Static load bearing exercises of individuals with transfemoral amputation fitted with an osseointegrated implant: Loading compliance

Changes in frontal plane kinematics over 12-months in individuals with the Percutaneous Osseointegrated Prosthesis (POP)

BACKGROUND

A bone-anchored prosthesis (BAP) eliminates the need for a conventional socket by attaching a prosthesis directly to the user's skeleton. Currently, limited research addresses changes in gait mechanics post BAP implantation.

OBJECTIVE

Examine changes in frontal plane movement patterns after BAP implantation.

METHODS

Participants were individuals with unilateral transfemoral amputation (TFA) enrolled in the US Food and Drug Administration (FDA) Early Feasibility Study examining the Percutaneous Osseointegrated Prosthesis (POP). The participants completed overground gait assessments using their conventional socket and at 6-weeks, 12-weeks, 6-months, and 12-months following POP implantation. Statistical parameter mapping techniques were used in examining changes in frontal plane kinematics over the 12-months and differences with reference values for individuals without limb loss.

RESULTS

Statistically significant deviations were found pre-implantation compared to reference values for hip and trunk angles during prosthetic limb stance phase, and for pelvis and trunk relative to the pelvis angles during prosthetic limb swing. At 6-weeks post-implantation, only the trunk angle demonstrated a statistically significant reduction in the percent of gait cycle with deviations relative to reference values. At 12-months post-implantation, results revealed frontal plane movements were no longer statistically different across the gait cycle for the trunk angle compared to reference values, and less of the gait cycle was statistically different compared to reference values for all other frontal plane patterns analyzed. No statistically significant within-participant differences were found for frontal plane movement patterns between pre-implantation and 6-weeks or 12-months post-implantation.

CONCLUSIONS

Deviations from reference values displayed prior to device implantation were reduced or eliminated 12-months post-implantation in all frontal plane patterns analyzed, while within-participant changes over the 12-month period did not reach statistical significance. Overall, the results suggest the transition to a BAP aided in normalizing gait patterns in a sample of relatively high functioning individuals with TFA.

Vibration transmission in bone-anchored prosthesis under vertical load. Cadaver study

BACKGROUND

Sensory feedback between a device and its user helps to improve the effectiveness of control and training processes. These improvements involve corrective actions and the accumulation of experience to accelerate patient training in device control.

OBJECTIVES

Vibrations from rehabilitation devices are used as sensory feedback signals for improving rehabilitation outcomes.

STUDY DESIGN

Variations in the bone-anchored prosthesis frequency responses and vibration transmissibility under compressive loading were studied.

METHODS

Five laboratory samples consisting of the above-knee prosthesis, custom-made implant, and cadaver bone were first axially compressed using universal testing machine; preloaded construction vibrations were generated with a shaker to imitate external forces acting on these samples. The oscillations at the sample surface control points were tested with a laser vibrometer. For different values of axial loading, the frequency responses of the samples and indexes of vibration attenuation were obtained to examine the correlations between vibration transmissibility in the samples and axial loads.

RESULTS

Increase in axial loading caused an increase in the resonance frequency and a simultaneous decrease in vibratory displacement within the sample. At low frequencies (40-80 Hz), increasing the axial load degraded transmissibility; at medium and high frequencies, transmissibility changes were unstable on increasing the axial load.

CONCLUSIONS

The osseoperception phenomenon is because of perceived prosthesis vibration analysis by the user. Vibration transmissibility of a prosthesis sample depends on the axial compression and frequency of excitation. Decreasing the vibration amplitude while increasing axial load is the primary reason for reduced perception of vibration.

Biomechanical compensations during a stand-to-sit maneuver using transfemoral osseointegrated prostheses: A case series

BACKGROUND

Patients with transfemoral amputation and socket prostheses are at a heightened risk of developing musculoskeletal overuse injuries, commonly due to altered joint biomechanics. Osseointegrated prostheses, which involve direct anchorage of the prosthesis to the residual limb through a bone anchored prosthesis, are a novel alternative to sockets yet their biomechanical effect is largely unknown.

METHODS

Four patients scheduled to undergo unilateral transfemoral prosthesis osseointegration completed two data collections (baseline with socket prosthesis and 12-months after prosthesis osseointegration) in which whole-body kinematics and ground reaction forces were collected during stand-to-sit tasks. Trunk, pelvis, and hip kinematics, and the surrounding muscle forces, were calculated using subject-specific musculoskeletal models developed in OpenSim. Peak joint angles and muscle forces were compared between timepoints using Cohen's d effect sizes.

