics of Medical Care Activities. Methods Meniscus surgeries by age group were counted from the National Database for 2014–2015, and meniscus repair ratios (meniscus repairs/meniscus surgeries) were calculated. The numbers were also counted from the Statistics of Medical Care Activities in 2011–2016. For statistical analysis of annual trends of meniscus repair ratios, the Cochran–Armitage trend test was used. Meniscus surgeries with concomitant knee ligament surgeries were excluded. Results According to the National Database, isolated meniscus surgeries totaled 34,966 in 2015, with peak ages of patients in their late teens and 60s. The meniscus repair ratio was 19% in 2014 and 24% in 2015. According to the Statistics of Medical Care Activities, the meniscus repair ratio was 9% in 2011 and significantly increased to 25% in 2016 (p = 0.0008). The ratio also increased significantly in each age group between the early 20s and late 70s. Conclusions Approximately 35,000 meniscus surgeries are performed in Japan annually, with peak ages in the late teens and 60s. The number of meniscus repairs has increased over the past six years.

In vitro chondrogenesis of mesenchymal stem cells (MSCs) mimics in vivo chondrogenesis of MSCs. However, the size of the cartilage pellets that can be attained in vitro is limited by current methods; therefore, some modifications are required to obtain larger pellets. Petaloid pieces of recombinant peptide (petaloid RCP) have the advantage of creating spaces between cells in culture. The RCP used here is based on the alpha‐1 sequence of human collagen type I and contains 12 Arg‐Gly‐Asp motifs. We examined the effect and mechanisms of adding petaloid RCP on the in vitro chondrogenesis of human synovial MSCs by culturing 125k cells with or without 0.125 mg petaloid RCP in chondrogenic medium for 21 days. The cartilage pellets were sequentially analyzed by weight, sulfated glycosaminoglycan content, DNA retention, and histology. Petaloid RCP significantly increased the weight of the cartilage pellets: The petaloid RCP group weighed 7.7 ± 1.2 mg (n = 108), whereas the control group weighed 5.3 ± 1.6 mg. Sulfated glycosaminoglycan and DNA contents were significantly higher in the petaloid RCP group than in the control group. Light and transmission electron microscopy images showed that the petaloid RCP formed the framework of the pellet at day 1, the framework was broken by production of cartilage matrix by the synovial MSCs at day 7, and the cartilage pellet grew larger, with diffuse petaloid RCP remaining, at day 21. Therefore, petaloid RCP formed a framework for the pellet, maintained a higher cell number, and promoted in vitro cartilage formation of synovial MSCs. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. J Orthop Res 37:1350–1357, 2019.

Introduction: The anterior cruciate ligament (ACL) consists of various components, such as collagen, elastin fibres, and fibroblasts. Because ACL has a poor regenerative ability, ACL reconstruction need require the use of autologous tendons. In recent years, tissue-resident stem cells have been studied to promote ACL regeneration as an alternatively method. However, the existence of stem cells in ligaments has not been clearly defined. Here, we prospectively isolated stem cells from ACLs and characterized their properties. Methods: ACLs from 11 donors and bone marrows (BM) from 8 donors were obtained with total knee arthroplasty. We used flow cytometry to screen the cell surface markers on ACL cells. Frozen sections were prepared from patient ACL tissues and stained with specific antibodies. Cultured ACL-derived and BM-derived cells at passage 3 were differentiated into adipocytes, osteoblasts and tendon/ligament cells. Results: ACL-derived mesenchymal stem/stromal cells (ACL-MSCs) expressed high levels of CD73 and CD90. Immunohistochemical analyses revealed that ACL-MSCs were located on the inner surface of ACL sinusoids. Furthermore, the expression of cell surface antigens was clearly different between ACL-MSCs and bone marrow (BM)-derived MSCs (BM-MSCs) at the time of isolation, but the two cell populations became indistinguishable after long-term culture. Interestingly, ACL-MSCs are markedly different from BM-MSCs in their differentiation ability and have a high propensity to differentiate into ligament-committed cells. Conclusions: Our findings suggest that ACL-MSCs express CD90 and CD73 markers, and their differentiation capacity is maintained even through culture. The cell population having tissue-specific properties is an important research target for investigating the ligament therapies. Keywords: Anterior cruciate ligament, Bone marrow, Mesenchymal stem/stromal cell, Cell surface marker, Differentiation, Regeneration therapy

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.

