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Venous thromboembolism (VTE) is one of the most important complications in orthopedic surgery. Deep-vein thrombosis occurs frequently after surgery but has few clinical symptoms. The emboli formed may cause pulmonary thromboembolism, which is associated with a high mortality rate. The cost of medical care is doubled when VTE develops after surgery. Thus, it is imperative to focus on preventing VTE after major orthopedic surgery. The prevention method should be selected after considering the balance between VTE risk and bleeding risk attributable to drug prophylaxis. Physical prophylaxis, drug prophylaxis, or both should be selected. When performing VTE prophylaxis, the risks and merits of prophylaxis must be made clear to patients. [ABSTRACT FROM AUTHOR]

Background: Although unicompartmental knee arthroplasty (UKA) has become more common because of its good outcomes, several complications have been reported. Tibial implant alignment, an important cause of such complications, has been investigated; however, the optimal alignment of the tibial implant has not been determined. This study used 3-dimensional finite element analysis to investigate changes in stress distribution in the proximal tibia after UKA at multiple tibial implant alignments. Methods: A 3-dimensional finite element model was created with CT digital imaging and communications in medicine (CT-DICOM) data from a medial osteoarthritic knee. Change in stress distribution of the tibial implant alignment on the coronal plane (middle position, varus 5°, valgus 5°) and sagittal plane (0°, 5°, 10°) under conditions of a loose boundary between implant and bone and no loosening was analyzed with 3-dimensional finite analysis. Results: In the absence of loosening, the stress distribution was high at the lateral rim of the subchondral bone in the varus alignment model, and the high stress distribution moved from the anterior to the posterior position with posterior tilting from 0° to 10°. With loosening, the stress distribution was high at the proximal tibial medial cortex in the valgus alignment model. Conclusions: To reduce UKA complications, the present findings indicate that the optimal alignment of the tibial implant is at the middle position on the coronal plane, with a posterior inclination similar to the original inclination on the sagittal plane. [ABSTRACT FROM AUTHOR]

Background: Hip endoprosthesis is one option for the treatment of displaced femoral neck fractures and avascular necrosis of the femoral head. Few reports are available describing acetabular cartilage metabolism after endoprosthesis surgery of the hip. The purpose of this study was to compare the biological effects on cartilage between cobalt-chrome (Co-Cr) and alumina ceramic heads wherein the cartilage articulates directly. Methods: We used the acetabular cartilage from six hips of three immature crossbred pigs to examine the effects on cytokines, the amount of hyaluronic acid (HA), and cartilage mRNA expression of ceramic head and Co-Cr head endoprosthesis. Mechanical loading of materials of Co-Cr and ceramic heads was performed on the acetabular cartilage in culture media as an organ culture model. Thereafter, protein levels of cytokines (MMP-1, 3, TNF-alpha (α), Interleukin (IL)-1 alpha (α), and IL-1 beta (β)) and the amount of HA were measured from the culture media. Cartilage RNA extraction was performed, and quantitative reverse transcriptase-polymerase chain reaction was performed with primer sets for type I, II, and III collagens; aggrecan; MMP-1, 3, 13; TNF-α; and IL-1 α, IL-1 β. Results: Protein level of IL-1 β and amount of HA in the Co-Cr group were significantly higher than those of the Ceramic group. Type II collagen mRNA expression in the Ceramic group was significantly higher than in the Co-Cr group. IL-1 β mRNA expression was significantly higher in the Co-Cr group than in the Ceramic group. Conclusions: The present study showed that ceramic bipolar produces smaller adverse effects on cartilage cells compared to Co-Cr bipolar. These results could have significant implications for implant usage not only in hip joints, but also in other joints, including the shoulder, talus and radial head. [ABSTRACT FROM AUTHOR]

