In-shoe plantar pressures within ankle-foot orthoses: implications for the management of achilles tendon ruptures

Foot offloading associated with carbon fiber orthosis use: A pilot study

BACKGROUND

Traumatic lower limb injuries can result in chronic pain. Orthotic interventions are a leading conservative approach to reduce pain, manage loading, and protect the foot. Robust carbon fiber custom dynamic orthoses (CDOs) designed for military service members have been shown to reduce foot loading. However, the effect of carbon fiber orthosis design, including designs widely used in the civilian sector, on foot loading is unknown.

RESEARCH QUESTION

Determine if carbon fiber orthoses alter foot loading during gait.

METHODS

Loadsol insoles were used to measure peak forces and force impulse acting on the forefoot, midfoot, hindfoot, and total foot. Nine healthy, able-bodied individuals participated. Force impulse was quantified as cumulative loading throughout stance phase. Participants walked without an orthosis and with three carbon fiber orthoses of differing designs: a Firm stiffness CDO, a Moderate stiffness CDO, and a medial and lateral strut orthosis (MLSO).

RESULTS

There were significant main effects of orthosis condition on peak forefoot forces as well as forefoot and hindfoot force impulse. Peak forefoot forces were significantly lower in the Moderate and Firm CDOs compared to no orthosis and MLSO. Compared to walking without an orthosis, forefoot force impulse was significantly lower and hindfoot force impulse was significantly greater in all carbon fiber orthoses. Additionally, hindfoot force impulse in the Firm CDO was significantly higher than in the MLSO and Moderate CDO.

SIGNIFICANCE

The three carbon fiber orthosis designs differed regarding foot loading, with more robust orthoses providing greater forefoot offloading. Orthosis-related changes in forefoot loading suggest that carbon fiber orthoses could reduce loading-associated pain during gait. However, increased hindfoot force impulse suggests caution should be used when considering carbon fiber orthoses for individuals at risk of skin breakdown with repetitive loading.

Testing protocols and measurement techniques when using pressure sensors for sport and health applications: A comparative review

Plantar pressure measurement systems are routinely used in sports and health applications to assess locomotion. The purpose of this review is to describe and critically discuss: (a) applications of the pressure measurement systems in sport and healthcare, (b) testing protocols and considerations for clinical gait analysis, (c) clinical recommendations for interpreting plantar pressure data, (d) calibration procedures and their accuracy, and (e) the future of pressure sensor data analysis. Rigid pressure platforms are typically used to measure plantar pressures for the assessment of foot function during standing and walking, particularly when barefoot, and are the most accurate for measuring plantar pressures. For reliable data, two step protocol prior to contacting the pressure plate is recommended. In-shoe systems are most suitable for measuring plantar pressures in the field during daily living or dynamic sporting movements as they are often wireless and can measure multiple steps. They are the most suitable equipment to assess the effects of footwear and orthotics on plantar pressures. However, they typically have lower spatial resolution and sampling frequency than platform systems. Users of pressure measurement systems need to consider the suitability of the calibration procedures for their chosen application when selecting and using a pressure measurement system. For some applications, a bespoke calibration procedure is required to improve validity and reliability of the pressure measurement system. The testing machines that are commonly used for dynamic calibration of pressure measurement systems frequently have loading rates of less than even those found in walking, so the development of testing protocols that truly measure the loading rates found in many sporting movements are required. There is clear potential for AI techniques to assist in the analysis and interpretation of plantar pressure data to enable the more complete use of pressure system data in clinical diagnoses and monitoring.

Effects of releasing ankle joint during electrically evoked cycling in persons with motor complete spinal cord injury

Literature has shown that simulated power production during conventional functional electrical stimulation (FES) cycling was improved by 14% by releasing the ankle joint from a fixed ankle setup and with the stimulation of the tibialis anterior and triceps surae. This study aims to investigate the effect of releasing the ankle joint on the pedal power production during FES cycling in persons with spinal cord injury (SCI). Seven persons with motor complete SCI participated in this study. All participants performed 1 min of fixed-ankle and 1 min of free-ankle FES cycling with two stimulation modes. In mode 1 participants performed FES-evoked cycling with the stimulation of quadriceps and hamstring muscles only (QH stimulation), while Mode 2 had stimulation of quadriceps, hamstring, tibialis anterior, and triceps surae muscles (QHT stimulation). The order of each trial was randomized in each participant. Free-ankle FES cycling offered greater ankle plantar- and dorsiflexion movement at specific slices of 20° crank angle intervals compared to fixed-ankle. There were significant differences in the mean and peak normalized pedal power outputs (POs) [F(1,500) = 14.03, p < 0.01 and F(1,500) = 7.111, p = 0.008, respectively] between fixed- and free-ankle QH stimulation, and fixed- and free-ankle QHT stimulation. Fixed-ankle QHT stimulation elevated the peak normalized pedal PO by 14.5% more than free-ankle QH stimulation. Releasing the ankle joint while providing no stimulation to the triceps surae and tibialis anterior reduces power output. The findings of this study suggest that QHT stimulation is necessary during free-ankle FES cycling to maintain power production as fixed-ankle.

