Life Course Epidemiology of Hip Osteoarthritis in Japan: A Multicenter, Cross-Sectional Study.

BACKGROUND: The incidence of developmental dysplasia of the hip (DDH) in Japanese newborns has reduced drastically following a primary prevention campaign initiated around 1972 to 1973; this perinatal education campaign promoted maintaining the hips of newborns in the naturally flexed-leg position. The purpose of the present study was to describe the life course epidemiology of hip osteoarthritis (OA) in adolescent and adult patients and to assess its association with exposure to the primary prevention campaign for DDH. METHODS: We included new patients with hip OA diagnosed from January 1, 2022, to December 31, 2022, at 12 core hospitals (8 special-function hospitals and 4 regional medical care support hospitals). The trend in the percentage of hips with a history of DDH treatment in childhood was estimated with use of a centered moving average using the birth year of the patient. We compared the prevalence of severe subluxation (Crowe type II, III, or IV) between patients with secondary hip OA due to hip dysplasia who were born in or before 1972 and those who were born in or after 1973. RESULTS: Overall, 1,095 patients (1,381 hips) were included. The mean age at the time of the survey was 63.5 years (range, 15 to 95 years). A total of 795 patients (1,019 hips; 73.8% of hips) were diagnosed with secondary OA due to hip dysplasia. Approximately 13% to 15% of hips among patients born from 1963 to 1972 had a history of DDH treatment in childhood; however, the percentage decreased among patients born in or after 1973. The prevalence of severe subluxation (Crowe type II, III, or IV) among patients born in or after 1973 was 2.4%, which was significantly less than that among patients born in or before 1972 (11.1%; odds ratio, 0.20; p < 0.001). CONCLUSIONS: As of 2022, secondary hip OA due to hip dysplasia is still responsible for most new cases of adolescent and adult hip OA seen in core hospitals in Japan. However, the perinatal education campaign initiated 50 years ago, which utilized a population approach and advocated for maintaining the hips of newborns in the naturally flexed-leg position, may have improved the environmental factors of DDH, as indicated by the apparently reduced need for treatment of DDH in childhood and the associated severe subluxation. This may result in a reduced need for challenging hip surgery later in life. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Protocol for the RETHINK study: a randomised, double-blind, parallel-group, non-inferiority clinical trial comparing acetaminophen and NSAIDs for treatment of chronic pain in elderly patients with osteoarthritis of the hip and knee.

INTRODUCTION: In patients with chronic pain, oral analgesics are essential treatment options to manage pain appropriately, improve activities of daily living abilities and achieve a higher quality of life (QOL). It is desirable to select analgesics for elderly patients based on comparative data on analgesic effect and risk of adverse events; however, there are few comparative studies so far. The purpose of this study is to determine whether the efficacy and safety of acetaminophen are non-inferior to non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of chronic pain associated with osteoarthritis of the hip and knee in elderly patients. METHODS AND ANALYSIS: This study is a multicentre, randomised controlled, double-blind, parallel-group study to compare the analgesic effect and adverse events between acetaminophen or NSAIDs (loxoprofen or celecoxib). A total of 400 elderly patients with osteoarthritis of the hip and knee will be recruited from five institutions in Japan. Patients of 65 years or older with osteoarthritis-related pain will be registered and randomly assigned to acetaminophen, loxoprofen or celecoxib with 2:1:1 allocation. The primary endpoint is change in the Brief Pain Inventory (BPI) item 3 (worst pain) score from baseline to week 8. The secondary endpoints are BPI item 3 score change from baseline to week 4, health-related QOL measured by Short Form-8 Health Survey, and occurrence of adverse events including gastrointestinal disorders and abnormal liver function. Data will be analysed in accordance with a predefined statistical analysis plan. ETHICS AND DISSEMINATION: This study protocol was approved by the Kyushu University Hospital Certified Institutional Review Board for Clinical Trials on 28 January 2021 (KD2020004) and the chief executive of each participating hospital. The results of the study will be submitted to international peer-reviewed journals, and the main findings will be presented at international scientific conferences. TRIAL REGISTRATION NUMBER: jRCTs071200112.

Meniscal ramp lesions should be considered in anterior cruciate ligament-injured knees, especially with larger instability or longer delay before surgery.

