Comparison of intraobserver single-task reliabilities of the Interactive Balance System (IBS) and Vertiguard in asymptomatic subjects

Characterization of Gait and Postural Regulation in Late-Onset Pompe Disease

Pompe disease is a multisystemic disorder with the hallmark of progressive skeletal muscle weakness that often results in difficulties in walking and balance. However, detailed characterization of gait and postural regulation with this disease is lacking. The objective of this investigation was to determine if differences exist between the gait and postural regulation of LOPD patients and a matched control group. The gaits of 16 patients with LOPD were assessed using a gait analysis mobile system (RehaGait) and a dynamometric treadmill (FDM-T 1.8). The Interactive Balance System (IBS) was used to evaluate postural regulation and stability. All measures were compared to individual reference data. Demographic (age, gender), morphological (body height, body mass) and clinical data (muscle strength according to the Medical Research Council Scale (MRC Scale), as well as the 6-min walking test and a 10-m fast walk) were also recorded. Compared to individual reference data, LOPD patients presented with reduced gait velocity, cadence and time in single stand. A total of 87% of LOPD patients had abnormalities during posturographic analysis presenting with differences in postural subsystems. This study provides objective data demonstrating impaired gait and posture in LOPD patients. For follow-up analysis and as outcome measurements during medical or physiotherapeutic interventions, the findings of this investigation may be useful.

Postural Stability and Regulation before and after High Tibial Osteotomy and Rehabilitation

Knee osteoarthrosis (OA) is a widespread orthopedic problem and a high tibial osteotomy (HTO) is a common treatment to minimize degeneration of the affected compartment. The primary aim of this study was to evaluate the postural regulation and stability among patients who underwent HTO and rehabilitation. This prospective study included 32 patients (55.3 ± 5.57 years) diagnosed with medial tibiofemoral OA. Each subject completed postural regulation and stability testing (Interactive Balance System), as well as pain intensity (visual analogue scale) and quality of life questionnaires (SF-36) prior to HTO (exam 1), and at six weeks (exam 2), twelve weeks (exam 3) and six months (exam 4) post HTO. For postural comparison, all patients were matched (sex, age, height) with asymptomatic subjects. Significant time effects (exam 1 vs. exam 4) were found for weight distribution index (WDI; ηp2 = 0.152), mediolateral weight distribution ηp2 = 0.163) and anterior–posterior weight distribution ηp2 = 0.131). The largest difference (exam 3: ηp2 = 0.251) and the most significant differences to the matched sample were calculated for the stability indicator (exam 1: ηp2 = 0.237; exam 2: ηp2 = 0.215; exam 3: ηp2 = 0.251; exam 4: ηp2 = 0.229). Pain intensity showed a significant reduction (ηp2 = 0.438) from exam 1 (50.7 ± 20.0 mm) to exam 4 (19.3 ± 16.0 mm). Physical pain was the quality of life parameter with the largest improvement between exams 1 and 4 (ηp2 = 0.560). HTO allows patients to improve their mediolateral weight distribution, whereas postural stability is consistently lower than in asymptomatic subjects. This surgery leads to marked improvements in quality of life and pain.

Postural regulation and stability with acoustic input in normal-hearing subjects

Background

Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control.

Objective

The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects.

Materials and methods

In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force–time relation.

Results

At the process level, we found a relevant reduction (η_p² ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system η_p² = 0.122) and F2–4 (peripheral vestibular system η_p² = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (η_p² = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed.

Conclusion

In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

[Postural regulation and stability with acoustic input in normal hearing subjects. German version]

BACKGROUND

Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control.

OBJECTIVE

The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects.

MATERIALS AND METHODS

In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force-time relation.

RESULTS

At the process level, we found a relevant reduction (η_p² ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system η_p² = 0.122) and F2-4 (peripheral vestibular system η_p² = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (η_p² = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed.

CONCLUSION

In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

Postural stability and regulation before and after anterior cruciate ligament reconstruction - A two years longitudinal study

OBJECTIVES

To evaluate postural regulation and stability among patients who underwent anterior cruciate ligament reconstruction (ACLR) and rehabilitation over a two-year follow-up period.

DESIGN

Longitudinal; SETTING: Biomechanics laboratory; PARTICIPANTS: 30 ACLR patients (32.0 ± 12.2 years, 14 males) with isolated ACL rupture.

MAIN OUTCOME MEASURES

Postural regulation was tested before ACLR, as well as at six-weeks, twelve-weeks, six-months, one-year and two-years post-ACLR and standardized rehabilitation. Postural regulation was measured for stability indicator (ST), weight distribution index (WDI), synchronization (foot coordination) and sway intensities (postural subsystems).

RESULTS

Significant time effects (pre-vs. two-years postoperative) were found for WDI (η_p² = 0.466), synchronization (η_p² = 0.368), mediolateral weight distribution (η_p² = 0.349), ST (η_p² = 0.205), visual/nigrostriatal systems (η_p² = 0.179) and peripheral-vestibular system (η_p² = 0.102). The largest difference (preoperative: η_p² = 0.180) to the matched sample was calculated for WDI. The most significant differences to the matched sample were observed for ST (preoperative: η_p² = 0.126; six-weeks postoperative: η_p² = 0.103) and WDI (preoperative: η_p² = 0.180; six-weeks postoperative: η_p² = 0.174).

CONCLUSION

ACLR and rehabilitation influence postural subsystems, postural stability, weight distribution and foot synchronization. Normalization of mediolateral weight distribution requires one year following ACLR. The ACLR leads to a suppression of the somatosensory and cerebellar system which was compensated by a higher activity of the visual and nigrostriatal systems.

Pre- and postoperative postural regulation following anterior cruciate ligament reconstruction

There are currently no longitudinal data describing the pre- and postoperative postural regulation and stability of patients with anterior cruciate ligament (ACL) damage. Therefore, the aim of this study was to evaluate postural regulation and stability prior to and during rehabilitation following surgery of the ACL. Fifty-four physically active subjects (age: 30.5±10.9 years, 29 male subjects) were examined with the Interactive Balance System pre-, 6, and at 12 weeks following surgical reconstruction of the ACL using a hamstring tendon graft. The average period of time from injury to surgery was 27 days. Data were calculated with unifactorial and univariate analysis of variance. Significant effects were found for the somatosensory system (η2=0.115), stability indicator (η2=0.123), weight distribution index (η2=0.176), and synchronization (foot coordination) (η2=0.249). Involved side weight distribution (parameter: left) increased significantly (patients with left-sided/right-sided injury: η2=0.234/0.272). Load distribution to the heel remained stable during all three examination periods (η2=0.035 and η2=0.071), although a remarkable load at forefoot was observed. In seven out of 10 parameters partial effects were seen during the first 6 weeks after surgery. The results of this study indicated that injury of the ACL and subsequent surgical reconstructions result in postural regulation, with improvements in somatosensory system function, postural stability, weight distribution index, and foot coordination. Also, overloading of the injured side on the feet reduces significantly during rehabilitation. Thus, the initial phase of rehabilitation (weeks 1 to 6) seems to be more effective than the second period (weeks 6 to 12) postoperatively.