Search

This study was undertaken to investigate the use of vibromyography (VMG) as a tool for quantifying skeletal muscle force production. Fourteen healthy volunteers were pretested using a Cybex isokinetic dynamometer to determine their isometric quadricep maximum voluntary contraction (MVC) values. On the basis of these results, the subjects were separated into two groups: high-force ("HF" MVC mean = 289 ft.lb., range 254-330) and low-force ("LF" MVC mean = 154 ft.lb., range 101-198). A vibromyographic piezoelectric accelerometer (Dytran 3115A) and electromyographic (EMG) surface electrodes were affixed to the rectus femoris muscle and recordings were obtained at 20, 40, 60, 80, and 100% MVC. Root mean squares, median and mean values were computed from digitized data in the time domain while peak values were calculated from a fast Fourier transform for both the VMG and EMG data. A two-way repeated measures MANOVA using relative values and a linear regression model using absolute values were studied using BMDP and MiniTab software. Linear correlations were found between quadricept force and all EMG variables (R2 range 0.71-0.90) except peak (R2 = 0.39). The relationship between VMG and force was less linear (R2 range 0.19-0.69) because VMG values reach a plateau or even drop at 80% and 100% MVC. The HF-LF group differences were significant (p < 0.05), for all VMG values with the exception of root mean squares, but were not significant (p > 0.05) for all four EMG values. This study shows that, while EMG can discriminate force production within a given subject, VMG is a better discriminator of absolute muscle force values between subjects, particularly up to 60% MVC.

Poor lumbar spine kinesthetic awareness is often observed in low back pain patients and is usually evaluated qualitatively in the clinical situation. The purpose of this study was to investigate a simple, kinesthetic test for the lumbar spine. The experimental protocol utilized a 3Space Fastrak to determine the error, within and between days, of 10 healthy subjects in reproducing a neutral lumbopelvic (T10-S2) position following movement into flexion. The mean value of the repositioning error for the sagittal plane movement (flexion/extension) over the three repetitions within day 1 was 2.6 +/- 1.2 degrees and for day 2 was 2.6 +/- 1.7 degrees. No statistically significant difference existed between days. These repositioning errors were well within the ranges described by other authors for various asymptomatic joint complexes. These results provide a basis for further evaluation of this test on patients with low back pain to investigate its ability to detect any kinesthetic deficit.

Plantar flexion and inversion stresses at the ankle may cause the tarsal cuboid to sublux in a plantar or dorsal direction resulting in pain and impaired joint function. Subluxation of the tarsal cuboid alters the passive physiological motion and accessory glides of the cuboid joints in characteristic patterns of motion restriction. Identification of the pattern of motion restriction is necessary for appropriate diagnosis and treatment. This paper presents the case reports of two patients with lateral foot pain. A subluxed cuboid bone was believed to be the cause of the patient's pain. Assessment and treatment are described and possible pathomechanics for cuboid subluxation are presented. Passive physiological motion of the cuboid and accessory joint glides should be assessed in patients complaining of lateral foot pain or with inversion ankle injuries. Pain and joint impairment can be alleviated with proper assessment and treatment.