Quadriceps femoris muscle weakness has long been associated with disuse atrophy in symptomatic knee osteoarthritis but more recently implicated in the aetiology of this condition. The purpose of this study was to assess the benefits of two interventions aimed at increasing quadriceps strength in subjects with moderate to severe knee osteoarthritis. Twenty-eight patients, aged fifty-five to seventy-five, were recruited and randomised to either a six-week home resistance-training exercise program or a six-week neuromuscular electrical stimulation (NMES) program. Eleven patients matched for age, gender and osteoarthritis severity formed a control group, receiving standard care. The resistance-training group performed six exercises three times per week, while the NMES group used the garment stimulator for twenty minutes five times per week Outcome measures included isometric and isokinetic quadriceps strength, functional capacity, quadriceps cross-sectional area, and validated health survey scores. These measures were assessed at baseline, post-intervention and at 6-weeks post-intervention. Both intervention groups showed significant improvements in all functional tests, in the global health survey, and in quadriceps cross-sectional area immediately post-intervention. An increase in isokinetic strength was seen in the exercise group only. With the exception of isokinetic strength, all benefits were maintained six weeks post-intervention. Both a six-week home resistance-training program and a six-week NMES program produce significant improvements in functional performance as well as physical and mental health for patients with moderate to severe knee osteoarthritis. Home-based NMES is an acceptable alternative to physical therapy, and is especially appropriate for patients who have difficulty complying with an exercise program.
To investigate the responsiveness to change of four different elbow-scoring instruments, two Hospital for Special Surgery (HSS) elbow assessment scales, the Mayo Clinic elbow-performance index (Mayo) and the Elbow Functional Assessment (EFA) scale.
A group of 24 RA patients (median age 60 years) undergoing either elbow arthroplasty (22 elbows) or synovectomy with radial head excision (3 elbows), were evaluated both prior and after surgery (median: seven months postoperatively). Score changes, obtained by using the scales under study, were calculated. The patient’s opinion of global perceived effect of the intervention was used as a criterion to classify them as ‘improved’ or ‘non-changed’. Responsiveness was evaluated with use of three approaches: using paired t-statistics (pre- and post-surgery scores), effect size statistics (standardized response mean, effect size and responsiveness ratios) and Receiver Operator Characteristic (ROC) curves.
Each of the elbow rating measures under study proved to be responsive to change when evaluating RA patients undergoing elbow arthroplasty or synovectomy. The EFA scale demonstrated the highest power to detect a clinically meaningful difference and had the best discriminative ability to distinguish improved from non-changed patients, as was revealed by all responsiveness statistics applied.
The HSS, the Mayo and the EFA elbow-scoring scales can all be used as an evaluative instrument to assess the efficacy of surgical treatment of the rheumatoid elbow joint. However, using the EFA scale will require smaller sample sizes to achieve a fixed level of statistical power than the other scales under study.
Chondrocyte sensitivity to strain depends on signal transduction pathways which include integrin-dependent increases in intracellular calcium. Human articular chondrocytes were cultured as monolayers in silicone dishes. After loading the cells with the calcium-fluorescent dye Fluo-3/AM the dishes were mounted in a 4-point bending apparatus and then fixed to a laser scanning confocal microscope. Biaxial substrate strain (15 000e) was applied to the silicone dish via a hand operated cam rotated at ~60 RPM (1 Hz) for 10 or for 50 cycles. Changes in intracellular calcium in single cells were determined by measuring the mean pixel values in the basal and stimulated images taken at different time points. The data reported for 50 cycle treatments represent 49 single cells of six independent cell isolations. The data for 10 cycle strain treatment are from a single experimental setup. Increases in intracellular calcium were consistently observed in chondrocytes exposed to 15 000me for 50 cycles in a range from 1.3- to 4.0-fold with an average of 2.3-fold (SD=0.79). Few cells responded before 30 minutes but most of the responses occurred 30–60 minutes after strain. Consistent intracellular Ca++-increases were also seen after 10 strain cycles, however responses were detected within 5 minutes post-strain. The relative increase (2.7-fold ± 1.7) was similar in magnitude to 50 cycle responses. Intracellular Ca++-fluxes in chondrocytes and other cells occur by at least two different mechanisms: through stretch-activated channels in the plasma membrane permit immediate Ca++-influx during strain application or by Ca++-efflux from intracellular compartments stimulated by slower acting second messengers. Our results suggest that the early response to 10 strain cycles is due to Ca++-influx via membrane channels while the later response to 50 cycles is due to Ca++-efflux from intracellular compartments, probably mediated by cytokines released in response to an initial Ca++-influx from the medium.
