Foot ulcer recurrence, plantar pressure and footwear adherence in people with diabetes and Charcot midfoot deformity: A cohort analysis

AIMS

To investigate people with Charcot midfoot deformity with regard to plantar pressure, footwear adherence and plantar foot ulcer recurrence.

METHODS

Twenty people with diabetes, Charcot midfoot deformity, plantar foot ulcer history and custom-made footwear were assessed with regard to barefoot and in-shoe plantar pressures during walking, footwear adherence (% of daily steps over 7-day period) and plantar foot ulcer recurrence over 18 months. In a cohort design, they were compared to 118 people without Charcot foot (non-Charcot foot group) with custom-made footwear and similar ulcer risk factors.

RESULTS

Median (interquartile range) barefoot midfoot peak pressures were significantly higher in the Charcot foot group than in the non-Charcot foot group [756 (260-1267) vs 146 (100-208) kPa; P<0.001]. In-shoe midfoot peak pressures were not significantly higher in the Charcot foot group [median (interquartile range) 152 (104-201) vs 119 (94-160) kPa] and significantly lower for all other foot regions. Participants in the Charcot foot group were significantly more adherent, especially at home, than participants in the non-Charcot foot group [median (interquartile range) 94.4 (85.4-95.0)% vs. 64.3 (25.4-85.7)%; P=0.001]. Ulcers recurred in 40% of the Charcot foot group and in 47% of the non-Charcot foot group (P=0.63); midfoot ulcers recurred significantly more in the Charcot foot group (4/8) than in the non-Charcot foot group (1/55; P=0.001).

CONCLUSIONS

Effective offloading and very high footwear adherence were found in people with diabetes and Charcot midfoot deformity. While this may help protect against plantar foot ulcer recurrence, a large proportion of such people still experience ulcer recurrence. Further improvements in adherence and custom-made footwear design may be required to improve clinical outcome.

Exhaust emissions from diesel engines fueled by different blends with the addition of nanomodifiers and hydrotreated vegetable oil HVO

Diesel emissions have a significant impact on the atmosphere, contributing to air pollution, smog and global warming. As a result, diesel exhaust is dangerous to human health. While emissions reduction efforts have often focused on changing engine design or improving aftertreatment, diesel fuel modifications can also play an important role in improving engine efficiency and reducing exhaust emissions. The aim of this work was to examine the potential for emissions reductions under real-world conditions when employing fuel additives. Three different additives were examined, consisting of hydrotreated vegetable oil (HVO) and two commercial additives containing nanoparticles of cerium dioxide and ferrocene. HVO was selected as a renewable fuel, an alternative to commonly used biodiesels with competitive advantages. The new European driving cycle (NEDC) procedure was used to measure emissions of regulated compounds: carbon monoxide, nitrogen oxides, hydrocarbons and particulates (by mass and number) from an 11-year-old passenger car equipped with a diesel engine powered by fuel blends. The fuel blends prepared met the quality requirements for diesel fuel. The results obtained confirm that the application of both HVO and nano-additives to diesel can achieve a significant reduction of carbon monoxide (52%) and hydrocarbon (47%) emissions compared to the B7 base fuel. Particulate emissions (up to 10% by mass of particulates and 7% by number of particulates) were found to be best reduced by adding nanoparticles of cerium dioxide to the B7 fuel (with 30% HVO), while the best results in reducing nitrogen oxide emissions were obtained by adding ferrocene nanoparticles to the B7 fuel with 30% HVO.

