According to the official arthroplasty registries the rate of revision after total knee arthroplasty (TKA) in Japan is lower in comparison to Australia, New Zealand, or the United States. The rate of infection after TKA is about 1% and it is almost the same in the aforementioned countries. According to the previous reports, the rate of infection after TKA for rheumatoid arthritis of the knee has been 1.6 to 3 times higher compared to TKA for osteoarthritis of the knee.

 The document “Proceedings of the International Consensus Meeting on Periprosthetic Joint Infection” was presented as a guide to clinicians who treated patients with periprosthetic joint infection (PJI) in 2013. This definition was reported to have high specificity and moderate sensitivity for PJI. In 2018, new diagnostic criteria were developed, and that showed high sensitivity and specificity for PJI.

 Gram staining of joint fluid is considered to be of limited value in the diagnosis of septic arthritis or infection after TKA owing to its low sensitivity to identify bacteria. We evaluated the sensitivity of the Gram stain of aspirated joint fluid in patients with septic arthritis or infection after TKA in our hospital. The sensitivity of Gram staining of joint fluid was 96%.

 Gram staining of aspirated joint fluid appears to be a reliable method for the diagnosis of knee joint infection.

Background: Previously, we explained the correlation between the Takakura-Tanaka classification of radiographic staging and bone marrow edema (BME). We illustrated the feasibility of estimating the BME onset in the talocrural joint based on the radiographic alignment to elucidate the pathophysiology of ostearthritis (OA) using magnetic resonance imaging (MRI). This study focused on the subtalar joint and investigated the correlation between talar lateral process impingement (TLPI) and alignment of the foot and ankle based on radiographic findings. In addition, we extensively investigated patterns of BME.

Methods: We examined 30 feet of 30 patients who were diagnosed with ankle OA and who underwent MRI at our hospital. We assessed alignment radiographically by evaluating the tibial anterior surface angle (TAS), tibial lateral surface angle (TLS), lateral talo-first metatarsal angle (LTMT), and the tibial axis-talar ratio (T-T ratio). Furthermore, we assessed the BME frequency in the talocrural, subtalar, and Chopart joints and their correlation with TLPI in MRI and plain radiograph results.

Results: The TLPI onset increased with the severity of the Takakura-Tanaka classification stage. The TLPI (+) group exhibited a significantly lower TLS angle, but a significantly higher LTMT angle. Moreover, it was associated with TLPI and BME occurrence in the posteromedial side of the talocrural joint (area 3’). Furthermore, the disease group was categorized into three stages according to the occurrence pattern of TLPI and area 3’. The frequency of BME also increased as the stage increased.

Conclusion: This study has revealed that there is an association with BME occurrence in TLPI and area 3’; this result could be a risk factor to generate extensive BME. Consequently, this novel finding indicates that a potential prognostic tool of the severity of clinical symptoms can be used.

Objective: The surgical results of the AVANTA artificial finger joint replacement by dorsal approach for osteoarthritis of proximal interphalangeal (PIP) joint of the hand was examined.

Methods: The subjects were 13 patients (14 fingers) who underwent surgery from 2014 to 2018 and were observed for a minimum of 10 months. The average age at the time of surgery was 68 years old (48 to 80 years old); 11 of them were women and two of them were males. The number of affected fingers was five middle fingers (two left and three right), seven ring fingers (six left and one right), and two little fingers (two left). We observed a high incidence of left ring fingers. We also operated on multiple fingers on the same hand (one case) and with the ring and middle fingers on the left. The average follow-up period was 23 months (10 to 56 months). Surgery was indicated for patients who had severe pain, severely restricted joint movement, and impaired activities of daily living (ADL). At operation, an arcuate incision on the dorsal side of the PIP joint exposed the extensor tendon longitudinally in addition to the joint. The head of the proximal phalanges were resected with a bone saw, and the middle phalangeal base was resected with Riuel, then reamed under radiographic imaging. After that, AVANTA artificial finger joints were then inserted.