Supracondylar humerus fractures are the most common upper limb injury in children, but the incidence of flexion-type fractures is relatively low. Herein, we report the clinical results for three children with Gartland type II flexion-type supracondylar humeral fractures treated by closed reduction and percutaneous pinning. From April 2004 to March 2020, 102 children with supracondylar humeral fractures underwent surgery at our hospital and related institutions. Four had a flexion-type supracondylar humeral fracture (3.9%). Three patients (1 boy and 2 girls) with Gartland type II flexion-type supracondylar humeral fractures were followed for more than 12 months. The patients were treated by closed reduction and percutaneous pinning. Age was 7-13 years at the time of injury, and the duration of postoperative follow-up was 12-16 months. In one case, ulnar nerve paresis was observed as a preoperative complication. After performing closed reduction, percutaneous Kirschner wire cross-fixation was performed. Subsequently, long upper limb cast fixation was carried out for 4 weeks postoperatively. One patient developed preoperative nerve paralysis but recovered in approximately 3 months, without postoperative complications such as infection, nerve paralysis, or cubitus varus or valgus deformity. Flynn’s criteria results were excellent for two patients and good for one patient. To maintain anatomical reduction of the fracture fragment, closed reduction using a traction table and percutaneous steel wire fixation are useful for treating flexion-type supracondylar humerus fractures in children with Gartland type II fractures. [ABSTRACT FROM AUTHOR]

Background: Management of transcondylar fracture of the humerus in older adults remains a challenging issue in trauma surgery. Both single- and double-plate fixation are used, and the best procedure is yet to be determined. This retrospective study evaluated and compared the clinical and radiological outcomes of single- and double-plate fixation for transcondylar humeral fracture. Methods: This study included older adults (age >65 years) with transcondylar fractures of the humerus (AO/OTA 13A2-3; transverse, transmetaphyseal fracture) treated at our hospital between 2002 and 2019. The patients were divided into two groups based on the fixation procedures they underwent, namely, single (group S) or double (group D) locking plate osteosynthesis. Postoperative outcomes were investigated. Results: Group S and group D comprised 11 (11 women) and 17 (2 men; 15 women) patients, respectively. In group S, the elbow was immobilized in a long-arm cast or splints for 2 weeks to prevent early displacement of fracture. Residual numbness of the ulnar digits was observed in two patients in group S and in nine patients in group D. No significant difference was noted between the two groups in the ratio of loss of reduction, loosening of the medial screw, ulnar nerve disturbance, or clinical outcomes. The ratio of elbow contracture significantly differed between 2 groups. The elbow flexion angle was significantly lower in group S. Conclusions: Open reduction and internal fixation with a double plate appears to be the optimal choice for early postoperative mobilization and maintenance of flexion and arc of the elbow joint. [ABSTRACT FROM AUTHOR]

The article presents case studies of two patients with dorsal radiocarpal dislocation and radial styloid fractures, treated with arthroscopy-assisted reduction and internal fixation. It is reported that wrist arthroscopy was used to assess intra-articular fractures and ligamentous tears, enabling accurate reduction and ligament repair. It is also noted that the procedure resulted in satisfactory outcomes, suggesting its effectiveness for such injuries.

The article examines nurses challenges in caring for patients with bone metastases and the impact of Bone Metastasis Cancer Board participation on nursing practice. It emphasizes improved symptom management, psychosocial support, and care coordination through multidisciplinary collaboration. It underscore the need for enhanced communication and knowledge exchange among nurses, leading to better patient outcomes.

