The effect of fatigue on spike jump biomechanics in view of patellar tendon loading in volleyball

BACKGROUND AND OBJECTIVE

Patellar tendinopathy (PT) is a highly prevalent overuse injury in volleyball and is often linked with overloading of the patellar tendon. Little is known, however, about whether and how patellar tendon loading is affected by fatigue during the most challenging jump activity in volleyball. Therefore, this study investigates the effect of a high-intensity, intermittent fatigue protocol on movement alterations in terms of patellar tendon loading during a volleyball spike jump.

METHODS

Forty-three male volleyball players participated in this study. Three-dimensional full-body kinematics and kinetics were collected when performing a spike jump before and after the fatigue protocol. Sagittal plane joint angles, joint work and patellar tendon loading were calculated and analyzed with curve analyses using paired sample t-tests to investigate fatigue effects (p < 0.05).

RESULTS

Fatigue induced a stiffer lower extremity landing strategy together with prolonged pelvis-trunk flexion compared to baseline (p = 0.001-0.005). Decreased patellar tendon forces (p = 0.001-0.010) and less eccentric knee joint work (-5%, p < 0.001) were observed after the fatigue protocol compared to baseline.

CONCLUSION

Protective strategies seem to be utilized in a fatigued state to avoid additional tensile forces acting on the patellar tendon, including proximal compensations and stiff lower extremity landings. We hypothesize that players might be more prone for developing PT if eccentric patellar tendon loads are high in the non-fatigued state and/or these loads are somehow not decreased after fatigue.

The role of core stability in the development of non-contact acute lower extremity injuries in an athletic population: A prospective study

OBJECTIVES

Stability of the core is associated with lower extremity functioning. Consequently, impaired core stability might play a role in developing non-contact acute lower extremity sports injuries. The objective was to investigate components of core stability as potential risk factors for acute lower extremity injuries.

DESIGN

A cohort study was set up with a follow-up and injury registration period of 1.5 years.

PARTICIPANTS

142 male and female physical education students were included.

MAIN OUTCOME MEASURES

Measures of isometric hip and core muscular strength, endurance, proprioception and neuromuscular control of the core, and postural control were taken at the start of the study. Sports-related injury occurrence was registered during follow-up.

RESULTS

27 (19%) injuries of interest occurred during follow-up. After multivariate model building, a significant predictive effect was found for side-to-side hip abduction strength asymmetry (p = .007). The hazard of developing an acute lower extremity injury increased with 6.2% with a 1 unit increase in side-to-side strength imbalance, regardless of gender.

CONCLUSION

Hip abduction strength imbalance was determined as a risk factor for the development of non-contact, acute lower extremity injuries. Normalizing hip strength imbalances might be beneficial for injury prevention. However, further research is needed to support this claim.

Is consumer behaviour towards footwear predisposing for lower extremity injuries in runners and walkers? A prospective study

Background

Runners and walkers often suffer from lower extremity injuries. Little is known about the relationship between their consumer behaviour towards footwear and the development of those injuries. Therefore, the aim of this study was to investigate if consumer behaviour towards footwear is a risk factor for lower extremity injuries.

Methods

A prospective cohort study was set-up in leisure-time walkers and runners. Potential risk factors in consumer behaviour were obtained by means of a baseline questionnaire related to the acquisition of current walking or running shoes. Information on injuries sustained during a 24 week period after the baseline questionnaire was obtained in 104 runners and 104 walkers using a 2-weekly questionnaire. Binary logistic regression analysis was used to identify risk factors for lower extremity injuries in the consumer behaviour.

Results

Forty- nine (24%) subjects suffered a self-reported lower extremity injury. 35 injuries occurred in runners and 14 among walkers.Undergoing a gait analysis before buying shoes was associated with an increased occurrence of lower extremity injuries (odds ratio (OR) 4.76). A protective factor was caring a lot about the right fitting of the shoes (OR 0.11).

Conclusion

Runners and walkers should pay attention to the correct size when buying footwear to diminish the risk of lower extremity injury. Buying footwear after a gait analysis increased the risk of a lower extremity injury in runners and walkers, however, this might be associated with the increased risk that was already present because of previous injury.

Trial registration

This trial was not registered since this was an observational study and no intervention took place.

Impaired Core Stability as a Risk Factor for the Development of Lower Extremity Overuse Injuries: A Prospective Cohort Study

BACKGROUND

Core stability has been suggested to influence lower extremity functioning and might contribute to the development of lower extremity overuse injuries. However, prospective studies to investigate this relationship are limited.

PURPOSE

To research the role of different components of core stability as risk factors for the development of lower extremity overuse injuries.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 142 first-year physical education students participated in this study. They were tested in 2015 and were prospectively followed for 1.5 years by means of a multilevel injury registration method. Three participants were excluded owing to physical complaints during testing. As such, 139 participants were included in the statistical analysis. At baseline, dynamic postural control, isometric core and hip muscle strength, core muscle endurance, core neuromuscular control and proprioception, and functional movement were measured for all participants. Competing risk regression analyses were performed to identify significant contributors to the development of lower extremity overuse injuries.

