BACKGROUND: There is currently no consensus on intraoperative references for determining the posterior tibial slope (PTS) in medial unicompartmental knee arthroplasty (UKA). The medial tibial plateau could serve as a direct reference for determining the native PTS through the placement of a hook probe in the anteroposterior direction of the medial tibial plateau. This study aimed to examine the accuracy of this new referencing method. METHODS: We consecutively performed 55 medial UKAs using our new method (study group), and the preoperative and postoperative PTS on lateral knee radiographs were examined. These outcomes were then compared with those of consecutive 50 medial UKAs performed using the conventional method (control group), which immediately preceded the start of the use of the new method. RESULTS: The correlation coefficient between the preoperative and postoperative PTS of the study group was larger than that of the control group (0.887 and 0.482, respectively). The mean implantation error of the PTS in the study group was smaller than that of the control group (-1.1° ± 1.3° and -3.0° ± 3.2°, respectively; P < .0001). The percentages of knees within 2° of implantation error were 73% and 34% in the study and control groups, respectively (P < .0001). The root mean square errors in the study and control groups were 1.7° and 4.3°, respectively. CONCLUSIONS: The direct referencing method with a probe can significantly improve the accuracy of tibial sagittal alignment.

There has been no consensus about how to determine the individual posterior tibial slope (PTS) intraoperatively. The purpose of this study was to investigate whether the tibial plateau could be used as a reference for reproducing individual PTS during medial unicompartmental knee arthroplasty (UKA). Preoperative computed tomography (CT) data from 48 lower limbs for medial UKA were imported into a three-dimensional planning software. Digitally reconstructed radiographs were created from the CT data as the lateral knee plain radiographs and the radiographic PTS angle was measured. Then, the PTS angles on the medial one-quarter and the center of the MTP (¼ and ½ MTP, respectively), and that on the medial tibial eminence (TE) were measured on the sagittal multiplanar reconstruction image. Finally, 20 lateral knee radiographs with an arthroscopic probe placed on the ¼ and the ½ MTP were obtained intraoperatively, and the angle between the axis of the probe and the tangent line of the plateau was measured. The mean radiographic PTS angle was 7.9 ± 3.0 degrees (range: 1.7-13.6 degrees). The mean PTS angles on the ¼ MTP, the ½ MTP, and the TE were 8.1 ± 3.0 degrees (1.2-13.4 degrees), 9.1 ± 3.0 degrees (1.4-14.7 degrees), and 9.9 ± 3.1 degrees (3.1-15.7 degrees), respectively. The PTS angles on the ¼ MTP and the ½ MTP were strongly correlated with the radiographic PTS angle (r =0.87 and 0.80, respectively, p < 0.001). A statistically significant difference was observed between the mean angle of the radiographic PTS and the PTS on the TE (p < 0.01). The mean angle between the axis of the probe and the tangent line of the tibial plateau was -0.4 ± 0.9 degrees (-2.3-1.3 degrees) on the ¼ MTP and -0.1 ± 0.7 degrees (-1.5-1.2 degrees) on the ½ MTP, respectively. An area from the medial one-quarter to the center of the MTP could be used as an anatomical reference for the individual PTS.

内側膝単顆置換術を施行した25膝(男性5膝、女性20膝、平均年齢75.5歳)を対象に、様々な膝解剖軸を参照した場合の膝デジタル再構成X線(DRR)前後像における膝蓋骨中心位置(膝正面性)を検討した。その結果、大腿骨側ではWhiteside lineまたは臨床的上顆軸(CEA)を参照軸とした場合、概ね膝蓋骨は大腿骨顆部の中心に位置していた。脛骨側ではAkagi's lineがWhiteside lineやCEAと似た傾向を示す参照軸であった。今回の結果から、単純X線撮影時にはCEAを皮膚上から触知して参照軸とすることで正面性の良い膝X線写真が得られると考えられた。