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.

Key Clinical Message Popliteal artery occlusion after total knee arthroplasty is rare (0.03–0.17%) but can lead to amputation if overlooked. We should carefully assess vascular patency by Doppler ultrasound and ankle brachial pressure index (ABPI) measurement before and after total knee arthroplasty (TKA) operation.

Background Extrusion of the meniscus has been reported to be correlated with progression of osteoarthritis. In cases with osteochondral lesions after extrusion of the meniscus, meniscal transplantation was the only surgical intervention. Recently, a novel procedure called arthroscopic centralisation has been developed to restore the meniscus function by centralising the midbody of the extruded meniscus onto the rim of the tibial plateau using suture anchors. Case report A combination of novel techniques—retrograde osteochondral autograft transplantation to retain hyaline articular cartilage and arthroscopic centralisation to restore residual meniscal function—was used to repair an osteochondral lesion of the lateral tibial plateau possibly caused by extrusion of the lateral meniscus. Good clinical and radiographic outcomes were achieved at the 2-year follow-up. Conclusion A combination of retrograde osteochondral autograft transplantation and arthroscopic centralisation can be a good option to treat the osteochondral lesion of the tibial plateau caused by extrusion of the meniscus.

Objectives: The EFEMP1 gene encoding fibulin-3 is specifically expressed in the superficial zone of articular cartilage. This study examined fibulin-3 expression patterns in joint aging and osteoarthritis (OA) and the role of fibulin-3 in OA pathogenesis. Methods: Immunohistochemical analysis was performed on normal and OA human and mouse knee cartilage. Experimental OA was induced in wild type and fibulin-3-/- mice and OA severity was evaluated by histological scoring. To examine fibulin-3 function, chondrocyte monolayer cultures were transfected with siRNA for quantitative PCR and Western blot analyses. Bone marrow mesenchymal stem cells (MSC) were transduced with EFEMP1 lentivirus and analyzed for chondrogenesis markers. Results: Fibulin-3 was specifically expressed in the SZ of normal cartilage in human and mouse knee joints and declined with aging. Both aging-related OA and experimental OA were significantly more severe in fibulin-3-/- mice compared with wild type mice. Fibulin-3 expression was high in undifferentiated MSC and decreased during chondrogenesis. Suppression of fibulin-3 by siRNA significantly increased SOX9, collagen II and aggrecan in articular chondrocytes, while overexpression of fibulin-3 inhibited chondrogenesis in MSC. Conclusion: Fibulin-3 is specifically expressed in the SZ of articular cartilage and its expression is reduced in aging and OA. Fibulin-3 regulates differentiation of adult progenitor cells and its aging-related decline is an early event in OA pathogenesis. Preventing or restoring aging-associated loss of fibulin-3 in SZ chondrocytes has potential to delay or prevent onset of OA. This article is protected by copyright. All rights reserved.