Evaluation of a 10 nm Particle Number Portable Emissions Measurement System (PEMS)

On-board portable emissions measurement systems (PEMS) are part of the type approval, in-service conformity, and market surveillance aspects of the European exhaust emissions regulation. Currently, only solid particles >23 nm are counted, but Europe will introduce a lower limit of 10 nm. In this study, we evaluated a 10-nm prototype portable system comparing it with laboratory systems measuring diesel, gasoline, and CNG (compressed natural gas) vehicles with emission levels ranging from approximately 2 × 10¹⁰ to 2 × 10¹² #/km. The results showed that the on-board system differed from the laboratory 10-nm system on average for the tested driving cycles by less than approximately 10% at levels below 6 × 10¹¹ #/km and by approximately 20% for high-emitting vehicles. The observed differences were similar to those observed in the evaluation of portable >23 nm particle counting systems, despite the relatively small size of the emitted particles (with geometric mean diameters <42 nm) and the additional challenges associated with sub-23 nm measurements. The latter included the presence of semivolatile sub-23 nm particles, the elevated concentration levels during cold start, and also the formation of sub-23 nm artefacts from the elastomers that are used to connect the tailpipe to the measurement devices. The main conclusion of the study is that >10 nm on-board systems can be ready for introduction in future regulations.

Gait alteration strategies for knee osteoarthritis: a comparison of joint loading via generic and patient-specific musculoskeletal model scaling techniques

Gait modifications and laterally wedged insoles are non-invasive approaches used to treat medial compartment knee osteoarthritis. However, the outcome of these alterations is still a controversial topic. This study investigates how gait alteration techniques may have a unique effect on individual patients; and furthermore, the way we scale our musculoskeletal models to estimate the medial joint contact force may influence knee loading conditions. Five patients with clinical evidence of medial knee osteoarthritis were asked to walk at a normal walking speed over force plates and simultaneously 3D motion was captured during seven conditions (0°-, 5°-, 10°-insoles, shod, toe-in, toe-out, and wide stance). We developed patient-specific musculoskeletal models, using segmentations from magnetic resonance imaging to morph a generic model to patient-specific bone geometries and applied this morphing to estimate muscle insertion sites. Additionally, models were created of these patients using a simple linear scaling method. When examining the patients' medial compartment contact force (peak and impulse) during stance phase, a 'one-size-fits-all' gait alteration aimed to reduce medial knee loading did not exist. Moreover, the different scaling methods lead to differences in medial contact forces; highlighting the importance of further investigation of musculoskeletal modeling methods prior to use in the clinical setting.

Geochemical markers and polycyclic aromatic hydrocarbons in solvent extracts from diesel engine particulate matter

Exhaust particulate from compression ignition (CI) engines running on engine and chassis dynamometers was studied. Particulate dichloromethane extracts were qualitatively and quantitatively analyzed for polycyclic aromatic hydrocarbons (PAHs) and biomarkers by gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). PAH group profiles were made and the PAH group shares according to the number of rings (2 or 3; 4; 5 or more) as well as diagnostic indices were calculated. Values of geochemical ratios of selected biomarkers and alkyl aromatic hydrocarbons were compared with literature values. A geochemical interpretation was carried out using these values and biomarker and alkyl aromatic hydrocarbon distributions. It has been shown that geochemical features are unequivocally connected to the emission of fossil fuels and biofuels burned in CI engines. The effect of the exothermic combustion process is limited to low-molecular-weight compounds, which shows that the applied methodology permits source identification of PAHs coexisting in the particulate emitted.

The effects of neat biodiesel and biodiesel and HVO blends in diesel fuel on exhaust emissions from a light duty vehicle with a diesel engine

The influence of fatty acid methyl esters (FAME) and hydrotreated vegetable oil (HVO) diesel blends on the exhaust emissions from a passenger car was examined. The impact of FAME for the cold urban phase (UDC) was increased CO and HC emissions, probably due to blend physical properties promoting incomplete combustion. The HVO blend caused the lowest CO and HC emissions for the UDC. NOx emissions did not change significantly with the fuel used, however the UDC was characterized by lower NOx emission for FAME blends. Particle emissions were highest with standard diesel. Emissions of carbonyl compounds increased as fuel biodiesel content increased, especially during the UDC. HVO in diesel fuel decreased carbonyl emissions. Formaldehyde and acetaldehyde were the most abundant carbonyl compounds in the exhaust gas. Total particle-bound PAH emissions were variable, the emission of heavier PAHs increased with blend biodiesel content. The HVO blend increased emission of lighter PAHs. Nitro-PAHs were identified only during the UDC and not for all blends; the highest emissions were measured for pure diesel. The results showed that emission of nitro-PAHs may be decreased to a greater extent by using biodiesel than using a HVO blend.