RESULTS

During the follow-up period, 34 (24%) of the 139 participants developed a lower extremity overuse injury. Significant predictive effects for an overuse injury were found for an increased side-by-side difference in dynamic postural control ( P = .038), decreased isometric hip extension:flexion strength ratio ( P = .046), and decreased abdominal core muscle endurance ( P = .032).

CONCLUSION

This study identified measures for dynamic postural control, core muscle strength, and core muscle endurance as significant risk factors for the development of overuse injuries after statistical model building. However, core neuromuscular control and proprioception and functional movement might not allow clinicians to identify patients at risk. These accessible, reliable screening tools could be used in clinical practice with regard to screening and injury prevention for overuse injuries. Injury prediction based on this model needs to be done with caution given the low relative predictive accuracy (53%).

Reliability of two functional clinical tests to evaluate trunk and lumbopelvic neuromuscular control and proprioception in a healthy population

OBJECTIVES

The need to accurately assess trunk and lumbopelvic proprioception and neuromuscular control is widely accepted. However, based on current literature, there is a lack of reliable clinical tests to evaluate these aspects in clinical practice. The objective of this study is to investigate intra- and inter-tester reliability of the lateral step down test and the lumbopelvic position-reposition test in a healthy population.

METHODS

Protocol and scoring methods were developed for the lateral step down test and lumbopelvic position-reposition test, used to assess trunk and lumbopelvic neuromuscular control and proprioception respectively. Each test was performed once by thirty participants and video analysis for test scoring was performed. Three items on the lateral step down test were scored to evaluate neuromuscular control and, four items on the lumbopelvic position-reposition test were scored to evaluate proprioception. Aggregate scores for each test were calculated based on the separate item scores. Intraclass correlation coefficients and linear weighted kappa coefficients were determined for intra- and inter-tester reliability.

RESULTS

Based on the aggregate score, excellent intra- and inter-tester reliability (ICC (2,1)=0.73-0.88) was found for both tests. Moderate/almost perfect intra-and inter-tester agreement (K=0.62-0.91) was found for the separate items of the lateral step down test and fair/substantial agreement (K=0.25-0.76) for the items of the lumbopelvic position-reposition test.

CONCLUSION

Current testing protocol and scoring method for the lateral step down test is reliable. Adjustments for the scoring method of the lumbopelvic position-reposition test are warranted to improve reliability.

Evaluating abdominal core muscle fatigue: Assessment of the validity and reliability of the prone bridging test

The aims of this study were to research the amplitude and median frequency characteristics of selected abdominal, back, and hip muscles of healthy subjects during a prone bridging endurance test, based on surface electromyography (sEMG), (a) to determine if the prone bridging test is a valid field test to measure abdominal muscle fatigue, and (b) to evaluate if the current method of administrating the prone bridging test is reliable. Thirty healthy subjects participated in this experiment. The sEMG activity of seven abdominal, back, and hip muscles was bilaterally measured. Normalized median frequencies were computed from the EMG power spectra. The prone bridging tests were repeated on separate days to evaluate inter and intratester reliability. Significant differences in normalized median frequency slope (NMF_slope ) values between several abdominal, back, and hip muscles could be demonstrated. Moderate-to-high correlation coefficients were shown between NMF_slope values and endurance time. Multiple backward linear regression revealed that the test endurance time could only be significantly predicted by the NMF_slope of the rectus abdominis. Statistical analysis showed excellent reliability (ICC=0.87-0.89). The findings of this study support the validity and reliability of the prone bridging test for evaluating abdominal muscle fatigue.

Hip Strength as an Intrinsic Risk Factor for Lateral Ankle Sprains in Youth Soccer Players: A 3-Season Prospective Study

BACKGROUND

Numerous epidemiological studies have emphasized the burden of lateral ankle sprains in youth soccer players. However, no prospective study has identified intrinsic physical and modifiable risk factors for these injuries in this particular population. Although injury prevention programs in soccer incorporate proximal hip and core stability exercises, it is striking that the relationship between impaired proximal hip function and ankle sprains has not yet been prospectively investigated in youth soccer players.

HYPOTHESIS

This prospective study aimed to examine whether hip muscle strength is a risk factor for sustaining a lateral ankle sprain in youth soccer players. We hypothesized that decreased hip muscle strength would predispose youth soccer players to an increased risk of lateral ankle sprains.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study included a total of 133 male youth soccer players (age divisions U11-U17) for analysis. At the beginning of the season, anthropometric characteristics were collected and hip muscle strength was assessed using a handheld dynamometer. Injury registration was performed by the team medical staff during 3 consecutive seasons. A principal-component, multivariate Cox regression analysis was performed to identify potential risk factors for sustaining a lateral ankle sprain.

RESULTS

Twelve participants (18% of all reported injuries) sustained a lateral ankle sprain (0.36 per 1000 athletic-exposure hours). After adjustment for body size dependencies and other hip muscle forces, an increase in hip muscle extension force was associated with a significant decrease in the hazard of the injury (hazard ratio, 0.3; 95% confidence interval, 0.1-0.9; P = .028). No other study variable could be identified as a risk factor for lateral ankle sprains.

