A CCL2/MCP-1 antagonist attenuates fibrosis of the infrapatellar fat pad in a rat model of arthritis.

Background: Fibrosis of the infrapatellar fat pad (IFP) is a feature of osteoarthritis and contributes substantially to the pain and dysfunction in patients' joints. However, the underlying mechanisms remain unclear. C-C motif chemokine ligand-2 (CCL2) plays a central role in tissue fibrosis.

Mid-term clinical outcomes of a posterior stabilized total knee prosthesis for Japanese patients: A minimum follow-up of 5 years.

Background: A high-flexion posterior-stabilized total knee prosthesis has been developed for the Asian population. The component design was based on computed tomography images of Japanese osteoarthritic knees. The femoral component is composed of zirconia ceramics, which exhibit low friction and high durability.

MRI study of medial meniscus degeneration of osteoarthritic knees with or without posterior root tear.

Purpose: The purpose of this study was to compare the medial meniscus (MM) degeneration, meniscus extrusion, and tibial joint inclination by using MRI to consider the pathogenesis of posterior root tear (PRT) in medial-type knee osteoarthritis (KOA) both with and without medial meniscus posterior root tear (MMPRT).

Methods: This study used open MRI with flexion sagittal view and included 324 medial-type osteoarthritic knees with a Kellegren-Lawrence grade of 2 or less. Following the exclusion process, 151 knees were selected for MRI analysis.

Do the distal femur and the proximal tibia have narrower aspect ratios in smaller knees? : A morphological analysis of osteoarthritic knees in the Japanese population using computed tomography.

Background: Whether the distal femur and the proximal tibia have narrower aspect ratios in smaller knees has not been clarified. The purpose of this study was to confirm the dimensional characteristics of the distal femur and the proximal tibia using a novel method for consistently determining knee size.

Methods: A total of 220 Japanese osteoarthritic knees (160 female and 60 male knees) were analyzed using computed tomography.

Consistent femoral external rotation during weight-bearing knee flexion is associated with better patient-reported pain and mediolateral balance after total knee arthroplasty.

Background: Normal knees generally show consistent femoral external rotation during knee flexion, although knees that have had total knee arthroplasty exhibit various rotational patterns with less rotational angle. This study aimed to determine whether consistent femoral external rotation during weight-bearing knee flexion after total knee arthroplasty is associated with better patient-reported outcomes and mediolateral joint balance.

Methods: A total of 40 total knee arthroplasty knees with a high-flexion posterior-stabilized prosthesis were divided into two groups based on their axial rotational kinematic pattern during squatting activity, and the clinical results including patient-reported outcomes and joint laxity were compared between the consistent external rotation group (20 knees) and the inconsistent external rotation group (20 knees).

Inflammatory and healing environment in synovial fluid after anterior cruciate ligament reconstruction: Granulocytes and endogenous opioids as new targets of postoperative pain.

Background: Biological processes after anterior cruciate ligament reconstruction (ACLR) is crucial for recovery. However, alterations in the of synovial fluid cell population during the acute phase following ACLR and the relationship between these cells and postoperative pain is unclear. The goal of this study was to reveal alterations in synovial fluid cell population during the acute phase following ACLR and relationship between postoperative pain and proportion of synovial fluid cells.

Effects of different surgical procedures for meniscus injury on two-year clinical and radiological outcomes after anterior cruciate ligament reconstructions. -TMDU MAKS study.

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.

Characteristic kinematics of floor-sitting activities after posterior-stabilized total knee arthroplasty determined using model-based shape-matching techniques.

Background: Detailed kinematics of floor-sitting activities after total knee arthroplasty (TKA) have not been well explored. Knee kinematics of cross-legged sitting, seiza-sitting, and side-sitting after TKA were examined to clarify the differences in tibiofemoral kinematics of each activity.

Methods: Subjects were 40 knees in 20 osteoarthritic patients who underwent bilateral TKA with a high-flexion fixed-bearing posterior-stabilized prosthesis.

Inhibition of fibrotic changes in infrapatellar fat pad alleviates persistent pain and articular cartilage degeneration in monoiodoacetic acid-induced rat arthritis model.

Objective: We have reported that fibrotic changes in infrapatellar fat pad (IFP) after acute joint inflammation are closely associated with persistent pain in rats. In this study, to examine the effects of anti-fibrotic treatment on persistent pain, we used C-type natriuretic peptides (CNP) at the recovery phase after acute joint inflammation.

Design: Thirty-two male Wistar rats were used in this study.

Effect of transplanted mesenchymal stem cell number on the prevention of cartilage degeneration and pain reduction in a posttraumatic osteoarthritis rat model.

Background: Mesenchymal stem cells (MSCs) transplantation therapy is considered an alternative therapy to prevent posttraumatic osteoarthritis (PTOA). However, consensus as to the sufficient number of MSCs for the prevention of PTOA is lacking. The purpose of this study was to determine the sufficient number of MSCs to achieve PTOA prevention and the reduction in pain after anterior cruciate ligament transection (ACLT).

Validity of intraoperative observation of graft length change pattern for medial patellofemoral ligament reconstruction.

Background: The clinical outcome of the medial patellofemoral ligament reconstruction (MPFLR) based on graft length change pattern (length pattern group) was compared with MPFLR based on visual examination combined with palpation (visual/palpation group).

Methods: Physical findings, patient-reported outcome, and radiographic demonstration were evaluated pre- and postoperatively.