PURPOSE: To determine the incidence of meniscal ramp lesions in an anterior cruciate ligament (ACL) injured knees and to clarify whether ramp lesions are related to chronic ACL deficiency and increased knee instability. METHODS: Consecutive ACL injured patients were evaluated arthroscopically for a ramp lesion via a trans-notch view and evidence of menisco-capsular injury was recorded. Other concomitant injuries to the knee were also noted. Incidence of meniscal ramp lesions, delay before surgery, and anterior-posterior stability was analyzed. All patients underwent bilateral KT-2000 evaluation. RESULTS: One hundred and three consecutive ACL injured patients with a mean age of 24 years were included in this study. In total, a ramp lesion was found in 10 knees (9.7%) via a trans-notch view. None of these lesions could be identified by the standard view from the anterolateral portal. Other medial meniscal lesions were found in 26 knees (25.2%) by standard arthroscopic viewing. The ramp lesion group had significantly longer delay before surgery with a median of 191 days (p < 0.01) as well as a larger side-to-side difference of KT-2000 measurement (7.3 ± 1.8 mm; p < 0.01), compared with the intact medial meniscus group (53 days and 5.5 ± 1.5 mm, respectively). CONCLUSION: Ramp lesions that were identified using a trans-notch view were not visualized with standard arthroscopic views. Increased anterior tibial translation and longer delay before surgery were seen in knees with ramp lesions. Careful inspection of the posteromedial menisco-capsular region is required as hidden menisco-capsular lesions may occur which may result in residual knee instability. LEVEL OF EVIDENCE: Level II.

Nicotinic activity depresses synaptic potentiation in layer V pyramidal neurons of mouse insular cortex.

The insular cortex is a critical brain region involved in nicotine addiction. However, its specific cellular and synaptic mechanisms underlying nicotine addiction remains largely unknown. In the present study, we examined how nicotine modulates synaptic transmission and plasticity in layer V pyramidal neurons of the mouse insular cortex. We also examined which type of neurons express functional nicotinic acetylcholine receptors (nAChRs) in layer V of the insular cortex. We found that nicotine suppresses synaptic potentiation induced by combination of presynaptic stimulation with postsynaptic depolarization (paired training). An application of nicotine significantly enhanced both spontaneous excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs): the former effect was mediated by activation of ß2-containing nAChRs while the latter one was mediated largely by activation of ß2-containing nAChRs and to a minor extent by activation of α7-containing nAChRs. The application of nicotine significantly enhanced evoked IPSCs but had no effect on evoked EPSCs. We also found that in layer V of the mouse insular cortex, majority of non-fast-spiking (non-FS) interneurons have ß2-containing nAChRs while about half of pyramidal neurons and FS interneurons have functional nAChRs. Blockade of GABAA receptors or ß2-containing nAChRs prevented the effects of nicotine on synaptic potentiation. Taken together, these results suggest that in layer V pyramidal neurons of the insular cortex, activation of ß2-containing nAChRs expressed in non-FS interneurons suppresses synaptic potentiation through enhancing GABAergic synaptic transmission. These findings provide important insights into the cellular and synaptic mechanisms of insular cortical changes in nicotine addiction.

Influence of Age on Healing Capacity of Acute Tears of the Anterior Cruciate Ligament Based on Magnetic Resonance Imaging Assessment.

OBJECTIVE: The purpose of this study was to evaluate the influence of patient age on the effects of conservative treatment of the anterior cruciate ligament (ACL). METHODS: A total of 102 consecutive patients with acute ACL injury were allowed to heal without surgery. Final magnetic resonance imaging images of the ACL were classified from grade I, indicating good morphological recovery, to grade IV, indicating poor recovery. Chi-square analysis was used to determine significant differences in the incidence of grades I and II among those less than 20 versus those 20 years or more of age. RESULTS: The mean follow-up to final magnetic resonance imaging was 9 months. A significant difference in the frequency of grades I and II was observed between age groups (<20 years, 13.0%; ≥20 years, 69.6%; P < 0.0001). CONCLUSION: ACL injury was more severe, and morphological recovery with conservative treatment was poorer among younger patients than among adults.

The anabolic response to parathyroid hormone is augmented in Rac2 knockout mice.

