A mechanical supination sprain simulator for studying ankle supination sprain kinematics

This study presents a free-fall mechanical supination sprain simulator for evaluating the ankle joint kinematics during a simulated ankle supination sprain injury. The device allows the foot to be in an anatomical position before the sudden motion, and also allows different degrees of supination, or a combination of inversion and plantarflexion. Five subjects performed simulated supination sprain trials in five different supination angles. Ankle motion was captured by a motion analysis system, and the ankle kinematics were reported in plantarflexion/dorsiflexion, inversion/eversion and internal/external rotation planes. Results showed that all sprain motions were not pure single-plane motions but were accompanied by motion in other two planes, therefore, different degrees of supination were achieved. The presented sprain simulator allows a more comprehensive study of the kinematics of ankle sprain when compared with some previous laboratory research designs

A three-pressure-sensor (3PS) system for monitoring ankle supination torque during sport motions

This study presented a three-pressure-sensor (3PS) system for monitoring ankle supination torque during sport motions. Five male subjects wore a pair of cloth sport shoes and performed 10 trials of walking, running, cutting, vertical jump-landing and stepping-down motions in a random sequence. A pair of pressure insoles (Novel Pedar model W, Germany) was inserted in the shoes for the measurement of plantar pressure at 100 Hz. The ankle joint torque was calculated by a standard lower extremity inverse dynamic calculation procedure with the data obtained by a motion capture system (VICON, UK) and a force plate (AMTI, USA), and was presented in a supination/pronation plane with an oblique axis of rotation at the ankle joint. Stepwise linear regression analysis suggested that pressure data at three locations beneath the foot were essential for reconstructing the ankle supination torque. Another group of five male subjects participated in a validation test with the same procedure, but with the pressure insoles replaced by the 3PS system. Estimated ankle supination torque was calculated from the equation developed by the regression analysis. Results suggested that the correlation between the standard and estimated data was high (R=0.938). The overall root mean square error was 6.91 N m, which was about 6% of the peak values recorded in the five sport motions (113 N m). With the good estimation accuracy, tiny size and inexpensive cost, the 3PS system is readily available to be implanted in sport shoe for the estimation and monitoring of ankle supination torque during dynamic sport motions

Differentiation of ankle sprain motion and common sporting motion by ankle inversion velocity

This study investigated the ankle inversion and inversion velocity between various common motions in sports and simulated sprain motion, in order to provide a threshold for ankle sprain risk identification. The experiment was composed of two parts: Firstly, ten male subjects wore a pair of sport shoes and performed ten trials of running, cutting, jump-landing and stepping-down motions. Secondly, five subjects performed five trials of simulated sprain motion by a supination sprain simulator. The motions were analyzed by an eight-camera motion capture system at 120. Hz. A force plate was employed to record the vertical ground reaction force and locate the foot strike time for common sporting motions. Ankle inversion and inversion velocity were calculated by a standard lower extremity biomechanics calculation procedure. Profiles of vertical ground reaction force, ankle inversion angle and ankle inversion velocity were obtained. Results suggested that the ankle was kept in an everted position during the stance. The maximum ankle inversion velocity ranged from 22.5 to 85.1°/s and 114.0 to 202.5°/s for the four tested motions and simulated sprain motion respectively. Together with the ankle inversion velocity reported in the injury case (623°/s), a threshold of ankle inversion velocity of 300°/s was suggested for the identification of ankle sprain. The information obtained in this study can serve as a basis for the development of an active protection apparatus for reducing ankle sprain injury. © 2010 Elsevier Ltd

Arthroscopic repair of isolated type II superior labrum anterior–posterior lesion

The effectiveness of arthroscopic repair of type II superior labrum anterior-posterior lesion (SLAP) was unclear as previous studies examined this treatment with patients of combined types of SLAP lesions. To address this research gap, we evaluated the clinical and functional outcomes of arthroscopic repair for 16 patients (mean = 24.2, SD = 6.5) with clinical evidence of isolated type II SLAP lesion. After having arthroscopic stabilizations with Bioknotless suture anchors (Mitek), the patients were offered post-operative rehabilitation programs (e.g., physiotherapy) for 6 months. The symptoms of SLAP lesion and the functions of the shoulder were assessed pre-operatively and 28-month post-operatively by O'Brien test, Speed test, Yergason test, and University of California at Los Angeles rating for pain and function of the shoulder. Wilcoxon Signed Ranks test and McNemar test were employed to analyze the difference between assessment in pre-operation and post-operation phases. The result showed that patients' shoulder functions improved (UCLA Shoulder Score), and symptoms of SLAP lesion reduced (O'Brien test, Speed test, and Yergason test) significantly (P < 0.05). Time for returning to play with pre-injury level was in average 9.4 months (range 4-24), and no complication or recurrence was detected. We concluded that arthroscopic repair is an effective operation of type II SLAP lesion with good clinical and functional outcomes; however, athletes with high demand of overhead throwing activities are likely to take longer duration of rehabilitation to attain full recovery

Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanics study

Background. Excessive pronation (or eversion) at ankle joint in heel-toe running correlated with lower extremity overuse injuries. Orthotics and inserts are often prescribed to limit the pronation range to tackle the problem. Previous studies revealed that the effect is product-specific. This study investigated the effect of medial arch-heel support in inserts on reducing ankle eversion in standing, walking and running. Methods. Thirteen pronators and 13 normal subjects participated in standing, walking and running trials in each of the following conditions: (1) barefoot, and shod condition with insert with (2) no, (3) low, (4) medium, and (5) high medial arch-heel support. Motions were captured and processed by an eight-camera motion capture system. Maximum ankle eversion was calculated by incorporating the raw coordinates of 15 anatomical positions to a self-compiled Matlab program with kinematics equations. Analysis of variance with repeated measures with post-hoc Tukey pairwise comparisons was performed on the data among the five walking conditions and the five running conditions separately. Results. Results showed that the inserts with medial arch-heel support were effective in dynamics trials but not static trials. In walking, they successfully reduced the maximum eversion by 2.1 degrees in normal subjects and by 2.5-3.0 degrees in pronators. In running, the insert with low medial arch support significantly reduced maximum eversion angle by 3.6 and 3.1 degrees in normal subjects and pronators respectively. Conclusion. Medial arch-heel support in inserts is effective in reducing ankle eversion in walking and running, but not in standing. In walking, there is a trend to bring the over-pronated feet of the pronators back to the normal eversion range. In running, it shows an effect to restore normal eversion range in 84% of the pronators

Clinical and biomechanical outcome of minimal invasive and open repair of the Achilles tendon

Introduction: With evolutions in surgical techniques, minimally invasive surgical (MIS) repair with Achillon applicator has been introduced. However, there is still a lack of literature to investigate into the clinical merits of MIS over open surgery. This study aims to investigate the correlation between clinical outcome, gait analysis and biomechanical properties comparing both surgical methods.Materials and methods: A single centre retrospective review on all the consecutive operated patients between January 2004 and December 2008 was performed. Twenty-six patients (19 male and 7 female; age 40.4 ± 9.2 years) had experienced a complete Achilles tendon rupture with operative repair. Nineteen of the patients, 10 MIS versus 9 open repairs (13 men with a mean age of 40.54 ± 10.43 (range 23-62 yrs) and 6 women with a mean age of 45.33 ± 7.71 (range 35-57 yrs) were further invited to attend a thorough clinical assessment using Holz's scale and biomechanical evaluation at a mean of 25.3 months after operation. This study utilized the Cybex II isokinetic dynamometer to assess the isokinetic peak force of plantar-flexion and dorsiflexion of both ankles. The patients were also invited to return to our Gait Laboratory for analysis. The eight-infrared camera motion capture system (VICON, UK) was utilized for the acquisition of kinematic variables. Their anthropometric data was measured according to the Davis and coworkers' standard.Results: The mean operative time and length of hospital stay were shorter in the MIS group. The operative time was 54.55 ± 15.15 minutes versus 68.80 ± 18.23 minutes of the MIS group and Open group respectively (p = 0.045), whereas length of stay was 3.36 ± 1.21 days versus 6.40 ± 3.70 days respectively (p = 0.039). There is statistically significant decrease (p = 0.005) in incision length in MIS group than the open surgery group, 3.23 ± 1.10 cm versus 9.64 ± 2.55 cm respectively. Both groups attained similar Holz's scores, 11.70 ± 0.95 versus 12.0 ± 1.50 respectively (p = 0.262). The mean percentage stance time of the injured leg for MIS patient was 58.44% while the mean percentage stance time of the injured leg for patients with open repair was 56.57%. T-test has shown there were no significance differences between the results of the two groups of patients. The loss of peak torque and total work done with respect to the injured side were similar between the MIS and open group.Discussion and conclusion: MIS using Achillon method can achieve smaller incisions, shorter operative time and hospital stay. There is no statistical significance difference in clinical outcome, the stance time to strike time ratio and biomechanical properties on the leg receiving Achilles tendon repair using MIS method and open surgery. © 2011 Chan et al; licensee BioMed Central Ltd

Clinical and biomechanical outcome of minimal invasive and open repair of the Achilles tendon

