3-dimensional Motion Analysis Research Articles

The influence of differences in neurocognitive function on lower limb kinematics, kinetics, and muscle activity during an unanticipated cutting motion.

Background Neurocognitive function may be a risk factor for anterior cruciate ligament (ACL) injury by changing neuromuscular control such as muscle activities. However, the effect of differences in neurocognitive function on biomechanics and neuromuscular control related to ACL injury risk is not clear. The purpose of this study was to examine the effect of differences in neurocognitive function on biomechanics and neuromuscular control during an unanticipated side-step cutting motion. Method The subjects were 15 collegiate female athletes who were divided into two groups using the Symbol Digit Modalities Test (SDMT). The experimental task was an unanticipated side-step cutting motion from a 30 cm high box. We calculated joint angles and moments using a 3-dimensional motion analysis system from the dominant leg, and measured muscle activities using a surface electromyography. We calculated the co-contraction ratio (CCR) as relative muscle activity of the quadriceps to the hamstring. Results As a result, subjects with a lower SDMT score had significantly increased quadriceps activity before and after ground contact and decreased CCR only after ground contact. Conclusion In the lower SDMT score group, the quadriceps showed stronger muscle activity than the hamstring during an unanticipated side-step cutting motion. This dominant quadriceps muscle activity has been reported to increase the load on the ACL, and there was a possibility of increasing the risk of the ACL injury. Considering these factors, subjects with lower neurocognitive function could have a high risk of ACL injury due to alterations in muscle activities surrounding the knee.

Stiff knee gait may increase risk of second total knee arthroplasty.

Osteoarthritis (OA) progression in the contralateral limb after unilateral total knee arthroplasty (TKA) may be related to altered and asymmetrical movement patterns that overload the contralateral joints. The purpose of this study was to determine if biomechanical factors after unilateral TKA were associated with future contralateral TKA. One hundred and fifty-eight individuals who underwent unilateral TKA completed three dimensional motion analysis 6-24 months after unilateral TKA (baseline). Subjects were re-contacted for follow-up (mean 5.89 years after baseline testing) to determine if they had undergone a contralateral TKA. Biomechanical variables from gait at baseline were compared between those who did and did not undergo contralateral TKA at follow-up using one-way ANOVAs. Odds ratios were calculated for variables found to be significant in the ANOVA models. Individuals who underwent contralateral TKA had less knee flexion excursion (10.5° vs. 12.1°; p = 0.032) and less knee extension excursion (8.2° vs. 9.6°; p = 0.035) at baseline on the operated side during walking. Individuals who underwent contralateral TKA also had less knee flexion excursion on the contralateral limb at baseline (11.9° vs. 14.0°; p = 0.017). For every additional degree of knee flexion excursion on the contralateral knee at baseline, there was a 9.1% reduction in risk of future contralateral TKA. Individuals who walked with stiffer gait patterns were more likely to undergo future contralateral TKA. Clinical Significance: Altered movement patterns after surgery may increase the risk for contralateral TKA. Knee excursion is an important metric to include in outcome studies and may serve as a target of rehabilitation after TKA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:397-402, 2019.

Concurrent Validity of Depth-Sensing Cameras for Noncontact ACL Injury Screening During Side-Cut Maneuvers in Adolescent Athletes: A Preliminary Study

Anterior cruciate ligament (ACL) injury is one of the most common knee injuries among adolescent athletes. Majority of the ACL injuries occur due to pivoting, sudden deceleration, and direction change without contact with any player. Preventive interventions can reduce risks of the ACL injury, thus developing a clinician friendly biomechanical assessment tool to identify athletes with such risk factors is crucial. In this study, the authors investigated the concurrent validity of a commercially available depth sensor, Microsoft Kinect, as a cost-effective alternative to the gold-standard 3-dimensional motion analysis systems in noncontact ACL screening for adolescent athletes during side-cut maneuvers. Study participants performed 45° side-cut maneuvers while collecting data from both systems concurrently. The sagittal and frontal plane kinematics were analyzed during the full stance phase and the first 20% of the stance (early deceleration). Absolute agreement (range: ICC = .767-.989) and consistency (range: ICC = .799-.992) were excellent for all measures except early deceleration frontal plane hip angle, which displayed good absolute agreement (ICC = .643) and consistency (ICC = .625). Findings showed that the Kinect has the potential to be an effective clinical assessment tool for sagittal and frontal plane trunk, hip, and knee kinematics during the side-cut maneuvers.

