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The Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions' effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s) than E (1.29 m s, p = 0.0004) and D (1.31 m s, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p < 0.0001) in the two diet groups compared with E. There also was a significant dose-response to weight loss; participants that lost >10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.
Copyright © 2019 Elsevier Ltd. All rights reserved.
Traveling-wave MRI, which uses relatively small and simple RF antennae, has robust matching performance and capability for large field-of-view (FOV) imaging. However, the power efficiency of traveling-wave MRI is much lower than conventional methods, which limits its application. One simple approach to improve the power efficiency is to place passive resonators around the subject being imaged. The feasibility of this approach has been demonstrated in previous works using a single small resonant loop. In this work, we aim to explore how much the improvements can be maintained in human imaging using an array design, and whether electric dipoles can be used as local elements. First, a series of electromagnetic (EM) simulations were performed on a human model. Then RF coils were constructed and the simulation results using the best setup for head imaging were validated in MR experiments. By using the passive local loop and transverse dipole arrays, respectively, the transmit efficiency (B) of traveling-wave MRI can be improved by 3-fold in the brain and 2-fold in the knee. The types of passive elements (loops or dipoles) should be carefully chosen for brain or knee imaging to maximize the improvement, and the enhancement depends on the local body configuration.
Copyright © 2017 Elsevier Inc. All rights reserved.
OBJECTIVE - To investigate the role of integrin α1β1 in the progression of post-traumatic osteoarthritis (PTOA), and elucidate the contribution of epidermal growth factor receptor (EGFR) signalling to the mechanism by which integrin α1β1 might control PTOA. We hypothesised that integrin α1β1 plays a protective role in the course of PTOA and that the effect of PTOA (e.g., synovitis, loss of cartilage and growth of osteophytes) would be exacerbated in mice lacking integrin α1β1 at every time point post destabilisation of medial meniscus (DMM).
METHODS - DMM or sham surgery was performed on integrin α1-null and wild type (WT) mice and the progression of PTOA analysed at 2, 4, 8 and 12 weeks post-surgery (PS) using micro-computed tomography (microCT), histology, and immunohistochemistry. In addition, the effects of EGFR blockade were examined by treating the mice with the EGFR inhibitor erlotinib.
RESULTS - Integrin α1-null female, but not male, mice showed earlier cartilage degradation post DMM surgery compared to WT controls. Furthermore, erlotinib treatment resulted in significantly less cartilage damage in integrin α1-null but not WT mice. Independent of genotype, erlotinib treatment significantly mitigated the effects of PTOA on many tissues of female mice including meniscal and fabella bone volume, subchondral bone thickness and density and cartilage degradation. In contrast, reduced EGFR signalling had little effect on signs of PTOA in male mice.
CONCLUSION - Integrin α1β1 protects against PTOA-induced cartilage degradation in female mice partially via the reduction of EGFR signalling. Furthermore, reduction of EGFR signalling protects against the development of PTOA in female, but not male mice.
Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
BACKGROUND - Anomalies of the meniscus are uncommon. These anomalous formations have been predominately described in the lateral compartment of the knee. Congenital abnormalities of the medial meniscus are rare.
METHODS - Chart and radiographic review of a single patient with a symptomatic congenital abnormality of the medial meniscus.
RESULTS - The patient was a 5-year-old boy with popliteal pterygium who developed painful snapping in the medial knee after anterior hemiepiphyseodesis to improve his knee extension. The patient had achieved full-knee extension from a preoperative 45-degree flexion contracture. The newly developed snapping was attributed to the hemiepiphyseodesis implants. After implant removal, the snapping persisted and was localized at the medial joint line. Through an arthrotomy, a medial meniscus abnormality was identified and excised with resolution of symptoms.
CONCLUSIONS - This report describes a symptomatic congenital abnormality of the medial meniscus in a child with popliteal pterygium. The patient was treated with excision of the anomalous structure with complete resolution of the symptoms. This is the first report of an intra-articular knee anomaly associated with popliteal pterygium syndrome.
BACKGROUND - Chronic kidney disease is associated with malnutrition and inflammation. These processes may lead to loss of skeletal muscle and reduced physical performance. Associations of kidney function with muscle composition and longitudinal measures of physical performance are unknown.
STUDY DESIGN - Prospective cohort study.
SETTING & PARTICIPANTS - We evaluated 826 community-dwelling older adults enrolled in the Invecchiare in Chianti (InCHIANTI) Study who were free of baseline stroke or activities of daily living disability.