Background: Bone metastases can cause severe pain, pathological fractures, and spinal cord paralysis, which interrupt treatment for tumors and cause patients to be bedridden. In this study, we aimed to clarify therapists' problems in the rehabilitation of patients with bone metastases and their countermeasures using the results of questionnaires to therapists and recommend safer and more rational rehabilitation. Methods: Questionnaire forms were sent to 21 therapists in our department. The questionnaire was conducted anonymously about problems during the rehabilitation procedure such as the risk of pathological fractures and paralysis. Results: All of the therapists had strong anxiety (43%) or some anxiety (57%) about the risk of pathological fractures or paralysis during a procedure. However, no therapist responded that this had ever occurred. Many of the respondents had changed a procedure to a milder one (81%) or interrupted a procedure (48%) due to the patient's condition on the day. Therapists chose many options to reduce the risk of pathological fractures and paralysis during the procedure. Among them, "pre-rehabilitation referral to orthopedic surgeon" (86%), "consultation with a doctor about changes in patient's symptoms and findings" (86%), and "regular cooperation between multiple occupations" (67%) were frequently selected. Conclusions: Our questionnaire survey of therapists regarding the treatment of patients with bone metastases found that there was considerable anxiety about the risk of pathological fractures and paralysis during treatment. Our findings suggest that it is necessary to strengthen cooperation with multiple occupations, especially those in the orthopedic field. [ABSTRACT FROM AUTHOR]

Posttraumatic malunion with combination of angular, rotational, and shortening deformity of the proxi)mal phalanx may cause scissoring of a finger and impairment of hand function. Cosmetic disfigurement and severe dysfunction of fingers require surgical correction, most often via open corrective osteotomies and rigid fixation with a plate or screws. However, such an approach requires a longer incision, inevita)bly results in a scar, and has a higher potential for extensor tendon adhesion. Also, abruption of the pe)riosteum and plating of the phalange requires longer bone healing time. Thus, we devised a technique of minimally invasive correction of phalangeal malunion using an external mini-fixator. We presented representative three cases of malunited fractures of phalanges treated with the Ilizarov mini-fixator in adolescence and review reports of similar cases. The usage of Ilizarov mini-fixator provided excellent outcomes for posttraumatic malunion of three fingers. [ABSTRACT FROM AUTHOR]

Background: In vivo three-dimensional (3D) motion under weight-bearing conditions was analyzed postoperatively in medial pivot cruciate-substituting (CS) knee systems with fixed and mobile inserts. Methods: Tibiofemoral knee kinematics during squatting were captured with X-ray fluoroscopy for 4 patients in each cohort. The 3D motion of implants was analyzed with KneeMotion motion analysis software (LEXI Corporation; Tokyo, Japan). In addition, anterior-posterior (AP) movement of the distalmost points and the angle of axial rotation of the femoral component on the tibial component were assessed in both cohorts. Results: Mean AP movement of the femoral component on the tibial component was 3.8±0.5 mm on the medial side and 9.5±0.5 mm on the lateral side in the cohort with fixed prostheses and 5.9±2.1 mm on the medial side and 10.0±2.5 mm on the lateral side in the cohort with mobile prostheses. The mean angle of axial rotation of the femoral component on the tibial component was 14.4±1.1 degrees and 8.2±2.7 degrees of external rotation for fixed knees and mobile knees, respectively. Conclusions: Postoperative motion analysis confirmed that fixed and mobile CS implants, which have a similar design, guided medial pivot motion under weight-bearing conditions. However, motion differed between these implant types after mid-flexion: bicondylar rollback after medial pivot motion was noted in the mobile cohort. [ABSTRACT FROM AUTHOR]

We present a case of solitary chondrosarcoma arising from the proximal phalanx of the ring finger in an elderly man. The chondrosarcoma developed over a period of 14 years, during which the phalanx became progressively more deformed. Several radiographic investigations were carried out, but the patient declined further suggested diagnostic examinations (computed tomography, magnetic resonance imaging, biopsy). Eventually, the lesion became significantly enlarged, and radiographs showed osteolytic lesions in the phalangeal bone. Ray amputation of the finger was required to establish a wide resection of the chondrosarcoma. Most osteochondral tumors arising from the phalanges are benign tumors such as enchondromas, but primary chondrogenic malignant bone tumors (chondrosarcomas) occasionally occur. Chondrosarcoma of the phalanx is difficult to distinguish from enchondroma of the phalanx, because histological investigations of the two neoplasms often produce similar findings. Even with a combination of clinical, biopsy, and imaging findings, differentiating these neoplasms is still challenging, because the characteristic clinical and radiological features of chondrosarcoma do not appear until it becomes aggressive and starts to cause destructive changes. Once that happens, radical expanded resection of the tumor is essential. Therefore, longstanding enchondroma-like lesions should be actively treated in elderly patients, even if a definite diagnosis of chondrosarcoma cannot be made. [ABSTRACT FROM AUTHOR]