The Effects of Ballistic and Nonballistic Bench Press on Mechanical Variables.

Moir, GL, Munford, SN, Moroski, LL, Davis, SE. The effects of ballistic and nonballistic bench press on mechanical variables. J Strength Cond Res 32(12): 3333-3339, 2018-The purpose of this study was to investigate the effects of ballistic and nonballistic bench press performed with loads equivalent to 30 and 90% 1 repetition maximum (1RM) on mechanical variables. Eleven resistance-trained men (age: 23.0 ± 1.4 years; mass: 98.4 ± 14.4 kg) attended 4 testing sessions where they performed one of the following sessions: (a) 3 sets of 5 nonballistic repetitions performed with a load equivalent to 30% 1RM (30N-B), (b) 3 sets of 5 ballistic repetitions performed with a load equivalent to 30% 1RM (30B), (c) 3 sets of 4 nonballistic repetitions with a load equivalent to 90% 1RM (90N-B), or (d) 3 sets of 4 ballistic repetitions with a load equivalent to 90% 1RM (90B). Force plates and a 3-dimensional motion analysis system were used to determine the velocity, force, power output (PO), and work during each repetition. The heavier loads resulted in significantly greater forces applied to the barbell (mean differences: 472-783 N, p < 0.001), but lower barbell velocities (mean differences: 0.85-1.20 m·s, p < 0.001) and PO (mean differences: 118-492 W, p ≤ 0.022). The ballistic conditions enhanced the mechanical variables only at the lower load, with 30B producing significantly greater force (mean difference: 263 N, p < 0.001), velocity (mean difference: 0.33 m·s, p < 0.001), and PO (mean difference: 335 W, p < 0.001) compared with 30N-B. Furthermore, the increase in PO across the 3 sets in 30B was significantly different from all other conditions (p = 0.013). The total mechanical work performed was significantly greater for the conditions with the heavier loads compared with those with the lighter loads (mean differences: 362-5,600 J, p < 0.001) and that performed during the ballistic conditions was significantly greater than that performed during the nonballistic conditions with the same load (mean differences: 945-1,030 J, p < 0.001). Ballistic bench press may be an effective exercise for developing PO, and multiple sets may elicit postactivation potentiation that enhances force production. However, these benefits may be negated at heavier loads.

Lower-limb muscle function during sidestep cutting

To investigate lower-limb muscle function during sidestep cutting, prior studies have analysed electromyography (EMG) data together with three dimensional motion analysis. Such an approach does not directly quantify the biomechanical role of individual lower-limb muscles during a sidestep cut. This study recorded three dimensional motion analysis, ground reaction force (GRF) and EMG data for eight healthy males executing an unanticipated sidestep cut. Using a musculoskeletal modelling approach, muscle function was determined by computing the muscle contributions to the GRFs and lower-limb joint moments. We found that bodyweight support (vertical GRF) was primarily provided by the vasti, gluteus maximus, soleus and gastrocnemius. These same muscles, along with the hamstrings, were also primarily responsible for modulating braking and propulsion (anteroposterior GRF). The vasti, gluteus maximus and gluteus medius were the key muscles for accelerating the centre-of-mass towards the desired cutting direction by generating a medially-directed GRF. Our findings have implications for designing retraining programs to improve sidestep cutting technique.