FINDINGS

Compared to baseline with socket prostheses, patients with osseointegrated prostheses demonstrated reduced lateral trunk bending (d = 1.46), pelvic obliquity (d = 1.09), and rotation (d = 1.77) toward the amputated limb during the stand to sit task. This was accompanied by increased amputated limb hip flexor, abductor, and rotator muscle forces (d> > 0.8).

INTERPRETATION

Improved lumbopelvic movement patterns and stabilizing muscle forces when using an osseointegrated prosthesis indicate that this novel prosthesis type likely reduces the risk of the development and/or progression of overuse injuries, such as low back pain and osteoarthritis. We attribute the increased muscle hip muscle forces to the increased load transmission between the osseointegrated prosthesis and residual limb, which allows a greater eccentric ability of the amputated limb to control lowering during the stand-to-sit task.

Examining trabecular morphology and chemical composition of peri-scaffold osseointegrated bone

Background

Porous titanium alloy scaffold fabricated by 3D printing technology could induce osseointegration well to repair bone defect during early postoperative period. However, trabecular histomorphological features and chemical compositions of ingrowth bone in the long term after surgery still lacked in-depth research.

Methods

Fourteen New Zealand rabbits were divided into two groups (7 rabbits in surgery group and 7 rabbits in control group). A 3D-printed porous titanium alloy scaffold was implanted into right femoral condyle of each rabbit in the surgery group. Preload was produced at the surface between bone tissue and scaffold through interference assembly during implantation process. Rabbits in the control group were feed free. All rabbits were sacrificed to extract femoral condyles at week 12 after surgery. All right femoral condyles were performed micro-CT scanning to test bone mineral density (BMD) and trabecular histomorphological parameters, including bone volume fraction (BV/TV), bone surface/volume ratio (BS/BV), bone surface density (BS/TV), structure model index (SMI), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), porosity (PO), connectivity density (Conn.Dn), and degree of anisotropy (DA). Scanning electron microscope was used to observe osteogenesis peri-scaffold. Fourier transform infrared spectroscopy (FTIR) scanning was performed to analyze chemical compositions of peri-scaffold trabeculae. All trabecular morphological parameters and BMDs were statistically analyzed between surgery group and control group.

Results

The pores of scaffold were filled with ingrowth bone tissues after 12 weeks osseointegration. However, the mean BMD peri-scaffold in surgery group was 800 ± 20 mg/cm³, which was 18.37% lower than that in the control group. There was a significant decrease in BV/TV, Tb.N, and BS/TV, and there was a significant increase in Tb.Sp and PO between the surgery group and control group (p < 0.05). There were no significant differences in Tb.Th, SMI, Conn.Dn, BS/BV, and DA. Although ingrowth of bone tissue was very effective, some fragmented connective tissues were still found instead of bone tissues on the partial beams of scaffolds through SEM images. It was found from FTIR that there was no significant hydroxyapatite peak signal in surgery group. Collagen in the control group mainly existed as cross-link structure, while non-cross-link structure in the surgery group.

Conclusions

Preload could promote the same good osseointegration ability as chemical surface modification method in the early term after surgery, and better osseointegration effect than chemical surface modification method in the mid-long term after surgery. However, histomorphological features of peri-scaffold trabeculae were still in deterioration and low collagen maturity caused by stress shielding. It was suggested from this study that extra physical training should be taken to stimulate the bone remodeling process for recovering to a healthy level.

Safety, prosthesis wearing time and health-related quality of life of lower extremity bone-anchored prostheses using a press-fit titanium osseointegration implant: A prospective one-year follow-up cohort study

BACKGROUND

We described safety and functional one-year follow-up outcomes of individuals with lower limb amputation treated with bone-anchored prostheses using titanium press-fit osseointegration implants.

METHODS

All consecutive individuals treated between March 2015 and June 2018 with curved osseointegration femur implant (OFI-C) indicated for a long femoral remnant, gamma osseointegration femur implant (OFI-Y) indicated for a short femoral remnant, or osseointegration tibia implant (OTI) were eligible for this study. All adverse events were evaluated, infections were graded as follows: grade 1 and 2: low- and high-grade soft tissue infection, respectively, grade 3: deep bone infection, grade 4: septic implant failure. Functional outcome measures included prosthesis wearing time (PUS), health-related quality of life (GS), and the overall situation as an amputee (GS Q3); evaluated with the Questionnaire of persons with trans-femoral amputation (Q-TFA) before surgery and at one-year follow-up.