Background: The pedicle sign is a radiographic indicator of spinal metastases. However, it is not only the pedicle sign that is important in radiographic diagnosis of bone metastases. In the present study, the radiological features of symptomatic spinal metastases in patients without the pedicle sign were retrospectively examined. Materials and Methods: Among 186 patients with symptomatic spinal metastases who visited our department between January 1, 2011, and December 31, 2017, 64 without the pedicle sign and with avail- able computed tomography (CT) and magnetic resonance imaging (MRI) data in the first visit were en- rolled and their data were analyzed. One author evaluated radiographs for findings suggestive of spinal metastases, CT to assess bone destruction, and MRI to evaluate the extent of lesions. Clinical vari- ables were also examined and compared between patients with and without bone changes on radiography. Results: Bone changes strongly suggesting bone metastasis, other than the pedicle sign, were observed in 31 out of 64 patients: bone cortical disappearance in 20, increased radiolucency of the central area in the vertebral body in 8, an irregular osteoblastic change in 5, and asymmetrical vertebral collapse in 10. An analysis of CT data revealed that intertrabecular, mildly osteolytic, and mildly osteoblastic types were more frequent in patients without any changes suggestive of bone metastases on radiographs. Conclusion: Radiographic findings other than the pedicle sign are useful for diagnosing bone metastases. The key to a radiographic diagnosis of spinal metastases is to pay attention to changes in the bone cortex of all vertebral components on radiographs in addition to the pedicle [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus infection of the upper extremities is uncommon. However, M abscessus can cause severe chronic tenosynovitis, and delayed diagnosis may result in poor outcomes. We describe an unusual clinical case of purulent flexor tendon synovitis followed by subcutaneous tendon rupture due to M abscessus infection in a patient with diabetes mellitus. A 76-year-old man presented to our hospital with painful, erythematous swelling over his left fourth finger. On physical examination, the left fourth finger was swollen and reddish, with persistent exudate from the surgical scar. The left elbow was also swollen and reddish with persistent discharge, which was consistent with olecranon bursitis. The patient was unable to flex his left fourth finger, and the passive range of motion of the finger was also restricted. The physical examination findings and patient history suggested purulent flexor tendinitis. His infection healed after radical debridement of necrotic tissue and administration of antibiotics effective against M abscessus. Third-stage flexor reconstruction restored the function of the fourth finger. The combination of surgical debridement and chemotherapy was the most effective treatment for mycobacterial tenosynovitis. This case shows that M abscessus can cause chronic severe purulent tenosynovitis and flexor tendon rupture after tendon surgery. Although early diagnosis and combination treatment with debridement and chemotherapy might improve outcomes by limiting the severity and duration of damage to the flexor synovial system, late-presenting patients require combined radical debridement of necrotic tissue and aggressive chemotherapy followed by staged flexor tendon reconstruction. [ABSTRACT FROM AUTHOR]

