Static Load Bearing During Early Rehabilitation Of Transfemoral Amputees Using Osseointegrated Fixation

Many transfemoral amputees wearing conventional socket prostheses experience pain related to the socket-residuum interface and difficulties with socket retention or fit due to a short residuum. In consideration of these problems a direct skeletal fixation method has been developed whereby a titanium implant is screwed into the medullary canal of the residual femur. Prosthetic components are directly attached to the fixation, once osseointegrated, removing the need for a prosthetic socket. The rehabilitation program to return to ambulation involves incremental static loading of the fixation until full weight bearing is achieved. The rate of loading, which is intended to be isolated to the long axis of the fixation, is determined by the quality of the residual skeleton and a qualitative assessment of the pain experienced by the amputee on loading. Rotational loading of the implant is to be avoided at this stage. The amputee uses a domestic weigh-scale to provide feedback of the load applied. This study aims to measure the true load applied to the fixation and compare this with the clinically prescribed axial load

Biomechanics of transfemoral amputees fitted with osseointegrated fixation: Loading data for evidence-based practice

This presentation will provide an overview of the load applied on the residuum of transfemoral amputees fitted with an osseointegrated fixation during (A) rehabilitation, including static and dynamic load bearing exercises (e.g., rowing, adduction, abduction, squat, cycling, walking with aids), and (B) activities of daily living including standardized activities (e.g., level walking in straight line and around a circle, ascending and descending slopes and stairs) and activities in real world environments. A particular emphasis will be placed on the outcomes of several studies for an evidence-based design of the rehabilitation program and components of the fixation (e.g., implant, abutment). It is anticipated that this work might contribute to the current effort aiming at shortening the rehabilitation program and reducing the incidence of replacement of abutments

Wear and corrosion interactions on titanium in oral environment : literature review

The oral cavity is a complex environment where corrosive substances from dietary, human saliva, and oral biofilms may accumulate in retentive areas of dental implant systems and prostheses promoting corrosion at their surfaces. Additionally, during mastication, micromovements may occur between prosthetic joints causing a relative motion between contacting surfaces, leading to wear. Both processes (wear and corrosion) result in a bio-tribocorrosion system once that occurs in contact with biological tissues and fluids. This review paper is focused on the aspects related to the corrosion and wear behavior of titanium-based structures in the oral environment. Furthermore, the clinical relevance of the oral environment is focused on the harmful effect that acidic substances and biofilms, formed in human saliva, may have on titanium surfaces. In fact, a progressive degradation of titanium by wear and corrosion (tribocorrosion) mechanisms can take place affecting the performance of titanium-based implant and prostheses. Also, the formation of wear debris and metallic ions due to the tribocorrosion phenomena can become toxic for human tissues. This review gathers knowledge from areas like materials sciences, microbiology, and dentistry contributing to a better understanding of bio-tribocorrosion processes in the oral environment.(undefined

Load Applied On Trans-Femoral Ossenintegrated Prostheses

A lower-limb prosthesis is conventionally attached to the residual limb by a socket and often some suspension devices. Although this approach has been used for over 50 years, previous studies have pointed the phenomena that local limb pain and soft tissue breakdown are common. High pressure applied from the prosthetic socket onto the residual limb is the major cause of the problems. Researchers are developing a surgical approach using osseointegration for directly connecting a prosthesis into the femur using a fixation system with a titanium implant. The absence of a prosthetic socket can alleviate the skin problems. This procedure increased significantly the quality of life of amputees. However, the current rehabilitation is long and some occasional mechanical failures of the fixation following a fall were reported. Understanding the load applied on the osseointegrated fixation is one important step to solve these problems. This article presents the load applied on the fixation of twelve trans-femoral amputees during level walking

Load Applied On The Abutment Of Transfemoral Amputees Fitted With An Osseointegrated Implant During Load Bearing Excersices Using A Long Pylon

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Load applied on bone-anchored transfemoral prosthesis: characterization of a prosthesis - a pilot study