INTRODUCTION: Nontuberculous mycobacterial (NTM) infections of the musculoskeletal system are uncommon. Such infections are typically acquired by direct inoculation after penetrating trauma, surgical procedures, or needle injections. There are no reported cases of NTM infection after arthrocentesis for idiopathic hemarthrosis of the knee. Here we report a case of NTM infection in the knee that developed after arthrocentesis for idiopathic hemarthrosis of the knee. PRESENTATION OF CASE: The patient was an 85-year-old woman who experienced swelling of the left knee. An arthrocentesis was carried out, and hemarthrosis was found. The patient was referred to our hospital for repeated recurrence of hematoma of the knee. Significant swelling was observed in the suprapatellar sac. Magnetic resonance imaging examination revealed a mass at the suprapatellar sac. Laboratory data showed elevation of inflammatory markers. Debridement was performed under arthroscopy and samples were collected for culture. Although routine microbiological cultures were negative, the patient continued to experience knee swelling and laboratory data showed high C-reactive protein levels. Therefore, open debridement was carried out. At 4 weeks after the first surgical treatment, intraoperative cultures yielded Mycobacterium intracellulare. At this point, we diagnosed septic arthritis of the knee due to NTM infection. The patient showed an excellent prognosis with three-drug medical treatment for 1 year. CONCLUSION: Clinically, diagnosis of septic arthritis due to NTM infection is not easy. Because selection of examination depends on clinical suspicion, NTM infections should be considered for patients with elevation of inflammatory markers after episodes of surgical procedures, and/or needle injections.

BACKGROUND: There is no consensus regarding how best to determine the tibial rotational alignment in unicompartmental knee arthroplasty (UKA). The purpose of this study was to clarify whether using the substitute anteroposterior (sAP) line of the tibia, as has recently been proposed, can improve tibial rotation. METHODS: The study included 57 consecutive medial UKAs. From May 2015 to September 2016, 28 knees in 28 patients underwent UKA using the medial intercondylar ridge (MIR) line as the tibial anteroposterior (AP) reference (MIR group). From October 2016 to March 2018, 29 knees in 29 patients underwent UKA using the sAP line (sAP group). In both groups, the external rotation angle of the tibial component relative to a line perpendicular to the surgical epicondylar axis was measured using computed tomography-based three-dimensional preoperative planning software for TKA and UKA. RESULTS: The mean external rotation angles of the tibial component in the MIR and sAP groups were 5.2° ± 8.5° (range, -12.4° to 20.8°) and 0.7° ± 3.2° (range, -6.0° to 7.4°), respectively (unpaired t test, P = 0.014). The variation in the external rotation angle of the tibial component was significantly smaller in the sAP group than in the MIR group (F test, P < 0.0001), as was the number of the outliers with more than ±5° error (Fisher's exact test, P < 0.0001). CONCLUSIONS: The use of the sAP line as the AP reference could improve and stabilize the rotational orientation of the tibial component in UKA procedures.

74歳男。自宅内で左肩を壁に強打して左鎖骨遠位端骨折を負い、8日後にclavicle hook plateを用いて内固定術を行った。術後3週時、明らかな外傷起点なく鎖骨遠位部の疼痛を自覚し、肩峰背側の皮下に突起物が触れるとのことで受診した。画像検査で肩峰骨折を伴うフックのカットアウトを認め、術後5週時に再手術を行う方針となった。骨折部の骨癒合はまだ得られていないと考えられたため再手術の方法として抜釘は選択せず、ロッキングプレートの入れ替えも骨折部の安定が得られないと考えられたため施行せず、フックプレート先端の切除のみ行った。結果、術直後に疼痛は消失し、13週後のX線検査で仮骨形成が認められ、肩関節JOAスコアは93点と良好な経過が得られた。

Winged scapula is a rare condition caused by injuries to the long thoracic nerve (LTN) and accessory nerves. A 69-year-old man underwent surgery for right lung cancer. Video-assisted thoracic surgery was converted to axillary thoracotomy at the fourth intercostal space. The latissimus dorsi was protected, and the serratus anterior was divided on the side anterior to the LTN. Two months after discharge, he presented with difficulty in elevating his right arm and protrusion of the scapula from his back. Active forward flexion of the right shoulder was limited to 110° and abduction to 130°. He was diagnosed with winged scapula. After 6 months of occupational therapy, the symptoms improved. The LTN may have been overstretched or damaged by the electric scalpel. We recommend an increased awareness of the LTN, and to divide the serratus anterior at a site as far as possible from the LTN to avoid postoperative winged scapula.

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. We measured the hip-knee-ankle (HKA) angle, the tibial joint-line orientation angle (JLOA), which indicates the angle of the joint line (tibial component) relative to the floor, and the medial proximal tibial angle (MPTA), which is the angle of the joint line (tibial component) relative to the tibial mechanical axis, before and after UKA in the coronal plane. RESULTS: The preoperative HKA angle (mean 7.3°, standard deviation (SD) 3.0) was significantly higher than the postoperative HKA angle (mean 3.4°, SD 3.0, P < 0.0001). The preoperative MPTA (mean 4.8°, SD 2.1) did not significantly differ from the postoperative MPTA (mean 4.5°, SD 3.0, P = 0.47). The mean postoperative JLOA was parallel to the floor (JLOA; 0.2°, SD 3.6). CONCLUSION: When the tibial component is positioned along the natural joint slope restoring pre-disease alignment of the overall lower limb in the coronal plane, the tibial component was positioned parallel to the floor. When UKA is indicated for the medial osteoarthritis patient, the surgeon should install the tibial component four to five degrees varus to the tibial mechanical axis to maintain joint-line parallelism.