Complex degenerative tears of the medial meniscus in the knee are usually treated using meniscectomy. However, this procedure increases the risk of osteoarthritis, while other treatments aimed at meniscal repair remain challenging due to the high possibility of failure. The use of synovial mesenchymal stem cells (MSCs) is an attractive additional approach for meniscal repair, as these cells have high proliferative and chondrogenic potential. In this case report, we surgically repaired a complex degenerative tear of the medial meniscus and then transplanted autologous synovial MSCs. We evaluated clinical outcomes at 2 years and assessed adverse events. We enrolled patients with clinical symptoms that included a feeling of instability in addition to pain caused by their complex degenerative tears of the medial meniscus. Two weeks after surgical repair of the torn meniscus, autologous synovial MSCs were transplanted onto the menisci of five patients. The total Lysholm knee score, the Knee Injury and Osteoarthritis Outcome Scale scores for “pain,” “daily living,” “sports activities,” and the Numerical Rating Scale were significantly increased after 2 years. Three adverse events, an increase in c-reactive protein, joint effusion, and localized warmth of the knee were recorded, although these could have been due to the meniscal repair surgery. This first-in-human study confirmed that the combination of surgical repair and synovial MSC transplantation improved the clinical symptoms in patients with a complex degenerative tear of the medial meniscus. No adverse events occurred that necessitated treatment discontinuation. These findings will serve as pilot data for a future prospective study.

Exact knowledge of risk factors for residual anterolateral rotatinoal instability (ALRI) after anterior cruciate ligament (ACL) reconstruction is limited. The purpose of this study was to analyse possible risk factors for ALRI after ACL reconstruction.Quantitative assessment of the pivot shift phenomenon by measuring tibial acceleration was performed in 46 patients during primary double-bundle ACL reconstructions. The absolute value of the acceleration of the injured knee after provisional fixation of the ACL grafts ('absolute residual acceleration') and the subtraction of the acceleration of the uninjured knee from absolute residual acceleration ('relative residual acceleration') were defined as indicators for residual ALRI. The associations between these indicators and nine candidate risk factors were analysed using univariate and multiple regression analyses.Multiple regression analysis revealed that absolute residual acceleration was positively associated with both preoperative acceleration difference between injured and uninjured knees (β = 0.469, P 0.001) and tibial acceleration of the uninjured knee (β = 0.597, P 0.001). Relative residual acceleration was also positively associated with preoperative acceleration difference between injured and uninjured knees (β = 0.446, P 0.001), but was negatively associated with tibial acceleration of the uninjured knee (β = -0.763, P 0.001).Patients with larger preoperative side-to-side difference of the pivot shift phenomenon have higher risk for both absolute and relative residual ALRIs after ACL reconstruction, whereas patients with larger pivot shift phenomenon in their uninjured knees are at higher risk for absolute residual ALRI but not for relative residual ALRI.

Unfortunately, the co-author "Hiroki Katagiri' was omitted in the original publication from the author group. The author name is added here. The original article has been corrected.

The purpose of this study was to investigate the effect of a longitudinal tear of the medial meniscus (MM) and its meniscal repair on MM extrusion in anterior cruciate ligament (ACL)-injured patients. The hypothesis underlying this study was that a longitudinal tear of the MM is correlated with MM extrusion, and that the extrusion would persist after ACL reconstruction with concomitant MM repair.Forty-three ACL-injured patients with a concomitant MM longitudinal tear were included in the MM tear group. Thirty-four solely ACL-injured patients without any meniscal injuries were included in the Control group. Medial meniscus extrusion width (MEW) was measured pre-operatively and three months after surgery on magnetic resonance imaging.Pre-operative MEW in the MM tear group was significantly larger than that in the Control group (MM tear group: 1.5 mm, Control: 0.3 mm, P 0.001). The MEW change in the MM tear group was significantly greater than that in the Control group three months after operation (MM tear group: 0.8 mm, Control: -0.2 mm, P 0.001). The number of sutures required for repair was correlated with MEW both pre-operatively and postoperatively in the MM tear group (pre-operative: P = 0.005, R = 0.42, postoperative: P 0.001, R = 0.54).Longitudinal tear of the MM was correlated with MM extrusion and the MM extrusion persisted after ACL reconstruction with concomitant MM repair in the MM tear group. The initial meniscal tear size was directly correlated with the pre-operative MEW. Therefore, meniscal extrusion after longitudinal tears of the medial meniscus should be taken into careful consideration.