Asymmetric Thickness of Oblique Capitis Inferior and Cervical Kinesthesia in Patients With Unilateral Cervicogenic Headache

ObjectiveThe purpose of this study was to compare the thickness of the oblique cervical inferior (OCI) and the error of the head reposition test between the painful and nonpainful sides of patients with cervicogenic headache (CeH) and between the patients and the asymptomatic group. MethodsThirteen patients (24.5 ± 4.8 years) and 14 asymptomatic participants (23.9 ± 2.7 years) were included. The head reposition test was recorded by a 3-dimensional motion analysis system. The thickness of the OCI was recorded by ultrasonography. The measured outcomes were compared between the painful and nonpainful sides and with the asymptomatic participants. ResultsThe thickness of the OCI in the rest condition on the painful side (9.92 ± 2.31 mm) was smaller than that of the nonpainful side (10.56 ± 2.24 mm). The constant error of the head-to-target test toward the nonpainful side was smaller in the patients with CeH (-1.6 ± 4.3°) than in the asymptomatic group (3.3 ± 3.7°, P = 0.005). ConclusionAsymmetric OCI and cervical proprioception were demonstrated in patients with CeH.

The kinematics of 1-on-1 rugby tackling: a study using 3-dimensional motion analysis

Although past studies using video analysis indicated that the arm tackle and head-in-front shoulder tackle are possible risks for shoulder dislocation, the underlying mechanisms of tackling-related shoulder dislocation have not been sufficiently investigated. This study aimed to analyze the kinematic aspects of these tackling motions in 1-on-1 tackles in an experimental setting using a 3-dimensional motion-capture system. A total of 65 one-on-one tackles were recorded using a marker-based, automatic, digitizing motion-capture system. A documented tackle was classified into 1 of 3 types, which was decided based on the first point of contact on the ball carrier and the head position at the time of impact: shoulder tackle (reference tackle), arm tackle, and head-in-front tackle. The orientations of the head, trunk, and shoulder at impact were calculated and statistically compared with each other. The distribution of tackles recorded in this study was as follows: 38 shoulder, 23 arm, and 4 head-in-front tackles. In comparison with the shoulder tackle as a reference, shoulder abduction on the side of impact was higher in both the arm and head-in-front tackles, while shoulder external rotation was lower in the head-in-front tackles. In the latter type of tackle, significant decreases in neck extension and ipsilateral neck rotation were also indicated. The kinematics in both the arm tackle and the head-in-front tackle is significantly different from that in the shoulder tackle and may represent a distinct risk factor for shoulder dislocation.

A Novel Method to Determine Optimal Load in Elastic-Based Power Training.

Buskard, AN, Oh, J, Eltoukhy, M, Brounstein, SR, and Signorile, JF. A novel method to determine optimal load in elastic-based power training. J Strength Cond Res 32(9): 2401-2408, 2018-The benefits of muscular power on sport performance and older adults' abilities to live independently and resist falls is well documented. Consequently, a substantial volume of research has focused on establishing the optimal loading patterns for improving muscular power using resistance exercise; however, to date, this research has only targeted optimal loading during training with free weights or selectorized exercise machines. Conversely, no approach has been developed to establish optimal loads for elastic modalities, such as tubes and bands, commonly used for sports rehabilitation, injury prevention, and training older adults. Therefore, the purpose of this study was to evaluate a new method for determining the optimal tubes to use in power training performed with elastic resistance. Thirty-eight recreationally active college students (age, 23.7 ± 4.5 years) were recruited to perform 3 single-arm bicep curls at a maximum intended velocity using 6 elastic tubes of varying resistance. Testing was performed in a 3-dimensional (3D) motion analysis laboratory using a specially constructed platform with an integrated strain gauge to which each tube was anchored. Force data from the strain gauge and velocity data from the 3D motion capture system were then used to compute power for each tube. An analysis based on individual's cable arm curl 1-repetition maximum (1RM) was then used to generate general guidelines for the most appropriate tube to use for arm curl power training based on upper arm 1RM. Our results demonstrate the feasibility of using this methodology for other exercises, thereby establishing optimal tube use for power training based on each exercise's 1RM.