Background: This study evaluated clinical outcomes of elderly adults with coronal shear fractures (CSFs) of the distal humerus treated by open reduction and internal fixation (ORIF). Methods: Between April 2002 and March 2019, data from eight elderly patients (76.3 ± 5.1 years) with CSFs of the distal humerus were analyzed retrospectively. Postoperative complications, range of motion of the elbow joint, and functional elbow scoring (Mayo Elbow Performance Score; MEPS) were assessed. Results: The mean follow-up duration was 23.6 ± 13.9 months. CSFs were treated by a buried implantable headless screw or Kirshner wires or bioresorbable screw with/without lateral locking plates. There were no superficial or deep infections or elbow joint instability. Seven patients obtained fracture healing, but one patient exhibited nonunion. Osteochondritis dissecans was present in one patient. Three patients had a step-off deformity (>2 mm) of the articular surface. Two patients exhibited collapse of the fractured articular surface. A patient with severe comminution of both the capitellum and trochlea exhibited collapse of the entire articular surface, with osteonecrosis of the capitellum and trochlea. Mean range of motion of the elbow was 116.3±12.7° of flexion and -28.8±14.1° of extension. The mean MEPS was 78.8±10.2 points, representing patients scored as excellent (n=1), good (n=3), and fair (n=4). Conclusions: ORIF yielded satisfactory outcomes for elderly adults with noncomminuted CSFs of the distal humerus. However, treatment of comminuted articular fracture fragment and complex posterior fracture remains challenging. [ABSTRACT FROM AUTHOR]

Background: Severe varus osteoarthritic knee has possibility of medial structure contracture. There is no report concerning the relationship between severity of varus deformity and contracture of medial structure. We aimed to reveal a threshold angle that could be corrected in proportion to the width of medial osteophyte removal, and to examine correction differences between larger and smaller than the threshold angle in total knee arthroplasty. Methods: This study included 27 varus osteoarthritic knees scheduled for total knee arthroplasty (TKA). Each knee was measured the hip-knee-ankle angles (HKA) using a navigation system, at maximum extension, 30 ° and 60° flexion before and after osteophyte removal, with and without external 10 N-m valgus torque loads. Subsequently, resected osteophyte widths were measured. Mean correction angle per 1 mm osteophyte removal was calculated, and the threshold angle was calculated using the receiver operating characteristic curve. HKA differences were compared against larger and smaller deformity than the threshold angle. Results: Mean osteophyte width was 7.1±2.20 mm. Osteophyte removal produced a mean 3.1° correction, which equaled a 0.4° correction per 1 mm osteophyte width removal. The varus deformity threshold angle was 9.5°, however, when comparing the groups larger and smaller than the threshold, there were no significant differences in HKA differences between each step and flexion angle. Conclusions: The threshold angle for expected correction with medial osteophyte removal was 9.5°. However, with no differences in correction between those with larger or smaller than this angle, medial structure contracture seemed to be unrelated to severity of deformity. [ABSTRACT FROM AUTHOR]

Ganglion cysts are common benign lesions in the hand and wrist. However, intratendinous ganglion cysts are uncommon. We present a case of intratendinous ganglion cyst in the extensor pollicis longus (EPL) tendon of the right hand of a 73-year-old woman. The subcutaneous mass moved in concert with the EPL tendon in her right thumb. Magnetic resonance imaging showed a space-occupying lesion in the EPL tendon. Biochemical and hemato-immunological examinations ruled out diabetes, rheumatoid arthritis, and other connective tissue diseases. She reported motion pain during thumb extension, for which she desired surgery. An intratendinous cyst was identified intraoperatively within the tendon substance of the EPL, in which a part of the cyst was herniated into a slit in the tendon substance, just distal to the extensor retinaculum, without notable proliferative synovial tissue. The EPL tendon was opened longitudinally, and a cystic lesion was enucleated. Pathological examination showed that the cyst wall consisted of fibrous tissue with degeneration and no epithelial lining. Postoperative recovery was uneventful. Six months after surgery, the patient had no residual pain and no cyst recurrence. The rarity of intratendinous ganglion cysts makes diagnosis and treatment challenging. Because intratendinous ganglion cysts and associated synovitis frequently weaken the structure of affected tendons, prompt diagnosis and surgical excision are necessary. [ABSTRACT FROM AUTHOR]