 Postoperative range of motion (ROM) exercise commenced with ‘buddy’ taping to the adjacent finger from the next day after surgery.

Results: Pain disappeared in all cases. According to the Mayo Clinic score, surgical results were good in 10 cases, fair in four cases and poor in no cases. There were no cases with implant breakage or reoperation.

Conclusion: AVANTA artificial finger joint replacement by the dorsal approach is relatively easy to perform and stable results are obtained after surgery. As our follow-up periods were short, we plan a longer follow-up period for future cases.

Objective: While good objective outcomes have been reported after total knee arthroplasty (TKA), 20% of patients are dissatisfied with the procedure. Psychiatric problems have been the recent focus of such dissatisfaction. The Brief Scale for Psychiatric Problems in Orthopaedic Patients (BS-POP) was developed in Japan. The purpose of the study was to assess the influence of psychiatric problems on clinical outcomes following primary TKA in Japanese patients with knee osteoarthritis.

Methods: A total of 173 patients were recruited in this study. They had a psychiatric evaluation using BS-POP preoperatively, and postoperative clinical assessments at three and six months after TKA. Subjective outcomes were evaluated using disease-specific and patient-derived quality of life measures, the Japanese Knee Osteoarthritis Measure (JKOM), and degree of satisfaction. In addition, objective outcomes were evaluated using the Knee Society score (KSS), Timed Up and Go (TUG) test, and range of motion of the knee. These clinical outcomes were compared between TKA patients with and without psychiatric problems.

Results: JKOM, KSS, TUG, and flexion contracture were not significantly different between the patient groups. Although patients without psychiatric problems had significantly higher knee flexion angles at three and six months after TKA, they demonstrated lower satisfaction three months after the procedure.

Conclusion: Our data indicate that psychiatric problems do not influence clinical outcomes after primary TKA. Since dissatisfaction after TKA is a multifactorial problem, we should continue to focus on the relationship between psychiatric problems and clinical outcomes, as many reports have demonstrated a significant correlation.

Objective: There have been many mid- or long-term longitudinal assessments using subjective or patient self-reported outcome scales, which are useful for patient education. However, short-term information is often necessary in clinical practice because patients are anxious to return to activities of daily living or complete functional recovery shortly after total knee arthroplasty (TKA). This in turn may lead to better patient satisfaction. If we can provide patients with short-term information and ameliorate concerns about their delayed recovery, their anxiety and dissatisfaction may be reduced. Therefore, the purpose of the study was to clarify longitudinal subjective and objective outcomes up to 12 months after primary unilateral TKA for varus knee osteoarthritis (VKOA).

Methods: We enrolled 92 patients who underwent unilateral primary TKA for VKOA (12 males and 80 females). The average age at the time of operation was 72.7 years (range, 60-87 years). Clinical evaluations were performed preoperatively and postoperatively at four time points: 3 months (3M), 6 months (6M), and 12 months (12M). Subjective evaluations were performed using a disease-specific and patient-derived quality of life measure: the Japanese Knee Osteoarthritis Measure, visual analogue scale for pain, and degree of satisfaction. For objective evaluations, we used the Knee Society score, the Timed Up and Go (TUG) test, and range of motion of the knee.

Results: All scales except for TUG showed significant improvement between pre- and post-3M, 3M and 6M, and 6M and 12M measures, respectively. TUG showed significant improvement between pre- and post-3M and 3M and 6M, respectively. The dissatisfaction rate was 25.0% at three months after TKA, but improved to 18% at six and 12 months after TKA.

Conclusion: Measures of subjective and objective evaluations following unilateral primary TKA for VKOA improved for 12 months post-operatively.

Objectives: This study retrospectively investigated the short-to mid-term outcome of primary legacy constrained condylar knee (LCCK) and rotating hinge knee (RHK) prosthesis in patients with rheumatoid arthritis (RA) having severe varus/valgus deformity, instability and/or bone loss.

