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Background: Despite impressive results of the pharmacological management of rheumatoid arthritis, still certain patients suffer from rheumatoid forefoot problems. Surgical treatment of these forefoot deformities can be an option. In literature no high-quality studies on this topic can be found. The goal of present study is to compare the results of a metatarsal head (MTH) resecting technique with a MTH preserving technique in the operative treatment of severe rheumatoid forefoot deformity., Methods: Patients suffering from well-defined rheumatoid forefoot deformity were prospectively enrolled in three institutions. This non-blinded study had a randomised clinical design and eligible patients were randomly assigned to undergo either resection of preservation of the MTH. The primary outcome measure consisted of the AOFAS score. Secondary outcome measures were: the FFI, the VAS for pain and the SF-36., Results: Twenty-three patients (10 in MTH preservation group) were included and analysed. After one year follow-up no significant differences in AOFAS score and additional outcome factors were found. A total of 10 complications in 23 patients were reported., Conclusions: This randomised clinical study did not show significant clinical difference between a MTH resecting and a preserving procedure in patients suffering from rheumatoid forefoot deformity. Both procedures resulted in considerable improvement of pain and activity scores., (Copyright © 2017 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Background: It is unclear whether proximal interphalangeal joint (PIPJ) resection or fusion leads to superior clinical outcome in patients undergoing hammertoe surgery. The purpose of this study was to prospectively evaluate a series of patients undergoing this surgery., Methods: Patients with one or more toes with rigid PIP flexion deformity were prospectively enrolled. These patients were randomly assigned to undergo either PIPJ resection or PIPJ fusion. In addition to the PIPJ procedure, a metatarsophalangeal joint (MTPJ) release was performed if deemed necessary. Follow-up was up to 1 year postoperatively. Twenty-six patients (39 toes) were included in the PIPJ resection group and 29 (50 toes) in the PIPJ fusion group., Results: Thirty-four underwent an MTPJ release. No significant difference in foot outcome scores (American Orthopaedic Foot & Ankle Society scale, the Foot Function Index, and visual analog scale pain) could be detected after 1-year follow-up. A statistically significant difference was found regarding the toe alignment in the sagittal plane in favor of PIPJ fusion., Conclusions: Our randomized controlled study did not show any clinical outcome difference between PIPJ fusion and PIPJ resection. Both procedures resulted in good to excellent outcome in pain and activity scores., Level of Evidence: Level II, lesser quality RCT or prospective comparative study., (© The Author(s) 2016.)

Background: Discrepancies observed between clinical findings and a weightbearing foot X-ray might be caused by a patients' positioning. This study's main objective was to determine the effect of a subjects' posture on the osseous relations of the foot., Methods: Anatomical markers were placed on the skin of the foot of 17 subjects. A plantar pressure plate assessed the percentage weight on the foot and weight distribution over the foot. Medial longitudinal foot angles were derived from the markers and compared between the 10 postures. The effect of percentage weight and weight distribution on the foot angles was determined by multiple regression analysis., Results: The foot angles were significantly affected by the postures. The multiple regression analysis revealed the weight on the foot and the mediolateral weight distribution over the foot as important factors for the foot angles., Conclusion: A subjects posture significantly influences the osseous relations in the foot., (Copyright © 2015 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Objective: To determine the validity of the Trunk Impairment Classification system (TIC) with 4 possible scores (0, most impaired; 0.5; 1.0; 1.5, least impaired) in relation to objective, instrumented measures of impairment., Design: Cross-sectional design., Setting: National wheelchair rugby and basketball competitions of The Netherlands and Belgium., Participants: Volunteer sample of athletes (N=34) with a minimum of 1-year experience in their sport., Interventions: Static sitting balance tasks on a stable and unstable surface; dynamic sitting balance tasks in anterior-posterior, left-right, and oblique directions; and trunk muscle strength tasks in forward, left, right, and backward directions., Main Outcome Measures: Sway area of the center of pressure in static sitting balance, maximum excursion of center of pressure displacement in dynamic sitting balance, and maximum isometric force in trunk muscle strength., Results: Athletes with TIC score 0 were not able to sit unsupported. The Kruskal-Wallis test showed a significant difference in trunk muscle strength (P<.001) and dynamic balance in the oblique direction forward to the left and backward to the right between the TIC scores (P=.012). Post hoc analysis showed a significant difference between TIC score 0 and the other TIC scores for trunk muscle strength in all directions. There was a significant difference between TIC score 1.5 on one hand and TIC scores 0.5 and 1.0 on the other hand for dynamic balance in the right oblique direction., Conclusions: The TIC is a valid scale for trunk impairment, which measures neuromusculoskeletal trunk impairment, independent of the health condition causing the impairment. Additional research is needed for coordination impairment and to assess whether TIC scores 0.5 and 1.0 should continue as separate scores., (Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Walking speed is one of the best measures of overall walking capacity. In plantar pressure measurements, walking speed can be assessed using contact time, but it is only moderately correlated with walking speed. The center of pressure might be of more value to indicate walking speed since walking speed alters foot loading. Therefore, the purpose of this study is to assess walking speed using the velocity of the center of pressure (VCOP). Thirty-three subjects walked over a Footscan pressure plate at three speed conditions; slow, preferred, and fast. Walking speed was measured by a motion analysis system. (Multiple) linear regression analysis was used to indicate the relation between walking speed and independent variables derived from the pressure plate such as mean VCOP and stance time for all walking conditions separately and together. The mean VCOP had the highest correlation coefficient value with walking speed for all walking conditions combined (0.94) and for the preferred walking condition (0.80). The multiple regression analysis, based on a number of additional parameters, revealed a small to modest increase in the performance of predicting walking speed (r=0.98 for combined and r=0.93 for preferred). The mean VCOP was the best predictor for walking speed when using a plantar pressure plate. The mean VCOP predicts the walking speed with a 95% accuracy of 0.20m/s when healthy subjects walk at their preferred walking speed., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: To determine patient independency, health-related and disease-specific quality of life (QOL), gait pattern, and muscle strength in patients after salvage arthroplasty for failed internal fixation of a femoral neck fracture., Design: Secondary cohort study to a randomized controlled trial., Setting: Multicenter trial in the Netherlands, including 14 academic and nonacademic hospitals., Patients: Patients after salvage arthroplasty for failed internal fixation of a femoral neck fracture were studied. A comparison was made with patients who healed uneventfully after internal fixation., Intervention: None (observatory study)., Main Outcome Measurements: Patient characteristics, SF-12, and Western Ontario McMaster osteoarthritis index scores were collected. Gait parameters were measured using plantar pressure measurement. Maximum isometric forces of the hip muscles were measured using a handheld dynamometer. Differences between the fractured and contralateral leg were calculated. Groups were compared using univariate analysis., Results: Of 248 internal fixation patients (median age, 72 years), salvage arthroplasty was performed in 68 patients (27%). Salvage arthroplasty patients had a significantly lower Western Ontario McMaster osteoarthritis index score (median, 73 vs. 90; P = 0.016) than patients who healed uneventfully after internal fixation. Health-related QOL (SF-12) and patient independency did not differ significantly between the groups. Gait analysis showed a significantly impaired progression of the center of pressure in the salvage surgery patients (median ratio, -8.9 vs. 0.4, P = 0.013) and a significant greater loss of abduction strength (median, -25.4 vs. -20.4 N, P = 0.025)., Conclusions: Despite a similar level of dependency and QOL, salvage arthroplasty patients have inferior functional outcome than patients who heal after internal fixation of a femoral neck fracture., Level of Evidence: Therapeutic level III.

