Can the hamstring muscles protect the anterior cruciate ligament during a side‐cutting maneuver?

Because anterior cruciate ligament (ACL) injuries are common in European handball the present study assessed knee joint shear forces to estimate ACL loading in six elite female handball players during a side-cutting maneuver. A pilot investigation in three dimensions showed that peak moments occurred in the sagittal plane at a high velocity. Therefore, analysis of the movement was performed in two dimensions using high-speed cinematography, ground reaction forces, and electromyography (EMG). Film and force plate data allowed for calculation of net joint moments (inverse dynamics), estimates of instantaneous muscle-tendon lengths, contraction velocities, and peak loading of the ACL. During the breaking phase of the maneuver the peak knee joint moment was 239 Nm (99-309), which yielded an ACL-load of 520 N (215-673). The corresponding peak EMG amplitudes for the hamstring muscles were 34-39% of maximum EMG. During the breaking phase the quadriceps muscle contracted eccentrically with a velocity of 216-253% fiber length/s. In contrast, the hamstring muscles contracted concentrically with a velocity of 222-427% fiber length/s. These results suggest that a side-cutting maneuver produces loads that are insufficient to rupture the ACL. Furthermore, the rapid concentric hamstring contraction suggests that even during maximal activation, the ability of the hamstrings to reduce the ACL load is marginal.     

Experimental osteoporosis induced by ovariectomy and vitamin D deficiency does not markedly affect fracture healing in rats

BACKGROUND: The question of whether fracture healing and mechanical properties of the callus are influenced by osteoporosis (OP) is still not settled. We therefore studied this issue in vitamin D-depleted ovariectomized (OVX) rats, an OP model previously shown to induce weakening of the femoral neck, and thus thought to be closer to the human condition than the classic OVX rat model. METHODS: 72 female Wistar rats were randomized into two groups: ovariectomy and vitamin D-deficient diet (Ovx-D group) or sham operation and normal rat chow (Sham group). After 12 weeks, a closed tibial midshaft fracture was performed on the right side and fixed with an intramedullary nail. Bone loss and callus formation were monitored with DXA; serum levels of estradiol and vitamin D3 were measured and histomorphometric analyses were performed. Mechanical properties of callus, tibia, femoral shaft, and femoral neck were examined in 3-point cantilever bending 6 weeks after fracture. RESULTS: The Ovx-D group showed reduced BMD in the spine and femoral neck, and reduced trabecular bone volume in the femoral head. There were no differences in BMD and mechanical properties of callus between the groups. Except for reduced stiffness of the right femoral neck in the Ovx-D group (p = 0.02), no differences in the mechanical strength of long bones were detected. INTERPRETATION: Our results suggest that the systemic effects of estrogen and vitamin D deficiency are not crucial for fracture healing or mechanical properties of the callus.     

Wound contraction in an experimental porcine model

Wound contraction is thought to be independent of site, and circular full-thickness skin wounds are thought not to contract completely. To verify these statements four circular full-thickness skin wounds were created on each side of eight pigs and randomised to treatment with either split-thickness skin grafts, or healing by secondary intention under a hydrocolloid dressing. Time to healing, contraction, and final scar shape were evaluated. The median healing time was 12 days (range 6-18) in the grafted wounds and 30 days (range 15-45) in the secondarily healing wounds. There were significant differences in healing time between the different sites on the pigs. In the secondarily healing group, medial-caudal wounds healed in 21 (15-21) days compared with lateral wounds which healed in 36 (21-45) days (p     

Impulse-forces during walking are not increased in patients with knee osteoarthritis

Background Impulsive forces in the knee joint have been suspected to be a co-factor in the development and progression of knee osteoarthritis. We thus evaluated the impulsive sagittal ground reaction forces (iGRF), shock waves and lower extremity joint kinematics at heel strike during walking in knee osteoarthritis (OA) patients and compared them to those in healthy subjects.

Subjects and methods We studied 9 OA patients and 10 healthy subjects using three-dimensional gait analyses concentrated on the heel strike. Impulse GRF (iGRF) was measured together with peak accelerations (PA) at the tibial tuberosity and sacrum. Sagittal lower extremity joint angles at heel strike were extracted from the gait analyses. As OA is painful and pain might alter movement strategies, the patient group was also evaluated following pain relief by intraarticular lidocaine injections.

Results The two groups showed similar iGRF, similar tibial and sacral PA, and similar joint angles at heel strike. Following pain relief, the OA patients struck the ground with more extended hip and knee joints and lower tibial PA compared to the painful condition. Although such changes occurred after pain relief, all parameters were within their normal ranges.

Interpretation OA patients and healthy subjects show similar impulse-forces and joint kinematics at heel strike. Following pain relief in the patient group, changes in tibial PA and in hip and knee joint angles were observed but these were still within the normal range. Our findings make us question the hypothesis that impulse-forces generated at heel strike during walking contribute to progression of OA.     

