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Several naturally occurring inhibitors of interleukin 1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) have been demonstrated both in serum and urine of febrile patients. These factors are considered to be part of a regulatory system counteracting potential deleterious effects of the cytokines. We have assayed plasma samples of volunteers who received a bolus intravenous injection of either 4 ng/kg body wt of Escherichia coli endotoxin (n = 6) or 0.9% saline (n = 4) for the presence of IL-1 and TNF-alpha inhibitory activity. Plasma obtained 3 h after endotoxin injection inhibited IL-1-induced PGE2 release from fibroblasts by 57% (P less than 0.001 vs. baseline and saline controls, respectively). Maximal IL-1 inhibitory capacity coincided with fever and tended to disappear with declining body temperature. Normal plasma was found to inhibit TNF-alpha-induced PGE2 release by 20-35%. This inhibitory effect increased to 50-60% in plasma obtained during endotoxinemia. Maximal TNF-alpha inhibitory capacity became detectable when circulating TNF-alpha levels peaked at 120 min after the injection of endotoxin. Our data demonstrate that both IL-1 and TNF-alpha inhibitory activity can be induced experimentally by intravenous endotoxin administration to humans and that their appearance coincides with fever and circulating TNF-alpha levels.

Kinematic differences between patients with osteoarthritis (OA) and control participants have been reported to be influenced by gait speed. The purpose of this study was to experimentally detect the effect of walking speed on differences in spatiotemporal parameters and kinematic trajectories between patients with hip OA and age‐matched asymptomatic participants using wearable sensors and statistical parametric mapping (SPM). Twenty‐four patients with severe unilateral hip OA and 48 control participants were included in this study. Patients walked at a self‐selected normal speed and control participants at self‐selected normal and slow speeds. Spatiotemporal parameters and kinematic trajectories were measured with the inertial sensor system Rehagait®. Gait parameters were compared between patients with hip OA and control participants for normal and matched speed using SPM with independent sample t‐tests. At self‐selected normal speed, the patient group walked slower (−0.20 m/s, p < .001) and at lower cadence (−5.0 steps/minute, p < .001) as well as with smaller hip flexion (−7.4°, p < .001) and extension (−4.1°, p = .001), higher knee flexion during terminal stance (+8.0°, p < .001) and higher ankle dorsiflexion and plantarflexion (+7.1°, p < .001). While differences in spatiotemporal parameters and the ankle trajectory disappeared at matched speed, some clinically relevant and statistically significant differences in hip and knee trajectories remained. Most differences in sagittal plane gait kinematics between patients with hip OA and control participants were present for matched speed, and therefore appear to be associated with a disease rather than gait speed. Nevertheless, studies investigating hip kinematics in patients with hip OA should involve trials at matched speeds.

Inertial measurement units (IMUs) are commonly used for gait assessment, yet their potential for quantifying improvements in gait function and patterns after total hip arthroplasty (THA) has not been fully explored. The primary aim of this study was to compare spatiotemporal parameters and sagittal plane kinematic patterns of patients with hip osteoarthritis (OA) before and after THA, and to asymptomatic controls.The secondary aim was to assess the association between dynamic hip range of motion (ROM) during walking and the Hip Osteoarthritis Outcome Scores (HOOS).Twenty-four patients with hip OA and 24 matched asymptomatic controls completed gait analyses using the RehaGait ® sensor system. Patients were evaluated pre-and 1 year postoperatively, controls in a single visit. Differences in kinematic data were analyzed using statistical parametric mapping, and correlations between dynamic hip ROM and HOOS were calculated. Walking speed and stride length significantly increased (+0.08 m/s, p = 0.019; +0.06 m, p = 0.048) after THA but did not reach the level of asymptomatic controls (−0.11 m/s, p = 0.028; −0.14 m, p = 0.001). Preoperative hip and knee kinematics differed significantly from controls.After THA, they improved significantly and did not differ from controls. Dynamic hip flexion-extension ROM correlated positively with all HOOS subscores (r > 0.417; p ≤ 0.001). The change in HOOS symptoms in patients was explained by the combination of baseline HOOS symptoms and change in dynamic hip ROM (r 2 = 0.748) suggesting that the additional information gained with IMU gait analysis helps to complement and objectify patient-reported outcome measures pre-and postoperatively and monitor treatment-related improvements.