Introduction: Based on the windlass mechanism theory of Hicks, the medial longitudinal arch (MLA) flattens during weight bearing. Simultaneously, foot lengthening is expected. However, changes in foot length during gait and the influence of walking speed has not been investigated yet., Methods: The foot length and MLA angle of 34 healthy subjects (18 males, 16 females) at 3 velocities (preferred, low (preferred -0.4 m/s) and fast (preferred +0.4 m/s) speed were investigated with a 3D motion analysis system (VICON(®)). The MLA angle was calculated as the angle between the second metatarsal head, the navicular tuberculum and the heel in the local sagittal plane. Foot length was calculated as the distance between the marker at the heel and the 2nd metatarsal head. A General Linear Model for repeated measures was used to indicate significant differences in MLA angle and foot length between different walking speeds., Results: The foot lengthened during the weight acceptance phase of gait and shortened during propulsion. With increased walking speed, the foot elongated less after heel strike and shortened more during push off. The MLA angle and foot length curve were similar, except between 50% and 80% of the stance phase in which the MLA increases whereas the foot length showed a slight decrease., Conclusion: Foot length seems to represent the Hicks mechanism in the foot and the ability of the foot to bear weight. At higher speeds, the foot becomes relatively stiffer, presumably to act as a lever arm to provide extra propulsion., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Since the brain is intact, persons with a spinal cord injury (SCI) might benefit from a brain-computer interface (BCI) to improve mobility by making use of functional near-infrared spectroscopy (fNIRS)., Objective: We aimed to use fNIRS to detect contralateral primary motor cortex activity during attempted foot movements in participants with complete SCI., Methods: A 6-channel fNIRS, including 2 reference channels, measured relative concentration changes of oxy- (HbO) and deoxy-hemoglobin (HbR) in the contralateral motor cortex for the right foot. Seven subjects, studied within 18 months after injury, performed 12 trials of attempted right foot and real hand movements., Results: T tests revealed significant HbO and HbR responses of the left motor cortex for attempted foot movements, but not for right hand movements. A 2-way repeated-measures analysis of variance revealed a larger decrease in HbR for attempted foot movements compared to hand movements. Individual results show major interindividual differences in (number of) channels activated and the sensitive chromophore (HbR or HbO)., Conclusions: On group level, activity in the motor cortex of the foot can be measured with fNIRS in patients with complete SCI during attempted foot movements and might in principle be used in future BCI studies and applications.