RESULTS

Ninety of 91 individuals were included (mean age: 54±14 yrs, 26 females); treated with 53, 16 and 21 OFI-C, OFI-Y and OTI, respectively. Soft tissue infections (grade 1: 11 events, grade 2: 10 events) were treated successfully with antibiotics except in two (OFI-C and OFI-Y), who required additional surgery due to recurrent stoma irritation and peri-stoma abscess drainage. One individual with dysvascular amputation (OTI) developed septic implant loosening and occlusion of the femoral artery resulting in a transfemoral amputation. No aseptic loosening's occurred. One individual (OFI-Y) required stoma surgical refashioning due to soft tissue redundancy. At baseline mean ±SD and median (25th to 75th PCTL) Q-TFA PUS and GS were 52±39, 52(7-90) and 40±19, 42(25-50) and improved significantly to 88±18, 90 (90-100) and 71±15, 75 (67-83) at one-year follow-up. The GS Q3 improved over time.

CONCLUSION

Titanium osseointegration implants can be safely used within a one-year follow-up period. The performance improved compared to the use of a socket-suspended prosthesis.

Kinetics of Lower Limb Prosthesis: Automated Detection of Vertical Loading Rate

Vertical loading rate could be associated with residuum and whole body injuries affecting individuals fitted with transtibial prostheses. The objective of this study was to outline one out of five automated methods of extraction of vertical loading rate that stacked up the best against manual detection, which is considered the gold standard during pseudo-prosthetic gait. The load applied on the long axis of the leg of three males was recorded using a transducer fitted between a prosthetic foot and physiotherapy boot while walking on a treadmill for circa 30 min. The automated method of extraction of vertical loading rate, combining the lowest absolute average and range of 95% CI difference compared to the manual method, was deemed the most accurate and precise. The average slope of the loading rate detected manually over 150 strides was 5.56 ± 1.33 kN/s, while the other slopes ranged from 4.43 ± 0.98 kN/s to 6.52 ± 1.64 kN/s depending on the automated detection method. An original method proposed here, relying on progressive loading gradient-based automated extraction, produced the closest results (6%) to manual selection. This work contributes to continuous efforts made by providers of prosthetic and rehabilitation care to generate evidence informing reflective clinical decision-making.

A novel device to measure static hindlimb weight-bearing forces in pronograde rodents

BACKGROUND

Joint pain is composed of both spontaneous and movement-induced pain. In animal models, static bodyweight distribution is a surrogate for spontaneous joint pain. However, there are no commercially-available instruments that measure static bodyweight distribution in normal, pronograde rodents.

NEW METHOD

We designed a Static Horizontal Incapacitance Meter (SHIM) to measure bodyweight distribution in pronograde standing rodents. We assessed the device for feasibility, repeatability, and sensitivity to quantify hindlimb bodyweight distribution. Mice and rats with unilateral inflammatory pain induced by subcutaneous injections of capsaicin or Complete Freund's Adjuvant (CFA) into the plantar surface of the left hind paw were used to measure static weight-bearing. The ability to attenuate inflammatory pain-associated weight-bearing asymmetry was tested by administering a non-steroidal anti-inflammatory drug, meloxicam.

RESULTS

The SHIM's ability to detect significant reductions in limb loading on the injected hindlimb in mice and rats was validated using both acute and sub-chronic pain models. Treatment with meloxicam partially reversed CFA-induced effects.

COMPARISON WITH EXISTING METHODS

In contrast with assays that measure kinetic or static weight-bearing forces (e.g., walking, or standing at a 45 ° incline), the SHIM allows evaluation of weight-bearing in rodents that are standing at rest in their normal pronograde position.

CONCLUSIONS

The SHIM successfully detected: (a) asymmetric weight-bearing in acute and sub-chronic pain models; and (b) the analgesic effects of meloxicam. This study provides a novel tool to objectively evaluate limb use dysfunction in rodents.

