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Purpose Research has shown that a cemented mobile-bearing component has a favorable effect on the bone mineral density (BMD) of the distal femur at 2 years after total knee arthroplasty (TKA). This study was performed to determine whether the advantage on BMD of a cemented mobile-bearing TKA over a conventional cemented fixed-bearing TKA changes with time. This report is an update of a matched cohort study initiated in 2004 and for which the 2-year results have been published. Methods Twenty-eight knees that were treated with a fixed-bearing posterior stabilized (PS) prosthesis and 28 matched knees from a database of 76 knees that were treated with a mobile-bearing PS prosthesis in the same period were investigated. All knees underwent dual-energy X-ray absorptiometry (DEXA) scans around the femoral component preoperatively, 2 weeks postoperatively, 5 years postoperatively, and annually thereafter. Eighteen knees with a cemented mobile-bearing PS prosthesis and 20 knees with a cemented fixed-bearing PS prosthesis were investigated for more than 6 years. The mean follow-up period was 11 years. Results The range of motion, Knee Society Score, BMD of the lumbar spine, and follow-up period were not significantly different preoperatively and postoperatively in the two groups. In the fixed-bearing group, the BMD of the anterior part of the femoral condyle decreased postoperatively. In the mobile-bearing group, the BMD of the posterior part of the femoral condyle increased postoperatively. The postoperative change in the BMD at 5 years and the latest follow-up period was statistically significant in the two groups. Conclusions This DEXA study revealed that a cemented mobile-bearing component had a favorable effect on the BMD of the distal femur after TKA even at a mean of 11 years postoperatively. Level of evidence Therapeutic study, level II, prospective comparative study.

Maintaining activities of daily living (ADL) in older adults requires muscle strength and physical activity. However, exercise motivation often declines with age. Enjoyable activities can enhance motivation and effectiveness. Boccia is a recreational sport with rehabilitation potential but requires substantial space. This study evaluated the enjoyment and lower limb muscle activity of \"Boccia XR,\" a virtual adaptation designed for limited spaces, comparing it with traditional Boccia and treadmill walking. Eighteen healthy older adults (mean age 73.3 ±  5.4 years) participated. Each performed Boccia XR, traditional Boccia, and treadmill walking in random order. Mood changes were assessed using the Profile of Mood States 2nd Edition (POMS2), and lower-limb muscle activity was measured via electromyography (EMG). Both Boccia XR and traditional Boccia significantly improved positive mood (Vigor-Activity) and reduced negative mood (Total Mood Disturbance) as compared to treadmill walking. Muscle activity analysis revealed that Boccia XR and traditional Boccia imposed muscle loads comparable to treadmill walking. Rectus femoris activity exceeded that of treadmill walking, and medial gastrocnemius activation was sufficient for strengthening in sedentary older adults during Boccia tasks. Boccia XR is an enjoyable and effective physical activity for older adults, requiring less space, than traditional Boccia while providing physical benefits similar to treadmill walking. It may enhance exercise adherence and overall function in space-limited settings.

Subtotal esophagectomy with lymph node dissection followed by neoadjuvant chemotherapy (NAC) is the standard treatment for stage II-III esophageal cancer. Esophagectomy is still associated with high morbidity rates, and reducing these rates remains challenging. Among several complications, postoperative pneumonia (PP) is sometimes fatal, which has been reportedly caused by sarcopenia. Thus, nutritional support and rehabilitation may be promising for preventing skeletal muscle mass loss and reduce the incidence of PP. This single-center, randomized, open-label, pilot trial will randomize a total of 40 patients with esophageal cancer in a 1:1 ratio either to ISOCAL Clear + rehabilitation arm or only rehabilitation arm. Although all patients will be educated about rehabilitation by a specialized physician and will be asked to undergo the prespecified rehabilitation program, patients treated with ISOCAL Clear + rehabilitation arm will be supplemented by 400 mL of ISOCAL Clear (Nestlé Japan Ltd, Tokyo, Japan) per day during two courses of NAC with docetaxel, cisplatin, and fluorouracil. Body composition will be assessed using Inbody (Inbody Co., Ltd., Tokyo, Japan) just before starting NAC and surgery. The primary endpoint is the change of skeletal muscle index (SMI) during NAC. Secondary endpoints include (i) body weight, total skeletal muscle mass, appendicular skeletal muscle mass, and lean body mass index changes; (ii) the percentage of ISOCAL Clear continuation; (iii) appetite evaluation; (iv) the percentage of targeted calorie achievement; (v) adverse events of NAC; (vi) postoperative complication rates; and (vii) postoperative hospital stay. This prospective trial assesses the efficacy of nutritional support in addition to rehabilitation during NAC for patients with esophageal cancer. The results will be utilized in assessing whether the effects of nutritional support by ISOCAL Clear are promising or not and in planning future larger clinical trials.