CONCLUSION

Reduced hip extension muscle strength is an independent risk factor for lateral ankle sprains in male youth soccer players. Other hip muscle strength outcomes were not identified as risk factors. Replication in larger samples with more injured cases is warranted to further ascertain the importance of this risk factor.

A novel device for standardizing marker placement at the calcaneus

BACKGROUND

The determination of anatomical reference frames in the rearfoot during three-dimensional multisegment foot modeling has been hindered by a variety of factors. One of these factors is related to the difficulty in palpating, or the absence of, anatomical landmarks. A novel device (the Calcaneal Marker Device) aimed at standardizing marker placement at the calcaneus was, therefore, developed and evaluated for its reliability.

METHODS

Throughout a random repeated-measures design, the repeatability of calcaneal marker placement was evaluated for two techniques: manual placement and placement using the Calcaneal Marker Device. Translational changes after marker placement and the clinical effect on intersegment angle calculation were quantified.

RESULTS

Intraobserver variability was greater in therapist 2 (<5.3 mm) compared with therapist 1 (<2.9 mm). Intraobserver variability was also found to be less than 1.6 mm throughout use of the device. Interobserver variability was found to be significantly higher for the position of markers placed manually (5.8 mm), whereas with the Calcaneal Marker Device, the variability remained lower (<1.3 mm). The effect on the computed intersegment angles followed a similar trend, with variability of 0.4° to 4.0° and 1.0° to 8.7° for CMD and manual placement, respectively.

CONCLUSIONS

These findings suggest that variations in marker placement are considerably reduced when the novel Calcaneal Marker Device is used, possibly toward the limits dictated by the fine motor skills of therapists and tissue artifacts.

Efficacy measures associated to a plantar pressure based classification system in diabetic foot medicine

AIMS

The concept of 'classification' has, similar to many other diseases, been found to be fundamental in the field of diabetic medicine. In the current study, we aimed at determining efficacy measures of a recently published plantar pressure based classification system.

METHODS

Technical efficacy of the classification system was investigated by applying a high resolution, pixel-level analysis on the normalized plantar pressure pedobarographic fields of the original experimental dataset consisting of 97 patients with diabetes and 33 persons without diabetes. Clinical efficacy was assessed by considering the occurence of foot ulcers at the plantar aspect of the forefoot in this dataset. Classification efficacy was assessed by determining the classification recognition rate as well as its sensitivity and specificity using cross-validation subsets of the experimental dataset together with a novel cohort of 12 patients with diabetes.

RESULTS

Pixel-level comparison of the four groups associated to the classification system highlighted distinct regional differences. Retrospective analysis showed the occurence of eleven foot ulcers in the experimental dataset since their gait analysis. Eight out of the eleven ulcers developed in a region of the foot which had the highest forces. Overall classification recognition rate exceeded 90% for all cross-validation subsets. Sensitivity and specificity of the four groups associated to the classification system exceeded respectively the 0.7 and 0.8 level in all cross-validation subsets.

CONCLUSIONS

The results of the current study support the use of the novel plantar pressure based classification system in diabetic foot medicine. It may particularly serve in communication, diagnosis and clinical decision making.

A Novel Method of Quantifying Gait Deviations Using Plantar Pressure Patterns

BACKGROUND

Comparing the dynamic pedobarographic patterns of individuals is common practice in basic and applied research. However, this process is often time-consuming and complex, and commercially available software often lacks powerful visualization and interpretation tools.

METHODS

We propose a simple method for displaying pixel-level pedobarographic deviations over time relative to a so-called reference pedobarographic pattern. This novel method contains four distinct automated preprocessing stages: 1) normalization of pedobarographic fields (for foot length and width), 2) temporal normalization, 3) a pixel-level z-score-based calculation, and 4) color coding of the normalized pedobarographic fields. Group and patient-level comparisons were illustrated using an experimental data set including diabetic and nondiabetic patients.

RESULTS

The automated procedure was found to be robust and quantified distinct temporal deviations in pedobarographic fields.

CONCLUSIONS

The advantages of the novel method cover several domains, including visualization, interpretation, and education.

Influence of balance surface on ankle stabilizing muscle activity in subjects with chronic ankle instability

OBJECTIVE

To evaluate the effect of balance surface type on muscle activity of ankle stabilizing muscles in subjects with chronic ankle instability.

DESIGN

Case-controlled, repeated-measures study design.

SUBJECTS

Twenty-eight subjects with chronic ankle instability and 28 healthy controls.

METHODS

Subjects performed a barefooted single-legged stance on uniaxial and multidirectional unstable surfaces. Muscle activity of the mm. peroneus longus/brevis, tibialis anterior, gastrocnemius medialis were registered using surface electromyography. Mixed model analysis was used to explore differences in muscle activity between subjects with chronic ankle instability and controls, and the effect of surface type on muscle activity levels within subjects with chronic ankle instability.