The Influence of Geometry of Implants for Direct Skeletal Attachment of Limb Prosthesis on Rehabilitation Program and Stress-Shielding Intensity

The purpose of the research was to evaluate the influence of selected parameters of the implants for bone anchored prostheses on possibility of conducting static load bearing exercises and stress-shielding intensity. A press-fit implant, a threaded implant, and the proposed design were compared using the finite element method. For the analyses two features were examined: diameter (19.0 – 21.0 mm) and length (75.0 – 130.0 mm). To define the possibility of conducting rehabilitation exercises the micromotion of implants while axial loading with a force up to 1000 N was examined to evaluate the changes at implant-bone interface. The stress-shielding intensity was estimated by bone mass loss over 60 months. The results suggest that, in terms of micromotion generated during rehabilitation exercises, the threaded (max. micromotion of 16.00 μm) and the proposed (max. micromotion of 45.43 μm) implants ensure low and appropriate micromotion. In the case of the press-fit solution the load values should be selected with care, as there is a risk of losing primary stabilisation. The allowed forces (that do not stimulate the organism to generate fibrous tissue) were approx. 140 N in the case of the length of 75 mm, increasing up to 560 N, while using the length of 130 mm. Moreover, obtained stress-shielding intensities suggest that the proposed implant should provide appropriate secondary stability, similar to the threaded solution, due to the low bone mass loss during long-term use (improving at the same time more bone remodelling in distal Gruen zones, by providing lower bone mass loss by approx. 13% to 20% in dependency of the length and diameter used). On this basis it can be concluded that the proposed design can be an appropriate alternative to commercially used implants.

Automated characterization of anthropomorphicity of prosthetic feet fitted to bone-anchored transtibial prosthesis

OBJECTIVE

This study describes differentiating prosthetic feet designs fitted to bone-anchored transtibial prostheses based on an automated characterization of ankle stiffness profile relying on direct loading measurements. The objectives were (A) to present a process characterizing stiffness using innovative macro, meso and micro analyses, (B) to present stiffness profiles for feet with and without anthropomorphic designs, where anthropomorphicity is defined as a similarity of the moment-angle dependency in prosthetic and in the anatomical ankle, (C) to determine sensitivity of characterization.

METHODS

Three participants walked consecutively with two instrumented bone-anchored prostheses including their own prosthetic feet and Free-Flow foot meeting the anthropomorphicity criterion by design. Angle of dorsiflexion was extracted from video footage. Bending moment was recorded using multi-axis transducer attached to osseointegrated fixation. The automated characterization of stiffness involved a 12-step process relying on data-based criterion.

RESULTS

The meso analyses confirmed bilinear behavior of moment-angle curves with Index of Anthropomorphicity of -2.966±2.369 Nm/Deg and 2.681±1.089 Nm/Deg indicating a convex and concave shape of usual and Free-Flow feet without and with anthropomorphic designs, respectively.

CONCLUSIONS

The proposed straightforward meso analysis of the stiffness was capable to report clinical meaningful differences sensitive to feet's anthropomorphicity. Results confirmed the benefits for clinicians to rely on direct loading measurement providing individualized complementary insight into impact of components.

SIGNIFICANCE

This work could assist the developments of standards and guidelines for manufacturing and safe fitting of components to growing population requiring transtibial prostheses with socket or direct skeletal attachment worldwide.

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.

Load characteristics following transfemoral amputation in individuals fitted with bone-anchored prostheses: a scoping review protocol

REVIEW QUESTION

The main purpose of this scoping review is to characterize loading information applied on the residuum of individuals with transfemoral amputation fitted with an osseointegrated fixation for bone-anchored prostheses.The objectives of this scoping review are: i) to map the scope of loading variables, and ii) to report the range of magnitude of loads that has been directly measured using a portable kinetic recording apparatus fitted at the distal end of the residuum during rehabilitation exercises, standardized and unscripted activities of daily living, and adverse events.The specific review questions are.

Cost-effectiveness of bone-anchored prostheses using osseointegrated fixation: Myth or reality?

BACKGROUND

In principle, lower limb bone-anchored prostheses could alleviate expenditure associated with typical socket manufacturing and residuum treatments due to socket-suspended prostheses.

OBJECTIVE

This study reports (a) the incremental costs and (b) heath gain as well as (c) cost-effectiveness of bone-anchored prostheses compared to socket-suspended prostheses.

STUDY DESIGN

Retrospective individual case-controlled observations and systematic review.

