Extra-articular synovial osteochondroma of the Hoffa's fat pad involving the patellar tendon: A case report and literature review.

Synovial osteochondroma (SO) is a relatively uncommon tumor affecting the synovial joints that is characterized by the development of hyaline cartilage from the synovial membrane. The basic pathophysiology of SO is thought to be the metaplastic change of the synovium to hyaline cartilage. Large extra- or para-articular lesions in the Hoffa's fat pad are relatively uncommon.

Transplantation of autologous bone marrow-derived mesenchymal stem cells under arthroscopic surgery with microfracture versus microfracture alone for articular cartilage lesions in the knee: A multicenter prospective randomized control clinical trial.

Introduction: To investigate the efficacy of the transplantation of autologous bone marrow-derived mesenchymal stem cells (BMSCs) under arthroscopy with microfracture (MFX) compared with microfracture alone.

Methods: Eleven patients with a symptomatic articular cartilage defect of the knee were included in the study. They were randomized to receive BMSCs with MFX (cell-T group, n=7) or MFX alone (control group, n=4).

Obliquity of tibial component after unicompartmental knee arthroplasty.

Background: The native knee joint line is varus relative to the tibia and remains parallel to the floor during gait even with varus lower-limb alignment. We investigated the desired degree of frontal obliquity for positioning the tibial component during unicompartmental knee arthroplasty (UKA).

Methods: We retrospectively analyzed full-leg, standing, hip to ankle digital radiographs from 107 osteoarthritic knees.

Anteroposterior Rotational References of the Tibia for Medial Unicompartmental Knee Arthroplasty in Japanese Patients.

Background: In unicompartmental knee arthroplasty (UKA), there is no consensus regarding how to determine the anteroposterior (AP) reference of the tibia. A number of surgeons in Japan perform the sagittal saw cut using the medial intercondylar ridge (MIR) of the tibia according to surgical manuals. However, there is no theoretical basis for this practice.

Location of the ankle center for total knee arthroplasty.

Background: The purpose of this study was to investigate the ankle center position as determined from the malleoli for total knee arthroplasty (TKA).

Methods: We retrospectively analyzed computed tomography data from 102 patients with osteoarthritic knees. The tibial anteroposterior (AP) axis and transmalleolar axis (TMA) were used as rotational reference axes of the knee and ankle joint, respectively.

The Valgus Inclination of the Tibial Component Increases the Risk of Medial Tibial Condylar Fractures in Unicompartmental Knee Arthroplasty.

Background: Medial tibial condylar fractures (MTCFs) are a rare but serious complication after unicompartmental knee arthroplasty. Although some surgical pitfalls have been reported for MTCFs, it is not clear whether the varus/valgus tibial inclination contributes to the risk of MTCFs.

Methods: We constructed a 3-dimensional finite elemental method model of the tibia with a medial component and assessed stress concentrations by changing the inclination from 6° varus to 6° valgus.

Comparison of MRI- and CT-based patient-specific guides for total knee arthroplasty.

Background: The patient-specific guide for total knee arthroplasty (TKA) is created from the data provided by magnetic resonance imaging (MRI) or computed tomography (CT) scans. It remains unknown which imaging technology is suitable for the patient-specific guide. The purpose of this study was to compare the accuracy of implant positioning and operative times between the two types of patient-specific guides for TKA.

Enhanced pre-operative thrombolytic status is associated with the incidence of deep venous thrombosis in patients undergoing total knee arthroplasty.

Background: Deep venous thrombosis (DVT), which is often associated with pulmonary embolism (PE), is a serious complication after total knee arthroplasty (TKA). In the present study, we examined the overall thrombotic and thrombolytic status using Global Thrombosis Test (GTT) in non-anticoagulated blood of patients undergoing TKA to develop the predictable marker for the incidence of DVT.

Methods: DVT was diagnosed using doppler ultrasonography a day after the surgery in 31 patients with osteoarthritis (n = 24), rheumatoid arthritis (n = 6) and ankylosing spondylitis (n = 1) by the well-trained operator.

Influence of the sagittal reference axis on the femoral component size.

The sagittal reference axes used for setting of the femoral component vary according to surgical methods. The purpose of the study was to clarify the relation of the sagittal reference axis with the anteroposterior (AP) length of the distal femur at the time of determining the femoral component size. Fifty consecutive varus osteoarthritic knees with primary total knee arthroplasty were divided into two groups according to surgical methods (intramedullary and extramedullary groups) and were examined based on CT data.

Tibia vara affects the aspect ratio of tibial resected surface in female Japanese patients undergoing TKA.

Background: Tibia vara seen in Japanese patients reportedly influences the tibial component alignment when performing TKA. However, it is unclear whether tibia vara affects the component position and size selection.

Questions/purposes: We therefore determined (1) the amount of medial tibial bow, (2) whether the tibia vara influences the aspect ratio of the tibial resected surface in aligning the tibial component with the tibial shaft axis, and (3) whether currently available tibial components fit the shapes of resected proximal tibias in terms of aspect ratio.

Estimation of frontal alignment error of the extramedullary tibial guide on the bi-malleolar technique: a simulation study with magnetic resonance imaging.

Purpose: The bi-malleolar technique for the extramedullary tibial guide is a representative method for determining the ankle center in total knee arthroplasty (TKA). The purpose of this study is to estimate three-dimensionally the lateral errors (difference between the real ankle center and the bi-malleolar center) and the varus angular errors of this technique under the condition that the malleolar prominences were correctly identified.

Methods: Magnetic resonance images of 51 lower limbs from 51 healthy volunteers were analyzed.

Increase in posterior tibial slope would result in correction loss in frontal plane after medial open-wedge high tibial osteotomy.

Purpose: The purpose of this study was to clarify the causes of the increase in the posterior tibial slope during open-wedge high tibial osteotomy (HTO) and to investigate whether its changes influenced the correction angle in frontal plane.

Methods: We retrospectively reviewed 20 patients (26 knees) treated with open-wedge HTO. They were divided into the following two groups.

Effects of cartilage remnants of the posterior femoral condyles on femoral component rotation in varus knee osteoarthritis.

Preoperative planning of total knee arthroplasty (TKA) based on computerized tomography (CT) data can produce a femoral rotational error due to lack of information on the femoral cartilage thickness. The research question of this study is how much femoral rotational error is expected due to the cartilage remnants when using the posterior condylar angles (PCA, angle between the posterior condylar line and the surgical epicondylar axis (SEA)) on CT data. CT arthrography was performed for 35 consecutive varus osteoarthritic knees in 31 patients who underwent TKA, on which the cartilage thicknesses of the posterior femoral condyles were measured.

Isolation and characterization of side population stem cells in articular synovial tissue.

Background: Autologous chondrocyte implantation is an established technique for the repair of degenerated articular cartilage. Recently, the detection of side population (SP) cells, which have the ability to strongly efflux Hoechst 33342 (Ho) fluorescence dye, has attracted attention as a method of stem cell isolation. Although SP cells from synovial tissue were expected to be an excellent source for this tissue engineering, their precise character in the synovial tissue has not been determined.