Recently, real time imaging of the cortical control of gait became possible with functional near-infrared spectroscopy (fNIRS). So far, little is known about the activations of various cortical areas in more complex forms of gait, such as precision stepping. From previous work on animals and humans one would expect precision stepping to elicit extra activity in the sensorimotor cortices (S1/M1), supplementary motor area (SMA), as well as in prefrontal cortices (PFC). In the current study, hemodynamic changes in the PFC, SMA, M1, and S1 were measured with fNIRS. In contrast to previous fNIRS gait studies, the technique was optimized by the use of reference channels (to correct for superficial hemodynamic interference). Eleven subjects randomly performed ten trials of treadmill walking at 3 km/h (normal walking) and ten trials of 3 km/h treadmill walking on predefined spots for the left and right foot presented on the treadmill (precision stepping). The walking trials of approximately 35 seconds were alternated with rest periods of 25-35 seconds consisting of quiet standing. The PFC revealed profound activation just prior to the onset of both walking tasks. There was also extra activation of the PFC during the first half of the task period for precision stepping. The SMA showed mainly increased activation prior to the start of both tasks. In contrast, the sensorimotor cortex did not show a change in activation during either task as compared to a condition of standing. The SMA, M1, and S1 revealed no significant differences between normal walking and precision stepping. It was concluded that fNIRS is suited to record the planning and initiation of gait. The lack of M1/S1 activation during gait suggests that even in the current precision stepping task the control of ongoing gait depended mostly on subcortical automatisms, while motor cortex contributions did not differ between standing and walking., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Study Design: Observational, cross-sectional., Objectives: A new classification system for trunk impairment in wheelchair rugby was introduced in 2010. It consists of 10 tests, arranged in an algorithm, to assign four different trunk scores (0, 0.5, 1.0 or 1.5) to athletes. The purpose of this study was to assess the inter-rater reliability of this classification system., Setting: National competition for wheelchair rugby and wheelchair basketball in the Netherlands and Belgium., Methods: Three experienced wheelchair rugby classifiers independently assigned trunk scores to wheelchair rugby and wheelchair basketball athletes in two sessions. After each session, test descriptions were adjusted. The inter-rater reliability was evaluated by determining the agreement and Fleiss Kappa., Results: In the first session, all classifiers agreed on the trunk score in 13 out of 16 athletes; the overall Kappa was 0.76 (P<0.001). The Kappa per trunk score ranged from 0.29 to 1. Four test descriptions were adjusted after the first session. In the second session, there was an agreement in trunk score between the classifiers in 15 out of 21 athletes. The overall Kappa was 0.75 (P<0.0001), and the Kappa per trunk scores ranged from 0.58 to 0.92. After the second session, two test descriptions were improved., Conclusion: The revised classification system for trunk impairment in wheelchair rugby showed a adequate inter-rater reliability for the allocation of trunk scores.

Fast cyclic movements and discrete motor acts are controlled differently, presumably because fast cyclic tasks are more automated, thereby depending on different circuits. If fast cyclic movements are made less predictable (e.g., by mixing frequencies), one would predict that their control will be less automated, requiring increased activity in motor cortical areas. The present functional near-infrared spectroscopy (fNIRS) study investigated whether switching between frequencies increases the motor cortex activity compared to movements at single rates. Therefore, hand tapping at mixed frequencies ("mixed") was compared with hand tapping at 0.4 ("low frequency"), 0.8 ("mid-frequency"), and 1.4 Hz ("high frequency"). Oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbR) concentration changes were studied in eleven healthy subjects with eight-channel fNIRS covering the hand motor cortex. Repeated-measures ANOVAs revealed significant main effects for the type of task in HbO and HbR. Post hoc analysis showed a larger HbO increase and HbR decrease for the mixed task compared to the low- and high-frequency conditions. In addition, the mid-frequency condition revealed a smaller HbR decrease compared to the mixed task. Single frequency data indicated the existence of separate motor control systems for low- and high-frequency movements. The increased activity for the mixed task is suggested to be the result of the recruitment of a voluntary command motor system instead of automated systems.

Objectives: To measure the variation in activity parameters in patients with stroke over several days, and to assess whether patients with chronic stroke differ from each other in their achievement of ambulatory activity level., Design: Descriptive study., Methods: A total of 14 patients with chronic stroke wore 2 tri-axial accelerometers in their pockets for 7 consecutive days. The mean and standard deviation of activity parameters (duration of activity in minutes, and length and number of bouts of activity) were assessed across days. Outcome parameters were divided into morning, afternoon and evening, in order to assess the activity pattern., Results: The total group had a mean activity time of 54 min and standard deviation of 23 min over several days (range 5-45 min). Inactive participants had a significantly lower mean number of activity bouts, but no clear difference in length of bouts. Although activity level decreased during the day for the total group, only 4 participants showed a significant difference between periods of the day., Conclusion: A high level of variation in activity parameters over several days indicates the importance of measuring multiple days when assessing a patient's ambulatory activity level. Moreover, individual differences between patients indicate the importance of tailored advice in promoting their level of physical activity.

This study assesses femoral neck shortening and its effect on gait pattern and muscle strength in patients with femoral neck fractures treated with internal fixation. Seventy-six patients from a multicenter randomized controlled trial participated. Patient characteristics and Short Form 12 and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were collected. Femoral neck shortening, gait parameters, and maximum isometric forces of the hip muscles were measured and differences between the fractured and contralateral leg were calculated. Variables of patients with little or no shortening, moderate shortening, and severe shortening were compared using univariate and multivariate analyses. Median femoral neck shortening was 1.1 cm. Subtle changes in gait pattern, reduced gait velocity, and reduced abductor muscle strength were observed. Age, weight, and Pauwels classification were risk factors for femoral neck shortening. Femoral neck shortening decreased gait velocity and seemed to impair gait symmetry and physical functioning. In conclusion, internal fixation of femoral neck fractures results in permanent physical limitations. The relatively young and healthy patients in our study seem capable of compensating. Attention should be paid to femoral neck shortening and proper correction with a heel lift, as inadequate correction may cause physical complaints and influence outcome., (Copyright 2013, SLACK Incorporated.)