To compare the position and direction of femoral and tibial tunnels for both the anteromedial bundle (AMB) and posterolateral bundle (PLB) among three different femoral tunnel drilling techniques, transtibial (TT), transportal (TP), and outside-in (OI) techniques, in anatomic double-bundle ACL reconstruction to clarify advantages and disadvantages of each technique. One-hundred and thirty-nine patients underwent primary ACL reconstruction with an autologous semitendinosus tendon in our institution between 2014 and 2016. Thirteen patients were excluded according to the exclusion criteria. Of the 126 patients, 98 patients agreed to be included in this study. Patients were then randomized into three groups according to the femoral tunnel drilling technique; the TT, TP, and OI groups. Femoral and tibial tunnel angles and positions were measured using three-dimensional computed tomography. Of patients who agreed to be included in this study, eight patients (seven in TT and one in OI) were excluded since the femoral tunnel could not be created at the intended position. Eighty-six patients (29 in TT, 29 in TP, and 28 in OI) were included for the analyses. Tunnel angles, as well as tunnel lengths, had significant differences among different techniques depending on each technique’s characteristics. In terms of tunnel position, femoral tunnel positions of both the AMB and PLB in the TT group were significantly higher than those in the TP group (AMB: p = 0.003, PLB: p = 0.001), and the PLB tunnel position in the TP group had significantly smaller vaciance than that in the TT group (p = 0.004) and OI group (0.002). The femoral tunnel positions created by the TT technique were significantly higher, with larger variance, than the TP technique in double-bundle ACL reconstruction, although the positions seemed to be within anatomical footprint. In addition, there were several cases in which femoral tunnels could not be created at the intended position by the TT technique. I

Although muscle wasting and/or degeneration are prevalent in patients with chronic kidney disease, it remains unknown whether FGF-23 influences muscle homeostasis and regeneration. Mesenchymal stem cells (MSCs) in skeletal muscle are distinct from satellite cells and have a known association with muscle degeneration. In this study we sought to investigate the effects of FGF-23 on MSCs isolated from human skeletal muscle in vitro. The MSCs expressed FGF receptors (1 through 4) and angiotensin-II type 1 receptor, but no traces of the Klotho gene were detected. MSCs and satellite cells were treated with FGF-23 and angiotensin-II for 48 h. Treatment with FGF-23 significantly decreased the number of MSCs compared to controls, while treatment with angiotensin-II did not. FGF-23 and angiotensin-II both left the cell counts of the satellite cells unchanged. The FGF-23-treated MSCs exhibited the senescent phenotype, as judged by senescence-associated β-galactosidase assay, cell morphology, and increased expression of p53 and p21 in western blot analysis. FGF-23 also significantly altered the gene expression of oxidative stress regulators in the cells. In conclusion, FGF-23 induced premature senescence in MSCs from skeletal muscle via the p53/p21/oxidative-stress pathway. The interaction between the MSCs and FGF-23 may play a key role in the impaired muscle reparative mechanisms of chronic kidney disease.

Background: Some types of meniscus tear, especially lateral meniscus tear, have been reported to be associated with rotatory knee laxity. However, precise information regarding the effect of meniscus repair on rotatory laxity is limited. The purpose of this study was to investigate the effects of lateral and medial meniscus repair on rotatory laxity in anterior cruciate ligament (ACL) injured knees. Methods: Forty-one patients who underwent ACL reconstruction were included in the study. The tibial acceleration during the pivot shift test was measured using a triaxial accelerometer preoperatively under anesthesia and intraoperatively before and after medial and lateral meniscus repair and ACL reconstruction during surgery. Effects of meniscus tear and its repair on rotatory laxity were analyzed. Results: Preoperative measurements revealed that patients with lateral meniscus tear showed significantly higher tibial acceleration compared to the patients without meniscus tear (P = 0.006). Intraoperative measurements revealed that medial and lateral meniscus repair significantly reduced tibial acceleration by 1.46 m/s2 (P = 0.002) and 1.91 m/s2 (P < 0.001), respectively. Conclusion: In ACL injured knees, knees with lateral meniscus tear showed greater rotatory laxity compared to the knees without meniscus tear. In addition, lateral meniscus repair, and to a lesser degree medial meniscus repair, reduced rotatory laxity during ACL reconstruction surgery. Therefore, the meniscus should be repaired as much as possible for its role as a secondary stabilizer of rotatory laxity. Besides, the effect of meniscus repair on rotatory laxity should be considered when the indication of anterolateral augmentation is determined.