Achilles tendon biomechanics in psoriatic arthritis patients with ultrasound proven enthesitis

OBJECTIVE

To investigate Achilles tendon (AT) biomechanics in psoriatic arthritis (PsA) patients with ultrasound confirmed features of enthesitis.

METHOD

PsA patients and healthy control subjects underwent three-dimensional (3D) gait analysis to measure walking speed, rotational joint motion and the moments, power, and AT force at the ankle-subtalar joint complex. The Glasgow Ultrasound Enthesitis Scoring System (GUESS) was used to score the presence of enthesophytes, erosions, retrocalcaneal bursitis, and tendon thickening. Power Doppler ultrasound signal (PDUS) was used to detect active disease. Peripheral joint arthritis, acute-phase reactants, global health, disability, and foot impairments were recorded. A core set of biomechanical variables that influence the insertion of the AT and indirect estimates of tendon loading were compared between PsA patients and control subjects with and without enthesitis.

RESULTS

Forty-two PsA patients with a mean disease duration of 10.6 (SD 9.4) years and 29 control subjects were studied. Seventeen (40%) PsA patients had clinically detectable AT entheseal pain. Twenty-eight (67%) PsA patients and nine (31%) control subjects had one or more GUESS enthesitis features, predominantly enthesophytes. PsA patients with enthesitis walked significantly more slowly than control subjects (p = 0.019) and generated lower peak ankle joint moments (p = 0.006), power (p = 0.001), and AT force (p = 0.003). Ankle-subtalar joint complex motion was comparable and no between-group differences were found for peak dorsiflexion (p = 0.59), eversion (p = 0.05), and internal rotation (p = 0.19).

CONCLUSIONS

In this group of PsA patients, the AT insertional angle was not influenced by ankle-subtalar joint motion in those with and without enthesitis. Moreover, the PsA patients with enthesitis had significantly lower AT loading.

The risk of foot ulceration in people with diabetes screened in community settings: findings from a cohort study

BACKGROUND

Annual foot checks are recommended in patients with diabetes mellitus (DM) to identify those at risk of foot ulceration. Systematic reviews have found few studies evaluating the predictive value of tests in community-based diabetic populations.

AIM

To quantify the predictive value of clinical risk factors in relation to foot ulceration in a community population.

METHODS

A cohort of 1192 people with diabetes receiving care in community settings was recruited and a screening procedure, covering symptoms, signs and diagnostic tests was conducted at baseline. At an average 1-year follow-up patients who developed a foot ulcer were identified by an independent blind assessor. Multivariable analysis was performed to identify clinical predictors of foot ulceration.

FINDINGS

The incidence of foot ulceration was 1.93% [95% confidence interval (CI) 1.27-2.89). Three time-independent clinical predictors with five factors were selected: previous amputation [odds ratio (OR) 14.7, 95% CI 3.1-69.5), use of insulin before 3 months with inability to distinguish between cool and cold temperatures (OR 2.97, 95% CI 1.9-4.5) and failure to obtain at least one blood pressure reading for the calculation of ankle-brachial index with the failure to feel touch with a 10-g monofilament (OR 1.7, 95% CI 1.3-2.2).

INTERPRETATION

Recommendations for annual diabetic foot check in low-risk, community-based patients should be reviewed as absolute events of ulceration are low. The accuracy of foot risk assessment tools to predict ulceration requires evaluation in randomized controlled trials with concurrent economic evaluations.

A novel device for improving marker placement accuracy

BACKGROUND

Repeatability of marker placement has been acknowledged as a major factor affecting the reliability of multi-segment foot models. A novel device is proposed that is intended to reduce marker placement error and its effect on the reliability of inter-segmental foot kinematic data is investigated.

