The Effect of an Interphase Interval on Electrically Induced Dorsiflexion Force and Fatigue in Subjects With an Upper Motor Neuron Lesion

The study objective was to investigate the effects of an interphase interval (IPI) interposed between the two phases of a biphasic symmetric pulse, on electrically induced contraction (EIC) forces and fatigue during stimulation of the ankle dorsiflexors in individuals with an upper motor neuron lesion (UMNL). The dorsiflexor muscles of 20 subjects with UMNL routinely using functional electrical stimulation to correct a foot drop during ambulation, were electrically stimulated with biphasic pulses (250 µs phase duration and 35 Hz pulse frequency) using nine IPI durations (ranging from 0 to 400 µs). The induced muscle force and fatigue were measured. A significant positive correlation was found between IPI duration and induced muscle force. Introducing a 250 µs IPI significantly decreased rate of muscle fatigue compared to stimulation with no IPI (P < 0.05). Thus, the introduction of an IPI may reduce the current intensity required to achieve a specific force during functional electrical stimulation in individuals with UMNL. Reduction in muscle fatigue may shorten the conditioning period necessary for first time users of functional electrical stimulation.     

The Evaluation of Postural Stability and Fall Risk in Patients with Primary Hip Osteoarthritis

BackgroundThe hip is a significant weight-bearing joint and hip osteoarthritis (HOA) is one of the common musculoskeletal disorders. HOA may affect postural stability and fall risk by disrupting joint biomechanics.MethodsFourty patients with unilateral primary HOA and a control group consisting of 41 healthy subjects were included in the study. HOA was radiographically graded by Kellgren Lawrence (KL) HOA classification. There were 26 patients with mild HOA (KL grade ≤ 2) and 14 patients with moderate-severe HOA (KL grade ≥ 3). The falls efficacy scale-international was used to assess fear of falling. Postural stability and the fall risk were evaluated by using the Biodex Stability System.ResultsThe postural stability and the fall risk indices were statistically significantly higher in the study group. Also, there was a positive correlation between the number of falls in the last 1 year, weight, and body mass index; and these correlations were statistically significant (r 0.686, p 0.003; r 0.477, p 0.002; r 0.444, p 0.004). There was no statistically significant difference in fall risk by the HOA was mild or moderate-severe.ConclusionsDetermining the deterioration in postural stability and the fall risk in patients with both mild and moderate-severe HOA may be a stimulus for early initiation of postural stability exercises in HOA.