태권도 앞차기 끊어차기와 뻗어차기 사이의 운동학적 차이

The purpose of this study is to investigate the difference of the kinematic variables between a type of swing-front-kick (SK) and of lock-out-front-kick (LK) during executing the kick. Based on these kinematic differences, we also aim to explain the causes of injury-related epidemiological findings in sports medicine. As methods, a total of five men (mean age 37±9 years) who experienced Taekwondo and other martial arts for 20 years (±6) participated in this study. The executing kick process of the SK and LK was taken at 200 Hz in 3-dimensional motion analysis system using six infrared cameras. We computed the three-dimensional position data of the anatomical boundary points with the modified Plugin Gait marker system. As results, the SK in the sagittal plane showed a natural and smooth generation of the proximal-to-distal segmental sequencing theory and counterbalance motion. On the other hand, the two kinematic principles have not been applied to the LK, which is mainly used in Poomsae. In conclusions, our findings suggest that there is a potential high risk of injury from the LK at the knee joint and other joints. In order to determine the causes of knee joint injuries, more research is required related to the ratio of hamstring vs quadriceps femoris in the future.

Kinematics of Rugby Tackling: A Pilot Study With 3-dimensional Motion Analysis

Background: Although improper tackling technique in rugby can affect the outcome of the tackle and lead to head, neck, and shoulder injuries, the effects of the height of the tackle or the side of the leading leg at the time of impact have not been investigated. Hypothesis/Purpose: The purpose was to characterize the trunk orientation at impact during various tackles. It was hypothesized that 3-dimensional motion analysis would be able to capture the critical kinematic differences in the 4 types of tackles studied. Study Design: Controlled laboratory study. Methods: A total of 66 tackles on a tackle bag were recorded among 13 elite rugby players. Four types of tackles were evaluated: the normal shoulder tackle, in which the tackler’s dominant shoulder made impact while the leading foot was on the same side as that shoulder; the low tackle, in which the tackler targeted the lower portion of the tackle bag; the opposite-leg tackle, in which the tackler’s leading leg was on the opposite side as the shoulder making impact; and the low and opposite-leg tackle, which was a combination of the previous 2 types of tackles. The orientation of the trunk at impact was calculated, and 2-way repeated-measures analyses of variance were used to compare the characteristics of these tackles. Results: Trunk inclination at impact was lower in the low tackle than in the normal tackle (P < .01), regardless of the side of the leading leg. Trunk bending to the side of the impacted shoulder was lower in the opposite-leg tackle (P < .01), and these findings were more significant in the normal-height tackles (P < .01). Trunk rotation to the side of the impacted shoulder was lower in the opposite-leg tackles (P < .01) and more significant in the lower-height tackles (P = .03). Conclusion: The 3-dimensional motion capture system was effective in investigating the kinematics of rugby tackling. The kinematics in the low and opposite-leg tackles were significantly different from those in the normal shoulder tackle, which may affect tackle performance and the possible risk of contact injury. Clinical Relevance: When a rugby coach provides tackling instructions to players, it is advantageous to have information about the kinematics of different types of tackles.

Validity and Reliability of a Virtual Reality Game in Evaluating the Projected Frontal Plane Knee Angle When Landing From a Drop Vertical Jump.

To determine the validity and reliability of the peak frontal plane knee angle evaluated by a virtual reality (VR) netball game when landing from a drop vertical jump. Laboratory. Forty participants performed 3 drop vertical jumps evaluated by 3-dimensional motion analysis and 3 drop vertical jumps evaluated by the VR game. Limits of agreement for the peak projected frontal plane knee angle and peak knee abduction were determined. Participants were given a consensus category of "above threshold" or "below threshold" based on a prespecified threshold angle of 9° during landing. Classification agreement was determined using kappa coefficient, and accuracy was determined using specificity and sensitivity. Ten participants returned 1 week later to determine intrarater reliability, standard error of the measure, and typical error. The mean difference in detected frontal plane knee angle was 3.39° (95% confidence interval [CI], 1.03° to 5.74°). Limits of agreement were -10.27° (95% CI, -14.36° to -6.19°) to 17.05° (95% CI, 12.97° to 21.14°). Substantial agreement, specificity, and sensitivity were observed for the threshold classification (κ = .66; 95% CI, .42 to .88; specificity = 0.96; 95% CI, 0.78 to 1.0; and sensitivity = 0.75; 95% CI, 0.43 to 0.95). The game exhibited acceptable reliability over time (intraclass correlation coefficient, ICC3,1 = .844), and error was approximately 2°. The VR game reliably evaluated a projected frontal plane knee angle. Although the knee angle detected by the VR game is strongly related to peak knee abduction, the accuracy of detecting the exact angle was limited. A threshold approach may be a more accurate approach for gaming technology to evaluate frontal plane knee angles when landing from a jump.