Commercially available pressure sensors for sport and health applications: A comparative review

Pressure measurement systems have numerous applications in healthcare and sport. The purpose of this review is to: (a) describe the brief history of the development of pressure sensors for clinical and sport applications, (b) discuss the design requirements for pressure measurement systems for different applications, (c) critique the suitability, reliability, and validity of commercial pressure measurement systems, and (d) suggest future directions for the development of pressure measurements systems in this area. Commercial pressure measurement systems generally use capacitive or resistive sensors, and typically capacitive sensors have been reported to be more valid and reliable than resistive sensors for prolonged use. It is important to acknowledge, however, that the selection of sensors is contingent upon the specific application requirements. Recent improvements in sensor and wireless technology and computational power have resulted in systems that have higher sensor density and sampling frequency with improved usability - thinner, lighter platforms, some of which are wireless, and reduced the obtrusiveness of in-shoe systems due to wireless data transmission and smaller data-logger and control units. Future developments of pressure sensors should focus on the design of systems that can measure or accurately predict shear stresses in conjunction with pressure, as it is thought the combination of both contributes to the development of pressure ulcers and diabetic plantar ulcers. The focus for the development of in-shoe pressure measurement systems is to minimise any potential interference to the patient or athlete, and to reduce power consumption of the wireless systems to improve the battery life, so these systems can be used to monitor daily activity. A potential solution to reduce the obtrusiveness of in-shoe systems include thin flexible pressure sensors which can be incorporated into socks. Although some experimental systems are available further work is needed to improve their validity and reliability.

The reliability, reproducibility and utilization of the radiographic Achilles Tendon Loading Angle in the management of Achilles Tendon rupture

BACKGROUND

During management of Achilles tendon rupture, determination of tendon-end approximation, either clinically or by ultrasound is difficult, following brace application of during loading. The Radiographic Achilles Tendon Loading Angle (RadATLA) is proposed as a method of measuring ankle position whilst loading in a brace during the management of Achilles tendon rupture. This study aims to determine the reliability and reproducibility of the RadATLA.

METHODS

A loaded true lateral ankle radiograph including the fifth metatarsal head was taken when wearing a brace at the 6-week time point in 18 patients (19 ankles). following Achilles tendon repair or reconstruction. The RadATLA was compared with the Tibio-talar angle, other radiographic and clinical measures used to quantify foot and ankle position during the first 6 weeks of early rehabilitation in a resting position and during loading.

RESULTS

The intra-rater reliability of both angles was found to be good (>0.8). The RadATLA was found to have an excellent intra-rater reliability with Intra-class correlation of (ICC) 0.992-0.996 (95%CI 0.889-0.999), standard error of the measurement (SEM) 1.03-3.65 and Minimal Detectable Change (MDC) 2.86-10.12. The inter-rater reliability was good with ICC of 0.798-0.969 (95%CI-0.03 to 0.964), SEM 2.9-7.6, and MDC 8.1-20.9. The RadATLA loaded at 6 weeks in all patients was at mean (SD) (range) 41.9˚ (16.5), (18.5-75.9). There was a significant difference between the patients in the Repair group compared with patients in the Reconstruction group both in RadATLA loaded at 6 weeks: 35.6˚ (11.2), (18.5-56.5) versus 55.5˚ (19), (20-75.9), (p = 0.01). The amount loaded in all patients was at mean (SD) (range) 29.2Kg (17.7), (2-56) and the percentage Body Weight was 30.7% (19), (2.1-63.2). There were no differences between the groups neither in amount loaded nor in percentage Body weight (p = 0.614-0.651).

CONCLUSIONS

The RadATLA is a reliable and reproducible angle and can be used to determine the position of the ankle, when loaded in a brace during rehabilitation following Achilles tendon rupture.