RESULTS

No differences were found between subjects with chronic ankle instability and healthy controls. Within subjects with chronic ankle instability, balancing along a frontal axis and on the Both Sides Up evoked overall highest muscle activity level, and the firm surface the least. Balancing on the firm surface showed the lowest tibialis anterior/peroneus longus muscle ratio, followed by balancing along a frontal axis and on the Airex pad.

CONCLUSION

Clinicians can use these findings to improve the focus of balance training programmes by gradually progressing in difficulty level based on muscle activation levels taking co-contraction ratios into account.

Evaluating fracture risk in acute ankle sprains: Any news since the Ottawa Ankle Rules? A systematic review

BACKGROUND

Ankle sprain is frequently encountered, both in primary care and in emergency departments. Since 1992, the Ottawa ankle rules (OAR) can assist clinicians in determining whether an X-ray should be performed to exclude a fracture. Several guidelines recommend the use of OAR based on a systematic review from 2003. Ten years later, one can wonder if this recommendation should be changed.

OBJECTIVE

To review systematically the current evidence on the most accurate method to assess the fracture risk after an ankle sprain in adults.

METHODS

A methodical search for systematic reviews, meta-analyses and primary studies was carried out in Medline, Cochrane Database of systematic reviews, Embase, Pedro, CINAHL, Medion and specific guideline search engines. At least two independent researchers performed selection, quality appraisal (with validated checklists) and data extraction.

RESULTS

One systematic review and 21 primary studies were selected. Sensitivity and specificity of the OAR range from 92-100% and from 16-51%, respectively. To improve the OAR specificity, other tools are proposed such as the Bernese ankle rules. Vibrating tuning fork test and ultrasound could be useful in patient with OAR positive to decrease the need for radiographs. No evidence was found in favour of the use of magnetic resonance imaging (MRI) or computed tomography (CT) in the acute phase of ankle sprain.

CONCLUSION

The findings confirm the value of the OAR at ruling out fractures after an ankle sprain and propose other or additional tools to decrease the need for X-rays.

Multi-segment foot landing kinematics in subjects with chronic ankle instability

BACKGROUND

Chronic ankle instability has been associated with altered joint kinematics at the ankle, knee and hip. However, no studies have investigated possible kinematic deviations at more distal segments of the foot. The purpose of this study was to evaluate if subjects with ankle instability and copers show altered foot and ankle kinematics and altered kinetics during a landing task when compared to controls.

METHODS

Ninety-six subjects (38 subjects with chronic ankle instability, 28 copers and 30 controls) performed a vertical drop and side jump task. Foot kinematics were obtained using the Ghent Foot Model and a single-segment foot model. Group differences were evaluated using statistical parametric mapping and analysis of variance.

RESULTS

Subjects with ankle instability had a more inverted midfoot position in relation to the rearfoot when compared to controls during the side jump. They also had a greater midfoot inversion/eversion range of motion than copers during the vertical drop. Copers exhibited less plantar flexion/dorsiflexion range of motion in the lateral and medial forefoot. Furthermore, the ankle instability and coper group exhibited less ankle plantar flexion at touchdown. Additionally, the ankle instability group demonstrated a decreased plantar flexion/dorsiflexion range of motion at the ankle compared to the control group. Analysis of ground reaction forces showed a higher vertical peak and loading rate during the vertical drop in subjects with ankle instability.

INTERPRETATION

Subjects with chronic ankle instability displayed an altered, stiffer kinematic landing strategy and related alterations in landing kinetics, which might predispose them for episodes of giving way and actual ankle sprains.

A color-code based method for the interpretation of plantar pressure measurements in clinical gait analysis

Comparing plantar pressure measurements (PPM) of a patient following an intervention or between a reference group and a patient-group is common practice in clinical gait analysis. However, this process is often time consuming and complex, and commercially available software often lacks powerful visualization and interpretation tools. In this paper, we propose a simple method for displaying pixel-level PPM deviations relative to a so-called reference PPM pattern. The novel method contains 3 distinct stages: (1) a normalization of pedobarographic fields (for foot length and width), (2) a pixel-level z-score based calculation and, (3) color coding of the normalized pedobarographic fields. The methodological steps associated to this novel method are precisely described and clinical output illustrated. We believe that the advantages of the novel method cover several domains. The strongest advantage of the novel method is that it provides a straightforward visual interpretation of PPM without decreasing the resolution perspective. A second advantage is that it may guide the selection of a local mapping technique (data reduction technique). Finally, it may be easily used as education tool during the therapist-patient interaction.