PREDICTOR - Baseline creatinine clearance (Clcr) based on 24-hour urine collection.
OUTCOMES - Cross-sectional and longitudinal trajectories of physical performance measured by 7-m usual gait speed, 400-m fast gait speed, and knee extension strength using isometric dynamometry. Calf muscle composition assessed by quantitative computed tomography.
RESULTS - Mean age of participants was 74 ± 7 (SD) years, with 183 having Clcr < 60 mL/min/1.73 m(2). After adjustment, each 10-mL/min/1.73 m(2) decrement in Clcr was associated with 0.01 (95% CI, 0.004-0.017) m/s slower 7-m usual walking speed and 0.008 (95% CI, 0.002-0.014) m/s slower 400-m walking speed. Each 10-mL/min/1.73 m(2) decrement in Clcr was associated with 28 (95% CI, 0.8-55) mm(2) lower muscle area and 0.15 (95% CI, 0.04-0.26) mg/cm(3) lower muscle density. After adjustment, lower Clcr was associated with slower mean 7-m (P=0.005) and 400-m (P=0.02) walk and knee extension strength (P=0.001) during the course of follow-up. During a mean follow-up of 7.1 ± 2.5 years, each 10-mL/min/1.73 m(2) lower baseline Clcr was associated with 0.024 (95% CI, 0.01-0.037) kg/y greater decline in knee strength.
LIMITATIONS - Single baseline measurement of Clcr and 3-year interval between follow-up visits may lead to nondifferential misclassification and attenuation of estimates.
CONCLUSIONS - Among older adults, lower Clcr is associated with muscle atrophy, reduced walking speed, and more rapid declines in lower-extremity strength over time.
Copyright © 2015 National Kidney Foundation, Inc. All rights reserved.
PURPOSE - Using three separate models that included total body mass, total lean and total fat mass, and abdominal and thigh fat as independent measures, we determined their association with knee joint loads in older overweight and obese adults with knee osteoarthritis (OA).
METHODS - Fat depots were quantified using computed tomography, and total lean and fat mass were determined with dual energy x-ray absorptiometry in 176 adults (age, 66.3 yr; body mass index, 33.5 kg·m) with radiographic knee OA. Knee moments and joint bone-on-bone forces were calculated using gait analysis and musculoskeletal modeling.
RESULTS - Higher total body mass was significantly associated (P ≤ 0.0001) with greater knee compressive and shear forces, compressive and shear impulses (P < 0.0001), patellofemoral forces (P < 0.006), and knee extensor moments (P = 0.003). Regression analysis with total lean and total fat mass as independent variables revealed significant positive associations of total fat mass with knee compressive (P = 0.0001), shear (P < 0.001), and patellofemoral forces (P = 0.01) and knee extension moment (P = 0.008). Gastrocnemius and quadriceps forces were positively associated with total fat mass. Total lean mass was associated with knee compressive force (P = 0.002). A regression model that included total thigh and total abdominal fat found that both were significantly associated with knee compressive and shear forces (P ≤ 0.04). Thigh fat was associated with knee abduction (P = 0.03) and knee extension moment (P = 0.02).
CONCLUSIONS - Thigh fat, consisting predominately of subcutaneous fat, had similar significant associations with knee joint forces as abdominal fat despite its much smaller volume and could be an important therapeutic target for people with knee OA.
PURPOSE - To evaluate the feasibility of measuring T1ρ values in epiphyseal cartilage in children, we have conducted a novel study of spin locking techniques. Adult articular cartilage has been widely studied with spin locking techniques by magnetic resonance imaging. However, no results are available for in vivo T1ρ imaging of developing cartilage.
MATERIALS AND METHODS - Ten volunteers of age 6 ± 3 years were recruited to have T1ρ mapping performed on the knee at the conclusion of their clinical study. T1ρ maps were generated using a spin-lock cluster followed by a fast spin-echo imaging sequence. Regions of interest (ROIs) were placed in non-load-bearing (NLB), load-bearing (LB), and articular cartilage.
RESULTS - Student's t-tests were performed to compare means among the ROIs. Mean T1ρ for epiphyseal and articular cartilage was 49.8 ± 9 and 76.6 ± 7 ms, respectively. LB and NLB T1ρ vales were 47.1 ± 9.5 and 52.5 ± 9 ms, respectively. Significant differences were found in T1ρ values between epiphyseal and articular cartilage layers (P = 0.0001). No difference in T1ρ was observed between NLB and LB layers. A modest trend was also noted for epiphyseal and articular cartilage regions with age.