Objectives: To investigate whether spinal cord stimulation (SCS) has a negative effect on static balance and gait, which is implicated by the increased incidence of falls leading to frequently occurring lead migrations., Materials and Methods: A controlled trial is performed with 11 subjects (four female, seven male) with a mean age of 46 years old. A baseline measurement consisting of static balance and gait tests was performed. Within two weeks after implantation of a spinal cord stimulator, subjects performed the same tests with both stimulation switched on and off. Static balance was assessed with eyes open and eyes closed on hard surface and foam surface. The velocity of the center of pressure and weight symmetry were the main outcome parameters. Kinematics and spatiotemporal outcome parameters were used to analyze gait. ANOVAs were used to compare between baseline, stimulation on, and stimulation off., Results:  Spinal cord stimulation resulted in significant pain relief as scored on a Visual Analog Scale (p < 0.001). Gait width decreased and this change (indicative of improvement in balance) was significant (p = 0.007). No other significant group differences were found between stimulation baseline and post-surgery measurements. SCS did not influence static balance or gait when group effects were analyzed. Four subjects showed significant differences in static balance between stimulation on and off., Conclusions:  The lack of group differences in normal gait and static balance cannot explain the increased incidence of falls. However, four subjects showed an effect of SCS on static balance. Further research to clarify why only a part of the subjects experienced balance problems is recommended and assessments of more demanding balance and gait tasks are desirable., (© 2012 International Neuromodulation Society.)

Background: Plantar pressure is widely used to evaluate foot complaints. However, most plantar pressure studies focus on the symptomatic foot with foot deformities. The purposes of this study were to investigate subjects without clear foot deformities and to identify differences in plantar pressure pattern between subjects with and without forefoot pain. The second aim was to discriminate between subjects with and without forefoot pain based on plantar pressure measurements using neural networks., Methods: In total, 297 subjects without foot deformities of whom almost 50% had forefoot pain walked barefoot over a pressure plate. Foot complaints and subject characteristics were assessed with a questionnaire and a clinical evaluation. Plantar pressure was analyzed using a recently developed method, which produced pressure images of the time integral, peak pressure, mean pressure, time of activation and deactivation, and total contact time per pixel. After pre-processing the pressure images with principal component analysis, a forward selection procedure with neural networks was used to classify forefoot pain., Findings: The pressure-time integral and mean pressure were significantly larger under the metatarsals II and III for subjects with forefoot pain. A neural network with 14 input parameters correctly classified forefoot pain in 70.4% of the test feet., Interpretation: The differences in plantar pressure parameters between subjects with and without forefoot pain were small. The reasonable performance of forefoot pain classification by neural networks suggests that forefoot pain is related more to the distribution of the pressure under the foot than to the absolute values of the pressure at fixed locations., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In contrast to western countries, foot complaints are rare in Africa. This is remarkable, as many African adults walk many hours each day, often barefoot or with worn-out shoes. The reason why Africans can withstand such loading without developing foot complaints might be related to the way the foot is loaded. Therefore, static foot geometry and dynamic plantar pressure distribution of 77 adults from Malawi were compared to 77 adults from the Netherlands. None of the subjects had a history of foot complaints. The plantar pressure pattern as well as the Arch Index (AI) and the trajectory of the center of pressure during the stance phase were calculated and compared between both groups. Standardized pictures were taken from the feet to assess the height of the Medial Longitudinal Arch (MLA). We found that Malawian adults: (1) loaded the midfoot for a longer and the forefoot for a shorter period during roll off, (2) had significantly lower plantar pressures under the heel and a part of the forefoot, and (3) had a larger AI and a lower MLA compared to the Dutch. These findings demonstrate that differences in static foot geometry, foot loading, and roll off technique exist between the two groups. The advantage of the foot loading pattern as shown by the Malawian group is that the plantar pressure is distributed more equally over the foot. This might prevent foot complaints.

Objective: To gain insight into the relationship between activity pacing and physical inactivity., Design: A cross-sectional study., Setting: Outpatient clinic of a rheumatology department., Subjects: Men and women diagnosed with rheumatoid arthritis., Main Measures: Physical activity was assessed using self-reported measures and an accelerometer-based activity monitor. An occupational therapist and specialized nurse analysed the self-reported physical activity data and classified on the basis of consensus the pacing of activities of all patients as 'adequate' or 'not adequate'., Results: Thirty rheumatoid arthritis patients participated in this study of whom nine were categorized as adequate activity pacers. None of these nine undertook sufficient exercise whereas 6 of the 20 people who did not pace activity appropriately did. Physical activity levels assessed by self-reported measures were significantly higher than when assessed by an accelerometer-based activity monitor., Conclusions: Activity pacing was associated with lower levels of physical activity. Since patients with rheumatoid arthritis are already at risk for inactivity, further inactivation by activity pacing might potentially be harmful.

The poor spatial resolution of near-infrared spectroscopy (NIRS) makes it difficult to distinguish two closely located cortical areas from each other. Here, a combination of multi-channel NIRS and a centre of gravity (CoG) approach (widely accepted in the field of transcranial magnetic stimulation; TMS) was used to discriminate between closely located cortical areas activated during hand and foot movements. Similarly, the possibility of separating the more anteriorly represented discrete movements from rhythmic movements was studied. Thirteen healthy right-handed subjects performed rhythmic or discrete ('task') hand or foot ('extremity') tapping. Hemodynamic responses were measured using an 8-channel NIRS setup. For oxyhemoglobin (OHb) and deoxyhemoglobin (HHb), a CoG was determined for each condition using the mean hemodynamic responses and the coordinates of the channels. Significant hemodynamic responses were found for hand and foot movements. Based on the HHb responses, the NIRS-CoG of hand movements was located 0.6 cm more laterally compared to the NIRS-CoG of foot movements. For OHb responses no difference in NIRS-CoG was found for 'extremity' nor for 'task'. This is the first NIRS study showing hemodynamic responses for isolated foot movements. Furthermore, HHb responses have the potential to be used in multi-channel NIRS experiments requiring differential activation of motor cortex areas linked to either hand or foot movements.