Methods: Between January 2000 and December 2016, LCCK and RHK prostheses had been performed for RA amelioration in 16 knees of 12 patients. There was a postoperative follow-up minimum of 1 year. Finally, 14 knees of 10 patients who underwent LCCK and two knees of two patients who underwent RHK were analyzed respectively. The average follow-up duration was 5.7±2.3 years, all patients were female, and the average age and RA duration at the time of surgery was 59.9±9.5 years old and 23.9±13.7 years, respectively. The clinical outcome was analyzed by the Knee Society Score (KSS) in addition to function preoperatively and at the final visit. Imaging outcome was investigated by the femoral tibial angle (FTA), and radiolucent lines both pre- and postoperatively.

Results: KSS knee score (8.0±9.1→95.4±4.3), function score (13.8±16.6→55.9±18.4), and radiographic FTAs (161.7±18.6→173.4±1.1) were improved after operation. Non-progressive radiolucent lines around components were seen in nine knees (56.3%). No infection or reoperation after LCCK and RHK have so far been observed in this study.

Conclusion: Primary LCCK and RHK prosthesis in patients with RA were achieved with excellent short-to mid-term clinical and radiographic results.

Objective: The aim of this study was to investigate characteristics of patients who required additional extensor tenolysis at the wrist level during metacarpophalangeal (MCP) joint arthroplasty for rheumatoid arthritis.

Patients and Methods: 255 fingers (excluding thumbs) of 72 hands in 57 patients who underwent silastic arthroplasty for MCP joints using AVANTA^® from 2009 to 2017 were included in the retrospective study. The mean age was 61.8±11.9 years, and the duration of disease was 25.2±17.2 years at the time of surgery. We investigated the number of patients who required extensor tenolysis at the wrist. Then, the relationship between the presence of tenolysis (tenolysis (+) group / tenolysis (−) group) and the history of wrist surgery was analyzed. We also compared the clinical results between the two groups with regard to pre- and postoperative range of motion (ROM) of the MCP joint, HAND 20 and DASH.

Results: In 12 hands (16.7%), additional extensor tenolysis at the wrist was required. Of 15 hands with previous wrist surgeries, extensor tendon adhesion at the wrist level occurred in six of them. The rate of cases which required extensor tenolysis was significantly higher in cases with a history of wrist surgery (P<0.01). ROM of MCP joints significantly improved irrespective of the presence of extensor tendon adhesion after MCP joint arthroplasty (P＜0.01). There were no significant differences in the improvement of ROM of MCP joints, HAND 20, and DASH between the tenolysis (+) group and the tenolysis (−) group, respectively. (P＜0.05).

Conclusion: In cases with a history of wrist surgery, extensor tenolysis at the wrist joint was required more frequently (40%). In RA cases with volar dislocation or subdislocation of the MCP joint, preoperative diagnosis of extensor tendon adhesion at wrist joint is often difficult to predict. However, the results of the current study showed that equivalent results were obtained after MCP joint arthroplasty by additional extensor tenolysis.

Objective: The purpose of this study was to investigate the factors influencing the alignment of the lower extremities in patients with rheumatoid arthritis.

Methods: The study included 83 knees in 66 patients with rheumatoid arthritis (RA) who underwent primary TKA between June 2010 and March 2018 inclusive at our hospital. Patients included six men and 60 women, with a mean onset of RA at 53.1 years and the mean duration of RA of 14.5 years, respectively. They were classified into three groups (valgus, neutral, varus) by femorotibial angle (FTA). We investigated the relationship between the alignment of the lower extremities and the following factors: gender, body mass index, age at onset of RA, era of onset of RA (before or after the year 2000), duration of RA, rheumatoid factor, anti-cyclic citrullinated peptide antibody, osteoporosis, use of glucocorticoid agents, methotrexate and biologic therapy, C-reactive protein, matrix metalloproteinase-3, and DAS28-ESR score. We compared these factors among the three groups.