Background Biomechanical changes in articular cartilage are associated with the onset of osteoarthritis. We developed an optical coherence tomography-based strain rate tomography method: stress relaxation optical coherence straingraphy (SR-OCSA). The purpose of this study was to establish an approach for measuring mechanical properties of articular cartilage using SR-OCSA, and to investigate the distribution of viscoelastic properties of articular cartilage in early osteoarthritis. Methods Anterior cruciate ligament transection surgery was performed on the left knees of 8–9-month-old New Zealand white rabbits. SR-OCSA was used to visualize and measure the viscoelastic properties of articular cartilage via attenuation coefficient of strain rate (ACSR). Using the same conditions as in the SR-OCSA test, an indentation test was conducted, and relaxation time was measured to evaluate the relationship between ACSR and relaxation time. Results SR-OCSA could nondestructively detect and visualize changes in the distribution of viscoelastic properties of articular cartilage in early osteoarthritis. SR-OCSA captured significant increases in ACSR in cartilage at 2 weeks after surgery, when a histologically slight osteoarthritis sign was present. As cartilage degeneration progressed, ACSR increased, whereas relaxation time decreased in a time-dependent manner. Moreover, ACSR negatively correlated with relaxation time. In particular, ACSR was elevated around the tidemark and the elevation tended to move as cartilage degeneration progressed. Conclusions SR-OCSA could tomographically and nondestructively detect and visualize changes in the distribution of viscoelastic properties of articular cartilage in early osteoarthritis. The mechanical properties around the tidemark were degraded as cartilage degeneration progressed. Thus, SR-OCSA provides important data needed to understand the biomechanics of early osteoarthritis.

IntroductionProper anteroposterior (AP) joint displacement is an important indicator of good clinical outcome following total knee arthroplasty (TKA). We hypothesized that a newly introduced mobile-bearing posterior stabilized (PS) prosthesis reduces the AP joint displacement. The aim of this study is to compare the AP joint displacement between a newly introduced mobile-bearing PS TKA in one knee and a conventional fixed-bearing PS TKA in other knee.Materials and methods82 knees in 41 patients who had bilateral TKAs were investigated. All the patients received a conventional fixed-bearing PS prosthesis in one knee and a highly congruent mobile-bearing PS prosthesis in the other knee. AP joint displacement was measured using the KT-2000 arthrometer, at 30° and 75° in flexion, at average of 3.3 years after the operation.ResultsAP joint displacements at 30° in flexion were 6 ± 3 mm in the knees with the mobile-bearing PS prosthesis and 9 ± 4 mm in the knee with fixed-bearing PS prosthesis (p < 0.001). AP joint displacements at 75° in flexion were 4 ± 2 mm in the knees with the mobile-bearing PS prosthesis and 6 ± 3 mm in the knee with fixed-bearing PS prosthesis (p < 0.001).ConclusionsThis study suggested that the design of the prosthesis can improve the AP joint stability in mid-flexion range.

Background Aspiration pneumonia is a potentially fatal condition that is more commonly seen in older people and has a high mortality rate. As the world population is aging, aspiration pneumonia may likely become more common worldwide, including Japan and the United States. Although aspiration pneumonia is regarded as a preventable condition, its prevention is attracting a great deal of attention, with many published studies reporting screening tests. We developed the Osaka Metropolitan University Hospital Eating and Swallowing (OMUES) manual for dysphagia triage in all hospitalized patients to prevent aspiration pneumonia. In this study, we investigated the effectiveness of the OMUES manual for dysphagia triage in hospitalized patients by assessing changes in the incidence of aspiration pneumonia after introducing the OMUES manual. Materials and method The OMUES manual is designed for use by nurses without didactic training. Inpatients who meet the criteria for using the OMUES manual undergo a swallowing function assessment in three stages: the Eating Assessment Tool-10 (EAT-10) (stage 1), the Repetitive Saliva Swallowing Test (RSST) (stage 2), and the eating scene observation (stage 3). The study participants included 12,395 patients (6,000 males and 6,395 females) who were admitted between September 1, 2021, and August 31, 2022, excluding minors, patients with aspiration pneumonia on admission, and patients on emergency hospitalization, whose data were retrospectively extracted from the electronic medical records. These patients were examined in two groups: before and after introducing the OMUES manual. We closely examined patients with aspiration pneumonia to identify the cause and compared these between the two groups. Furthermore, as a secondary analysis, we also evaluated the implementation status of the OMUES manual. Results Before introducing the OMUES manual, there were 6,546 patients (3,164 males/3,382 females) and 52 patients with aspiration pneumonia (0.8%). After introducing the OMUES manual, the number of patients was 5,849 (2,836 males/3,013 females) and 42 cases (0.7%) with aspiration pneumonia. No statistically significant difference was observed between the two groups. As for the causes of aspiration pneumonia, factors associated with poor arousal were significantly reduced after introducing the OMUES manual, but the number of iatrogenic cases remained unchanged (21/52 cases [40.4%] and 19/42 cases [45.2%] before and after introducing the OMUES manual, respectively). The majority were associated with upper gastrointestinal endoscopy. The utilization rate was 92.5% in stage 1 of the OMUES manual, 50.9% in stage 2, and 60.0% in stage 3. The OMUES manual utilization rate, calculated by multiplying the utilization rates at each of stages 1, 2, and 3, was 28.3%. Conclusions We investigated the effectiveness of using the OMUES manual for dysphagia triage on all hospitalized patients. Although there was no statistically significant difference in the incidence of aspiration pneumonia before and after introducing the OMUES manual, our results suggest that it is contributing to its prevention. In addition, endoscopic examination revealed cases of aspiration pneumonia even in patients with normal swallowing function, and further investigation is required.