Background: Metatarsal pads are frequently prescribed for patients with metatarsalgia to reduce pain under the distal metatarsal heads. Several studies showed reduced pain and reduced plantar pressure just distal to the metatarsal pad. However, only part of the pain reduction could be explained by the decrease in plantar pressure under the forefoot. Therefore, an alternative hypothesis is proposed that pain relief is related to a widening of the foot and the creation of extra space between the metatarsal heads. This study focused on the effect of a metatarsal pad on the geometry of the forefoot by studying forefoot width and the height of the second metatarsal head., Methods: Using a motion analysis system, 16 primary metatarsalgia feet and 12 control feet were measured when walking with and without a metatarsal pad., Results: A significant mean increase of 0.60 mm in forefoot width during the stance phase was found when a metatarsal pad was worn. During midstance, the mean increase in forefoot width was 0.74 mm. In addition, walking with a metatarsal pad revealed an increase in the height of the second metatarsal head (mean, 0.62 mm). No differences were found between patients and controls., Conclusions: The combination of increased forefoot width and the height of the second metatarsal head produced by the metatarsal pad results in an increase in space between the metatarsal heads. This extra space could play a role in pain reduction produced by a metatarsal pad.

Near-infrared spectroscopy (NIRS) is a non-invasive optical imaging technique, which is increasingly used to measure hemodynamic responses in the motor cortex. The location at which the NIRS optodes are placed on the skull is a major factor in measuring the hemodynamic responses optimally. In this study, the validity of using transcranial magnetic stimulation (TMS) in combination with a 3D motion analysis system to relocate the TMS derived position was tested. In addition, the main goal was to quantify the advantage of using TMS to locate the optimal position in relation to the most commonly used EEG C3 position. Markers were placed on the TMS coil and on the head of the subject. In eleven subjects, a TMS measurement was performed to determine the individual motor-evoked potential center-of-gravity (MEP-CoG). This procedure was repeated in nine subjects to test the validity. Subsequently, hemodynamic responses were measured at the MEP-CoG position and at the C3 position during a thumb abduction and adduction task. On average, the MEP-CoG location was located 19.2mm away from the C3 position. The reproducibility study on the MEP-CoG relocation procedure revealed no systematic relocations. No differences in early and delayed hemodynamic responses were found between the C3 and MEP-CoG position. These results indicate that using TMS for NIRS optodes positioning on the motor cortex does not result in higher hemodynamic response amplitudes. This could be explained if NIRS and TMS assess slightly different functions., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background and Purpose: In the present study a classification system for the rheumatoid forefoot is reported with its intra- and interobserver reliability and clinical relevance. The classification is based on the sequence of anatomical changes resulting from the loss of integrity of the MTP joints, loss of motion and changes regarding the quality and position of the plantar soft tissues. It is hypothesized that with progression of the amount of deformity of the MTP joint(s), patients have more pain and functional loss., Patients and Methods: In total 94 patients were included in the study following precise inclusion criteria. The forefeet of the patients were classified according to the introduced classification system by two observers in order to determine the intra- and interobserver reliability. The relation of the suggested classification between pain, function scores, and plantar foot pressure measurements was examined., Results and Conclusion: According to the Cohen's kappa and the ICC, the intra- and inter-observer reliability were high. Despite the large variation between subjects in a certain grade, a clear trend was found between increase in classification and VAS for pain, FFI difficulty with activities, and plantar peak pressure under the metatarsals. The suggested classification is of clinical relevance and can be used to develop therapeutical algorithms and to test interventions., (Copyright © 2010 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Purpose: Femoral component rotation is believed to be one of the factors influencing patellar tracking behavior. With the balanced gap implantation technique, the rotation of the femoral component can vary as it is guided by the ligaments. This study investigated whether femoral component rotation influenced patella position after primary total knee replacement (TKR)., Methods: In this prospective cohort study, a primary TKR was implanted in 49 patients using a balanced gap technique and a CT-free navigation system. Femoral component rotation was measured using the navigation data of the distal femur cut, referenced from the posterior condyles. At the 2-year follow-up, lateral patellar tilt and patellar displacement were measured on axial patella radiographs. Logistic regression analysis on femoral component rotation and preoperative patella position was conducted to identify predictors for postoperative patellar tilt and displacement., Results: Femoral component rotation that varied between -3 and 12° exorotation was not a predictor for postoperative tilt and displacement. Only preoperative displacement significantly predicted patella displacement., Conclusions: Although the balanced gap implantation technique resulted in a wide inter-patient variability for femoral component rotation, this variable rotation was not found to be associated with abnormal patellar position. Preoperative displacement results in a higher risk at a postoperatively displaced patella. The balanced gap technique can safely be used without an elevated risk for patella malposition.