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. METHODS: Preoperative computed tomography data from 32 lower limbs of 31 Japanese patients who received UKA were used. First, the angles between the surgical epicondylar axis and the MIR and the substitute AP (sAP) line connecting the medial border of the patellar tendon at the articular surface level and the medial intercondylar tubercle were measured. Next, the mediolateral (ML)/AP ratio of the tibial cut surface was measured when cut parallel to the MIR and sAP line. Finally, the ML/AP ratio of the tibial component was investigated in 4 contemporary UKA implants. RESULTS: The MIR and sAP line were externally rotated 94.9° ± 4.1° and 90.4° ± 3.6° relative to the surgical epicondylar axis, respectively. Compared with a cut parallel to the MIR, the mean ML/AP ratio of the cut surface was significantly larger, and the ML/AP ratio was closer to the ML/AP ratio of the components for a cut parallel to the sAP line. CONCLUSION: Obtaining the tibial AP orientation is one of the key steps not only in total knee arthroplasty but also in UKA. The sagittal cut referencing the sAP line provides better AP rotation and fitting of the tibia in UKA than referencing the MIR.

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. With these axes, we regarded the offset distance from the intermalleolar midpoint as the position of the ankle center and investigated any angular osteotomy errors on the proximal tibia when the ankle center was assumed to the intermalleolar midpoint. RESULTS: The mean offset distances relative to the tibial AP axis were 1.8±0.9mm medial and 4.2±1.2mm anterior, and the distances relative to the TMA were 3.0±0.9 and 3.6±1.1mm in the coronal and sagittal planes, respectively. Mean angular osteotomy errors were 0.3±0.2° in the coronal plane and 0.8±0.2° in the sagittal plane. CONCLUSIONS: The ankle center was located around the intermalleolar midpoint. The position of the ankle center observed along the knee reference axis further approached the intermalleolar midpoint than when observed along the ankle reference axis in the coronal plane, but not in the sagittal plane. And the coronal angular osteotomy error was smaller than the sagittal error. Therefore, the intermalleolar midpoint in the coronal plane is a reliable landmark for the ankle center during TKA. However, surgeons should be cognizant of this sagittal angular error.

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. Subsequently, we repeated the same procedure adding extended sagittal bone cuts of 2° and 10° in the posterior tibial cortex. Furthermore, we calculated the bone volume that supported the tibial component, which is considered to affect stress distribution in the medial tibial condyle. RESULTS: Stress concentrations were observed on the medial tibial metaphyseal cortices and on the anterior and posterior tibial cortices in the corner of cut surfaces in all models; moreover, the maximum principal stresses on the posterior cortex were larger than those on the anterior cortex. The extended sagittal bone cuts in the posterior tibial cortex increased the stresses further at these 3 sites. In the models with a 10° extended sagittal bone cut, the maximum principal stress on the posterior cortex increased as the tibial inclination changed from 6° varus to 6° valgus. The bone volume decreased as the inclination changed from varus to valgus. CONCLUSION: In this finite element method, the risk of MTCFs increases with increasing valgus inclination of the tibial component and with increased extension of the sagittal cut in the posterior tibial cortex.

Objectives: The lectin-like oxidized low density lipoprotein (ox-LDL) receptor 1 (LOX-1)/ox-LDL system, which contributes to the pathogenesis of atherosclerosis, may be involved in the development of osteoarthritis (OA). However, the mechanisms by which the LOX-1/ox-LDL system contributes to OA development in vivo are unclear. In this study, we investigated the direct involvement of LOX-1/ox-LDL in OA development by using LOX-1-knockout (LOX-1(-)/(-)) mice in a joint instability-induced model of OA. Method: OA development was evaluated with histological scoring at 4 and 8 weeks after surgery to induce knee destabilization in LOX-1(+)/(+) and Lox-1(-)/(-) mice. Immunohistological analysis was used to evaluate the expression of LOX-1, ox-LDL, Runt-related transcription factor 2 (Runx2), and type X collagen (COL X) in articular chondrocytes and osteophyte-forming cells. In addition, double immunofluorescence staining was performed to determine the relationships between LOX-1 and Runx2 or COL X expression. Results: In the model of knee destabilization, symptoms were significantly suppressed in LOX-1(-)/(-) mice. LOX-1, ox-LDL, Runx2, and COL X were overexpressed in articular chondrocytes and osteophyte-forming cells in LOX-1(+)/(+) mice and were significantly downregulated in articular chondrocytes and osteophyte-forming cells in LOX-1(-)/(-) mice compared with those in LOX-1(+)/(+) mice. Double immunostaining indicated that LOX-1 localization coincided with Runx2 and COL X expression. Conclusions: These data indicate that the LOX-1/ox-LDL system plays a pivotal role in the pathogenesis of instability induced OA through endochondral ossification. LOX-1-positive chondrocytes and osteophyte-forming cells may be possible targets to prevent disease progression in OA.