Review of clinical approaches and diagnostic quantities used in pedobarographic measurements

The non-invasive nature of pedobarographic measurements is particularly attractive to researchers for analyzing and characterizing the impact of specific pathological foot conditions. However, adequate clinical use of pedobarographic technology requires a profound technical and methodological knowledge. Several papers summarized the technical capacities of pedobarographic technology. Moreover, methodological expertise has grown considerably during the last two decades. Therefore, two crucial decisions have to be made before pathomechanical modelling or functional interpretation of foot and lower limb disorders can be pursued. The first is the selection of the specific method to analyse the dynamic plantar footprint, and the second is the choice of parameters to quantify the results. In the first part of this paper, we review the different methods used to analyse the dynamic plantar footprint and discuss their conceptual backgrounds. We also aim to illustrate the clinical relevance of each method and elaborate on the future perspectives. In the second part, we review quantification methods of pedobarographic measurements. The latter is of primary relevance to clinicians and investigators with a special interest in foot and lower limb biomechanics.

Foot orientation affects muscle activation levels of ankle stabilizers in a single-legged balance board protocol

CONTEXT

The main goal of balance training is regaining a normal neuromuscular control to a functional level. Although uniaxial balance boards are commonly used, no research has been done on the effect of foot orientation on muscle activation levels.

OBJECTIVE

To investigate the effect of foot orientation on muscle activation levels and modulation of the ankle stabilizing muscles in a single-legged balance protocol on a uniaxial balance board.

METHODS

Sixty-nine healthy subjects (age: 21.8±1.7years; mass: 67.5±11.9kg; body height: 174.7±8.6cm; BMI: 21.5±3.0) participated in this study. Subjects were asked to keep their balance during a single leg stance on a uniaxial balance board for four different foot orientations, aligning the board's rotation axis with frontal, sagittal, diagonal and subtalar axes of the foot, respectively. Surface electromyography registered muscle activity of peroneus longus, tibialis anterior, medial and lateral gastrocnemius muscles.

RESULTS

Highest muscle activation levels and modulation for the peroneus longus were registered exercising along the frontal axis; for the tibialis anterior along the diagonal axis; for the medial gastrocnemius along the sagittal axis; and for the lateral gastrocnemius along the diagonal axis.

CONCLUSION

Foot orientation modifications on a uniaxial balance board allows to differentially target specific ankle stabilizing muscles during balance training.

Classification of forefoot plantar pressure distribution in persons with diabetes: a novel perspective for the mechanical management of diabetic foot?

Background

The aim of this study was to identify groups of subjects with similar patterns of forefoot loading and verify if specific groups of patients with diabetes could be isolated from non-diabetics.

Methodology/Principal Findings

Ninety-seven patients with diabetes and 33 control participants between 45 and 70 years were prospectively recruited in two Belgian Diabetic Foot Clinics. Barefoot plantar pressure measurements were recorded and subsequently analysed using a semi-automatic total mapping technique. Kmeans cluster analysis was applied on relative regional impulses of six forefoot segments in order to pursue a classification for the control group separately, the diabetic group separately and both groups together. Cluster analysis led to identification of three distinct groups when considering only the control group. For the diabetic group, and the computation considering both groups together, four distinct groups were isolated. Compared to the cluster analysis of the control group an additional forefoot loading pattern was identified. This group comprised diabetic feet only. The relevance of the reported clusters was supported by ANOVA statistics indicating significant differences between different regions of interest and different clusters.

Conclusion/s Significance

There seems to emerge a new era in diabetic foot medicine which embraces the classification of diabetic patients according to their biomechanical profile. Classification of the plantar pressure distribution has the potential to provide a means to determine mechanical interventions for the prevention and/or treatment of the diabetic foot.

Pattern description and reliability parameters of six force-time related indices measured with plantar pressure measurements

BACKGROUND

Functional interpretation of plantar pressure measurements is commonly done through the use of ratios and indices which are preceded by the strategic combination of a subsampling method and selection of physical quantities. However, errors which may arise throughout the determination of these temporal indices/ratio calculations (T-IRC) have not been quantified. The purpose of the current study was therefore to estimate the reliability of T-IRC following semi-automatic total mapping (SATM).

METHODS

Using a repeated-measures design, two experienced therapists performed three subsampling sessions on three left and right pedobarographic footprints of ten healthy participants. Following the subsampling, six T-IRC were calculated: Rearfoot-Forefoot_fti, Rearfoot-Midfoot_fti, Forefoot medial/lateral_fti, First ray_fti, Metatarsal 1-Metatarsal 5_fti, Foot medial-lateral_fti.

FINDINGS

Patterns of the T-IRC were found to be consistent and in good agreement with corresponding knowledge from the literature. The inter-session errors of both therapists were similar in pattern and magnitude. The lowest peak inter-therapist error was found in the First ray_fti (6.5 a.u.) whereas the highest peak inter-therapist error was observed in the Forefoot medial/lateral_fti (27.0 a.u.) The magnitude of the inter-session and inter-therapist error varied over time, precluding the calculation of a simple numerical value for the error. The difference between both error parameters of all T-IRC was negligible which underscores the repeatability of the SATM protocol.

CONCLUSION

The current study reports consistent patterns for six T-IRC and similar inter-session and inter-therapist error. The proposed SATM protocol and the T-IRC may therefore serve as basis for functional interpretation of footprint data.

