Increased postural stiffness during challenging postural tasks in patients with knee osteoarthritis with high pain sensitization

Posturography measures in specific ballet stance position discriminate ballet dancers with different occurrences of musculoskeletal injuries

BACKGROUND

This study aimed to identify the postural sway variables that can distinguish between ballet dancers with high and low occurrences of musculoskeletal injuries.

METHODS

Fourteen professional ballet dancers were assigned to a high-occurrence group (N = 5, reports >2 injuries in the previous 6-months) or a low-occurrence group (N = 9, reports ≤1 injury). Center-of-pressure (COP) data were acquired using a force platform during the following tasks: single-leg stance with eyes open, single-leg stance with eyes closed, and demi-pointe stance with eyes open. The COP standard deviation (SD) and range (RA) in both the medial-lateral (ML) and anterior-posterior (AP) directions were estimated. Between-group comparisons were made through Welch's t-tests for unequal sample size along the effect size measure (Cohen's d). Spearman's rho was used to estimate the association between the number of injuries and the COP variables. The statistical threshold was set at 1%.

RESULTS

A between-group effect was found only for the demi-pointe stance, with large effects for SDML (P = 0.006, d = 1.7), RAAP (P = 0.006, d = 1.7), and RAML (P = 0.005, d = 1.7). An inverse relationship was found between the number of injuries and the demi-pointe's COP range in both directions (Spearman's rho from -0.681 to -0.726, P = 0.007).

CONCLUSIONS

COP measures taken in ballet-specific positions can distinguish between dancers with a high and low occurrence of musculoskeletal injuries. Suggestions are made to include ballet-specific tasks in the functional assessments of professional dancers.

What Influences Proprioceptive Impairments in Patients with Rheumatic Diseases? Analysis of Different Factors

Rheumatic diseases lead to postural problems, which increase the risk of falls and lead to greater disability. The aim of the present work is to evaluate posture disorders in patients with osteoarthritis (OA) and rheumatoid arthritis (RA), as well as to evaluate the influence of other factors. A total of 71 subjects were enrolled in this study. Joint position sense (JPS) and the functional assessment of proprioception on a balance platform for both lower limbs were examined. The Average Trace Error (ATE), test time (t), and Average Platform Force Variation (AFV) were calculated. Additionally, an equilibrium test was carried out in the one-legged standing position (Single Leg Stance-SLS). The results were compared in several ways and revealed the following: (1) A JPS of 10° plantar flexion in RA obtained significantly worse results when repeating the movement than OA; the ATEs were significantly lower in RA; and RA needed more support during SLS assessment. (2) RA patients with higher DAS28 had statistically significantly higher values in JPS, with 5° plantar flexion and 10° dorsal flexion, SLS assessment, and stabilometric rates. A statistically significant correlation between DAS28 and RA was found in a JPS of 10° plantar flexion. The VAS ruler demonstrated a significant moderate correlation with t. (3) Patients who experienced at least one fall demonstrated higher JPS and t. Our study shows that proprioception is the most influenced by the nature of the disease and the level of disease activity. We can see that the stability and balance functions are also greatly influenced by the patient's falling experience and the level of pain. These findings may be useful in designing an optimal proprioception-enhancing movement training plan.

Asymmetries and relationships between muscle strength, proprioception, biomechanics, and postural stability in patients with unilateral knee osteoarthritis

Background: The pathological mechanism of knee osteoarthritis (KOA) is unknown. KOA degeneration may be associated with changes in muscle strength, proprioception, biomechanics, and postural stability.

Objective: This study aimed to assess asymmetries in muscle strength, proprioception, biomechanics, and postural stability of bilateral lower limbs in patients with unilateral KOA and healthy controls and analyze correlations between KOA and these parameters.

Methods: A total of 50 patients with unilateral KOA (age range: 50-70) and 50 healthy subjects were recruited as study participants (age range: 50-70). Muscle strength, proprioception, femorotibial angle (FTA), femoral condylar–tibial plateau angle (FCTP), average trajectory error (ATE), and center of pressure (COP) sways areas were accessed in study participants, and the correlation between these variables was investigated.

Results: In patients with unilateral KOA, lower limb muscle strength was significantly lower on the symptomatic side than on the asymptomatic side (p < 0.01), while the proprioception (degree error), FTA, FCTP, and ATE were substantially higher compared to the asymptomatic side (p < 0.01). However, no significant difference was observed in the healthy controls (p > 0.05). Patients with unilateral KOA had lower muscle strength than healthy controls (p < 0.05), but their proprioception (degree error: the difference between the target and reproduction angles), ATE, and COP sway areas were higher (p < 0.05). Muscle strength was found to be negatively correlated with ATE and COP sways areas (p < 0.05), whereas proprioception (degree error) was positively correlated with ATE and COP sways areas (p < 0.05) in all study participants. However, no correlation was found between FTA, FCTP, and ATE, COP sways areas in patients with unilateral KOA (p > 0.05).

Conclusion: In patients with unilateral KOA, muscle strength, proprioception, biomechanics, and postural stability of bilateral limbs are asymmetrical in unilateral KOA patients. Muscle strength, proprioception, and postural stability are significantly associated variables, and changes in these variables should be considered in KOA prevention and rehabilitation.

Difference in postural stability between STarT Back Tool subgroups of patients with low back pain under conditions of sensory deprivation and cognitive load

Objective

We explored differences in postural stability between subgroups of patients with low back pain (LBP) and varying risk levels for developing chronicity measured using the Subgroups for Targeted Treatment (STarT) Back Tool.