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. METHODS: Forty arthritic knees were divided into two treatment groups using MRI-based (PS-MRI group) or CT-based (PS-CT group) patient-specific guides in this prospective, comparative study. The guide in the PS-MRI group had a cutting slot, whereas that in the PS-CT group only had a pin locator. The operative times were compared between the two groups. The angular error and number of outliers (deviations >3°) of the implant position using pre- and postoperative CT were investigated in both groups. RESULTS: The mean operative time was significantly shorter in the PS-MRI group (109.2 ± 16.5 min) than in the PS-CT group (129.5 ± 19.4 min) (p<0.001). There were no significant differences in the accuracy of the implant position regarding the coronal, sagittal, and axial planes between the groups (p>0.05). CONCLUSIONS: To reduce the operative time, guides with additional functions, such as cutting and positioning, should be used. Both CT- and MRI-based-guides would result in the same accuracy in three planes but high inaccuracy in the sagittal plane. The use of patient-specific guide based on MRI might not be cost-effective. LEVEL OF EVIDENCE: level 2.

In 2013, we reported that local renin-angiotensin system (local RAS) components express during the hypertrophic differentiation of chondrocytes and can modulate it, using ATDC5 cell line that involves differentiation from mesenchymal stem cells to calcified hypertrophic chondrocytes. However, the expressions of local RAS components in normal chondrocytes have not been revealed yet. The purpose of this study is to examine the expression of the local RAS components in chondrocytes in vivo and the conditions allowing the expression. We stained five major regions of 8-week-old C57BL/6 adult mice in which chondrocytes exist, including epiphyseal plates and hyaline cartilages, with antibodies to local RAS components. We also examined the expression of local RAS components in the cultured bovine's articular cartilage chondrocytes using quantitative reverse transcription polymerase chain reaction and western blot analysis. In result, hypertrophic chondrocytes of epiphyseal plates included in the tibia and the lamina terminals expressed local RAS components. However, hyaline chondrocytes, including the knee articular cartilages, the parenchyma of nasal septums and of the tracheal walls, did not express local RAS components. Cultured bovine's articular cartilage chondrocytes also did not express local RAS components. However, inducing hypertrophy by administering interleukin-1 beta or tumor necrosis factor-a, the cultured articular chondrocytes also expressed angiotensin II type 1 receptor and angiotensin II type 2 receptor. In conclusion, local RAS components express particularly in chondrocytes which occur hypertrophy and do not in hyaline chondrocytes. The results are in accord with our previous in vitro study. We think this novel knowledge is important to investigate cartilage hypertrophy and diseases induced by hypertrophic changes like osteoarthritis.

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. We measured overall thrombotic and thrombolytic status using GTT and other biomarkers, which is associated with blood coagulation and fibrinolysis, before and immediately after the surgery. RESULTS: Newly-generated DVT during the operation was detected in 11 of 31 patients (35.4%) 1 day after TKA. There were no differences in markers of coagulation (PT and APTT), platelet activity (platelet aggregation-induced by ADP and collagen) and fibrinolysis (FDP and D-dimer) between non-DVT and DVT group both before and after the surgery. Both Pre- and Post-operative GTT-occlusion times (OT), an index of platelet reactivity, were tended to be shorter, but not significant, in DVT group compared with non-DVT group. Pre-operative GTT-lysis time (LT), an index of thrombolytic activity, was significantly shorter in DVT group compared with non-DVT group, while there were no differences in post-operative value of this index between DVT group and non-DVT group, suggesting overall thrombolytic activity was enhanced in DVT group before surgery. CONCLUSIONS: Our data suggest that enhancement of pre-operative thrombolytic activity assessed by GTT may be a predictable marker for the incidence of DVT after TKA.

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. AP length of the distal femur changed nearly 0.6mm corresponding to each 1° flexion of the sagittal reference axis. The size of the femoral component in the intramedullary group was larger than that in the extramedullary group. The sagittal reference axis had an influence on the component size.