Background: Obtaining well-balanced soft tissues is important to achieve natural knee kinematics after total knee arthroplasty (TKA). In conventional procedures, soft tissue balance is evaluated with spacer blocks or lamina spreaders. However, the evaluation depends on the surgeons' experience and is not quantitative. This study aims to measure the mechanical properties of knee soft tissue with a new ligament balancer and to determine the optimal distraction force for evaluating tibiofemoral joint gaps in TKA. Methods: This study included 30 consecutive patients with medial knee osteoarthritis who were scheduled to undergo posterior stabilized TKA. The mean age of patients was 73 ± 9.6 years at the time of surgery, and the mean hip-knee-ankle angle was 13.1 ± 6.5° in varus. After distal femoral and proximal tibial resections, the tibiofemoral joint gaps under several distraction forces were measured in extension and at 90° flexion. The load-displacement curves in extension and flexion were drawn with these data, and the stability range, which was defined as the shift range from the toe region to the linear region in the curves, was calculated. Results: The stability ranges were 160 Newtons (N) in extension and 140 N in flexion. Conclusions: These displacement forces were considered optimal for evaluating tibiofemoral joint gaps during surgery and ensuring knee stability after TKA. [ABSTRACT FROM AUTHOR]

Background: This study sought to assess the efficacy of a deep-tissue thermal therapy system with a resonant cavity applicator (DTT-RCA), which safely heats deep joint tissue for treating osteoarthritis (OA) of the knee. Methods: Two groups of participants were recruited. The DTT-RCA group comprised 20 knees. Kellgren-Lawrence (K-L) grade was I and II in 8 knees (DTT-RCA I/II group) [mean age 73.3 years (standard deviation 11.4)], III and VI in 12 knees (DTT-RCA III/IV group) [75.4 (8.6) years]. The control group comprised 13 knees [68.2 (10.8) years]. K-L grade was I in 7 knees and II in 6 knees. This group received exercise therapy. The DTT-RCA I/II group and the control group were imaged by MRI T2 mapping at baseline and 6 months to determine the area of cartilage degeneration. Results: Visual Analogue Scale improved only in the DTT-RCA I/II post-intervention (p < 0.01). Japanese Orthopedic Association knee rating scores (DTT-RCA I/II: p < 0.01, control group: p < 0.01), the Japanese Knee Osteoarthritis Measure (DTT-RCA I/II: p < 0.05, control: p < 0.01), and the Knee injury and Osteoarthritis Outcome Score (DTT-RCA I/II: p < 0.01, DTT-RCA III/IV: p < 0.05, control: p < 0.01) post-intervention. The magnitude of change did not differ significantly between the three groups. The area of cartilage degeneration did not change significantly post-intervention in the DTT-RCA I/II group, not even relative to the control group. Conclusions: This was the first study to test a DTT-RCA system in patients with knee OA. The system reduced the clinical symptoms of knee OA and could potentially be effective for conservative therapy. [ABSTRACT FROM AUTHOR]

Posttraumatic malunion of the phalanx with rotational deformity may cause crossing of the finger and impair hand function. Cosmetic disfigurement and severe dysfunction of the fingers require surgical correction, most often via open corrective osteotomies and rigid fixation with plates. However, such an approach requires a longer incision, inevitably results in a scar, and has a higher potential for extensor tendon adhesions, which result in extension lags. In addition, abruption of the periosteum and plating of the phalanges require longer bone healing. This report describes the straightforward, minimally invasive correction of phalangeal malunions with a mini-external fixator. In this procedure, a digital block of the affected finger can be performed. The fully flexed position of all fingers provides accurate correction of phalangeal malunions. Although treatment of phalangeal malunions remains challenging, the present procedure is an alternative solution for phalangeal malunions. [ABSTRACT FROM AUTHOR]

