Joint Reaction Forces during the Recovery of Postural Balance of Human Body

2005 ◽  
Vol 297-300 ◽  
pp. 2308-2313
Author(s):  
Min Jwa Seo ◽  
Hyeon Ki Choi

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces (JRF) of the ankle joint during the waist pulling, and to assess the ankle JRF according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 camera motion analysis system, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and JRF during the recovery of postural balance control. From the experiment using mass-falling perturbation, joint moments were larger than those from the experiment with milder perturbation using air cylinder pulling system. However, joint reaction forces were similar nevertheless the difference in joint moment. From the results, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movements or compensating JRF by distributing the forces on surrounding soft tissues. The results of this study provide us important insights for understanding the relationship between balance control and ankle injury mechanism.

Author(s):  
Dong Sun ◽  
Gusztáv Fekete ◽  
Julien S. Baker ◽  
Qichang Mei ◽  
Bíró István ◽  
...  

The purpose of this study was to compare the inter-limb joint kinematics, joint moments, muscle forces, and joint reaction forces in patients after an Achilles tendon rupture (ATR) via subject-specific musculoskeletal modeling. Six patients recovering from a surgically repaired unilateral ATR were included in this study. The bilateral Achilles tendon (AT) lengths were evaluated using ultrasound imaging. The three-dimensional marker trajectories, ground reaction forces, and surface electromyography (sEMG) were collected on both sides during self-selected speed during walking, jogging and running. Subject-specific musculoskeletal models were developed to compute joint kinematics, joint moments, muscle forces and joint reaction forces. AT lengths were significantly longer in the involved side. The side-to-side triceps surae muscle strength deficits were combined with decreased plantarflexion angles and moments in the injured leg during walking, jogging and running. However, the increased knee extensor femur muscle forces were associated with greater knee extension degrees and moments in the involved limb during all tasks. Greater knee joint moments and joint reaction forces versus decreased ankle joint moments and joint reaction forces in the involved side indicate elevated knee joint loads compared with reduced ankle joint loads that are present during normal activities after an ATR. In the frontal plane, increased subtalar eversion angles and eversion moments in the involved side were demonstrated only during jogging and running, which were regarded as an indicator for greater medial knee joint loading. It seems after an ATR, the elongated AT accompanied by decreased plantarflexion degrees and calf muscle strength deficits indicates ankle joint function impairment in the injured leg. In addition, increased knee extensor muscle strength and knee joint loads may be a possible compensatory mechanism for decreased ankle function. These data suggest patients after an ATR may suffer from increased knee overuse injury risk.


2010 ◽  
Vol 25 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Susanne Rein ◽  
Tobias Fabian ◽  
Hans Zwipp ◽  
Jan Heineck ◽  
Stephan Weindel

OBJECTIVE: The aim of this study was to examine the influence of extensive work-related use of the feet on functional ankle stability among musicians. METHODS: Thirty professional organists were compared to professional pianists and controls. All participants completed a questionnaire. Range of motion (ROM), peroneal reaction time, and positional sense tests of the ankle were measured. The postural balance control was investigated with the Biodex Stability System for the stable level 8 and unstable level 2. Statistical analysis was done with the Kruskal-Wallis test, Mann-Whitney test with Bonferroni-Holm correction, and Fisher’s exact test. RESULTS: Nine of 30 organists compared to 5 of 30 pianists and controls reported ankle sprains in their medical history. Pianists had a significant increased flexion of both ankle joints compared to organists (p≤0.01) and increased flexion of the right ankle joint compared to controls (p=0.02). The positional sense test and postural balance control showed no significant differences among groups. The peroneal reaction time of the right peroneus longus muscle was significantly increased in pianists compared to controls (p=0.008). CONCLUSIONS: Organists have shown a high incidence of ankle sprains. Despite their extensive work-related use of the ankle joints, organists have neither increased functional ankle stability nor increased ROM of their ankle joints in comparison to controls. Pianists have increased flexion of the ankle joint, perhaps due to the exclusive motion of extension and flexion while using the pedals. To minimize injuries of the ankle and improve functional ankle stability as well as balance control, proprioceptive exercises of the ankle in daily training programs are recommended.


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