Results: Before TKA, the FTA was distributed between 150 and 203º (mean, 178.1º). Varus deformity was observed in 50.6% of the patients, valgus deformity in 26.5%, and neutral in 22.9%, respectively. Onset of RA of the varus group occurred later than in the neutral and valgus groups. In other words, patients with eldery onset RA (EORA) showed varus deformity of the knee (VDK), whereas juvenile onset RA (JORA) demonstrated valgus or neutral changes. Forty percent of patients whose onset of RA was before the year 2000 showed VDK, whereas only 16.7% of patients whose onset of RA occurred after the year 2000 showed such changes. In patients whose onset of RA was before the year 2000 showed a decreased frequency of VDK compared to after the year 2000. In addition, the frequency of varus and neutral knee changes increased.

Conclusion: Patients with EORA showed varus deformity of the knee, whereas patients with JORA showed valgus or neutral changes. Recently, the frequency of VDK has decreased compared to before the year 2000, whereas the frequency of varus knee and neutral knee changes have increased.

Objective: It is increasingly important to reproduce the patient's native joint line orientation when performing unicompartmental knee arthroplasty (UKA). Posterior tibial slope (PTS) also plays an important role in achieving excellent postoperative knee function. In preoperative planning, plain lateral radiographs have been used to evaluate native PTS (XP-PTS). However, it is unclear which part of the tibial articular surface the XP-PTS indicates, and it is not easy to accurately reproduce the intraoperative XP-PTS angle. The purpose of this study was to explore the useful intraoperative landmark for patient's native PTS during medial UKA.

Methods: Preoperative computed tomography (CT) data from 49 lower limbs of 40 Japanese patients who were to undergo scheduled medial UKA were used. Five PTS angles were obtained from different parts of the tibial surface; PTS in the center of the medial and lateral plateau, the inner one quarter of the medial plateau, and in the peri-medial and lateral tibial eminences, were measured using 3-dimensional preoperative planning software. Then, the XP-PTS angle was reconstructed from the same CT data and were measured and compared with those five PTS angles.

Results: The mean XP-PTS was 7.6°±3.0° (± SD). The PTS in the center of the medial and lateral plateaus were 8.9°±3.2° and 7.0°±2.8°, respectively. The PTS in the inner one quarter of the medial plateau was 7.6°±3.4°, and in the peri-medial and lateral tibial eminences were 9.9°±3.4° and 6.3°± 3.4°, respectively. The strongest positive correlation was observed between the XP-PTS and the PTS in the inner one quarter of the medial plateau (R＝0.78, P<0.001).

Conclusion: The PTS obtained from preoperative plain radiographs represented the PTS in the inner one quarter of the medial plateau. During operation, this part possibly be visible even before the femoral posterior resection by external rotation of the leg and removal of the medial meniscus. It can be an intraoperative landmark for native PTS during medial UKA.

 Cases of extensor mechanism failure after total knee arthroplasty (TKA) have often been reported. However, they used standard sutures and did not describe about the articular capsular suturing method. Our aim is to report two cases of extensor mechanism failure with barbed suture in patients undergoing TKA.

 The patients did not have a history of diabetes mellitus, autoimmune diseases or use of corticosteroids. TKAs were performed on the right knees of both patients for osteoarthritis and STRATAFIX^® was used for suturing of the articular capsules. No intraoperative adverse events occurred.

Case 1: An obese 77-year-old woman with a body mass index (BMI) of 33.5kg/m². A medial parapatellar approach was undertaken in the primary TKA and a FINE^® PS type prosthesis was used. However, the patient fell on the floor the next day, and the medial retinaculum and quadriceps tendon of her right knee ruptured, so a repair of the extensor mechanism was performed.

Case 2: A 73-year-old woman with a BMI of 25.1kg/m². A subvastus approach was undertaken for the primary TKA and a FINE^® PS type prosthesis was used. Similarly, the patient fell on to the floor when ambulating, and the medial retinaculum and patella tendon of her right knee ruptured, so a reconstruction of the extensor mechanism was performed. There were no recurrences and additional surgery was unnecessary.

 Previous reports have indicated that barbed suture is stronger than standard suture. However, barbed suture had been associated with rupture and infection compared to standard suture. As a result, it is imperative to understand the risks of barbed suture in total joint surgery.