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. 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. We measured the tibia vara angle (TVA), proximal varus angle (PVA), and the mediolateral and middle AP dimensions of the resected surface using three-dimensional preoperative planning software in 90 knees of 74 female patients with varus osteoarthritis. We determined the correlations of the aspect ratio with TVA or PVA and compared the aspect ratios to those of five prosthesis designs. The mean TVA and PVA were 0.6A degrees and 2.0A degrees, respectively. The aspect ratio negatively correlated with both TVA and PVA (r = -0.53 and -0.55, respectively). The mean aspect ratio of the resected surface was 1.48 but gradually decreased with increasing AP dimension, whereas four of the five prostheses had a constant aspect ratio. The aspect ratio of resected tibial surface was inversely correlated to the degree of tibia vara, and currently available prosthesis designs do not fit well to the resected surface in terms of aspect ratio. The design of a tibial component with a smaller aspect ratio could be developed to obtain better bone coverage in Japanese patients.

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. The lateral errors were measured, including or excluding the subcutaneous thickness, along the line perpendicular to the transmalleolar axis (TMA) or along the tibial anteroposterior (AP) axis. Furthermore, we evaluated the effects of the tibial torsion and the difference between the subcutaneous thicknesses on the malleoli on the lateral error. RESULTS: When including the skin, the mean lateral errors of the ankle center observed along the line perpendicular to the TMA and along the tibial AP axis were 3.7 ± 1.4mm and 1.2 ± 1.5mm, respectively. The mean angular errors were 0.6 ± 0.2° and 0.2 ± 0.3°, respectively. A significant correlation between the tibial torsion and the lateral error was noted when observed along the tibial AP axis. The difference between the subcutaneous thicknesses on the malleoli affected the lateral error. CONCLUSION: The errors were small enough to determine the mechanical axis of the tibia if the tibial guide could catch the bi-malleolar prominences of the ankle accurately and align along the tibial AP axis.

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. We retrospectively reviewed 20 patients (26 knees) treated with open-wedge HTO. They were divided into the following two groups. Group A consisted of the knees whose opening gaps were fixed using a spacer plate having the trapezoidal block with a 2A degrees posterior slope. In Group B, anterior and posterior opening gaps were fixed separately. The posterior tibial slope and the hip-knee-ankle angle were measured based on CT data. The relationship between the correction rate in frontal plane and the changes of posterior tibial slope was investigated. Increase in the posterior tibial slope was 2.1 +/- A 2.5A degrees in Group A and 0.2 +/- A 1.2A degrees in Group B, which showed a statistical difference (P = 0.02). The difference between the hip-knee-ankle angles before and after operation was 5.2 +/- A 2.3A degrees in Group A and 5.5 +/- A 2.5A degrees in Group B. The correction rate was statistically correlated with the changes of posterior tibial slope (R = -0.55, P = 0.003). To avoid increase in the posterior tibial slope, the trapezoidal block with a only 2A degrees posterior slope in a spacer plate was not sufficient, and it was necessary to fix anterior and posterior gaps separately. The correction angle in frontal plane had a trade-off relationship with the changes in posterior tibial slope. Thus, we thought that increase in the posterior tibial slope might result in correction loss. Therapeutic study, Retrospective comparative study, Level III.

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. The PCAs when including or excluding the cartilage remnants were also measured. The cartilage thicknesses of the medial and lateral posterior condyles averaged 0.39mm (SD=0.53) and 1.55mm (SD=0.26), respectively (p<0.0001). When the cartilage was included or excluded, the PCA averaged 2.2° (SD=1.5) and 3.3° (SD=1.5), respectively (p=0.002). The cartilage remnants in the posterior femoral condyles produced an average of 1.1° and a maximum of 2.1° of additional femoral external rotation when using CT data for the preoperative planning. CT scan measurements of femoral rotation are subject to error. Although this is said to be small and within the safety margin for setting the femoral component parallel to the trans-epicondylar axis, this difference should be considered by surgeons who use the posterior condylar axis, in order to avoid excessive external rotation of the femoral component.