Methods

This was a cross-sectional, single-session, double-blind experimental study among 65 participants who had LBP for more than 14 days. Postural stability was assessed by measuring the center of pressure (COP) range, displacement area, and velocity in anterior–posterior and mediolateral directions under four sensory and cognitive conditions: (i) eyes open and counting forward, (ii) eyes closed and counting forward, (iii) eyes closed and counting forward in multiples of seven, and (iv) eyes closed and counting backward in multiples of seven. The participants were stratified into low-/medium- (n = 53) and high-risk (n = 9) subgroups.

Results

There were no significant between-group differences among patients with LBP stratified as having a low/medium or high risk of chronicity in postural stability and sensory and cognitive conditions.

Conclusions

Impaired postural stability is important to consider when treating patients with LBP. However, we found that these impairments were not strongly aggravated in groups with a higher risk of chronicity, as measured using the STarT Back Tool.

Could emotional and sensitization status affect postural sway in adults with knee osteoarthritis?

BACKGROUND AND PURPOSE

The manipulation of sensory conditions and attentional demand affect the postural sway in older adults with knee osteoarthritis (KOA). However, it is not known if emotional and sensitization status affects postural sway in this population. This study aimed to test if older adults with mild and moderate knee osteoarthritis with symptoms of depression and high sensitization would change the profile of postural sway.

METHODS

Design: A cross-sectional study was undertaken.

PARTICIPANTS

The center of pressure parameters of 30 older adults with mild and moderate knee osteoarthritis and 15 healthy controls were evaluated under different conditions manipulating the visual and attentional demand. We used the pressure pain threshold to measure the sensitization status. Furthermore, we applied the Beck Depression Inventory index to assess emotional status.

RESULTS

Manipulating the visual demand affected the center of pressure parameters for both groups, without differences between them. Compared to the healthy control group, the knee osteoarthritis group presented with worse scores on the Beck Depression Inventory, lower pressure pain threshold scores, and the correlations between the symptoms of depression and sensitization status ranged from weak to moderate. Finally, in the knee osteoarthritis group, we observed few and weak significant associations between the center of pressure parameters and the Beck Depression Inventory and the pressure pain threshold scores.

DISCUSSION

Emotional and sensitization status seem not to be more associated with the center of pressure of older adults with mild to moderate KOA than healthy adults. Thus, it suggests that this population can safely maintain postural sway, irrespective of depression symptoms and high sensitization.

The effects of pain and a secondary task on postural sway during standing

BACKGROUND

Pain impairs available cognitive resources and somatosensory information, but its effects on postural control during standing are inconclusive. The aim of this study was to investigate whether postural sway is affected by the presence of pain and a secondary task during standing.

METHODS

Sixteen healthy subjects stood as quiet as possible at a tandem stance for 30s on a force platform at different conditions regarding the presence of pain and a secondary task. Subjects received painful stimulations on the right upper arm or lower leg according to a relative pain threshold [pain 7 out 10 on a Visual Analog Scale (VAS) - 0 representing "no pain" and 10 "worst pain imaginable"] using a computer pressurized cuff. The secondary task consisted of pointing to a target using a head-mounted laser-pointer as visual feedback. Center of Pressure (COP) sway area, velocity, mean frequency and sample entropy were calculated from force platform measures.

FINDINGS

Compared to no painful condition, pain intensity (leg: VAS = 7; arm VAS = 7.4) increased following cuff pressure conditions (P < .01). Pain at the leg decreased COP area (P < .05), increased COP velocity (P < .05), mean frequency (P < .05) and sample entropy (P < .05) compared with baseline condition regardless the completion of the secondary task. During condition with pain at the leg, completion of the secondary task reduced COP velocity (P < .001) compared with condition without secondary task.

INTERPRETATION

Pain in the arm did not affect postural sway. Rather, postural adaptations seem dependent on the location of pain as pain in the lower leg affected postural sway. The completion of a secondary task affected postural sway measurements and reduced the effect of leg pain on postural sway. Future treatment interventions could benefit from dual-task paradigm during balance training aiming to improve postural control in patients suffering from chronic pain.

The Effects of Baduanjin Qigong on Postural Stability, Proprioception, and Symptoms of Patients With Knee Osteoarthritis: A Randomized Controlled Trial

Background: Knee osteoarthritis is a common disease affecting a large number of old individuals worldwide. This study aimed to explore the effects of Baduanjin Qigong in patients with knee osteoarthritis. Methods: Fifty participants with knee osteoarthritis were randomly assigned to either an experimental group (n = 25) or a control group (n = 25). Participants in the experimental group received Baduanjin Qigong training for 12 weeks, with three sessions per week lasting 40 min per session. Participants in the control group did not receive any additional physical training. All of participants completed outcome (proprioception, postural stability, and functional ability) assessments at three time points (baseline, Week 8, 12). Results: Proprioception and Western Ontario and McMaster Universities Osteoarthritis Index function were statistically improved at eighth and 12th week of the intervention in the Baduanjin Qigong group (p < 0.05), while the control group did not have any significant changes. For postural stability at the anterior-posterior direction with eyes closed, Baduanjin Qigong group showed significant improvement compared to controls after the 12 weeks of intervention (p < 0.05). Conclusions: Regular Baduanjin Qigong practice helped the improvement of knee joint proprioception and postural stability, and reduction of pain, stiffness, and functional impairments of old adults with knee osteoarthritis. Well-designed randomized controlled trials with long-term assessment are needed. The trial was registered in Chinese Clinical Trial Registry (ChiCTR-IOR-16010042). URL: http://www.chictr.org.cn/hvshowproject.aspx?id=10550.