Pedobarographic images reflect the dynamic interaction between the plantar foot and supporting surfaces during gait and postural activities. Since intra-foot and inter-subject contact geometry are grossly similar, images may be spatially registered and directly compared. Previously arbitrary subjects have been selected as registration templates, but this can conceivably introduce anatomical bias. The purposes of this study were: (i) to compute an unbiased pedobarographic template from a large sample of healthy young adult subjects, and (ii) to demonstrate how the resulting template may be used for practical clinical and scientific analyses. Images were obtained from N=104 subjects and were registered (10,712 pairs) using (i) an optimal linear scaling technique and (ii) a nonlinear, locally affine, globally smooth technique. The nonlinear technique was found to offer biomechanically non-trivial advantages over the linear technique, most likely due to non-proportional inter-subject geometry. Specifically, the nonlinear template was able to detect morphological signals in a hallux valgus sample with greater sensitivity than the linear template. Validity of the approach was confirmed by independently assessing left and right feet, through a statistical comparison of local maximal pressures, and also through examination of random subject subsets. The current template, representative of an average healthy foot, could be a valuable resource for automated clinical and scientific analyses of foot morphology and function., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background: Although many patients with foot complaints receive customized insoles, the choice for an insole design can vary largely among foot experts. To investigate the variety of insole designs used in daily practice, the insole design and its effect on plantar pressure distribution were investigated in a large group of patients., Materials and Methods: Mean, peak, and pressure-time-integral per sensor for 204 subjects with common foot complaints for walking with and without insoles was measured with the footscan® insole system (RSscan International). Each insole was scanned twice (precision3D), after which the insole height along the longitudinal and transversal cross section was calculated. Subjects were assigned to subgroups based on complaint and medial arch height. Data were analyzed for the total group and for the separate subgroups (forefoot or heel pain group and flat, normal or high medial arch group)., Results: The mean pressure significantly decreased under the metatarsal heads II-V and the calcaneus and significantly increased under the metatarsal bones and the lateral foot (p<0.0045) due to the insoles. However, similar redistribution patterns were found for the different foot complaints and arch heights. There was a slight difference in insole design between the subgroups; the heel cup was significantly higher and the midfoot support lower for the heel pain group compared to the forefoot pain group. The midfoot support was lowest in the flat arch group compared to the high and normal arch group (p<0.05)., Conclusion: Although the insole shape was specific for the kind of foot complaint and arch height, the differences in shape were very small and the plantar pressure redistribution was similar for all groups., Clinical Relevance: This study indicates that it might be sufficient to create basic insoles for particular patient groups.

Purpose: The popularity of long-distance walking (LDW) has increased in the last decades. However, the effects of LDW on plantar pressure distribution and foot complaints, in particular, after several days of walking, have not been studied., Methods: We obtained the plantar pressure data of 62 subjects who had no history of foot complaints and who walked a total distance of 199.8 km for men (n = 30) and 161.5 km for women (n = 32) during four consecutive days. Plantar pressure was measured each day after the finish (posttests I–IV) and compared with the baseline plantar pressure data, which was obtained 1 or 2 d before the march (pretest). Mean, peak, and pressure–time integral per pixel as well as the center of pressure (COP) trajectory of each foot per measurement day were calculated using the normalization method of Keijsers et al. A paired t-test with an adjusted P value was used to detect significant differences between pretest and posttest., Results: Short-term adjustment to LDW resulted in a significant decreased loading on the toes accompanied with an increased loading on the metatarsal head III–V (P < 0.001). At all stages, particularly at later stages, there was significantly more heel loading (P < 0.001). Furthermore, the COP significantly displaced in the posterior direction but not in the mediolateral direction after marching. Contact time increased slightly from 638.5 +/- 24.2 to 675.4 +/- 22.5 ms (P < 0.001)., Conclusions: The increased heel loading and decreased function of the toes found after marching indicate a change of walking pattern with less roll-off. It is argued that these changes reflect the effect of fatigue of the lower leg muscles and to avoid loading of the most vulnerable parts of the foot.

This prospective study investigated whether ligament releases necessary during total knee replacement (TKR) led to a higher varus-valgus laxity during intraoperative examination after implantation of the prosthesis and after 6 months. The laxity values of TKR patients were also compared to healthy controls. Varus-valgus laxity was assessed intra- and postoperatively in extension and 70 degrees flexion in 49 patients undergoing TKR, implanted using a balanced gap technique. Knees were catalogued according to ligament releases performed during surgery. Postoperative varus-valgus laxity and laxity after 6 months had not increased following release of the posteromedial capsule, iliotibial tract, and the superficial medial collateral ligament. The obtained postoperative laxity compares well with a healthy equally aged control group. It can be concluded that the balanced gap technique results in stable knees and that releases can safely be performed to achieve neutral leg alignment without causing postoperative laxity.

Foot size and shape vary between individuals and the foot adopts arbitrary stance phase postures, so traditional pedobarographic analyses regionalize foot pressure images to afford homologous data comparison. An alternative approach that does not require explicit anatomical labelling and that is used widely in other functional imaging domains is to register images such that homologous structures optimally overlap and then to compare images directly at the pixel level. Image registration represents the preprocessing cornerstone of such pixel-level techniques, so its performance warrants independent attention. The purpose of this study was to evaluate the performance of four between-subjects warping registration algorithms including: Principal Axes (PA), four-parameter Optimal Scaling (OS4), eight-parameter Optimal Projective (OP8), and locally affine Nonlinear (NL). Fifteen subjects performed 10 trials of self-paced walking, and their peak pressure images were registered within-subjects using an optimal rigid body transformation. The resulting mean images were then registered between-subjects using all four methods in all 210 (15x14) subject combinations. All registration methods improved alignment, and each method performed qualitatively well for certain image pairs. However, only the NL consistently performed satisfactorily because of disproportionate anatomical variation in toe lengths and rearfoot/forefoot width, for example. Using three independent image (dis)similarity metrics, MANOVA confirmed that the NL method yielded superior registration performance (p<0.001). These data demonstrate that nonlinear spatial warping is necessary for robust between-subject pedobarographic image registration and, by extension, robust homologous data comparison at the pixel level.