Does Total Ankle Arthroplasty Preserve Midfoot Function and Mitigate Excessive Adjacent Joint Loading?

Category: Ankle Arthritis Introduction/Purpose: The progressive decline of ankle motion secondary to ankle arthritis increases midfoot joint loading during forward propulsive activities. Preservation or improvement of ankle motion following total ankle arthroplasty (TAA) is theorized to preserve adjacent joint function and potentially mitigate the cumulative effect of midfoot joint loading. If this theory were sound, the biomechanical profile of midfoot function would not change following TAA. Examination of this theory may inform TAA operative care and will directly impact postoperative rehabilitation paradigms. The purpose of this ongoing study was to be the first to prospectively evaluate the effect of TAA on midfoot function during walking, as measured by midfoot range of motion and power, at six month follow up. Methods: Nine adults [Mean (SD): Age 60.2 (3.5) years; BMI 30.4 (1.4) Kg/m2; 100% male] who received a TAA for end-stage ankle arthritis walked barefoot on level ground preoperatively and six months postoperatively. Three dimensional motion analysis was used to record three-segment foot motion (forefoot, rearfoot, tibia) and ground reaction forces. Midfoot (forefoot with respect to rearfoot) sagittal and transverse plane range of motion were measured. Inverse dynamic calculations were used to obtain midfoot negative (absorption) and positive (generation) peak power (joint torque x segmental velocity), since these metrics are biomechanical correlates of midfoot instability and stability, respectively. Accordingly, greater midfoot joint loading would be characterized by increased power absorption. Greater power generation would indicate an increased midfoot contribution to forward propulsion. Paired t-tests were used to evaluate differences across time in the involved limb and between limbs postoperatively for power variables. Results: Midfoot dorsiflexion / plantarflexion and abduction / adduction range of motion were not significantly different pre to postoperatively (mean differences &lt; 0.4 degrees; both p &gt; 0.7). Similarly, involved limb midfoot negative and positive power did not change (mean differences &lt; 0.1 W/Kg; negative power p = 0.1; positive power p = 1.0). Postoperatively, negative power was minimally different between sides (mean difference 0.1 W/Kg; p = 0.4). However, involved limb midfoot positive power was 44% less than the uninvolved limb postoperatively (mean difference 0.3 W/Kg; p = 0.1) (Figure 1). Conclusion: Study findings provide preliminary substantiation to the theory that midfoot function is preserved following TAA. At six months, the biomechanical profile of individuals receiving TAA for end-stage ankle arthritis was not different from preoperative measures. Further, since postoperative power absorption was similar between limbs, the current TAA operative approach may help mitigate midfoot joint loading. However, the asymmetrical power generation (44% less on the involved limb) suggests the midfoot is unprepared to respond to anticipated ankle power improvements as patients advance to higher level activities. Accordingly, rehabilitation targeting midfoot stability through strengthening is recommended to complement current postoperative efforts.

Does Ankle Muscle Performance Mirror Improved Pain Following Total Ankle Arthroplasty?