PTH is the only currently available anabolic therapy for osteoporosis. In clinical practice, the skeletal response to PTH varies and because therapy is limited to 2 yr, approaches to maximize the therapeutic response are desirable. Rac2 is a small GTPase that is expressed only in hematopoietic tissue. Rac2(-/-) mice have a slight increase in bone mass and osteoclasts isolated from these animals have reduced basal resorptive activity and reduced chemotaxis. To evaluate the anabolic response to PTH in Rac2(-/-) mice, we treated 18 Rac2(-/-) and 17 control, age-matched wild-type animals once daily for 28 d with 80 ng/g body weight of h(1-34)PTH. Treatment resulted in significantly greater increments in spinal, femur, and total bone density in the Rac2(-/-) as compared with wild-type animals. Microcomputed tomography analysis demonstrated greater increases in trabecular thickness and cortical thickness in the knockout mice. Interestingly, histomorphometric analysis showed an equivalent increase in osteoblast and osteoclast number in response to PTH treatment in both groups of animals. However, as judged by changes in serum markers, the resorptive response to PTH was impaired. Thus, telopeptide of type 1 collagen was 15.9+/-6.9 ng/ml after PTH treatment in the knockout animals and 26.8+/-11.1 ng/ml in the PTH-treated wild-type group. In contrast, serum aminoterminal propeptide of type 1 collagen and osteocalcin were equivalent in both groups. We conclude that, in the genetic absence of Rac2, the anabolic response to PTH is increased. This appears to be due to attenuated resorptive activity of osteoclasts.

The oblique posterior femoral condylar radiographic view following total knee arthroplasty.

BACKGROUND: It is often difficult to evaluate the posterior aspects of the femoral condyles after total knee arthroplasty. We have developed an imaging technique involving the use of the oblique posterior condylar view for the evaluation of the posterior aspects of the femoral condyles. The purpose of the present study was to compare the efficacy of this view with that of the true-lateral view. METHODS: Three orthopaedic surgeons analyzed fifty-five sets of radiographs (consisting of oblique posterior condylar and true-lateral views) for patients who had undergone total knee arthroplasty. The accuracy and reproducibility of the oblique posterior condylar view for the detection of radiolucencies were compared with those of the true-lateral view. RESULTS: The oblique posterior condylar view was significantly better than the true-lateral view for the detection of radiolucencies of the posterior aspects of the femoral condyles (p < 0.0005). CONCLUSIONS: Radiographic analysis with use of the oblique posterior condylar view is technically easy and is accurate for the evaluation of radiolucencies of the posterior aspects of the femoral condyles after total knee arthroplasty.

Alignment in total knee arthroplasty following failed high tibial osteotomy.

In total knee arthroplasty (TKA) following failed high tibial osteotomy, the mechanical axis does not intersect the center of the tibial component if the tibia has been resected perpendicular to the anatomical axis. Therefore, tibial resection referencing the predicted postoperative mechanical axis instead of the tibial shaft axis is advocated. To obtain the optimal tibial resection, characteristics of the tibial proximal deformity were measured radiographically and predicted postoperative lower limb alignment was calculated using full-length, weight-bearing, lower limb anteroposterior radiographs. Two finite element analysis models also were examined. The proximal tibia was resected perpendicular to the tibial shaft axis in model 1, and perpendicular to the predicted postoperative tibial mechanical axis in model 2. When the proximal tibia was resected perpendicular to the tibial shaft axis, the predicted lower limb mechanical axis was significantly shifted medially to the center of the tibial joint surface. The results of the finite element analysis reflected the medial shift of the lower limb mechanical axis in model 1, where stresses were increased in the medial tibial compartment. Tibial resection referencing the predicted postoperative tibial mechanical axis, instead of the tibial shaft axis, should be performed, especially in cases with a deformed tibia.

Changes in anteroposterior stability following total knee arthroplasty.

This study evaluated the changes in anteroposterior stability at flexion and extension following posterior cruciate ligament (PCL)-retaining and PCL-substituting total knee arthroplasty (TKA), in comparison with normal knees. Altogether, 29 knees of 24 patients underwent either PCL-retaining ( n = 19) or PCL-substituting ( n = 10) TKA. Anteroposterior displacement was measured with a KT-2000 arthrometer preoperatively, 1 month after surgery, and again an average of 3 years after surgery. Anteroposterior stability at flexion and extension did not change following PCL-retaining TKA and was not significantly different from that of normal subjects, whereas anteroposterior stability increased following PCL-substituting TKA and was significantly greater than that of normal subjects an average of 3 years after surgery.