METHOD

The novel device was tested on eight healthy subjects. Landmarks were identified and indicated on the subject's foot at the start of testing using pen, and these points were used to guide placement. Markers were twice attached by a podiatrist using a standard approach, and twice by a researcher who used the novel device. Replacement accuracy and the kinematic reliability of the foot model data for both techniques were analysed.

RESULTS

The mean marker placement variability using the novel device placement device was 1.1mm (SD 0.28) compared to 1.4mm (SD 0.23) when using standard placement techniques. Results suggest that these reductions in placement error tended to improve the overall reliability of the multi-segment data from the foot model.

DISCUSSION

The novel device is a simple and inexpensive tool for improving the placement consistency of skin-mounted markers.

The FOOTSTEP self-management foot care programme: are rheumatoid arthritis patients physically able to participate?

BACKGROUND

The FOOTSTEP self-management foot care programme is a clinical and cost-effective programme for basic foot care in the elderly. The aim of this study was to determine if patients with rheumatoid arthritis (RA) would be physically able to participate.

METHODS

A consecutive cohort of RA patients undergoing podiatry care underwent tests for sight, reach and grip strength to determine their physical ability to undertake self-managed foot care.

RESULTS

Thirty RA patients (10 male, 20 female), with a median age of 61 years (range 42 to 84) and disease duration of 10 years (range one to 40), were recruited. All patients passed the sight test, whereas the reach and grip tests were passed by 77% and 67% of patients, respectively. Only 57% of patients passed all the physical tests. Patients who failed the physical tests were older, and had longer disease duration and higher physical disability, pain and general health scores but these were not statistically different.

CONCLUSIONS

Just over half the patients in this present cohort may be physically able to undertake some aspects of self-managed foot care, including nail clipping and filing, callus filing and daily hygiene and inspection.

A survey of foot problems in juvenile idiopathic arthritis

BACKGROUND

Evidence suggests that foot problems are common in juvenile idiopathic arthritis (JIA), with prevalence estimates over 90%. The aim of this survey was to describe foot-related impairment and disability associated with JIA and foot-care provision in patients managed under modern treatment paradigms, including disease-modifying anti-rheumatic drugs (DMARDs) and biologic therapies.

METHODS

The Juvenile Arthritis Foot Disability Index (JAFI), Child Health Assessment Questionnaire (CHAQ), and pain visual analogue scale (VAS) were recorded in 30 consecutive established JIA patients attending routine outpatient clinics. Foot deformity score, active/limited joint counts, walking speed, double-support time (s) (DS) and step length symmetry index % (SI) were also measured. Foot-care provision in the preceding 12 months was determined from medical records.

RESULTS

Sixty-three per cent of children reported some foot impairment, with a median (range) JAFI subscale score of 1 (0-3); 53% reported foot-related activity limitation, with a JAFI subscale score of 1 (0-4); and 60% reported participation restriction, with a JAFI subscale score of 1 (0-3). Other reported variables were CHAQ 0.38 (0-2), VAS pain 22 (0-79), foot deformity 6 (0-20), active joints 0 (0-7), limited joints 0 (0-31), walking speed 1.09 m/s (0.84-1.38 m/s), DS 0.22 s (0.08-0.26 s) and SI +/-4.0% (+/-0.2-+/-31.0%). A total of 23/30 medical records were reviewed and 15/23 children had received DMARDS, 8/23 biologic agents and 20/23 multiple intra-articular corticosteroid injections. Ten children received specialist podiatry care comprising footwear advice, orthotic therapy and silicone digital splints together with intrinsic muscle strengthening exercises.

CONCLUSION

Despite frequent use of DMARD/biologic therapy and specialist podiatry-led foot care, foot-related impairment and disability persists in some children with JIA.

The optimal assessment of the rheumatoid arthritis hindfoot: a comparative study of clinical examination, ultrasound and high field MRI

OBJECTIVES

The aim of this pilot study was to compare clinical examination (CE) and ultrasound (US) with high field MRI (as the reference standard) for the detection of rearfoot and midtarsal joint synovitis and secondly tenosynovitis of the ankle tendons in patients with established rheumatoid arthritis (RA).