Results: The length pattern group had significantly lower risk of a positive apprehension test (Odds ratio 0.

Fibrotic changes in the infrapatellar fat pad induce new vessel formation and sensory nerve fiber endings that associate prolonged pain.

The infrapatellar fat pad (IFP) contains nerve fiber endings and is considered to play an important role in the perception of knee pain. However, it is unclear whether and to what degree prolonged pain influences the nociceptive role of the IFP. To answer this question, we established a novel rat model of knee pain in which inflammation is restricted to the IFP.

Synovial fluid-derived mesenchymal cells have non-inferior chondrogenic potential and can be utilized for regenerative therapy as substitute for synovium-derived cells.

Recent progress in the field of mesenchymal stem cell (MSC) biology has enabled their clinical application. In the autologous cell transplantation therapy, the source of MSCs are quite important to reduce patients' physical burden. In this study, we isolated MSCs from the synovial fluid (SF) and synovial membrane (Syn) of the same patients and compared the biological characteristics of them.

Risk factors for residual anterolateral rotational instability after double bundle anterior cruciate ligament reconstruction: Evaluation by quantitative assessment of the pivot shift phenomenon using triaxial accelerometer.

Background: 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.

Methods: Quantitative assessment of the pivot shift phenomenon by measuring tibial acceleration was performed in 46 patients during primary double-bundle ACL reconstructions.

The Anterolateral Structure of the Knee Does Not Affect Anterior and Dynamic Rotatory Stability in Anterior Cruciate Ligament Injury: Quantitative Evaluation With the Electromagnetic Measurement System.

Background: The biomechanical function of the anterolateral structure (ALS), which includes the anterolateral joint capsule and anterolateral ligament (ALL), remains a topic of debate.

Hypothesis: The ALS contributes to knee joint stability during the Lachman test and the pivot-shift test in anterior cruciate ligament (ACL)-deficient knees.

Study Design: Controlled laboratory study.

Biomechanical Effects of Additional Anterolateral Structure Reconstruction With Different Femoral Attachment Sites on Anterior Cruciate Ligament Reconstruction.

Background: Recently reported anterolateral structure reconstructions (ALSRs) to augment intra-articular anterior cruciate ligament reconstruction (ACLR) use various femoral attachment sites, and their biomechanical effects are still unknown.

Hypothesis: ALSR concomitant with ACLR would control anterolateral rotational instability better than ACLR alone, and if ALSR had different femoral attachment sites, there would be different effects on its control of anterolateral rotational instability.

Study Design: Controlled laboratory study.

Benefit of subcutaneous patient controlled analgesia after total knee arthroplasty.

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).

Anatomic femoral tunnel placement is difficult by the transtibial technique: comparison of three different femoral tunnel drilling techniques in double-bundle anterior cruciate ligament reconstructions.

Purpose: 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.

Methods: 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.

Additional Use of Synovial Mesenchymal Stem Cell Transplantation Following Surgical Repair of a Complex Degenerative Tear of the Medial Meniscus of the Knee: A Case Report.

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.

Transplantation of Aggregates of Autologous Synovial Mesenchymal Stem Cells for Treatment of Cartilage Defects in the Femoral Condyle and the Femoral Groove in Microminipigs.

Background: Previous work has demonstrated that patients with cartilage defects of the knee benefit from arthroscopic transplantation of autologous synovial mesenchymal stem cells (MSCs) in terms of magnetic resonance imaging (MRI), qualitative histologic findings, and Lysholm score. However, the effectiveness was limited by the number of cells obtained, so large-sized defects (>500 mm) were not investigated. The use of MSC aggregates may enable treatment of larger defects by increasing the number of MSCs adhering to the cartilage defect.

Correction to: Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

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.

Coronal and sagittal laxity affects clinical outcomes in posterior-stabilized total knee arthroplasty: assessment of well-functioning knees.

Purpose: 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.

Methods: 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.

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect.

Purpose: The aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL-reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL-reconstructed knee.

Methods: Twelve fresh-frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.

Biomechanical analysis of the centralization procedure for extruded lateral menisci with posterior root deficiency in a porcine model.

Purpose: The purpose of this study was to investigate the biomechanical properties of load distribution following a centralization procedure for extruded lateral menisci with posterior root deficiency in a porcine model.

Methods: Six porcine knee joints were analyzed in a universal tester, as follows: 1) Intact; 2) Extrusion (meniscus extrusion was created by resecting the posterior root of the lateral meniscus, as well as the posterior synovial capsule); and 3) Centralization (two anchors were inserted at the lateral tibial plateau, and the meniscus was sutured to secure it close to the original position). Meniscus extrusion was evaluated using two markers put on the posterior cruciate ligament and the lateral meniscus, and the load distribution were assessed using a pressure mapping sensor system after applying a loading force of 200 N to the knee joint.

Time course analyses of structural changes in the infrapatellar fat pad and synovial membrane during inflammation-induced persistent pain development in rat knee joint.

Background: Osteoarthritis (OA) is a common joint disease in aging societies, which is accompanied by chronic inflammation and degeneration of the joint structure. Inflammation of the infrapatellar fat pad (IFP) and synovial membrane (IFP surface) plays essential roles in persistent pain development in patients with OA. To identify the point during the inflammatory process critical for persistent pain development, we performed a time course histological analysis in a rat arthritis model.