CONCLUSION - It is feasible to quantify differences in epiphyseal and articular cartilage layers with SL techniques. T1ρ holds promise as a noninvasive method of studying normal and abnormal developmental states of cartilage in children.
Copyright © 2012 Wiley Periodicals, Inc.
MRI plays a critical role in all orthopaedic practices. A basic working knowledge of the most commonly used pulse sequences in musculoskeletal imaging and the appearance of normal tissues on those sequences is critical to confident MRI interpretation. The orthopaedic surgeon should be familiar with appropriate use of intravenous and intra-articular contrast and its limitations. Concepts key to MRI interpretation include image contrast and resolution, signal, noise, and pulse sequence. Recent advances in anatomic and functional imaging highlight the robust potential of MRI for musculoskeletal evaluation. As MRI technology evolves, the orthopaedic surgeon must stay current on these technologic advances to use this tool to its fullest potential.
BACKGROUND - Increased knee pain at the time of anterior cruciate ligament reconstruction may potentially predict more difficult rehabilitation, prolonged recovery, and/or be predictive of increased knee pain at 2 years.
HYPOTHESIS - A bone bruise and/or other preoperative factors are associated with more knee pain/symptoms at the time of index anterior cruciate ligament reconstruction, and the presence of a bone bruise would be associated with specific demographic and injury-related factors.
STUDY DESIGN - Cohort study (prevalence); Level of evidence, 2.
METHODS - In 2007, the Multicenter Orthopaedic Outcomes Network (MOON) database began to prospectively collect surgeon-reported magnetic resonance imaging bone bruise status. A multivariable analysis was performed to (1) determine if a bone bruise, among other preoperative factors, is associated with more knee symptoms/pain and (2) examine the association of factors related to bone bruise. To evaluate the association of a bone bruise with knee pain/symptoms, linear multiple regression models were fit using the continuous scores of the Knee injury and Osteoarthritis Outcome Score (KOOS) symptoms and pain subscales and the Short Form 36 (SF-36) bodily pain subscale as dependent variables. To examine the association between a bone bruise and risk factors, a logistic regression model was used, in which the dependent variable was the presence or absence of a bone bruise.
RESULTS - Baseline data for 525 patients were used for analysis, and a bone bruise was present in 419 (80%). The cohort comprises 58% male patients, with a median age of 23 years. The median Marx activity level was 13. Factors associated with more pain were higher body mass index (P < .0001), female sex (P = .001), lateral collateral ligament injury (P = .012), and older age (P = .038). Factors associated with more symptoms were a concomitant lateral collateral ligament injury (P = .014), higher body mass index (P < .0001), and female sex (P < .0001). Bone bruise is not associated with symptoms/pain at the time of index anterior cruciate ligament reconstruction. None of the factors included in the SF-36 bodily pain model were found to be significant. After controlling for other baseline factors, the following factors were associated with a bone bruise: younger age (P = .034) and not jumping at the time of injury (P = .006).
CONCLUSION - After anterior cruciate ligament injury, risk factors associated with a bone bruise are younger age and not jumping at the time of injury. Bone bruise is not associated with symptoms/pain at the time of index anterior cruciate ligament reconstruction.
Concerned by a perceived high revision rate, we retrospectively reviewed the survivorship of a series of 43 cemented, medial, mobile-bearing Preservation unicompartmental knee replacements implanted during a 2-year period at a single institution. The initial post-operative AP and lateral radiographs were independently assessed to test the hypothesis that suboptimal implantation of the prosthesis was responsible for early failure. An X-ray scoring system based on the criteria for assessing the Oxford mobile-bearing unicompartmental knee replacement was devised. The components of this score included assessment of prosthesis alignment, sizing and cementation. Nine (21%) LCS Preservation mobile-bearings prostheses had required revision at a mean of 22 months post-implantation. The commonest causes for failure were pain (44%) and tibial component loosening (33%). Analysis of post-operative radiographs showed no difference (n.s.) between the compound error scores for the revised and the surviving prostheses. No particular surgical error was identifiable leading to subsequent need for revision. The high failure rates shown in this study have led us to cease using this implant. The clinical relevance of this study is that the captive running track of the LCS mobile-bearing prosthesis may over constrain the meniscal component leading to early failure.