Category: Ankle Arthritis Introduction/Purpose: Total ankle arthroplasty (TAA) outcomes include pain reduction and improved gait speed. Ankle push off power, which requires gastroc-soleus muscle strength, is a critical aspect of healthy gait and increases as gait speed increases. It appears that improvements in pain translate to improved ankle muscle performance. However, ankle power after TAA is surprisingly low. It is possible years of arthritis and latent muscle memory result in reduced gastroc-soleus muscle strength and a gait pattern reliant on proximal joints for power. Evaluating these hypotheses will drive postoperative care. The purpose of this ongoing prospective study is to be the first to evaluate the interplay of pain, gait speed, and ankle muscle performance (strength and power) in people following TAA for end-stage ankle arthritis. Methods: Twelve people [Mean (SD): Age 61 (14.3) years; BMI 30.0 (5.4) Kg/m2; 83% male] with end-stage ankle arthritis who were candidates for TAA participated (12 preoperative and 9 six-month postoperative visits). Performance of adjunct soft tissue procedures and postoperative care were patient specific. A twenty point numeric pain rating scale was used to measure worst pain in the past week. Three dimensional multi-segment foot motion analysis was performed while participants walked barefoot on level ground over a force plate. Ankle peak push-off power (joint torque x segmental velocity) was calculated. Ankle peak isokinetic plantarflexion strength (torque at 60 degrees / second) and ankle sagittal plane passive range of motion were measured with a dynamometer. Participants also completed the six minute walk test. Wilcoxon Signed Rank tests were used to evaluate preoperative to postoperative changes and between limb differences postoperatively. Results: Pain decreased (postoperative mean = 2.8; p = 0.01) and gait speed increased following TAA (p = 0.02). Ankle plantarflexion strength and ankle power during walking were preserved following TAA (both p &gt; 0.8) (Figure 1). Postoperative group mean dorsiflexion was 25.1 degrees and plantarflexion was 18.9 degrees, suggesting sufficient ankle motion was present for plantarflexor muscle performance. However, between limb differences were significant for both strength and power (both p &lt; 0.05) postoperatively. The involved ankle produced 36% less strength and generated 45% less power during walking in comparison to the uninvolved limb. This asymmetry demonstrates that involved limb ankle muscle performance was not normalized at six-month follow up, despite improvements in pain. Conclusion: Study findings provide preliminary evidence that improved pain and gait speed are disconnected from ankle muscle performance following TAA. Postoperative improvements in gait speed were likely driven by more proximal joints (i.e. hip). Without additional targeted postoperative plantarflexion strengthening and gait training to improve ankle muscle involvement, gains in ankle power, a symmetrical gait pattern, and patient tolerance to higher level activity (i.e. stairs) are unlikely to occur long-term. The underpinning mechanisms limiting the necessary strength to drive power generation (i.e. length-tension relationship, atrophy), and the possible cumulative effect of how abnormal gait may influence implant survivorship deserve further attention.

Assessment of Biomechanical Changes After Sacroiliac Joint Fusion by Application of the 3-Dimensional Motion Analysis Technique

Sacroiliac (SI) joint motion is complex and is poorly understood overall. In this study we evaluated a new biomechanical method developed to provide more insight into SI joint movement and to elucidate biomechanical changes after SI joint fusion surgery in a one-leg standing model. Eight lumbosacral cadaver specimens (L5-pelvis specimens, age 28-57 years, 6 female and 2 male) were used in this experiment. We analyzed the changes in range of motion (ROM) in single-plane motion and mobility in 3 groups of patients: intact, unilateral fusion, and bilateral fusion groups. For statistical analysis, we used repeated-measures analysis of variance to compare SI joint ROM among the 3 groups. iFuse implants were prepared using the standard posterior placement technique. Pure-moment multidirectional bending tests were performed in each direction (nutation and counternutation, axial rotation, and lateral bending). Average ROM in single-plane motion and mobility of the intact SI joint were 4.5 ± 3.3° and 4.8 ± 3.4°, respectively in nutation-counternutation; 2.9 ± 2.1° and 3.3 ± 2.3°, respectively, in axial rotation; and 1.5 ± 1.5° and 2.8 ± 2.5°, respectively, in lateral bending. We observed statistically significantly (P= 0.05) greater mobility in lateral moment testing than in single motion testing. Comparisons among the intact, unilateral fusion, and bilateral fusion groups showed statistically significant differences in the lateral moment test. This study suggests that our new biomechanical method for SI joint evaluation may provide improved insight into SI joint movement and biomechanical changes after SI joint fusion surgery in a one-leg standing model.