Background: To restore neutral limb alignment in total knee arthroplasty (TKA), the procedure usually starts with removing osteophytes in varus osteoarthritic knees. However, the exact effect on alignment correction is unknown. The purpose of this study was to determine the effect of osteophyte removal alone during TKA for varus knees on correction of limb alignment on the coronal plane. Methods: Fifteen knees with medial osteoarthritis and varus malalignment scheduled for TKA were studied. After registration in a navigation system, each knee was tested at maximum extension, and at 30, 40, and 60 degrees of flexion, before and after osteophyte removal. External loads of 10 Nm valgus torque at each angle and in both states were applied. Later, the widths of the resected osteophytes were measured. Results: The average preoperative hip-knee-ankle angle was -14.2 degrees. The average width of osteophytes was 7.6 mm in the femur and 5.3 mm in the tibia. Angle corrections after osteophyte removal were 3.4 degrees at maximum extension, 3.4 degrees at 30 degrees flexion, and 3.6 degrees at 60 degrees flexion; the difference was significant for all angles. There was a positive correlation between osteophyte width and the degree of angle correction at 30 degrees. Conclusion: At 30 degrees of knee flexion, osteophyte width was correlated with the degree of angle correction on the coronal plane in TKA. The degree of angle correction per 1 mm of width of removed osteophytes was 0.4 degrees. [ABSTRACT FROM AUTHOR]

Background: Total knee arthroplasty (TKA) aims to correct the rotation, as well as the alignment and articulation, of the osteoarthritic knee. We hypothesized that, in addition to improving knee kinematics, TKA affects hip rotational movement. The objective of this study was to evaluate variation in lower extremity alignment and hip rotational range of motion (ROM) after TKA. Methods: A total of 47 patients (53 knees) with primary varus knee osteoarthritis who were scheduled for primary TKA at our center were enrolled. Hip rotational ROM was measured with the patient in supine position with 90° flexion of the hip and knee before and 3 weeks after TKA. Plain radiography and computed tomography were used to compare variations in tibial axis alignment and femoral axis alignment after bone resection, which was defined as changes in the joint lines of the distal femur and the proximal tibia. Results: Average internal ROM, and the sum of internal and external hip rotational ROM, increased significantly; however, external hip rotational ROM did not significantly differ after TKA. Imaging findings showed that the axis of the lower leg externally rotated by 2.5°, with a 4° internal rotation of the distal femur and a 6.5° correction of the varus deformity. Conclusion: TKA changed the neutral position of hip rotational movement and increased hip rotational ROM. [ABSTRACT FROM AUTHOR]

Background: Methotrexate (MTX) is still the first-choice drug for the treatment of rheumatoid arthritis (RA). In Japan, MTX doses of up to 16 mg/week were approved in 2011. In this study, we aimed to identify the gene polymorphisms that can predict therapeutic effects of MTX in Japanese patients in current clinical settings. Methods: This study involved 171 patients with RA (all Japanese nationals, age 63.5±10.0 years) who had been administered MTX. The analyzed polymorphisms included 82 single nucleotide polymorphisms (SNPs) involved in the MTX pharmacological pathway or in the pathogenesis of RA. Responders were patients who showed high sustained remission or low disease activity with MTX or conventional disease-modifying anti-rheumatic drugs (DMARDs) treatment beyond 6 months. Non-responders were patients who showed moderate or high disease activity, who were prescribed biological DMARDs. A logistic model was constructed with Responder/Non-responder as the target variable, and minor allele frequency was set as an explanatory variable. Results: None of the 82 SNPs targeted for analysis met the Bonferroni significance threshold of 6.098x10-4. However, we identified SLCO1B1 rs11045879 as an SNP that might yield significant results if the number of patients were to be increased (P=0.015). Conclusions: The rs11045879 minor allele in the SLCO1B1 gene is a potential predictor of non-responders to MTX treatment among Japanese RA patients. In future collaborative research, we will investigate whether the association with SLCO1B1 polymorphism is significant by performing statistical analysis with a larger study population. [ABSTRACT FROM AUTHOR]