Surface electromyographic activity of five residual limb muscles recorded during isometric contraction in transfemoral amputees with osseointegrated prostheses

Osseointegrated prostheses improve balance and balance confidence in individuals with unilateral transfemoral limb loss

BACKGROUND

More than half of patients with lower-limb amputation who use socket prostheses experience at least one fall annually. These falls are primarily attributed to reduced proprioception which negatively affects balance. A promising alternative to socket prostheses are osseointegrated prostheses that involve direct fixation of the prosthetic limb to the residual limb through a bone-anchored implant, yet its effect on balance remains unknown.

RESEARCH QUESTION

Do osseointegrated prostheses change static and dynamic balance, as well as patient reported measures of balance confidence, compared to a socket prosthesis?

METHODS

A sample of 10 patients with unilateral transfemoral amputation scheduled to undergo prosthesis osseointegration were enrolled (6 F/4 M, BMI: 26.7 ± 2.9 kg/m2, Age: 46.1 ± 6.3 years). Motion capture data during quiet standing (eyes opened and eyes closed) and overground walking at a self-selected speed, and the Activities-Specific Balance Confidence (ABC) scale, were collected before (with socket prosthesis) and 12-months following osseointegration. Postural sway via the center of pressure (COP), variability of spatiotemporal parameters, and ABC scores were compared using a repeated measures design before and after osseointegration.

RESULTS

Following prosthesis osseointegration, COP path length and 95 % confidence ellipse area were reduced during quiet standing (d = 0.75, P = 0.09; d = 0.52, P = 0.29, respectively) and the variability of step width and length were reduced during overground walking (d = 0.50, P = 0.06; d = 0.72, P = 0.06, respectively). Furthermore, patients reported significantly improved ABC scores with an osseointegrated prosthesis compared to a socket prosthesis (d = -1.36, P = 0.01).

SIGNIFICANCE

Improvements in postural sway, reductions in gait variability, and greater balance confidence indicate that osseointegrated prostheses improve balance for people with unilateral transfemoral amputation.

Neuromuscular adaptations after osseointegration of a bone-anchored prosthesis in a unilateral transfemoral amputee - a case study

PURPOSE

Many individuals with a lower limb amputation experience problems with the fitting of the socket of their prosthesis, leading to dissatisfaction or device rejection. Osseointegration (OI)- the implantation of a shaft directly interfacing with the remaining bone- is an alternative for these patients. In this observational study, we investigated how bone anchoring influences neuromuscular parameters during balance control in a patient with a unilateral transfemoral amputation.

MATERIAL AND METHODS

Center of pressure (CoP) and electromyography (EMG) signals from muscles controlling the hip and the ankle of the intact leg were recorded during quiet standing six months before and one and a half years after this patient underwent an OI surgery. Results were compared to a control group of nine able-bodied individuals.

RESULTS

Muscle co-activation and EMG intensity decreased after bone anchoring, approaching the levels of able-bodied individuals. Muscle co-activation controlling the ankle decreased in the high-frequency range, and the EMG intensity spectrum decreased in the lower-frequency range for all muscles when vision was allowed. With eyes closed, the ankle extensor muscle showed an increased EMG intensity in the high-frequency range post-surgery. CoP length increased in the mediolateral direction of the amputated leg.

CONCLUSIONS

These findings point to shifts in the patient's neuromuscular profile towards the one of able-bodied individuals.

Load applied on osseointegrated implant by transfemoral bone-anchored prostheses fitted with state-of-the-art prosthetic components

BACKGROUND

This study presented the load profile applied on transfemoral osseointegrated implants by bone-anchored prostheses fitted with state-of-the-art ÖSSUR microprocessor-controlled Rheo Knee XC and energy-storing-and-returning Pro-Flex XC or LP feet during five standardized daily activities.

METHODS

This cross-sectional cohort study included 13 participants fitted with a press-fit transfemoral osseointegrated implant. Loading data were directly measured with the tri-axial transducer of an iPecsLab (RTC Electronics, USA) fitted between the implant and knee unit. The loading profile was characterized by spatio-temporal gaits variables, magnitude of loading boundaries as well as onset and magnitude of loading extrema during walking, ascending and descending ramp and stairs.

FINDINGS

A total of 2127 steps was analysed. The cadence ranged between 36 ± 7 and 47 ± 6 strides/min. The absolute maximum force and moments applied across all activities was 1322 N, 388 N and 133 N as well as 22 Nm, 52 Nm and 88 Nm on and around the long, anteroposterior and mediolateral axes of the implant, respectively.