Comparison of foot segmental mobility and coupling during gait between patients with diabetes mellitus with and without neuropathy and adults without diabetes

BACKGROUND

Reduction in foot mobility has been identified as a key factor of altered foot biomechanics in individuals with diabetes mellitus. This study aimed at comparing in vivo segmental foot kinematics and coupling in patients with diabetes with and without neuropathy to control adults.

METHODS

Foot mobility of 13 diabetic patients with neuropathy, 13 diabetic patients without neuropathy and 13 non-diabetic persons was measured using an integrated measurement set-up including a plantar pressure platform and 3D motion analysis system. In this age-, sex- and walking speed matched comparative study; differences in range of motion quantified with the Rizzoli multisegment foot model throughout different phases of the gait cycle were analysed using one-way repeated measures analysis of variance (ANOVA). Coupling was assessed with cross-correlation techniques.

FINDINGS

Both cohorts with diabetes showed significantly lower motion values as compared to the control group. Transverse and sagittal plane motion was predominantly affected with often lower range of motion values found in the group with neuropathy compared to the diabetes group without neuropathy. Most significant changes were observed during propulsion (both diabetic groups) and swing phase (predominantly diabetic neuropathic group). A trend of lower cross-correlations between segments was observed in the cohorts with diabetes.

INTERPRETATION

Our findings suggest an alteration in segmental kinematics and coupling during walking in diabetic patients with and without neuropathy. Future studies should integrate other biomechanical measurements as it is believed to provide additional insight into neural and mechanical deficits associated to the foot in diabetes.

Intratest reliability in determining the subtalar joint axis using the palpation technique described by K. Kirby

BACKGROUND

Exact determination and classification of the spatial position of the subtalar joint axis could be a predictive clinical variable in biomechanical analysis and a valuable tool in the design of functional foot orthoses.

METHODS

Three clinicians with different levels of experience determined and classified the subtalar joint axis location, three times, on 52 individuals, using the clinical palpation, allocation and interpretation technique, as described by K. Kirby.

RESULTS

High intratester precision (ICC 0.72 to 0.93) was found for determining the axis location (SEM, 3.72° for angle/0.27 cm for X-axis); however, classification of the spatial position of the axis has large intertester variation (κ = 0.243 to 0.494)

CONCLUSIONS

The clinical palpation technique itself is reliable; the consistent attribution of a classification, in other words, interpretation, is weak.

Quantitative assessment of foot structure in rheumatoid arthritis by a foot digitizer: detection of deformities even in the absence of erosions

OBJECTIVE

Foot involvement is a major feature in rheumatoid arthritis (RA), leading to structural deformities. Methods to allow a 3-dimensional (3-D) evaluation of foot structure in RA to be applicable in daily clinical practice have not been evaluated. This study assessed the use of a foot digitizer, a noninvasive 3-D scanner collecting objective quantitative data of the feet, to evaluate the presence of foot structure abnormalities in an RA outpatient cohort.

METHODS

Foot digitizer data of RA patients were compared with healthy controls. Subanalyses were performed to find relationships with erosive disease and the presence of swollen and/or tender joints. Linear mixed models were applied with correction, including sex, age, body weight and height, foot length, Disease Activity Score in 28 joints, and disease duration.

RESULTS

Forty-one percent of the patients showed >1 abnormal parameter, measured with the 3-D foot scanner. Most differences found were located in the forefoot, the most frequently affected area of the RA foot. Strikingly, even in the absence of joint erosions, marked alterations were found. Comparable differences were also observed between the patients with and without swollen and/or tender joints. Additionally, alterations were not strongly related to foot pain and disability, suggesting the capacity of the foot digitizer to detect early changes in foot structure.

CONCLUSION

The results highlight the impact of RA on foot structure, even in the absence of clinical signs of swelling or radiographic erosions. The foot digitizer offers a valuable tool to screen for such foot deformities before the presence of erosions.

A clinically applicable six-segmented foot model

We describe a multi-segmented foot model comprising lower leg, rearfoot, midfoot, lateral forefoot, medial forefoot, and hallux for routine use in a clinical setting. The Ghent Foot Model describes the kinematic patterns of functional units of the foot, especially the midfoot, to investigate patient populations where midfoot deformation or dysfunction is an important feature, for example, rheumatoid arthritis patients. Data were obtained from surface markers by a 6 camera motion capture system at 500 Hz. Ten healthy subjects walked barefoot along a 12 m walkway at self-selected speed. Joint angles (rearfoot to shank, midfoot to rearfoot, lateral and medial forefoot to midfoot, and hallux to medial forefoot) in the sagittal, frontal, and transverse plane are reported according to anatomically based reference frames. These angles were calculated and reported during the foot rollover phases in stance, detected by synchronized plantar pressure measurements. Repeated measurements of each subject revealed low intra-subject variability, varying between 0.7° and 2.3° for the minimum values, between 0.5° and 2.1° for the maximum values, and between 0.8° and 5.8° for the ROM. The described movement patterns were repeatable and consistent with biomechanical and clinical knowledge. As such, the Ghent Foot model permits intersegment, in vivo motion measurement of the foot, which is crucial for both clinical and research applications.