Plantar pressure measurement provides important information about the structure and function of the foot and is a helpful tool to evaluate patients with foot complaints. In general, average and maximum plantar pressure of 6-11 areas under the foot are used to compare groups of subjects. However, masking the foot means a loss of important information about the plantar pressure distribution pattern. Therefore, the purpose of this study was to develop and test a simple method that normalizes the plantar pressure pattern for foot size, foot progression angle, and total plantar pressure. Moreover, scaling the plantar pressure to a standard foot opens the door for more sophisticated analysis techniques such as pattern recognition and machine learning. Twelve subjects walked at preferred and half of the preferred walking speed over a pressure plate. To test the method, subjects walked in a straight line and in an approaching angle of approximately 40 degrees . To calculate the normalized foot, the plantar pressure pattern was rotated over the foot progression angle and normalized for foot size. After normalization, the mean shortest distance between the contour lines of straight walking and walking at an angle had a mean of 0.22 cm (SD: 0.06 cm) for the forefoot and 0.14 cm (SD: 0.06 cm) for the heel. In addition, the contour lines of normalized feet for the various subjects were almost identical. The proposed method appeared to be successful in aligning plantar pressure of various feet without losing information.

We developed an algorithm that distinguishes between on and off states in patients with Parkinson's disease during daily life activities. Twenty-three patients were monitored continuously in a home-like situation for approximately 3 hours while they carried out normal daily-life activities. Behavior and comments of patients during the experiment were used to determine the on and off periods by a trained observer. Behavior of the patients was measured using triaxial accelerometers, which were placed at six different positions on the body. Parameters related to hypokinesia (percentage movement), bradykinesia (mean velocity), and tremor (percentage peak frequencies above 4 Hz) were used to distinguish between on and off states. The on-off detection was evaluated using sensitivity and specificity. The performance for each patient was defined as the average of the sensitivity and specificity. The best performance to classify on and off states was obtained by analysis of movements in the frequency domain with a sensitivity of 0.97 and a specificity of 0.97. We conclude that our algorithm can distinguish between on and off states with a sensitivity and specificity near 0.97. This method, together with our previously published method to detect levodopa-induced dyskinesia, can automatically assess the motor state of Parkinson's disease patients and can operate successfully in unsupervised ambulatory conditions., (Copyright (c) 2005 Movement Disorder Society.)

The purpose of this study was to assess the accuracy of measuring angle and angular velocity of the upper body and upper leg during rising from a chair with accelerometers, using low-pass filtering of the accelerometer signal. Also, the improvement in accuracy of the measurement with additional use of high-pass filtered gyroscopes was assessed. Two uni-axial accelerometers and one gyroscope (DynaPort) per segment were used to measure angles and angular velocities of upper body and upper leg. Calculated angles and angular velocities were compared to a high-quality optical motion analysis system (Optotrak), using root mean squared error (RMS) and correlation coefficient (r) as parameters. The results for the sensors showed that two uni-axial accelerometers give a reasonable accurate measurement of the kinematics of rising from a chair (RMS = 2.9, 3.5, and 2.6 degrees for angle and RMS = 9.4, 18.4, and 11.5 degrees /s for angular velocity for thorax, pelvis, and upper leg, respectively). Additional use of gyroscopes improved the accuracy significantly (RMS = 0.8, 1.1, and 1.7 degrees for angle and RMS = 2.6, 4.0 and 4.9 degrees /s for angular velocity for thorax, pelvis and upper leg, respectively). The low-pass Butterworth filter had optimal cut-off frequencies of 1.05, 1.3, and 1.05 for thorax, pelvis, and upper leg, respectively. For the combined signal, the optimal cut-off frequencies were 0.18, 0.2, and 0,38 for thorax, pelvis and upper leg, respectively. The filters showed no subject specificity. This study provides an accurate, inexpensive and simple method to measure the kinematics of movements similar to rising from a chair.

Indirect evidence suggests that patients with Parkinson's disease (PD) have deficits not only in motor performance, but also in the processing of sensory information. We investigated the role of sensory information processing in PD patients with a broad range of disease severities and in a group of age-matched controls. Subjects were tested in two conditions: pointing to a remembered visual target in complete darkness (DARK) and in the presence of an illuminated frame with a light attached to the index finger (FRAME). Differences in pointing errors in these two conditions reflect the effect of visual feedback on pointing. PD patients showed significantly larger constant and variable errors than controls in the DARK and FRAME condition. The difference of the variable error in the FRAME and DARK condition decreased as a function of the severity of PD. This indicates that any deficits in the processing of proprioceptive information occur already at very mild symptoms of PD, and that deficits in the use of visual feedback develop progressively in later stages of the disease. These results provide a tool for early diagnosis of PD and shed new light on the functional role of the brain structures that are affected in PD.