Biomechanical evaluation of cable and suture cerclages for tuberosity reattachment in a 4-part proximal humeral fracture model treated with reverse shoulder arthroplasty

Sufficient tuberosity fixation in proximal humeral fractures treated with shoulder arthroplasty is essential to gain a good clinical outcome. This biomechanical study evaluated the strength of the reattached tuberosities in reverse total shoulder arthroplasty fixed with cables or with sutures in a cerclage-like technique. Considering the mechanical advantages of flexible titanium alloy cables compared with conventional sutures for cerclage-like fixations, we hypothesized that titanium alloy cables would achieve higher fixation strengths of the tuberosities compared with heavy nonabsorbable sutures. A 4-part fracture was created on 8-paired proximal human humeri. The tuberosities were reduced anatomically and fixed by 2 heavy nonabsorbable sutures (suture group) or by two 1-mm titanium alloy cables (cable group) in a cerclage-like technique around the neck of the prosthesis. The humeri were placed in a custom-made test setup enabling internal and external rotation. Cyclic loading with a stepwise increasing load magnitude was applied with a material testing machine, starting with 1 Nm and increasing the load by 0.25 Nm after each 100th cycle until failure of the fixation occurred (>15° rotation of the tuberosities). Any motion of the tuberosities was measured with a 3-dimensional ultrasound motion analysis system. Overall, the cable group reached 1414 ± 372 cycles, and the suture group reached 1257 ± 230 cycles until the fixations failed (P = .313). The suture group showed a significantly higher rotation of the lesser tuberosity relative to the humerus shaft axis after 200, 400, and 600 cycles compared with the cable group (P = .018-.043). Tuberosities reattached with cable cerclages showed higher fixation strength and therefore less rotation compared with suture cerclages in a 4-part proximal humeral fracture model treated with reverse total shoulder arthroplasty. Whether this higher fixation strength results in higher bony ingrowth rates of the tuberosities and thus leads to a better clinical outcome needs to be investigated in further clinical studies.

Postural balance and neck angle changes in school children while carrying a traditional backpack versus a double-sided bag

Summary Study aim: This study compared the body balance and neck angle differences in children when carrying a traditional backpack versus a double-sided bag. Material and methods: By using the Biodex balance system and a three dimensional motion analysis system, the postural bal­ance and neck angles were assessed in 33 school children while carrying a traditional backpack or a double-sided bag, weigh­ing 15% of body weight. Results: The overall and anteroposterior stability indices were significantly higher when carrying a traditional backpack com­pared to no load and a double-sided bag (p &lt; 0.05). The mediolateral stability index was significantly higher when carrying the traditional backpack and the double-sided bag compared to no load (p &lt; 0.05). The craniohorizontal angle was significantly greater, and the craniovertebral angle and sagittal shoulder posture were significantly lesser when carrying the traditional back­pack compared to no load and the double-sided bag conditions (p &lt; 0.05). Conclusion: Carrying the double-sided bag restores the body balance and head posture to a condition that is similar to the no load condition.

The Difference in Kinematic Chain Behavior between Pronation/Supination of Calcaneus and Rotation of Shank in Standing Position by Individual, Age, Gender and Right and Left: Analysis of Kinematic Using Optical Three Dimensional Motion Analysis System

The Difference in Kinematic Chain Behavior between Pronation/Supination of Calcaneus and Rotation of Shank in Standing Position by Individual, Age, Gender and Right and Left: Analysis of Kinematic Using Optical Three Dimensional Motion Analysis System

Relationships Between Trunk Movement Patterns During Lifting Tasks Compared With Unloaded Extension From a Flexed Posture