We investigated the surface properties and wear performances of a standard cobalt-chromium (Co-Cr) alloy and 2 kinds of ceramic femoral components (alumina and zirconia) in tibial polyethylene inserts tested in a knee simulator. Hardness, wettability (lubricity), and presimulator and postsimulator test roughness values of the component surfaces were measured for each material. The simulator was run up to 5.0 million cycles using gait kinematics to determine the wear rate of the tibial polyethylene against each group. Vickers hardness values of the femoral components made of Co-Cr, alumina, and zirconia averaged 339 ± 14.8, 1869 ± 40.6, and 1382 ± 15.8, respectively. Contact angles with distilled water (in degrees) of the femoral components made of Co-Cr, alumina, and zirconia averaged 76.9 ± 3.2, 34.9 ± 1.5, and 73.5 ± 0.8, respectively. The aggregate volumetric wear rate for the Co-Cr femoral components was 3.35 ± 1.33 mm per million cycle those of the alumina and zirconia femoral components were 0.15 ± 0.08 and 0.57 ± 0.18 mm/M, respectively. Differences between the wear rate of the Co-Cr and ceramic femoral components were statistically significant (n = 3 P < 0.01). The posttest roughness values of ceramic femoral condyles were significantly smaller than that of the Co-Cr condyles. The reduction in the tibial polyethylene wear was likely attributable to the greater wettability and resistance to roughening of the ceramic components. © 2007 Lippincott Williams & Wilkins, Inc.

Objective: Using human cartilage samples and cultured chondrocytes, to assess the possible involvement of oxidized low-density lipoprotein (ox-LDL) and lectin-like ox-LDL receptor-1 (LOX-1) in pathogenesis and progression of osteoarthritis (OA). Methods: Thirty-two cartilage samples were obtained from 16 patients with knee OA, and 12 Control samples from six with femoral neck fracture. LOX-1 mRNA expressions in 12 OA and six Control samples were analyzed by reverse transcription-polymerase chain reaction (RTPCR). Immunohistochemistry for ox-LDL and LOX-1 was performed in all samples. The histological CA grade was assessed with the modified Mankin score. The relative percentage of the ox-LDL and LOX-1 immunopositive chondrocytes was calculated in all samples. The effects of ox-LDL on cell viability in cultured human chondrocytes were 5 investigated by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay and on proteoglycan synthesis by monitoring [S-35] sulfate incorporation. Results: There was a statistically significant difference between mean LOX-1/GAPDH (LOX-1/human glyceralclehyde-3-phosphate dehydrogenase) ratio of OA samples and that of Control samples (40.6% +/- 10.3 and 11.9% +/- 2.8, respectively, P < 0.0001). The mean percentage of ox-LDL-positive cells was 23.0 +/- 15.7% in OA and 4.3 +/- 3.7% in Control cells (P = 0.0002). The mean percentage of LOX-1-positive cells was 51.7 +/- 29.5% in OA and 10.0 +/- 8.1% in Control cells (P < 0.0001). Both the ox-LDL immunoreactivity and the LOX-1 immunoreactivity were significantly correlated with the modified Mankin scores (R-2 = 0.67 and 0.48, respectively; P < 0.0001 for each). ox-LDL significantly reduced the human chondrocyte viability and proteoglycan synthesis, and pretreatment with anti-human LOX-1 monoclonal antibody reversed these effects. Conclusion: The ox-LDL/LOX-1 system may be involved in human OA. (C) 2006 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Axial micromotion of bone fragments enhances callus formation during fracture repair or limb lengthening. To examine this, we used an axial-shortening model of the tibial callus in rabbits and performed histological analyses. After 10-mm lengthening of the left tibia with an external fixator, we shortened the callus by 2 mm. Radiographs and quantitative evaluation of corrected bone mineral density showed a significant increase in mineralization in the shortened callus (57.3 vs. 36.2%, p = 0.001). Histologically, greater osteoblast proliferation and more vigorous trabecular bone formation were noted in the shortened calluses than in the controls. Around the front of membranous bone formation in the shortened callus, there was a significant decrease in mean percentage area of vascular lumens (1.8 vs. 4.5%, p = 0.009), which seemed attributable to compressive force, and a significantly increased production of vascular endothelial growth factor (VEGF; 422.5 vs. 142.7 pg/mg protein, p = 0.007) and its receptors. There were also increased numbers of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts and proliferating cell nuclear antigen (PCNA)-positive cells. A marked increase of hypoxia inducible factor-1 alpha (HIF-1 alpha) expression in osteoblasts was also observed in this area. Thus, enhancement of membranous bone formation by static compression or axial dynamization may be at least partly attributable to HIF-1 alpha-mediated VEGF induction following the local hypoxia caused by collapse of vascular lumens. (c) 2006 Orthopaedic Research Society.