Microvascular circulatory changes in the lower extremities after reconstructive vascular surgery for intermittent claudication

We have studied the circulatory changes in the lower extremities after reconstructive vascular surgery in ten patients with intermittent claudication. The following examinations were carried out 3 days before, 3 days, and 28 days after the operation: measurement of ankle systolic blood pressure, calf plethysmography, resting calf muscle blood flow and resting subcutaneous foot blood flow. The vasoconstrictor response (veno-arteriolar reflex) was also assessed. On the night before the operation and on the 28th night after aorto-bifemoral bypass surgery, subcutaneous adipose tissue blood flow in the forefoot was measured during sleep. The ankle systolic blood pressure and the ankle index rose significantly. The former increased from 57 +/- 16.4 mmHg to 93 +/- 24.0 mmHg (mean +/- S.E.M.) and was still elevated on the 28th postoperative day. The total limb blood flow, the muscle blood flow and the blood flow in the subcutaneous tissue of the forefoot during daytime were unchanged. In contrast, the blood flow in the forefoot during sleep increased significantly from 3.5 +/- 1.63 ml x (min x 100 g)-1 to 5.2 +/- 2.14 ml x (min x 100 g)-1 (mean +/- S.E.M.) on the 28th night. The vasoconstrictor response was potentiated, and increased from 27% before the operation to 45% on the third postoperative day. This change was maintained 28 days postoperatively. In conclusion the increase in arterial blood pressure was only reflected in the vasoconstrictor response which had returned to normal by the third postoperative day and nocturnal blood flow in the subcutaneous adipose tissue which did likewise.     

Skin symptoms among workers in the fish processing industry are caused by high molecular weight compounds

Scratch tests were performed with fish juice containing high and low molecular weight compounds obtained by ultrafiltration and with degradation compounds known to accumulate in fish stored on ice. 75 volunteers were tested. The peptide pattern in raw fish juice and its high and low molecular weight fractions were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and the concentration of protein in the various fractions was determined. Fish products were analysed for bacteria and algae and the concentration of degradation compounds was measured. Mainly high molecular weight compounds (polypeptides) of fish juice were found to be responsible for the skin symptoms.     

Combined effects of irritants and allergens. Synergistic effects of nickel and sodium lauryl sulfate in nickel- sensitized individuals

Knowledge of the combined effects of irritants and allergens is of interest with respect to accurate risk assessment. The threshold for elicitation of allergic contact dermatitis in previously sensitized individuals may theoretically be markedly influenced by the simultaneous presence of irritants and allergens. Combined exposures have, however, only been studied infrequently. In the present study, the combined effect of an irritant and an allergen was evaluated in a dose-response designed experimental study. 20 nickel-sensitized subjects were exposed to patch testing with varying concentrations of NiCl2 (nickel chloride) and sodium lauryl sulfate (SLS) alone and in combination. Evaluation of skin reactions was performed by colorimetry, measurement of transepidermal water loss and clinical evaluation, and the data were analyzed by logistic dose-response models. A synergistic effect was found of combined exposure to NiCl2 and SLS, as compared to each of the substances applied separately, as evaluated by colorimetry and clinical scoring. This means that the effect produced by the combined exposure was substantially greater than the effect produced by either of the substances alone. A synergistic effect of combined exposure on skin barrier impairment was not found, since the barrier function is significantly influenced by SLS-exposure only and not by NiCl2. Concentration limits are used by industry and government agencies to protect consumers. The present results clearly illustrate that elicitation thresholds and concentration limits may be influenced considerably by combined exposure to allergens and irritants.     

Development of an in vivo animal model for skin penetration in hairless rats assessed by mass balance

The aim of the study was to develop an in vivo animal model for studies of the penetration of topically applied drugs into the skin of hairless rats. Protective appliances were designed for non-occluded and finite-dose application of topical formulations. The design allowed 2 test sites for each rat and free mobility throughout the test period. By consecutive tape stripping, monitored by measurements of transepidermal water loss and confirmed by histological examination of skin biopsies, 10 tape strippings were found to remove the stratum corneum completely. For assessment of the model, (14)C-salicylic acid and (14)C-butyl salicylate were topically applied. Rapid and differentiated percutaneous absorption of both compounds were shown by urinary excretion data. For (14)C-salicylic acid the amount on the skin surface, in the stratum corneum and in the viable skin was determined. Total mass balance on the applied radioactivity was performed and a recovery of 90 +/- 2% was achieved. The radioactivity found in the protective appliances (<10%) was explained by lateral skin diffusion of the model compounds into the dressings.     

An outbreak of legionnaires disease caused by long-distance spread from an industrial air scrubber in Sarpsborg, Norway.

BACKGROUND: On 21 May 2005, the Norwegian health authorities were alerted by officials from a local hospital that several recent patients had received the diagnosis of legionnaires disease; all patients resided in 2 neighboring municipalities. We investigated the outbreak to identify the source and to implement control measures. METHODS: We interviewed all surviving case patients and investigated and harvested samples from 23 businesses with cooling towers and other potential infection sources. The locations of the businesses and the patients' residences and movements were mapped. We calculated attack rates and risk ratios among people living within various radii of each potential source. Isolates of Legionella pneumophila were compared using molecular methods. RESULTS: Among 56 case patients, 10 died. The case patients became ill 12-25 May, resided up to 20 km apart, and had not visited places in common. Those living up to 1 km from a particular air scrubber had the highest risk ratio, and only for this source did the risk ratio decrease as the radius widened. Genetically identical L. pneumophila serogroup 1 isolates were recovered from patients and the air scrubber. The air scrubber is an industrial pollution-control device that cleans air for dust particles by spraying with water. The circulating water had a high organic content, pH of 8-9, and temperature of 40 degrees C. The air was expelled at 20 m/s and contained a high amount of aerosolized water. CONCLUSIONS: The high velocity, large drift, and high humidity in the air scrubber may have contributed to the wide spread of Legionella species, probably for >10 km. The risk of Legionella spread from air scrubbers should be assessed.     

Which ultrasound lesions contribute to dactylitis in psoriatic arthritis and their reliability in a clinical setting

Clinical Rheumatology - To explore the frequency of ultrasound elementary lesions in dactylitis in psoriatic arthritis (PsA), and the reliability of scoring these lesions in a clinical setting. In...