The effect of a long-distance run on plantar pressure distribution during running

The purpose of this study was to assess plantar pressure alterations after long-distance running. Prior to and after a 20 km run, force distribution underneath the feet of 52 participants was registered using Footscan(®) pressure plates while the participants ran shod at a constant self-selected pace. Peak force, mean force and impulse were registered underneath different zones of the foot. In addition, temporal data as total foot contact time, time of contact and end of contact were derived for these zones. Furthermore, a medio-lateral pressure distribution ratio was calculated in different phases of the roll-off. After the run, increases in the loading of the forefoot, midfoot and medial heel were noted and decreases in loading of the lateral toes. In the forefoot push off phase a more lateral pressure distribution was observed. The results of this study demonstrated plantar pressure deviations after long-distance running which could give additional information related to several running injuries.

Reliability and validity of the INFOOT three-dimensional foot digitizer for patients with rheumatoid arthritis

BACKGROUND

Abnormal foot posture and deformities are identified as important features in rheumatoid arthritis. There is still no consensus regarding the optimum technique(s) for quantifying these features; hence, a foot digitizer might be used as an objective measurement tool. We sought to assess the validity and reliability of the INFOOT digitizer.

METHODS

To investigate the validity of the INFOOT digitizer compared with clinical measurements, we calculated Pearson correlation coefficients. To investigate the reliability of the INFOOT digitizer, we calculated intraclass correlation coefficients, SEMs, smallest detectable differences, and smallest detectable difference percentages.

RESULTS

Most of the 38 parameters showed good intraclass correlation coefficients, with values greater than 0.9 for 30 parameters and greater than 0.8 for seven parameters. The left heel bone angle expressed a moderate correlation, with a value of 0.609. The SEM values varied between 0.31 and 3.51 mm for the length and width measures, between 0.74 and 5.58 mm for the height data, between 0.75 and 5.9 mm for the circumferences, and between 0.78° and 2.98° for the angles. The smallest detectable difference values ranged from 0.86 to 16.36 mm for length, width, height, and circumference measures and from 2.17° to 8.26° for the angle measures. For the validity of the INFOOT three-dimensional foot digitizer, Pearson correlation coefficients varied between 0.750 and 0.997.

CONCLUSIONS

In this rheumatoid arthritis population, good validity was demonstrated compared with clinical measurements, and most of the obtained parameters proved to be reliable.

Body of evidence supporting the clinical use of 3D multisegment foot models: a systematic review

BACKGROUND

A critical component in the characterization of foot mechanics during clinical gait analysis is the quantitative measurement of foot kinematics. Currently, the use of 3D multisegment foot models (3DMFMs) is popular in gait laboratories as it would seem to be an adequate tool for the in vivo analysis of dynamic foot kinematics. This systematic review identifies and evaluates current evidence for the use of 3DMFMs in clinical gait analysis.

METHODS

A targeted search strategy traced full papers that fulfilled the inclusion and exclusion criteria. The papers were classified and evaluated for quality using a custom made quality appraisal form.

FINDINGS

Forty-one manuscripts were included yielding a total number of fifteen 3DMFMs. Generally, study procedures and sample selection were adequately described; however, the methodological quality varied widely. Evidence regarding the repeatability of the identified models also varied widely. Models facing the highest level of scientific credibility were characterized by adequate repeatability indices obtained from between-trial, between-day and between and within assessor studies. Generally, the highest reliability indices were found for the sagittal plane kinematics. Within-subject variability was found to be the lowest, contrarily, between-subject and between-day variabilities were found to be highest.

INTERPRETATION

Reported repeatability indices such as the coefficient of multiple correlation, standard deviation and standard error of measurement provide evidence for the continued use of 3DMFMs. While a number of published models exist, there is no adequate evidence available to support their clinical use. More reliability and validity studies are needed to confirm adequate measurement properties of 3DMFMs.

Human ankle cartilage deformation after different in vivo impact conditions

Recently, the general finding of increased ankle cartilage stiffness to loading has been challenged, suggesting the need for the investigation of different in vivo loading conditions. Therefore, the objectives of the present study were to determine ankle (talar) cartilage deformation after in vivo loading using 3D volume change calculation and to establish any difference in volume change between four weight-bearing exercises. The four exercises represented increasing impact (bilateral knee bends <unilateral knee bends <drop jumps) as well as two types of loading: dynamic and static loading (i.e. unilateral knee bends and unilateral static stance). Based on MRI, 3D reconstructions of talar cartilage were generated to determine 3D volumes before and after four exercises in 13 healthy subjects (bilateral and unilateral knee bends, static unilateral stance, drop jumps). Mean talar deformation (volume decrease) was 8.3% after bilateral knee bends (P = 0.001), 7.7% after unilateral knee bends (P = 0.020), 14.6% after unilateral static stance (P < 0.001), 12.5% after drop jumps (P = 0.001). Statistical analysis also revealed deformation to be significantly higher after unilateral static stance than after unilateral knee bends (P = 0.017). These results suggest that talar cartilage endures substantial deformation during in vivo loading characterized by more deformation (i.e. higher volume change) after static than after dynamic loading.