Anatomic reference axes that determine rotational alignment of the tibial component have not been established. To assess variability of three anatomic reference axes (a new tibial anteroposterior axis that we proposed, the transmalleolar axis of the ankle, and the second metatarsus bone axis of the foot), we measured the angles between a defined anteroposterior axis of the tibia (a line perpendicular to the transepicondylar axis) and each of the three axes in 57 knees of healthy subjects using computed tomography scans. The angle between the defined anteroposterior axis and our proposed anteroposterior axis (a line connecting the middle of the posterior cruciate ligament and the medial edge of the patellar tendon attachment) averaged -0.2 degrees +/- 2.8 degrees (range, -5.5 degrees-6.3 degrees). The angle between the defined anteroposterior axis and the transmalleolar axis averaged 25.9 degrees +/- 9 degrees (range, 8 degrees-49.4 degrees), and the angle between the defined anteroposterior axis and the second metatarsus bone axis averaged 5.2 degrees +/- 10 degrees (range, -21.9 degrees-24 degrees). The variability of the anteroposterior axis was less than than the other reference axes. These data indicate that our proposed tibial anteroposterior axis is more reliable for determining rotational alignment of the tibial component in total knee arthroplasty.

Alumina-on-alumina bearings for total hip arthroplasty have been introduced as a promising alternative to reduce wear debris and to increase the life expectancy of the prosthesis. We report a case of a late dissociation of an alumina-on-alumina bearing modular acetabular component, which occurred 2 years, 8 months after surgery. Detailed analysis of the retrieved prosthesis suggested that the cause of the failure may be strong rotational torque developed by a roughening of the bearing's alumina surface caused by edge loading (microseparation). The strong friction torque in articulation may explain the higher reported rate of mechanical loosening of the acetabular component in alumina-on-alumina bearing total hip prostheses. (C) 2004 Elsevier Inc. All rights reserved.

We hypothesized that reactive oxygen species play an important role in avascular/ischemic osteonecrosis. When isolated chick osteocytes were cultured with hydrogen peroxide. annexin V binding., which is the earliest marker of apoptosis, increased in a dose-dependent fashion. Hydrogen peroxide also induced the Ca2+ activation of caspase-3 and increase in cytosolic Ca2+. Treatment with BAPTA/AM (cheletor of cytosolic Ca2+) and Ac-DEVD-cho (caspase inhibitor) attenuated hydrogen peroxide-induced apoptosis. These data demonstrated the signal transduction pathways that participate in this hydrogen peroxide-induced cell damage.

【背景】手術中に血栓は形成されるとの報告は古くは125I fibrinogen uptake testにより証明された2）が，下肢の術中血栓形成を直接画像で証明した報告は我々の調べた範囲では認められない．【目的】術中血栓形成を証明した症例の超音波検査をretrospectiveに検討し，その特徴を検討した．【方法】本研究に同意が得られた平成16年12月までのTKA連続59症例を執刀直前と術直後に下肢静脈エコーを行い下肢静脈血栓の術中形成の有無を検索した．撮像条件は中心周波数10～5M Hz，リニアプローブを用いた．特に管腔内占拠病変の有無，下腿深部静脈の血管径，ミルキングテスト，呼吸性変動，圧迫テストなどをカラードップラー法による検討を行った． 静脈は膝窩部を境界とし近位遠位を分け，さらに筋間静脈と筋肉内静脈（腓腹筋，ヒラメ筋静脈）に分け検討した．また血栓の形態をA:充満閉塞型，B:浮遊型，C:壁在隆起型，D:壁肥厚（壁不整）型，E:閉塞退縮型に分類した．【結果】平均年齢は73.4±5

静脈血栓塞栓症の頻度が高い整形外科人工膝関節置換術における凝固線溶検査の変動について検討した。

我々は平成１４年度より大学アメリカンフットボールのチームドクターとして選手の健康管理を行なっている。競技の性格上スポーツ障害・外傷の頻度が高く，事前の健康調査が必須と考えられ，アンケート調査を行なった。頚椎障害は相手とのコンタクトが多いラインバッカーに多く，１４名中６名が頚椎障害を現在のスポーツ障害として訴えていた。

症例は78歳女性．変形性膝関節症手術目的で当院入院．人工膝関節置換術前後 に静脈エコーを実施し術中血栓形成と考えられた．術後血栓症は以外に速い時 期に形成される可能性が考えられ過去の文献を考察し報告した．