METHODS

Patients with RA (as determined by the modified American College of Rheumatology (ACR) criteria) with symptoms of midfoot and rearfoot disease were recruited. Demographic data were collected. All underwent CE, US and high field MRI (with intravenous gadolinium contrast) of their right foot. Percentage exact agreement (PEA), sensitivity and specificity were calculated for CE and US when compared to MRI. Inter-reader reliability for CE and US was also assessed.

RESULTS

Compared to the gold standard of MRI, for CE (joint synovitis) the ranges for sensitivity, specificity and PEA were 55-83%, 23-46% and 46-60%, and for US were 64-89%, 60-80% and 64-78%, respectively. Compared to the gold standard of MRI, for CE (tenosynovitis) the ranges for sensitivity, specificity and PEA were 0-100%, 20-91% and 55-91%, and for US were 0-67%, 86-100% and 59-86%, respectively.

CONCLUSION

CE was sensitive but US more specific in identifying hindfoot pathology in RA when compared to the reference standard of MRI. There was poor interobserver variability between ultrasonographers suggesting a need for standardisation of acquisition and interpretation of US images of the hindfoot.

Biomechanics of the foot in rheumatoid arthritis: identifying abnormal function and the factors associated with localised disease 'impact'

BACKGROUND

Rheumatoid arthritis is a chronic inflammatory joint disease which affects the joints and soft-tissues of the foot and ankle. The aim of this study was to evaluate biomechanical foot function and determine factors associated with localised disease burden in patients with this disease.

METHODS

Seventy-four rheumatoid arthritis patients (mean (standard deviation) age, 56 years (12); median (interquartile range) disease duration, 13 (5,19)) and 54 able-bodied adults (mean (standard deviation) age, 55 years (12)) completed the Leeds foot impact scale. Biomechanical foot function was measured using three-dimensional instrumented gait analysis. Disease activity score, the number of swollen and tender foot joints, and rearfoot and forefoot deformity were recorded. Sequential multiple linear regression was undertaken to identify independent predictors of foot disease burden.

FINDINGS

The median (interquartile range) Leeds foot impact scale scores in the impairment and activity/participation subscales were 13 (10,14) and 17 (12,22) for the rheumatoid arthritis and 1 (0,3) and 0 (0,1) for the able-bodied adults, P<0.0001 both subscales. The patients had significantly higher numbers of swollen (P<0.0001) and tender foot joints (P<0.0001) and greater rearfoot (P<0.0001) and forefoot (P<0.0001) deformity. Rheumatoid arthritis patients walked slower (P<0.0001) and had altered biomechanical foot function. Sequential regression analysis revealed that when the effects of global disease activity and disease duration were statistically controlled for, foot pain, the number of swollen foot joints and walking speed, and foot pain and walking speed were able to predict disease burden on the Leeds foot impact scale impairment (P<0.0005) and Leeds foot impact scale activity/participation (P<0.0005) subscales, respectively.

INTERPRETATION

In this cohort of rheumatoid arthritis patients, foot pain, swollen foot joint count and walking speed were identified as independent predictors of impairment and activity limitation and participation restriction. The foot disease burden model comprises important elements of pain, inflammatory and functional (biomechanical) factors.

The relationship between passive range of motion and range of motion during gait and plantar pressure measurements

AIMS

To investigate the relationship between limited joint mobility (LJM; measured both passively and during gait) and plantar pressure measurements.

METHODS

A cross-sectional study involving 28 diabetic patients with peripheral neuropathy but no plantar ulceration (DN), 25 diabetic patients with ulceration (DU), 25 diabetic control patients with no ulceration or peripheral neuropathy (DC), and 25 non-diabetic reference subjects (NDR). Movements of the ankle joint complex (AJC) and 1st metatarsophalangeal (MTP) joint were recorded, together with plantar pressures.

