Magnitude and variability of loading on the osseointegrated implant of transfemoral amputees during walking

This study directly measured the load acting on the abutment of the osseointegrated implant system of transfemoral amputees during level walking, and studied the variability of the load within and among amputees. Twelve active transfemoral amputees (age: 54 +/- 12 years, mass: 84.3 +/- 16.3 kg, height: 17.8 +/- 0.10 m) fitted with an osseointegrated implant for over 1 year participated in the study. The load applied on the abutment was measured during unimpeded, level walking in a straight line using a commercial six-channel transducer mounted between the abutment and the prosthetic knee. The pattern and the magnitude of the three-dimensional forces and moments were revealed. Results showed a low step-to-step variability of each subject, but a high subject-to-subject variability in local extrema of body-weight normalized forces and moments and impulse data. The high subject-to-subject variability suggests that the mechanical design of the implant system should be customized for each individual, or that a fit-all design should take into consideration the highest values of load within a broad range of amputees. It also suggests specific loading regime in rehabilitation training are necessary for a given subject. Thus the loading magnitude and variability demonstrated should be useful in designing an osseointegrated implant system better able to resist mechanical failure and in refining the rehabilitation protocol.     

Back pain and MRI changes in the thoraco-lumbar spine of top athletes in four different sports: a 15-year follow-up study

A total 71 male athletes (weight lifters, wrestlers, orienteers, and ice-hockey players) and 21 non-athletes were randomly selected, for a baseline MRI study. After 15 years all the participants at baseline were invited to take part in a follow-up examination, including a questionnaire on back pain and a follow-up MRI examination. Thirty-two athletes and all non-athletes had disc height reduction at one or several disc levels. Disc degeneration was found in more than 90% of the athletes and deterioration had occurred in 88% of the athletes, with the highest frequency in weight lifters and ice-hockey players. 78% of the athletes and 38% of the non-athletes reported previous or present history of back pain at baseline and 71 and 75%, respectively at follow-up. There was no statistically significant correlation between back pain and MRI changes. In conclusion, athletes in sports with severe or moderate demands on the back run a high risk of developing disc degeneration and other abnormalities of the spine on MRI and they report high frequency of back pain. The study confirmed our hypothesis, i.e. that most of the spinal abnormalities in athletes seem to occur during the growth spurt, since the majority of the abnormalities demonstrated at follow-up MRI after the sports career were present already at baseline. The abnormalities found at young age deteriorated to a varying degree during the 15-year follow-up, probably due to a combination of continued high load sporting activities and normal ageing. Preventive measures should be considered to avoid the development of these injuries in young athletes.     

Effect of long-term salmeterol therapy compared with as-needed albuterol use on airway hyperresponsiveness.

STUDY OBJECTIVES: To determine the effect of long-term salmeterol aerosol therapy on airway hyperresponsiveness measured by methacholine challenge. DESIGN: Randomized, double-blind, placebo-controlled, multicenter study. SETTING: Thirty-one clinical centers in the United States. PATIENTS: Four hundred eight asthmatic patients > or = 12 years of age with baseline FEV1 of > or = 70% of predicted values. Patients were not using inhaled corticosteroids. INTERVENTIONS: Twice-daily salmeterol aerosol, 42 microg, or placebo via metered-dose inhaler for 24 weeks. Backup albuterol was available. MEASUREMENTS AND RESULTS: Pulmonary function tests were performed before, during, and after treatment. Subjects recorded asthma-related symptoms, morning and evening peak expiratory flow (PEF) levels, and use of supplemental albuterol daily on diary cards. Methacholine challenges were performed 10 to 14 h postdose at weeks 4, 12, and 24, and 3 and 7 days posttreatment. Over 24 weeks of treatment, salmeterol provided significant (p < 0.001) protection against methacholine-induced bronchoconstriction of approximately one doubling dose of methacholine when compared to placebo with no evidence for a progressive decrease in protection. A rebound increase in airway hyperresponsiveness was not observed 3 and 7 days after cessation of salmeterol therapy. Salmeterol treatment resulted in sustained improvements of 0.21 to 0.26 L in morning premedication FEV1 and an improvement of 26.2 L/min in morning PEF when compared to placebo (p < 0.001). The use of salmeterol significantly reduced combined daytime asthma symptoms by 20% when compared to placebo (p = 0.005). A total of 34 and 48 exacerbations, respectively, were reported in the Salmeterol and placebo groups, and no evidence was present for a difference in the severity of asthma exacerbations between groups. Adverse event profiles were similar for the salmeterol and placebo groups. CONCLUSIONS: Regular long-term use of salmeterol aerosol resulted in sustained improvements in pulmonary function and asthma symptom control over the 24-week treatment period. There was no increase in bronchial hyperresponsiveness or loss of bronchoprotection at 24 weeks from that seen following 4 weeks of therapy. There was no evidence of rebound airway hyperresponsiveness after cessation of salmeterol treatment. Regular treatment with the long-acting beta-agonist salmeterol does not lead to clinical instability or vulnerability to unpredictable asthma attacks.