【Purpose】 Recently, it has been demonstrated in in-vivo and vitro studies that lectin-like oxidized low-density lipoprotein LDL (ox-LDL) receptor-1 (LOX-1) expresses on articular chondrocytes and suggested that its ligand ox-LDL plays some roles in degeneration of articular cartilage. The purpose of this study is to examine effects of hyperlipidemic loading on articular cartilage degeneration using a congenital hyperlipidemic rabbit (KHC). 【Methods】 Japanese white rabbits (JW, n=6) and KHC rabbits (n=6) underwent transection of the anterior cruciate ligament and excision of the medial meniscus in the right knee. Sham operation was performed in the left knee. All animals were killed at 8 weeks following the surgery. The weight-bearing areas of the medial femoral condyle were subjected to histological evaluation according to the modified Mankin scoring system. Furthermore, these were subjected to LOX-1, ox-LDL and basic fibroblast growth factor (bFGF) immunohistochemical staining. To examine effect of ox-LDL on bFGF expression in chondrocytes rabbit articular chondrocytes (RACs) were stimulated with ox-LDL (0, 50, 100 μg/m1) and bFGF mRNA expression was investigated with RT-PCR. To know whether the effect is mediated by LOX-1, cells were pre-incubated with anti-human LOX-1 antibody (JTX92, 50 μg/m1), and then stimulated with ox-LDL at various concentrations. 【Results】 Mean Mankin score in the right knee of the KHC rabbits was significantly larger than that of JW rabbits (23.0±1.8 and 15.2±4.8, respectively, p < 0.01). Mean Mankin score in the left knee (Sham op. side) of the KHC rabbits was also significantly larger than that of JW rabbits (6.5±1.4 and 2.5±2.0, respectively, p<0.05). Presence of ox-LDL and expression of LOX-1 were noted in the right knee cartilage of both rabbits. However, immunoreactivity of ox-LDL was stronger in the left knee of KHC rabbits than in that of JW rabbits. Immunoreactivity of bFGF in both right and left knee cartilages was significantly less in the KHW rabbits than in JW rabbits. In rabbit chondrocyte culture, ox-LDL significantly reduced bFGF mRNA expression in a dose dependent manner, and pretreatment with anti-LOX-1 monoclonal antibody (JTX92) significantly reversed this reduction. 【Conclusion】 These observations support the hypothesis that hyperlipidemia may be one of risk factors for osteoarthritis and suggest that the ox-LDL/LOX-1 system may be involved. Reduction of bFGF expression in chondrocytes due to the system may cause the acceleration of cartilage degeneration.

Biophysical stimulation loaded on the bone must rely on both the biological and biomechanical principle according to the local tissue environment and the type of mechanical stress. Physiological loading is widely believed to benefit the maintenance of skeletal integrity. However, excessive nonphysiological loading is associated with bone injuries, including stress fractures and osteoporotic fractures, indicating that such loading decreases the functional capacity of bone. Consequently, this mechanical stress must be transduced to a biochemical signal in bone and osteoblasts. We previously loaded cyclic tensile stretch on osteoblast-like cells and found an enhanced synthesis of reactive oxygen species (ROS) and superoxide dismutase (SOD). However, the precise pathway of SOD induction has not been elucidated. Cyclic tensile stretch was loaded on the osteoblast-like cells using Flexercell Strain Instrument. To generate intracellular ROS, paraquat was used. Paraquat significantly enhanced SOD activity, suggesting that the intracellular generation of ROS, is essential for the induction of SOD. Cyclic tensile stretch enhanced ROS and SOD synthesis. SOD inhibited stretch-enhanced ROS and SOD synthesis. SOD induction by mechanical stimuli is regulated by intracellular ROS. We also examined the effect of axial loading using axial shortening during distraction osteogenesis in vivo. We found mechanical stress leads to enhanced bone formation in a rabbit model through the hypoxia-inducing-factor-1 alpha/vascular endothelial growth factor system. Taken together, redox status plays an important role in the signal transduction of mechanical stress loaded on the bone.

Many tissues or organs including bone and joint adopted their morphology under the influence of the environmental mechanical loading. The purpose of this study is to solve this mysterious process and apply it for therapeutic aspect as tissue engineering. We introduce the distraction osteogenesis, which afford to correct the deformity and lengthen the limb. Although mechanical stretch on bone, tendon and vessel is possible to apply, lag period in the bone maturation is necessary. To improve this system, we investigate the role of reactive oxygen species(ROS) under the influence of mechanical stress. We used in vivo model of leg-lengthening *and found the characteristic morphology, such as the invasion of endothelial cells and apoptosis of mesenchymal cells. We first focused on the distribution of apoptosis of the osteoblast in this model. Recent observations revealed the significant role of ROS in ischemia-reperfusion induced cell apoptosis. We then examine the effect of mechanical stress on generation of the ROS and apoptosis of osteoblast. Cyclic tensile stretch loaded oh these cells clearly enhanced ROS synthesis in a time-and magnitude-dependent fashion. The disruption of micro filaments abolished the stress-induced ROS synthesis. Rotenone, an inhibitor of the mitochondrial electron transport chain, enhanced stress-induced ROS synthesis. These data suggest that actin filament and mitochondria are involved in this action.