RESULTS

The passive range of motion at the AJC was significantly reduced in all the diabetes groups, but the gait range of motion was comparable with non-diabetic subjects. At the AJC, no correlation was found between the passive and gait range of motion (ROM) and these were not correlated with plantar pressure variables. At the 1st MTP, a correlation was found between the passive and gait dorsiflexion ROM and a significant correlation existed between gait dorsiflexion ROM at the 1st MTP joint and peak forefoot pressures in the DU group.

CONCLUSIONS

Despite a significant reduction in the passive ROM at the AJC in the diabetic groups, the gait ROM was indistinguishable from reference subjects and was not correlated with plantar pressure variables. At the 1st MTP joint, a correlation was found between the passive and gait ROM and furthermore the gait ROM was correlated with peak forefoot pressures, suggesting ROM measures at the 1st MTP joint may be preferable to ROM measures at the AJC.

Debridement of plantar callosities in rheumatoid arthritis: a randomized controlled trial

OBJECTIVE

To compare forefoot pain, pressure and function before and after normal and sham callus treatment in rheumatoid arthritis (RA).

PATIENTS AND METHODS

Thirty-eight RA patients were randomly assigned to normal (NCT group) or sham (SCT) scalpel debridement. The sham procedure comprised blunt-edged scalpel paring of the callus which delivered a physical stimulus but left the hyperkeratotic tissue intact, the procedure being partially obscured from the patient. Forefoot pain was assessed using a 100 mm visual analogue scale (VAS), pressure using a high-resolution foot pressure scanner and function using the spatial-temporal gait parameters measured on an instrumented walkway. Radiographic scores of joint erosion were obtained for metatarsophalangeal (MTP) joints with and without overlying callosities. The trial consisted of a randomized sham-controlled phase evaluating the immediate same-day treatment effect and an unblinded 4-week follow-up phase.

RESULTS

During the sham-controlled phase, forefoot pain improved in both groups by only 3 points on a VAS and no statistically significant between-group difference was found (P = 0.48). When data were pooled during the unblinded phase, the improvement in forefoot pain reached a peak after 2 days and gradually lessened over the next 28 days. Following debridement, peak pressures at the callus sites decreased in the NCT group and increased in the SCT group, but there was no statistically significant between-group difference (P = 0.16). The area of and duration of contact of the callus site on the ground remained unchanged following treatment in both groups. Following debridement, walking speed was increased, the stride-length was longer and the double-support time shorter in both groups; however, between-group differences did not reach levels of statistical significance. MTP joints with overlying callus were significantly more eroded than those without (P = 0.02).

CONCLUSIONS

Treatment of painful plantar callosities in RA using scalpel debridement lessened forefoot pain but the effect was no greater than sham treatment. Localized pressure or gait function was not significantly improved following treatment.

Three-dimensional kinematics at the ankle joint complex in rheumatoid arthritis patients with painful valgus deformity of the rearfoot

OBJECTIVE

To evaluate the three-dimensional (3D) kinematics of the ankle joint complex (AJC) in rheumatoid arthritis (RA) patients with painful valgus deformity of the rearfoot.

METHODS

Fifty patients with RA underwent gait analysis using electromagnetic tracking techniques to measure 3D kinematics at the AJC under barefoot and shod walking conditions. Three axial rotations (dorsiflexion/plantarflexion, inversion/eversion and internal/external rotation) were measured during the gait cycle, and the angular positions at key gait events, range of motion and the motion: time integral were measured. Descriptive and analytical comparisons were made with normative data derived from a sex- and age-matched population (n=45).

RESULTS

AJC dysfunction in RA was characterized by excessive eversion motion (within an eversion range) and no inversion motion through the neutral joint position for the subtalar component of the joint complex, in both barefoot and shod walking conditions. Motion was coupled such that internal rotation of the leg relative to the rearfoot was greater than normal. AJC motion was different for all rotations between barefoot and shod conditions, but in both situations there were statistically significant between-group differences in the motion:time integral for inversion/eversion (barefoot, P<0.0001; shod, P<0.0001) and external/internal rotation (barefoot, P<0.0001; shod, P<0.0001). There were no statistically significant differences between RA and normative data for dorsiflexion/plantarflexion motion under barefoot (P=0.16) and shod (P=0.50) walking conditions.