Purpose Polyethylene wear particle generation is one of the most important factors that affects the mid- to long-term results of total knee arthroplasties (TKA). Mobile-bearing total knee prostheses were developed to reduce polyethylene wear generation. However, whether mobile-bearing prostheses actually generate fewer polyethylene wear particles than fixed-bearing prostheses remains controversial. The aim of this study was to compare, within individual patients, the in vivo polyethylene wear particles created by a newly introduced mobile-bearing prosthesis in one knee and a conventional fixed-bearing prosthesis in other knee. Methods Eighteen patients receiving bilateral TKAs to treat osteoarthritis were included. The synovial fluid was obtained from 36 knees at an average of 3.5 years after the operation. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined using a scanning electron microscope and an image analyser. Results The size and shape of the polyethylene wear particles from the mobile-bearing prostheses were similar to those from the conventional fixed-bearing prostheses. Although the number of wear particles from the mobile-bearing prosthesis (1.63 × 10 7  counts/knee) appeared smaller than that from the fixed-bearing prosthesis (2.16 × 10 7  counts/knee), the difference was not statistically significant. Conclusions The current in vivo study shows that no statistically significant differences were found between the polyethylene wear particles generated by a newly introduced mobile-bearing PS prosthesis and a conventional fixed-bearing PS prosthesis during the early clinical stage after implantation. Level of evidence Therapeutic study, Level III.

Purpose The medial pivot total knee prosthesis has been designed to reproduce physiological knee kinematics. It has been reported that alumina ceramic femoral components reduce polyethylene wear. Thus, medial pivot total knee prostheses with alumina ceramic femoral components were introduced. The purpose of this study was to evaluate the clinical results of patients who underwent newly introduced alumina medial pivot total knee arthroplasties (TKA). Methods We evaluated the clinical results of 107 alumina medial pivot TKAs in 80 consecutive patients with a mean follow-up period of 5 years. Results Alumina medial pivot TKAs provided significant improvements in the patients’ Knee Society knee scores, function scores and post-operative ranges of motion compared with their pre-operative statuses (each, P  < 0.05). There was no statistical correlation between the change in maximum knee flexion and the increase in posterior condylar offset. Revision surgery was required in one knee due to a post-operative fracture of the tibial plateau after a fall that occurred 2 years postoperatively. No knees had aseptic loosening, osteolysis, or ceramic fractures. The survival rate was 98.6% at 5 years. Conclusions This study demonstrates satisfactory mid-term clinical results for patients receiving the alumina medial pivot prosthesis. Level of evidence Therapeutic study, Level IV.

This is the first report of in vivo wear particles from four total hip arthroplasties using remelted highly crosslinked polyethylene. The number of particles was (1.51 ± 0.45) × 107 g−1 (mean ± standard error); particle size (equivalent circle diameter), 0.72 ± 0.15 µm; and roundness, 1.45 ± 0.05. Remelted highly crosslinked polyethylene generates fewer, rounder, equivalently sized particles compared with corresponding reported values for particles generated from conventional polyethylene.

Purpose Navigation systems have recently been developed to achieve highly reliable prosthetic alignment in total knee arthroplasty (TKA). However, component alignment in the sagittal plane is less reliable than that in the coronal plane even when navigation systems are used. Previous reports examining men showed differences in targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems. However, there have been few studies examining the use of this technique in women, who are the primary candidates for TKA. Methods Radiographs of the entire lower extremity were obtained from 20 elder women while standing and sagittal prosthetic alignments in TKA were planned using the conventional technique as well as three navigation approaches to establish reference frames, and the observations were compared. Results Sagittal alignments simulated using the radiographs for the conventional technique and navigation systems differed within a mean of 3.2° ± 1.7° (mean ± SD) to 6.3° ± 2.0°. The use of different reference points on the distal femoral condyles (insertion point of the intramedullary rod, center of the anteroposterior direction of the femoral condyles, and most distal point of the femoral condyles) for each navigation system resulted in differences in the sagittal plane up to 3.0° ± 1.5°. The use of navigation systems resulted in a more hyperextended position between the femoral and tibial components compared to that for the conventional technique. Conclusions Targeted sagittal prosthetic alignments of TKA achieved using the conventional technique and various navigation systems differed in elderly women. The use of different reference points on the distal femoral condyle for navigation systems resulted in different alignment in the sagittal plane. This study showed that alignment tendencies are similar in men and women. Level of evidence Prognostic studies, IV.