INTERPRETATION

This study provided new benchmark loading data applied by transfemoral bone-anchored prostheses fitted with selected ÖSSUR state-of-the-art components. Outcomes suggested that such prostheses can generate relevant loads at the interface with the osseointegrated implant to restore ambulation effectively. This study is a worthwhile contribution toward a systematic recording, analysis, and reporting of ecological prosthetic loading profiles as well as closing the evidence gaps between prescription and biomechanical benefits of state-of-the-art components. Hopefully, this will contribute to improve outcomes for growing number of individuals with limb loss opting for bionic solutions.

Inter-Day Reliability and Changes of Surface Electromyography on Two Postural Muscles Throughout 12 Weeks of Hippotherapy on Patients with Cerebral Palsy: A Pilot Study

Cerebral palsy (CP) is an umbrella term covering a group of permanent developmental disorders of movement and posture characterized by highly variable clinical features. The aim of this study was to assess the short-term and mid-term effects of neurorehabilitation via hippotherapy on the contractile properties of two key postural muscles during functional sitting in such patients. Thirty-minute hippotherapy sessions were conducted biweekly for 12 weeks in 18 patients (18.1 ± 5.7 years old). Surface electromyography (EMG) was implemented bilaterally in rectus abdominis and adductor magnus. We quantitatively analyzed the amplitude of EMG signals in the time domain and its spectral characteristics in the frequency domain. EMGs were recorded at the beginning and end of each session on day one and at week six and week twelve. Statistical analysis revealed a substantial inter-day reliability of the EMG signals for both muscles, validating the methodological approach. To a lesser extent, while beyond the scope of the current study, quantitative changes suggested a more selective recruitment/contractile properties’ shift of the examined muscles. Exploring postural control during functional activities would contribute to understanding the relationship between structural impairment, activity performance and patient capabilities, allowing the design of neurorehabilitation programs aimed at improving postural and functional skills according to each individual’s needs. The present study provides basic quantitative data supporting the body of scientific evidence making hippotherapy an approach of choice for CP neurorehabilitation.

A Comparative Analysis of Standardised Threads for Use in Implants for Direct Skeletal Attachment of Limb Prosthesis: A Finite Element Analysis

The aim of the research was to determine the optimal thread's shape to be used in implants for direct skeletal attachment of limb prosthesis. In addition, by testing appropriate parameters' modification of the suitable thread, an attempt was made to maximise its effectiveness. The analyses included three thread types described in the ISO standards: shallow, symmetrical, and asymmetrical. The obtained results suggest that shallow thread ensures the lowest equivalent and directional stress peaks generated in the bone as well as favourable stress patterns and profiles during implant loading in relation to symmetrical and asymmetrical threads. Moreover, shallow thread ensured the generation of single equivalent and directional stress peaks, while symmetrical and asymmetrical threads provided additional stress peak for equivalent as well as for each of directional peaks. Subsequently, optimisation of the shallow thread's shape was conducted by changing two relevant thread's parameters (flank angle and rounding arc) which influence the generated stress distribution. The highest reduction of stress peaks was obtained while reducing the rounding arc by 0.2 mm. Therefore, it can be stated that the proposed modification of the HA thread can lead to obtaining a higher biomechanical effectiveness of implants for direct skeletal attachment of limb prosthesis.

Clinically Relevant Outcome Measures Following Limb Osseointegration; Systematic Review of the Literature

OBJECTIVES

The current standard of care for an amputee is a socket-based prostheses. An osseointegrated implant (OI) is an alternative for prosthetic attachment. Osseointegration addresses reported problems related to wearing a socket interface, such as skin issues, discomfort, diminished function, quality of life, prosthetic use, and abandonment. The purpose of this report is to systematically review current literature regarding OI to identify and categorize the reported clinically relevant outcome measures, rate the quality of available evidence, and synthesize the findings.

DATA SOURCES

A multidisciplinary team used PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methods. Search methodology was based on identifying clinically relevant articles. Three databases were searched: PubMed, CINAHL, and Web of Science.

STUDY SELECTION

Clinical studies with aggregated data reporting at least 1 clinically relevant outcome measure were included.

DATA EXTRACTION

The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criterion was used for critical appraisal and recommendations.