Background Synovial mesenchymal stem cells (MSCs) are an attractive cell source for cartilage and meniscus regeneration. Synovial tissue can be histologically classified into three regions; surface, stromal and perivascular region, but the localization of synovial MSCs has not been fully investigated. We identified markers specific for each region, and compared properties of MSCs derived from each region in the synovium. Methods The intensity of immunostaining with 19 antibodies was examined for surface, stromal, and perivascular regions of human synovium from six osteoarthritis patients. Specific markers were identified and synovial cells derived from each region were sorted. Proliferation, surface marker expression, chondrogenesis, calcification and adipogenesis potentials were compared in synovial MSCs derived from the three regions. Results We selected CD55+ CD271− for synovial cells in the surface region, CD55− CD271− in the stromal region, and CD55− CD271+ in the perivascular region. The ratio of the sorted cells to non-hematopoietic lineage cells was 5% in the surface region, 70% in the stromal region and 15% in the perivascular region. Synovial cells in the perivascular fraction had the greatest proliferation potential. After expansion, surface marker expression profiles and adipogenesis potentials were similar but chondrogenic and calcification potentials were higher in synovial MSCs derived from the perivascular region than in those derived from the surface and stromal regions. Conclusions We identified specific markers to isolate synovial cells from the surface, stromal, and perivascular regions of the synovium. Synovial MSCs in the perivascular region had the highest proliferative and chondrogenic potentials among the three regions.

Background Latent microorganism infection is a safety concern for the clinical application of mesenchymal stem cells (MSCs). The aim of this study is to investigate the frequencies and sensitivities of the latent virus and mycoplasma infections in synovium, bone marrow, peripheral blood cells, and blood plasma and cultured synovial MSCs. Methods Total DNA and RNA of the synovium (n = 124), bone marrow (n = 123), peripheral blood cells (n = 121), plasma (n = 121), and 14-day cultured synovial MSCs (n = 63) were collected from patients who underwent total knee arthroplasty or anterior ligament reconstruction after written informed consents were obtained. The multiplex polymerase chain reaction (PCR) primers were designed to quantitatively measure the representative genomes of 13 DNA viruses, 6 RNA viruses, and 9 mycoplasmas. Multi-spliced mRNA detection and virus spike test were also performed to demonstrate the sensitivity of synovial MSCs to the candidate pathogens. Results In synovium and bone marrow, the positive rates of parvovirus B19 genome were significantly higher than in peripheral blood cells (18.7% and 22% vs. 0.8%, respectively). Multi-alignment analysis of amplified and sequenced viral target genes showed the proximity of the parvovirus B19 gene from different tissue in the same patients. Synovial MSCs cultured for 14 days were positive for virus infection only in two patients (2/62 = 3%). Parvovirus B19 multi-spliced mRNAs were not detected in these two samples. Virus spike test demonstrated the sensitivity of synovial MSCs to herpes simplex virus (HSV)1 and cytomegalovirus (CMV), but not to parvovirus B19. Conclusion This study revealed a relatively high incidence of latent parvovirus B19 in synovium and bone marrow tissue. Electronic supplementary material The online version of this article (10.1186/s13287-018-0811-7) contains supplementary material, which is available to authorized users.