We have investigated pointing movements toward remembered targets after an intervening self-generated body movement. We tested to what extent visual information about the environment or finger position is used in updating target position relative to the body after a step and whether gaze plays a role in the accuracy of the pointing movement. Subjects were tested in three visual conditions: complete darkness (DARK), complete darkness with visual feedback of the finger (FINGER), and with vision of a well-defined environment and with feedback of the finger (FRAME). Pointing accuracy was rather poor in the FINGER and DARK conditions, which did not provide vision of the environment. Constant pointing errors were mainly in the direction of the step and ranged from about 10 to 20 cm. Differences between binocular fixation and target position were often related to the step size and direction. At the beginning of the trial, when the target was visible, fixation was on target. After target extinction, fixation moved away from the target relative to the subject. The variability in the pointing positions appeared to be related to the variable errors in fixation, and the co-variance increases during the delay period after the step, reaching a highly significant value at the time of pointing. The significant co-variance between fixation position and pointing is not the result of a mutual dependence on the step, since we corrected for any direct contributions of the step in both signals. We conclude that the co-variance between fixation and pointing position reflects 1) a common command signal for gaze and arm movements and 2) an effect of fixation on pointing accuracy at the time of pointing.

We examined the role of gaze in a task where subjects had to reproduce the position of a remembered visual target with the tip of the index finger, referred to as pointing. Subjects were tested in 3 visual feedback conditions: complete darkness (dark), complete darkness with visual feedback of the finger position (finger), and with vision of a well-defined environment and feedback of the finger position (frame). Pointing accuracy increases with feedback about the finger or visual environment. In the finger and frame conditions, the 95% confidence regions of the variable errors have an ellipsoidal distribution with the main axis oriented toward the subjects' head. During the 1-s period when the target is visible, gaze is almost on target. However, gaze drifts away from the target relative to the subject in the delay period after target disappearance. In the finger and frame conditions, gaze returns toward the remembered target during pointing. In all 3 feedback conditions, the correlations between the variable errors of gaze and pointing position increase during the delay period, reaching highly significant values at the time of pointing. Our results demonstrate that gaze affects the accuracy of pointing. We conclude that the covariance between gaze and pointing position reflects a common drive for gaze and arm movements and an effect of gaze on pointing accuracy at the time of pointing. Previous studies interpreted the orientation of variable errors as indicative for a frame of reference used for pointing. Our results suggest that the orientation of the error ellipses toward the head is at least partly the result of gaze drift in the delay period.

It is well known that long-term use of levodopa by patients with Parkinson's disease causes dyskinesia. Several methods have been proposed for the automatic, unsupervised detection and classification of levodopa induced dyskinesia. Recently, we have demonstrated that neural networks are highly successful to detect dyskinesia and to distinguish dyskinesia from voluntary movements. The aim of this study was to use the trained neural networks to extract parameters, which are important to distinguish between dyskinesia and voluntary movements. Thirteen patients were continuously monitored in a home-like situation performing in about 35 daily life tasks for a period of approximately 2.5 h. Behavior of the patients was measured using triaxial accelerometers, which were placed at six different positions of the body. A neural network was trained to assess the severity of dyskinesia. The neural network was able to assess the severity of dyskinesia and could distinguish dyskinesia from voluntary movements in daily life. For the trunk and the leg, the important parameters appeared to be the percentage of time that the trunk or leg was moving and the standard deviation of the segment velocity of the less dyskinetic leg. For the arm, the combination of the percentage of time, that the wrist was moving, and the percentage of time, that a patient was sitting, explained the largest part of the variance of the output. Dyskinesia differs from voluntary movements in the fact that dyskinetic movements tend to have lower frequencies than voluntary movements and in the fact that movements of different body segments are not well coordinated in dyskinesia.

We developed an objective and automatic procedure to assess the severity of levodopa-induced dyskinesia (LID) in patients with Parkinson's disease during daily life activities. Thirteen patients were continuously monitored in a home-like situation for a period of approximately 2.5 hours. During this time period, the patients performed approximately 35 functional daily life activities. Behavior of the patients was measured using triaxial accelerometers, which were placed at six different positions on the body. A neural network was trained to assess the severity of LID using various variables of the accelerometer signals. Neural network scores were compared with the assessment by physicians, who evaluated the continuously videotaped behavior of the patients off-line. The neural network correctly classified dyskinesia or the absence of dyskinesia in 15-minute intervals in 93.7, 99.7, and 97.0% for the arm, trunk, and leg, respectively. In the few cases of misclassification, the rating by the neural network was in the class next to that indicated by the physicians using the AIMS score (scale 0-4). Analysis of the neural networks revealed several new variables, which are relevant for assessing the severity of LID. The results indicate that the neural network can accurately assess the severity of LID and could distinguish LID from voluntary movements in daily life situations., (Copyright 2002 Movement Disorder Society)

Levodopa-induced dyskinesias (LID) in Parkinson's disease (PD) have remained a clinical challenge. We evaluated the feasibility of neural networks to detect LID and to quantify their severity in 16 patients with PD at rest and during various activities of daily living. The movements of the patients were measured using four pairs of accelerometers mounted on the wrist, upper arm, trunk, and leg on the most affected side. Using parameters obtained from the accelerometer signals, neural networks were trained to detect and to classify LID corresponding to the modified Abnormal Involuntary Movement Scale. Important parameters for classification appeared to be the mean segment velocity and the cross-correlation between accelerometers on the arm, trunk, and leg. Neural networks were able to distinguish voluntary movements from LID and to assess the severity of LID in various activities. Based on the results in this study, we conclude that neural networks are a valid and reliable method to detect and to assess the severity of LID corresponding to the modified Abnormal Involuntary Movement Scale.