CONCLUSIONS

This review identified 21 clinically relevant observational studies. Outcome measures were categorized into the following 9 categories: vibratory stimulation, complications, biomechanics, economics, patient-reported outcome measures, electromyography, x-ray, physical functional performance, and energy consumption. This systematic review consisted of Level III and IV observational studies. Homogeneous outcome measures with strong psychometric properties across prospective studies do not exist to date. Higher-level, prospective, randomized, long-term, clinically relevant trials are needed to prove efficacy of OI compared with socket prosthetic attachment. Osseointegration was at least equivalent to sockets in most studies. In some cases, it was superior. Osseointegration represents a promising alternative to socket prosthetic attachments for extremity amputees.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Can real-time visual feedback during gait retraining reduce metabolic demand for individuals with transtibial amputation?

The metabolic demand of walking generally increases following lower extremity amputation. This study used real-time visual feedback to modify biomechanical factors linked to an elevated metabolic demand of walking in individuals with transtibial amputation. Eight persons with unilateral, traumatic transtibial amputation and 8 uninjured controls participated. Two separate bouts of real-time visual feedback were provided during a single session of gait retraining to reduce 1) center of mass sway and 2) thigh muscle activation magnitudes and duration. Baseline and post-intervention data were collected. Metabolic rate, heart rate, frontal plane center of mass sway, quadriceps and hamstrings muscle activity, and co-contraction indices were evaluated during steady state walking at a standardized speed. Visual feedback successfully decreased center of mass sway 12% (p = 0.006) and quadriceps activity 12% (p = 0.041); however, thigh muscle co-contraction indices were unchanged. Neither condition significantly affected metabolic rate during walking and heart rate increased with center-of-mass feedback. Metabolic rate, center of mass sway, and integrated quadriceps muscle activity were all not significantly different from controls. Attempts to modify gait to decrease metabolic demand may actually adversely increase the physiological effort of walking in individuals with lower extremity amputation who are young, active and approximate metabolic rates of able-bodied adults.

Comparison of bone-anchored prostheses and socket prostheses for patients with a lower extremity amputation: a systematic review

PURPOSE

This study aimed to provide an overview of a) the used measurement instruments in studies evaluating effects on quality of life (QoL), function, activity and participation level in patients with a lower extremity amputation using bone-anchored prostheses compared to socket prostheses and b) the effects themselves.

METHOD

A systematic literature search was conducted in MEDLINE, Cochrane, EMBASE, CINAHL and Web of Science. Included studies compared QoL, function, activity and/or participation level in patients with bone-anchored or socket prostheses. A best-evidence synthesis was performed.

RESULTS

Out of 226 studies, five cohort and two cross-sectional studies were eligible for inclusion, all had methodological shortcomings. These studies used 10 different measurement instruments and two separate questions to assess outcome. Bone-anchored prostheses were associated with better condition-specific QoL and better outcomes on several of the physical QoL subscales, outcomes on the physical bodily pain subscale were inconclusive. Outcomes on function and activity level increased, no change was found at participation level. The level of evidence was limited.

CONCLUSIONS

There is a need for a standard set of instruments. There was limited evidence that bone-anchored prostheses resulted in higher QoL, function and activity levels than socket prostheses, in patients with socket-related problems. Implications for Rehabilitation Use of bone-anchored prostheses in combination with intensive outpatient rehabilitation may improve QoL, function and activity level compared with socket prosthesis use in patients with a transfemoral amputation and socket-related problems. All clinicians and researchers involved with bone-anchored prostheses should use and publish data on QoL, function, activity and participation level. There needs to be an agreement on a standard set of instruments so that interventions for patients with a lower extremity amputation are assessed consistently.

Design features of implants for direct skeletal attachment of limb prostheses

In direct skeletal attachment (DSA) of limb prostheses, a construct is implanted into an amputee's residuum bone and protrudes out of the residuum's skin. This technology represents an alternative to traditional suspension of prostheses via various socket systems, with clear indications when the sockets cannot be properly fitted. Contemporary DSA was invented in the 1990s, and several implant systems have been introduced since then. The current review is intended to compare the design features of implants for DSA whose use in humans or in animal studies has been reported in the literature.

Recording of electric signal passing through a pylon in direct skeletal attachment of leg prostheses with neuromuscular control

Direct recordings were made of electrical signals emanating from the muscles in a rabbit's residuum. The signals were transmitted via wires attached on one end to the muscles, and on the other to an external recording system. The cable was held in a titanium tube inside a pylon that had been transcutaneously implanted into the residuum's bone. The tube was surrounded by porous titanium cladding to enhance its bond with the bone and with the skin of the residuum. This study was the first known attempt to merge the technology of direct skeletal attachment of limb prostheses with the technology of neuromuscular control of prostheses, providing a safe and reliable passage of the electrical signal from the muscles inside the residuum to the outside recording system.