The objectives of this study were (A) to record the inner prosthesis loading during activities of daily living (ADL), (B) to present a set of variables comparing loading data, and (C) to provide an example of characterisation of two prostheses. The load was measured at 200 Hz using a multi-axial transducer mounted between the residuum and the knee of an individual with unilateral transfemoral amputation fitted with a bone-anchored prosthesis. The load was measured while using two different prostheses including a mechanically (PRO1) and a microprocessor controlled (PRO2) knee during six ADL. The characterisation of prosthesis was achieved using a set of variables split into four categories, including temporal characteristics, maximum loading, loading slopes and impulse. Approximately 360 gait cycles were analysed for each prosthesis. PRO1 showed a cadence improved by 19% and 7%, a maximum force on the long axis reduced by 11% and 19%, as well as an impulse reduced by 32% and 15% during descent of incline and stairs compared to PRO2, respectively. This work confirmed that the proposed apparatus and characterisation can reveal how changes of prosthetic components are translated into inner loading

Kinetics of Transfemoral Amputees with Osseointegrated Fixation Performing Common Activities of Daily Living

Background: Direct anchorage of a lower-limb prosthesis to the bone through an implanted fixation (osseointegration) has been suggested as an excellent alternative for amputees experiencing complications from use of a conventional socket-type prosthesis. However, an attempt needs to be made to optimize the mechanical design of the fixation and refine the rehabilitation program. Understanding the load applied on the fixation is a crucial step towards this goal. Methods: The load applied on the osseointegrated fixation of nine transfemoral amputees was measured using a load transducer, when the amputees performed activities which included straight-line level walking, ascending and descending stairs and a ramp as well as walking around a circle. Force and moment patterns along each gait cycle, magnitudes and time of occurrence of the local extrema of the load, as well as impulses were analysed. Findings: Managing a ramp and stairs, and walking around a circle did not produce a significant increase (P>0.05) in load compared to straight-line level walking. The patterns of the moment about the medio-lateral axis were different among the six activities which may reflect the different strategies used in controlling the prosthetic knee joint. Interpretations: This study increases the understanding of biomechanics of bone-anchored osseointegrated prostheses. The loading data provided will be useful in designing the osseointegrated fixation to increase the fatigue life and to refine rehabilitation protocol

Direct Measurement Of 3D Force And Moment On Lower-Limb Osseointegrated Fixation

Implant loosening and mechanical failure are two major concerns for trans-femoral amputees using osseointegrated fixation. Understanding the true load applied on osseointegrated fixation is one important step in solving the two problems. Conventionally, the load magnitude can be calculated based on the motion of the prosthesis and the ground reaction forces measured by a force plate using inverse dynamics. However, this approach allowed only one or two walking steps to be measured and errors are compounded when involving more than one joint. In this study, we directly measured load acting on the abutment of an osseointegrated prosthesis with a load transducer for twelve trans-femoral amputees. Three-dimensional force and moment patterns at the abutment along a gait cycle were displayed. Step-to-step variability of each subject in various kinetic and temporal parameters as well as subject-to-subject variability in temporal parameters were found low. High subject-to-subject variability in force and moment data was demonstrated

Loading Applied To The Implant Of Transfemoral Amputees Fitted With A Direct Skeletal Fixation During Walking In A Straight Line And Around A Circle

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Gait analysis of transfemoral amputees: Errors in inverse dynamics are substantial and depend on prosthetic design

Quantitative assessments of prostheses performances rely more and more frequently on gait analysis focusing on prosthetic knee joint forces and moments computed by inverse dynamics. However, this method is prone to errors, as demonstrated in comparison with direct measurements of these forces and moments. The magnitude of errors reported in the literature seems to vary depending on prosthetic components. Therefore, the purposes of this study were (A) to quantify and compare the magnitude of errors in knee joint forces and moments obtained with inverse dynamics and direct measurements on ten participants with transfemoral amputation during walking and (B) to investigate if these errors can be characterised for different prosthetic knees. Knee joint forces and moments computed by inverse dynamics presented substantial errors, especially during the swing phase of gait. Indeed, the median errors in percentage of the moment magnitude were 4% and 26% in extension/flexion, 6% and 19% in adduction/abduction as well as 14% and 27% in internal/external rotation during stance and swing phase, respectively. Moreover, errors varied depending on the prosthetic limb fitted with mechanical or microprocessorcontrolled knees. This study confirmed that inverse dynamics should be used cautiously while performing gait analysis of amputees. Alternatively, direct measurements of joint forces and moments could be relevant for mechanical characterising of components and alignments of prosthetic limbs