METHODS

Actual costs were extracted from financial records and completed by typical costs when needed over 6-year time horizon for a cohort of 16 individuals. Health gains corresponding to quality-adjusted life-year were calculated using health-related quality-of-life data presented in the literature.

RESULTS

The provision of bone-anchored prostheses costed 21% ± 41% more but increased quality-adjusted life-years by 17% ± 5% compared to socket-suspended prostheses. The incremental cost-effectiveness ratio ranged between -$25,700 per quality-adjusted life-year and $53,500 per quality-adjusted life-year with indicative incremental cost-effectiveness ratio of approximately $17,000 per quality-adjusted life-year. Bone-anchored prosthesis was cost-saving and cost-effective for 19% and 88% of the participants, respectively.

CONCLUSION

This study indicated that bone-anchored prostheses might be an acceptable alternative to socket-suspended prostheses at least from a prosthetic care perspective in Australian context. Altogether, this initial evidence-based economic evaluation provided a working approach for decision makers responsible for policies around care of individuals with lower limb amputation worldwide. Clinical relevance For the first time, this study provided evidence-based health economic benefits of lower limb bone-anchored prostheses compared to typical socket-suspended prostheses from a prosthetic care perspective that is essential to clinicians and decision makers responsible for policies.

Development of a Procedure for the Government Provision of Bone-Anchored Prosthesis Using Osseointegration in Australia

BACKGROUND

Governmental organizations are facing challenges in adjusting procedures providing equitable assistance to consumers with amputation choosing newly available osseointegrated fixations for bone-anchored prostheses (BAPs) over socket-suspended prostheses.

OBJECTIVES

The aims of this study were to (1) present a procedure focusing on tasks, documents and costs of prosthetic care, and (2) share observed obstacles and facilitators to implementation.

METHODS

This research aimed at developing a governmental procedure for the provision of BAPs was designed as an action research study. A total of 18 individuals with transfemoral amputation solely funded by a Queensland State organization were considered.

RESULTS

The procedure, developed between January 2011 and June 2015, included seven processes involving fixed expenses during treatment and five processes regulating ongoing prosthetic care expenses. Prosthetic care required 22 h of labor, corresponding to AUD$3300 per patient, during rehabilitation. Prosthetists spend 64 and 36% of their time focusing on prosthetic care and other activities, respectively. The procedure required adjustments related to the scope of practice of prosthetists, funding of prosthetic limbs during rehabilitation, and allocation of microprocessor-controlled prosthetic knees. Approximately 41% (7) and 59% (10) of obstacles were within (e.g. streamlining systematic processes, sustaining evaluation of this complex procedure) or outside (e.g. early and consistent consultations of stakeholders, lack of a definitive rehabilitation program) governmental control, respectively, and approximately 89% (17) of the facilitators were within governmental control (e.g. adapting existing processes).

CONCLUSION

This study provides a working plan to stakeholders developing and implementing policies around the care of individuals choosing osseointegration for BAPs.

[Function of prosthesis components in lower limb amputees with bone-anchored percutaneous implants : Biomechanical aspects]

BACKGROUND

Bone anchorage of an artificial limb has been proven to be an alternative intervention for amputees when prosthesis use is seriously reduced because of stump problems. Little is known about how prosthesis components interact with bone and joints and which potential the optimum use provides with respect to quality of treatment of leg amputees.

OBJECTIVE

Does osseointegration influence the motor activity of residual limbs differently compared with socket prostheses? How should prosthesis components be aligned? What type of prosthetic knee joints should be preferred in transfemoral amputees?

MATERIAL AND METHODS

Transfer of biomechanical knowledge of socket prosthetics to bone-anchored prostheses. Pilot studies with a limited number of amputees.

RESULTS

Force transmission at the interface between the prosthesis and residual limb stump is completely different for osseointegrated fixation and socket design; however, the number of muscles available for control remains unchanged. Because the iliotibial tract is missing, bending moments of the femur are expected to be greater. Prosthetic alignment is very critical for gait pattern and the basic rules seem to be the same as for socket design. The foot position determines the knee function for below-knee amputees. The position of the femur influences the gait pattern of above-knee amputees. The lowest risk of falls and best functional properties are shown by microprocessor controlled knee joints.

CONCLUSION

Osseointegrated leg prostheses have some biomechanical advantages over the socket design. Since rehabilitation quality is clearly affected the prosthetic alignment has to be done carefully and precisely. As a rule microprocessor controlled knee joints are indicated.