CONCLUSION

Painful valgus deformity of the rearfoot is associated with changes in the 3D kinematics affecting eversion at the AJC and internal rotation of the leg, both when walking barefoot and in shoes.

Preliminary investigation of debridement of plantar callosities in rheumatoid arthritis

OBJECTIVE

To determine the effect of expert debridement of foot callosities on forefoot pain and plantar pressure distribution in rheumatoid arthritis (RA).

METHODS

Plantar callosities on 14 feet of eight RA patients were debrided by a single podiatrist. Measurements of subjective pain severity in the forefoot and global arthritis pain were undertaken using a visual analogue scale, repeated at 7-day intervals to the next treatment (28 days). Plantar pressures were recorded at the lesion sites using an in-shoe flexible transducer insole before and after lesion debridement.

RESULTS

Following debridement, all patients reported symptomatic relief with an average change in pain score of 48% (P = 0.01) but the treatment effect was lost by 7 days. Immediately following scalpel debridement, peak pressures were elevated in 10 of 14 feet, whilst contact time was reduced and peak force increased. None, however, reached statistical significance.

CONCLUSION

Scalpel debridement of forefoot plantar callosities reduces forefoot pain for about 7 days, but pressure distribution is not significantly altered.

A preliminary study determining the feasibility of electromagnetic tracking for kinematics at the ankle joint complex

OBJECTIVE

To determine the feasibility of using electromagnetic tracking (EMT) for quantifying three-dimensional kinematics at the ankle joint complex (AJC).

METHODS

AJC kinematics were recorded in 10 normal healthy adults, and 10 rheumatoid arthritis patients presenting with AJC instability and deformity who were undergoing footwear and orthotic intervention.

RESULTS

Kinematics in normal subjects had strong face validity, curve shape showing moderate (n=9), good (n=8) or excellent (n=4) agreement with data from seven published studies. The range of motion about the x-axis (15.2 degrees ) was similar to reference values (17.0 degrees ), but our technique underestimated rotations about the y- (8.1 degrees vs 14.0 degrees ) and z-axes (7.7 degrees vs 12.2 degrees ). In the rheumatoid arthritis pronated foot group, eversion and internal rotation during the stance phase of gait were between 2 and 5 times greater than for normal subjects. The use of a corrective foot orthosis in this group restored normal kinematics, reducing maximum eversion and internal rotation by 57 and 68%, respectively.

CONCLUSION

A new technique for measuring kinematics at the AJC is described. Based upon the findings of this pilot study, EMT may be useful for diagnosing AJC dysfunction and quantifying the mechanical efficacy of footwear and orthosis interventions.

Observations on the F-Scan in-shoe pressure measuring system

BACKGROUND:: F-Scan (Tekscan Inc.) is a commercial in-shoe force/pressure measurement system. The system has been used in a number of useful clinical studies focused mainly on the evaluation of various therapeutic measures including footwear and in-shoe orthoses. More recently, the accuracy and reliability of the system has come under closer scrutiny, highlighting the need for further debate supported by experimental studies. We have critically evaluated the performance of the F-Scan sensor and report here on bench test findings examining calibration error, hysteresis and creep, and the accuracy and repeatability of output force measurements. METHOD:: The F-Scan system was used to measure output mass following calibration using the standard protocol across a range of subject determined input masses. A small jig-mounted force meter was used to test groups of individual sensing units (4 @ cm(2)) for within and between sensor accuracy in full size and adjusted sensors. An Instron servohydraulic materials testing unit was used to evaluate creep, hysteresis and the repeatability of output forces over repeated loading cycles for full size and cut sensors. RESULTS:: Average calibration error: 4% Creep: 19% Hysteresis: 21% [Table: see text] CONCLUSION:: 1. The F-Scan calibration protocol is inaccurate. 2. Significant within and between sensor variability in output forces can be expected. 3. The creep and hysteresis properties of the sensor are poor. 4. The F-Scan sensor does not yield repeatable measurements. 5. When the sensor is adjusted to a smaller size output is adversely affected. The F-Scan system has a limited capability for absolute accuracy but may be used for quantitative studies provided its limitations are noted.