Background Mobilization of mesenchymal stem cells (MSCs) from the synovium was revealed using a “suspended synovium culture model” of osteoarthritis (OA). The pathology of rheumatoid arthritis (RA) differs from that of OA. We investigated whether mobilization of MSCs from the synovium also occurred in RA, and we compared the properties of synovial MSCs collected from suspended synovium culture models of RA and OA. Methods Human synovium was harvested during total knee arthroplasty from the knee joints of patients with RA (n = 8) and OA (n = 6). The synovium was suspended in a bottle containing culture medium and a culture dish at the bottom. Cells were harvested from the dish and analyzed. Results No significant difference was observed between RA and OA in the harvested cell numbers per g of synovium. However, the variation in the number of cells harvested from each donor was greater for RA than for OA. The harvested cells were multipotent and no difference was observed in the cartilage pellet weight between RA and OA. The surface epitopes of the cells in RA and OA were similar to those of MSCs. Conclusion Mobilization of MSCs from the synovium was demonstrated using a suspended synovium culture model for RA. The harvested cell numbers, chondrogenic potentials, and surface epitope profiles were comparable between the RA and OA models.

To investigate the risk factors for residual pivot shift test after anterior cruciate ligament (ACL) reconstruction based on a multicenter prospective cohort study. This study included patients who were registered in the Multicenter Arthroscopic Knee Surgery Study, a prospective longitudinal multicenter cohort study, and who underwent primary ACL reconstruction using autologous hamstring tendon graft between 2013 and 2016. The exclusion criteria included prior injuries or surgeries in the contralateral knee, prior ligamentous injuries in the involved knee, grade 2 or 3 concomitant ligament injuries, and inflammatory or other forms of osteoarthritis. Data from the preoperative period and at 1-year follow-up were used for further analysis, and patients with incomplete data, re-injury and loss to follow-up were also excluded. Logistic regression analysis was conducted with age, gender, Lachman test, pivot shift test, KT measurement, hyperextension, single-bundle vs. double-bundle, meniscus injury sites, and meniscus treatments as the independent variables, and postoperative pivot shift test was used as the dependent variable. Three hundred and sixty-eight patients were included in the study. Hyperextension knee (P = 0.025) and a preoperative pivot shift test under anesthesia (P = 0.040) were identified as risk factors for a postoperative pivot shift via logistic regression analysis. There were no statistically significant differences in the other variables. The results from a multicenter cohort study indicated that knee hyperextension and greater preoperative pivot shift under anesthesia were risk factors for residual pivot shift at 1 year after ACL reconstruction. In cases with a preoperative high-grade pivot shift and knee hyperextension, additional anterolateral structure augmentation might be considered in order to eliminate pivot shift and eventually obtain better outcomes after ACL reconstruction. II.

Osteoarthritis (OA), a common chronic joint disorder in both humans and canines, is characterized by a progressive loss of articular cartilage. Canines can serve as an animal model of OA for human medicine, and this research can simultaneously establish effective veterinary treatments for canine OA. One attractive treatment that can lead to cartilage regeneration is the use of mesenchymal stem cells (MSCs). However, for canine OA, little information is available regarding the best source of MSCs. The purpose of this study was to identify a promising MSC source for canine cartilage regeneration. We collected synovial, infrapatellar fat pad, inguinal adipose, and bone marrow tissues from six canines and then conducted a donor-matched comparison of the properties of MSCs derived from these four tissues. We examined the surface epitope expression, proliferation capacity, and trilineage differentiation potential of all four populations. Adherent cells derived from all four tissue sources exhibited positivity for CD90 and CD44 and negativity for CD45 and CD11b. The positive rate for CD90 was higher for synovium-derived than for adipose-derived and bone marrow-derived MSCs. Synovium-derived and infrapatellar fat pad-derived MSCs displayed substantial proliferation ability, and all four populations underwent trilineage differentiation. During chondrogenesis, the wet weight was heavier for cartilage pellets derived from synovium MSCs than from the other three sources. The synovium is therefore a promising source for MSCs for canine cartilage regeneration. Our findings provide useful information about canine MSCs that may be applicable to regenerative medicine for treatment of OA.