Plaster cast versus functional bracing for Achilles tendon rupture: the UKSTAR RCT

BACKGROUND

Achilles tendon rupture affects > 11,000 people each year in the UK, leading to prolonged periods away from work, sports and social activities. Traditionally, the ruptured tendon is held still in a plaster cast for ≥ 8 weeks. Functional bracing is an alternative treatment that allows patients to mobilise earlier, but there is little evidence about how bracing affects patients' recovery.

OBJECTIVES

To measure the Achilles Tendon Rupture Score, quality of life, complications and resource use of patients receiving non-operative treatment for an Achilles tendon rupture treated with plaster cast compared with those treated with functional bracing.

DESIGN

This was a multicentre, randomised, pragmatic, two-group superiority trial.

SETTING

The setting was 39 NHS hospitals.

PARTICIPANTS

A total of 540 adult patients treated non-operatively for Achilles tendon rupture were randomised from July 2016 to May 2018. Exclusion criteria included presenting after 14 days, having had previous rupture and being unable to complete questionnaires.

INTERVENTIONS

A total of 266 participants had a plaster cast applied, with their toes initially pointing to the floor. The cast was changed over 8 weeks to bring the foot into a walking position. A total of 274 patients had a functional brace that facilitated immediate weight-bearing. The foot position was adjusted within the brace over the same 8-week period.

MAIN OUTCOME MEASURES

Achilles Tendon Rupture Score is patient reported and assesses symptoms and physical activity related to the Achilles tendon (score 0-100, with 100 being the best possible outcome). The secondary outcomes were quality of life, complications and resource use at 8 weeks and at 3, 6 and 9 months.

RESULTS

Participants had a mean age of 48.7 years, were predominantly male (79%) and had ruptured their tendon during sports (70%). Over 93% of participants completed follow-up. There was no statistically significant difference in Achilles Tendon Rupture Score at 9 months post injury (-1.38, 95% confidence interval -4.9 to 2.1). There was a statistically significant difference in Achilles Tendon Rupture Score at 8 weeks post injury in favour of the functional brace group (5.53, 95% confidence interval 2.0 to 9.1), but not at 3 or 6 months post injury. Quality of life showed the same pattern, with a statistically significant difference at 8 weeks post injury but not at later time points. Complication profiles were similar in both groups. Re-rupture of the tendon occurred 17 times in the plaster cast group and 13 times in the functional brace group. There was no difference in resource use.

CONCLUSIONS

This trial provides strong evidence that early weight-bearing in a functional brace provides similar outcomes to traditional plaster casting and is safe for patients receiving non-operative treatment of Achilles tendon rupture. The probability that functional bracing is cost-effective exceeds 95% for the base-case imputed analysis, assuming a cost-effectiveness threshold of £20,000 per quality-adjusted life-year. On average, functional brace is associated with lower costs (-£103, 95% confidence interval -£290 to £84) and more quality-adjusted life-years (0.015, 95% confidence interval -0.0013 to 0.030) than plaster cast.

LIMITATIONS

Some patients declined to participate in the trial, but only a small proportion of these declined because they had a preference for one treatment or another. Overall, 58% of eligible patients agreed to participate, so the participants are broadly representative of the population under investigation.

FUTURE WORK

Although the UK Study of Tendo Achilles Rehabilitation provides guidance with regard to early management, rehabilitation following Achilles tendon rupture is prolonged and further research is required to define the optimal mode of rehabilitation after the initial cast/brace has been removed.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN62639639.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 8. See the NIHR Journals Library website for further project information.

The Effect of Ankle Foot Orthosis' Design and Degree of Dorsiflexion on Achilles Tendon Biomechanics—Tendon Displacement, Lower Leg Muscle Activation, and Plantar Pressure During Walking

Background: Following an Achilles tendon rupture, ankle foot orthoses (AFO) of different designs are used to protect the healing tendon. They are generally designed to protect against re-rupture by preventing undesired dorsiflexion and to prevent elongation by achieving plantarflexion in the ankle. There is limited knowledge of the biomechanical effects of different AFO designs and ankle angles on the tendon and lower leg muscles.

Hypothesis: The hypothesis was that non-uniform displacement in the Achilles tendon, lower leg muscle activity, and plantar pressure distribution would be affected differently in different designs of AFO and by varying the degree of dorsiflexion limitation.

Study Design: Controlled laboratory study.