Relation between heel position and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis

OBJECTIVE

To investigate the relation between the position of the rearfoot and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis.

METHOD

Plantar pressures and callosity patterns were measured in 102 rheumatoid arthritis patients (120 feet with normal heel alignment and 84 feet with valgus heel alignment measured by goniometry) and in 42 (84 feet) age matched healthy adults. Peak pressures (kPa) were measured across the metatarsal heads in-shoe using an FScan system and the distribution of plantar callosities was visually mapped for each foot.

RESULTS

Peak pressures were significantly greater at all but the first metatarsal head in the rheumatoid normal heel alignment and healthy adult groups than in the rheumatoid valgus heel group. The feet of both the rheumatoid normal heel group and the healthy adult group behaved the same, the highest peak pressures registering on the central metatarsal heads. However, only in the rheumatoid group were plantar callosities found at these sites. In the rheumatoid valgus heel group, lateral metatarsal heads were frequently non-weightbearing, producing gross loading patterns with a dominant medial distribution. Peak pressures were shifted to the medial fore-foot accompanied by a higher prevalence of callosities. The results, however, failed to establish clearly an association between peak pressures and callus formation.

CONCLUSIONS

In rheumatoid arthritis there is an important interrelation between the rearfoot position and forefoot pressure sites.

Observations on the F-Scan in-shoe pressure measuring system

OBJECTIVE: To evaluate the physical characteristics (durability, calibration, creep and hysteresis) and the accuracy and repeatability of the F-Scan in-shoe sensor. DESIGN: Observations of the system in clinical use combined with material bench-test experiments. BACKGROUND: The F-Scan system is a commercially produced in-shoe force/pressure measurement system. Whilst useful clinical studies have been reported there is little information on the performance characteristics of the system. METHODS: Output mass error following calibration was directly measured from the F-Scan system. A jig-mounted force meter tested groups of individual sensing units (4 @ 1 cm(-2)) for within and between sensor accuracy in full size and adjusted sensors. An Instron servohydraulic materials testing unit was used to evaluate creep, hysteresis and the repeatability of output forces over repeated loading cycles for full size and cut sensors. RESULTS: The F-Scan system lacks durability and suffers significant calibration error. Creep (19%) and hysteresis (21%) properties were poor. Within and between sensor variability in output was demonstrated and overall repeatability was poor. Adjusting the sensor size adversely affects output. CONCLUSIONS: Our findings suggest the F-Scan system has a limited capability for absolute accuracy but could still be used for quantitative studies provided its limitations are noted. RELEVANCE: These findings may help F-Scan users evaluate the relevance of clinical data and refine measurement protocols in the context of their own field of work.

ABC of rheumatology. Pain in the foot

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Effect of some triphenylethylenes on oestradiol binding in vitro to macromolecules from uterus and anterior pituitary

The effects of a series of triphenylethylenes (I.C.I. 46,474, I.C.I. 47,699 and clomiphene isomers A and B) on oestradiol binding to receptors from rat, rabbit and mouse uteri and rat anterior pituitary were studied. Binding of oestradiol to receptors from uteri was inhibited competitively by I.C.I. 46,474. Receptors from uteri of the three species and from rat anterior pituitary have very similar affinities for oestradiol and the four triphenylethylenes. The order of activity of the triphenylethylenes as inhibitors of oestradiol binding is: clomiphene B > I.C.I. 46,474 > I.C.I. 47,699 > clomiphene A. Some correlations are made with the activity of the compounds in vivo.