Intrinsic gait-related risk factors for Achilles tendinopathy in novice runners: a prospective study

The purpose of this prospective cohort study was to identify dynamic gait-related risk factors for Achilles tendinopathy (AT) in a population of novice runners. Prior to a 10-week running program, force distribution patterns underneath the feet of 129 subjects were registered using a footscan pressure plate while the subjects jogged barefoot at a comfortable self-selected pace. Throughout the program 10 subjects sustained Achilles tendinopathy of which three reported bilateral complaints. Sixty-six subjects were excluded from the statistical analysis. Therefore the statistical analysis was performed on the remaining sample of 63 subjects. Logistic regression analysis revealed a significant decrease in the total posterior-anterior displacement of the Centre Of Force (COF) (P=0.015) and a laterally directed force distribution underneath the forefoot at 'forefoot flat' (P=0.016) as intrinsic gait-related risk factors for Achilles tendinopathy in novice runners. These results suggest that, in contrast to the frequently described functional hyperpronation following a more inverted touchdown, a lateral foot roll-over following heel strike and diminished forward force transfer underneath the foot should be considered in the prevention of Achilles tendinopathy.

Effective prevention of sports injuries: a model integrating efficacy, efficiency, compliance and risk-taking behaviour

In 1992 van Mechelen et al published a "sequence of prevention model" based on a four-step process. This model has been widely used to implement preventive measures in response to sports injuries. However, the execution of this model has been shown to lack validity in determining the success of a preventive measure. A modified model has therefore been proposed which incorporates additional steps that enable the inclusion of external factors with a significant effect on the outcome of a prevention intervention. This expansion of van Mechelen's model leads to a more global model in which the compliance level and risk-taking behaviour of the individual and the assessment of efficiency of the stakeholders have a key influence on the preventive measure. This model gives a better insight into the different processes in injury prevention that can be used by clinicians, coaches and managers to decide whether to implement a preventive measure programme.

The role of stretching in tendon injuries

The function of tendons can be classified into two categories: tensile force transmission, and storage and release of elastic energy during locomotion. The action of tendons in storing and releasing energy is mainly seen in sports activities with stretch-shortening cycles (SSCs). The more intense the SSC movements are (jumping-like activities), the more frequently tendon problems are observed. High SSC movements impose high loads on tendons. Consequently, tendons that frequently deal with high SSC motion require a high energy-absorbing capacity to store and release this large amount of elastic energy. As the elasticity of tendon structures is a leading factor in the amount of stored energy, prevention and rehabilitation programmes for tendon injuries should focus on increasing this tendon elasticity in athletes performing high SSC movements. Recently, it has been shown that ballistic stretching can significantly increase tendon elasticity. These findings have important clinical implications for treatment and prevention of tendon injuries.

Reliability and accuracy of biomechanical measurements of the lower extremities

The reliability of biomechanical measurements of the lower extremities, as they are commonly used in podiatric practice, was quantified by means of intraclass correlation coefficients (ICCs). This was done not only to evaluate interrater and intrarater reliability but also to provide an estimate for the accuracy of the measurements. The measurement protocol involved 30 asymptomatic subjects and five raters of varying experience. Each subject was measured twice by the same rater, with the retest immediately following the test. The study demonstrated that the interrater ICCs were quite low (< or =0.51), except for the measurements of relaxed calcaneal stance position and forefoot varus (both 0.61 and 0.62 for left and right, respectively). However, the intrarater ICCs were relatively high (>0.8) for most raters and measurement variables. Measurement accuracy was moderate between raters.

Electrodynographic evaluation of the foot during treadmill versus overground locomotion

Biomechanical foot function as expressed by the duration of successive ground contact phases and by dynamic variables, such as the peak pressure on different parts of the foot, their respective loading rate, and duration, is compared for two walking and running conditions: overground on a 20-m walkway and on a treadmill. Statistical analysis revealed foot pressure characteristics as measured with a Electrodynogram during walking and running to alter significantly when using a treadmill. The differences were more pronounced for walking than for running. During walking, loading of the forefoot tends to last longer (longer propulsion phase) on a treadmill. Loading rate is decreased for the whole foot during either walking or running. Maximum heel pressure is diminished for walking but increased during running on a treadmill. Moderate variations of treadmill velocity were shown to have no significant influence on the measurements.

Double-blind- evaluation of bromperidol versus haloperidol treatment in chronic psychotic patients

Twenty four chronic psychotic patients were assigned at random to bromperidol or haloperidol. The mean dose for bromperidol was 4 to 8 mg in one intake in the morning and for haloperidol 4 mg given twice a day. Regular evaluation was performed by BPRS, global clinical impression, side-effects scale, hematological and biochemical screening. It appears that bromperidol is a potent antipsychotic drug with a duration of 24 h. Compared to haloperidol, it favours social integration by a mild but definite activating property. No major side-effects were observed.