Methods: Ultrasound of the Achilles tendon, EMG of the lower leg muscles and plantar pressure distribution were recorded in 16 healthy subjects during walking on a treadmill unbraced and wearing three designs of AFO. Ultrasound speckle tracking was used to estimate motion within the tendon. The tested AFO designs were a rigid AFO and a dorsal brace used together with wedges and an AFO with an adjustable ankle angle restricting dorsiflexion to various degrees.

Results: There were no significant differences in non-uniform tendon displacement or muscle activity between the different designs of AFO. For the rigid AFO and the adjustable AFO there was a significant reduction in non-uniform displacement within the tendon and soleus muscle activity as restriction in dorsiflexion increased.

Conclusion: The degree of dorsiflexion allowed within an AFO had greater effects on Achilles tendon displacement patterns and muscle activity in the calf than differences in AFO design. AFO settings that allowed ankle dorsiflexion to neutral resulted in displacement patterns in the Achilles tendon and muscle activity in the lower leg which were close to those observed during unbraced walking.

Plaster cast versus functional brace for non-surgical treatment of Achilles tendon rupture (UKSTAR): a multicentre randomised controlled trial and economic evaluation

BACKGROUND

Patients with Achilles tendon rupture who have non-operative treatment have traditionally been treated with immobilisation of the tendon in plaster casts for several weeks. Functional bracing is an alternative non-operative treatment that allows earlier mobilisation, but evidence on its effectiveness and safety is scarce. The aim of the UKSTAR trial was to compare functional and quality-of-life outcomes and resource use in patients treated non-operatively with plaster cast versus functional brace.

METHODS

UKSTAR was a pragmatic, superiority, multicentre, randomised controlled trial done at 39 hospitals in the UK. Patients (aged ≥16 years) who were being treated non-operatively for a primary Achilles tendon rupture at the participating centres were potentially eligible. The exclusion criteria were presenting more than 14 days after injury, previous rupture of the same Achilles tendon, or being unable to complete the questionnaires. Eligible participants were randomly assigned (1:1) to receive a plaster cast or functional brace using a centralised web-based system. Because the interventions were clearly visible, neither patients nor clinicians could be masked. Participants wore the intervention for 8 weeks. The primary outcome was patient-reported Achilles tendon rupture score (ATRS) at 9 months, analysed in the modified intention-to-treat population (all patients in the groups to which they were allocated, excluding participants who withdrew or died before providing any outcome data). The main safety outcome was the incidence of tendon re-rupture. Resource use was recorded from a health and personal social care perspective. The trial is registered with ISRCTN, ISRCTN62639639.

FINDINGS

Between Aug 15, 2016, and May 31, 2018, 1451 patients were screened, of whom 540 participants (mean age 48·7 years, 79% male) were randomly allocated to receive plaster cast (n=266) or functional brace (n=274). 527 (98%) of 540 were included in the modified intention-to-treat population, and 13 (2%) were excluded because they withdrew or died before providing any outcome data. There was no difference in ATRS at 9 months post injury (cast group n=244, mean ATRS 74∙4 [SD 19∙8]; functional brace group n=259, ATRS 72∙8 [20∙4]; adjusted mean difference -1∙38 [95% CI -4∙9 to 2∙1], p=0·44). There was no difference in the rate of re-rupture of the tendon (17 [6%] of 266 in the plaster cast group vs 13 [5%] of 274 in the functional brace group, p=0·40). The mean total health and personal social care cost was £1181 for the plaster cast group and £1078 for the functional bract group (mean between-group difference -£103 [95% CI -289 to 84]).

INTERPRETATION

Traditional plaster casting was not found to be superior to early weight-bearing in a functional brace, as measured by ATRS, in the management of patients treated non-surgically for Achilles tendon rupture. Clinicians may consider the use of early weight-bearing in a functional brace as a safe and cost-effective alternative to plaster casting.

FUNDING

UK National Institute for Health Research Health Technology Assessment Programme.

Tendon morphology and mechanical properties assessed by ultrasound show change early in recovery and potential prognostic ability for 6-month outcomes

PURPOSE

Optimizing tendon structural recovery during the first 12 weeks after Achilles tendon rupture is a prime target to improve patient outcomes, but a comprehensive understanding of biomarkers is needed to track early healing. The purpose of this study was to observe healing of tendon structure over time using ultrasound-based, tendon-specific measures and to identify relationships between tendon structural characteristics and clinical measures of gait and strength.

METHODS

Twenty-seven participants (21 males, mean (SD) age 39 (11) years) were assessed at 4, 8, 12, and 24 weeks after injury or surgery using ultrasound imaging techniques. Gait analysis and strength testing were added at the later time points.