ObjectivesThe purpose of this study was to investigate between movement patterns of trunk extension from full unloaded flexion and lifting techniques, which could provide valuable information to physical therapists, doctors of chiropractic, and other manual therapists. MethodsA within-participant study design was used. Whole-body kinematic and kinetic data during lifting and full trunk flexion were collected from 16 healthy male participants using a 3-dimensional motion analysis system (Vicon Motion Systems). To evaluate the relationships of joint movement between lifting and full trunk flexion, Pearson correlation coefficients were calculated. ResultsThere was no significant correlation between the amount of change in the lumbar extension angle during the first half of the lifting trials and lumbar movement during unloaded trunk flexion and extension. However, the amount of change in the lumbar extension angle during lifting was significantly negatively correlated with hip movement during unloaded trunk flexion and extension (P < .05). ConclusionsThe findings that the maximum hip flexion angle during full trunk flexion had a greater influence on kinematics of lumbar–hip complex during lifting provides new insight into human movement during lifting. All study participants were healthy men; thus, findings are limited to this group.

SeeSway – A free web-based system for analysing and exploring standing balance data

Background and objectivesComputerised posturography can be used to assess standing balance, and can predict poor functional outcomes in many clinical populations. A key limitation is the disparate signal filtering and analysis techniques, with many methods requiring custom computer programs. This paper discusses the creation of a freely available web-based software program, SeeSway (www.rehabtools.org/seesway), which was designed to provide powerful tools for pre-processing, analysing and visualising standing balance data in an easy to use and platform independent website. MethodsSeeSway links an interactive web platform with file upload capability to software systems including LabVIEW, Matlab, Python and R to perform the data filtering, analysis and visualisation of standing balance data. Input data can consist of any signal that comprises an anterior-posterior and medial-lateral coordinate trace such as center of pressure or mass displacement. This allows it to be used with systems including criterion reference commercial force platforms and three dimensional motion analysis, smartphones, accelerometers and low-cost technology such as Nintendo Wii Balance Board and Microsoft Kinect. Filtering options include Butterworth, weighted and unweighted moving average, and discrete wavelet transforms. Analysis methods include standard techniques such as path length, amplitude, and root mean square in addition to less common but potentially promising methods such as sample entropy, detrended fluctuation analysis and multiresolution wavelet analysis. These data are visualised using scalograms, which chart the change in frequency content over time, scatterplots and standard line charts. This provides the user with a detailed understanding of their results, and how their different pre-processing and analysis method selections affect their findings. ResultsAn example of the data analysis techniques is provided in the paper, with graphical representation of how advanced analysis methods can better discriminate between someone with neurological impairment and a healthy control. ConclusionsThe goal of SeeSway is to provide a simple yet powerful educational and research tool to explore how standing balance is affected in aging and clinical populations.

Motion analysis on patients with knee osteoarthritis merged with varus deformity

Aiming at comparing the pre-operative and post-operative gait characteristics and therefore establishing post-operative rehabilitation guidance for patients with end-stage knee osteoarthritis (KOA) merged with varus deformity, this study captured the level walking and sit-to-stand trials of 9 patients with 3-dimensional motion analysis system and after which musculoskeletal multi-body dynamic analysis was conducted. The study indicated that the average range of motion (ROM) of the proposed-surgical knee was 24.4°-57.6° and that of the non-surgical knee was 22.5°-71.5°. The knee ROM of control group during level walking was 7.2°-62.4°. When the unilateral KOA patients stood up from chair to complete the sit-to-stand movement, the ground reaction forces (GRFs) symmetry was 0.72-0.85, which means that the non-surgical limb bear the majority of body weight. The GRFs of the bilateral KOA patients were smallest during the sit-to-stand movement. The strategy that the non-surgical limb dominates in loading bearing taken by the unilateral KOA patients to cover most post-operative daily activities could increase the risk of KOA among non-surgical side joints as a result of long-term excessive loading-bearing. The study, on kinematics and biomechanical characteristics of patients with KOA merged with varus deformity, could help to understand the pathogenesis of KOA merged with varus deformity from the perspective of biomechanics and to provide strong clinic guidance for the pre-operative evaluation, prevention and post-operative recovery for patients.