Introduction: With evolutions in surgical techniques, minimally invasive surgical (MIS) repair with Achillon applicator has been introduced. However, there is still a lack of literature to investigate into the clinical merits of MIS over open surgery. This study aims to investigate the correlation between clinical outcome, gait analysis and biomechanical properties comparing both surgical methods.Materials and methods: A single centre retrospective review on all the consecutive operated patients between January 2004 and December 2008 was performed. Twenty-six patients (19 male and 7 female; age 40.4 ± 9.2 years) had experienced a complete Achilles tendon rupture with operative repair. Nineteen of the patients, 10 MIS versus 9 open repairs (13 men with a mean age of 40.54 ± 10.43 (range 23-62 yrs) and 6 women with a mean age of 45.33 ± 7.71 (range 35-57 yrs) were further invited to attend a thorough clinical assessment using Holz's scale and biomechanical evaluation at a mean of 25.3 months after operation. This study utilized the Cybex II isokinetic dynamometer to assess the isokinetic peak force of plantar-flexion and dorsiflexion of both ankles. The patients were also invited to return to our Gait Laboratory for analysis. The eight-infrared camera motion capture system (VICON, UK) was utilized for the acquisition of kinematic variables. Their anthropometric data was measured according to the Davis and coworkers' standard.Results: The mean operative time and length of hospital stay were shorter in the MIS group. The operative time was 54.55 ± 15.15 minutes versus 68.80 ± 18.23 minutes of the MIS group and Open group respectively (p = 0.045), whereas length of stay was 3.36 ± 1.21 days versus 6.40 ± 3.70 days respectively (p = 0.039). There is statistically significant decrease (p = 0.005) in incision length in MIS group than the open surgery group, 3.23 ± 1.10 cm versus 9.64 ± 2.55 cm respectively. Both groups attained similar Holz's scores, 11.70 ± 0.95 versus 12.0 ± 1.50 respectively (p = 0.262). The mean percentage stance time of the injured leg for MIS patient was 58.44% while the mean percentage stance time of the injured leg for patients with open repair was 56.57%. T-test has shown there were no significance differences between the results of the two groups of patients. The loss of peak torque and total work done with respect to the injured side were similar between the MIS and open group.Discussion and conclusion: MIS using Achillon method can achieve smaller incisions, shorter operative time and hospital stay. There is no statistical significance difference in clinical outcome, the stance time to strike time ratio and biomechanical properties on the leg receiving Achilles tendon repair using MIS method and open surgery. © 2011 Chan et al; licensee BioMed Central Ltd

Effect of anticipation on knee kinematics during a stop-jump task

Knee stability during a functional assessment of the stop-jump task is a key factor to determine if an athlete is adequately rehabilitated after knee ligamentous injury. This study aimed to investigate knee stability due to the effect of anticipation on landing maneuvers during planned and unplanned stop-jump tasks. Knee kinematics of ten healthy male participants were collected using an optical motion analysis system during stop-jump tasks. Stop jumps were performed in four different landing positions either in planned movement or in an unplanned movement on a signal triggered as participants passed through a photocell gate. Kinematic data at the time of foot strike at landing in the stop-jump considered for investigating the anticipation effect during the stop-jump tasks. Two-way multivariate analysis of variance (MANOVA) with repeated measures and stratified paired t-tests were conducted to compare the knee kinematics data between planned and unplanned tasks. Statistical significance was set at the p< 0.05 level. External rotational angle showed a significant decrease in unplanned stop-jump tasks during forward (p< 0.05) and right (p< 0.05) jumps when compared to that of planned tasks. Flexion angle and abduction angle during forward, vertical and right jumps were significantly decreased in the unplanned tasks. Anticipation significantly influenced the landing maneuvers of stop-jump task. The results indicated that both planned and unplanned stop-jump tasks should be considered when monitoring the rehabilitation progress after a ligamentous injury

Estimating the complete ground reaction forces with pressure insoles in walking

This study presented a method to estimate the complete ground reaction forces from pressure insoles in walking. Five male subjects performed 10 walking trials in a laboratory. The complete ground reaction forces were collected during a right foot stride by a force plate at 1000 Hz. Simultaneous plantar pressure data were collected at 100 Hz by a pressure insole system with 99 sensors covering the whole plantar area. Stepwise linear regressions were performed to individually reconstruct the complete ground reaction forces in three directions from the 99 individual pressure data until redundancy among the predictors occurred. An additional linear regression was performed to reconstruct the vertical ground reaction force by the sum of the value of the 99 pressure sensors. Five other subjects performed the same walking test for validation. Estimated ground reaction forces in three directions were calculated with the developed regression models, and were compared with the real data recorded from force plate. Accuracy was represented by the correlation coefficient and the root mean square error. Results showed very good correlation in anterior-posterior (0.928) and vertical (0.989) directions, and reasonable correlation in medial-lateral direction (0.719). The root mean square error was about 12%, 5% and 28% of the peak recorded value. Future studies should aim to generalize the methods or to establish specific methods to other subjects, patients, motions, footwear and floor conditions. The method gives an extra option to study an estimation of the complete ground reaction forces in any environment without the constraints from the number and location of force plates

Results of walking trial with walking shoe and walking inserts (W series)

<p><b>Copyright information:</b></p><p>Taken from "Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanics study"</p><p>http://www.josr-online.com/content/3/1/7</p><p>Journal of Orthopaedic Surgery and Research 2008;3():7-7.</p><p>Published online 20 Feb 2008</p><p>PMCID:PMC2266906.</p><p></p