RESULTS

Ruptured tendons had significantly lower dynamic shear modulus (p < 0.001), greater tendon cross-sectional area (p < 0.001), and greater length (p < 0.001) than the uninjured side. Dynamic shear modulus, cross-sectional area, and length were found to increase over time (p < 0.01). Tendon structure at 4 weeks post-injury [cross-sectional area symmetry (r = 0.737, p = 0.002) and dynamic shear modulus (r = 0.518, p = 0.040)] related to stance phase walking symmetry at 24 weeks.

CONCLUSIONS

Tendon structure assessed by ultrasound imaging changes over the first 24 weeks of healing after Achilles tendon rupture, suggesting it could be used as a biomarker to track tendon healing early in recovery. Additionally, tendon structure within the first 12 weeks relates to later walking gait and heel-rise symmetry, which may indicate that tendon structure could have prognostic value in the care of these patients. This study's clinical relevance is in its support for using ultrasound imaging to assess early patient healing and prognosticate later patient outcomes after Achilles tendon rupture.

LEVEL OF EVIDENCE

Level 2, prospective cohort prognostic study.

Cast versus functional brace in the rehabilitation of patients treated non-operatively for a rupture of the Achilles tendon: protocol for the UK study of tendo achilles rehabilitation (UK STAR) multi-centre randomised trial

INTRODUCTION

Achilles tendon rupture affects over 11 000 people yearly in the UK, and the incidence is increasing. Controversy remains with regard to the best rehabilitation strategy for these patients. In operatively treated patients, functional bracing provides better outcomes compared with plaster casts. However, the role of functional bracing in non-operatively managed patients is unclear. This is the protocol for a multicentre randomised trial of plaster cast immobilisation versus functional bracing for patients with a non-operatively managed Achilles tendon rupture.

METHODS AND ANALYSIS

All adults presenting with a primary rupture of the Achilles tendon will be screened. Non-operatively treated patients will be eligible to take part in the trial. Broad eligibility criteria will ensure that the results of the study can be generalised to the wider patient population. Randomisation will be on a 1:1 basis. Both rehabilitation strategies are widely used within the National Health Service. Standardised protocols will be followed, and details of plaster material and brace will be as per the site's usual practice.A minimum of 330 patients will be randomised to obtain 90% power to detect a difference of 8 points in Achilles Tendon Total Rupture Score at 9 months. Quality of life and resource use will be collected at 3, 6 and 9 months. The differences between treatment groups will be assessed on an intention-to-treat basis. The results of the trial-based economic evaluation will be expressed in terms of incremental cost per quality-adjusted life-year gained.

ETHICS AND DISSEMINATION

The National Research Ethic Committee approved this study on 18 March 2016 (16/SC/0109).The National Institute for Health Research Health Technology Assessment monograph and a manuscript to a peer-reviewed journal will be submitted on completion of the trial (summer 2019). The results of this trial will substantially inform clinical practice on the clinical and cost-effectiveness of the treatment of this injury. This study has been registered on the International Standard Randomised Controlled Trial Number registry with reference no ISRCTN62639639.

Achilles tendon rupture rehabilitation: a mixed methods investigation of current practice among orthopaedic surgeons in the United Kingdom

OBJECTIVES

The evidence base to inform the management of Achilles tendon rupture is sparse. The objectives of this research were to establish what current practice is in the United Kingdom and explore clinicians' views on proposed further research in this area. This study was registered with the ISRCTN (ISRCTN68273773) as part of a larger programme of research.

METHODS

We report an online survey of current practice in the United Kingdom, approved by the British Orthopaedic Foot and Ankle Society and completed by 181 of its members. A total of ten of these respondents were invited for a subsequent one-to-one interview to explore clinician views on proposed further research in this area.

RESULTS

The survey showed wide variations in practice, with patients being managed in plaster cast alone (13%), plaster cast followed by orthoses management (68%), and orthoses alone (19%). Within these categories, further variation existed regarding the individual rehabilitation facets, such as the length of time worn, the foot position within them and weight-bearing status. The subsequent interviews reflected this clinical uncertainty and the pressing need for definitive research.

CONCLUSIONS

The gap in evidence in this area has resulted in practice in the United Kingdom becoming varied and based on individual opinion. Future high-quality randomised trials on this subject are supported by the clinical community. Cite this article: Bone Joint Res 2015;4:65-9.