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Original Research Article

Cost Comparison of Socket-Suspended and Bone-Anchored Transfemoral Prostheses

Frossard, Laurent PhD; Berg, Debra BBA; Merlo, Gregory PhD; Quincey, Tanya MS; Burkett, Brendan PhD

Author Information
Journal of Prosthetics and Orthotics: October 2017 - Volume 29 - Issue 4 - p 150-160
doi: 10.1097/JPO.0000000000000142
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Abstract

Individuals with lower-limb transfemoral amputation fitted with conventional prosthetic limbs often experience ongoing socket-related discomfort leading to a dramatic decrease in quality of life.1–3 Most of these issues can be overcome by replacing the socket with a bone-anchored prosthesis (BAP) attached directly to the residual bone using a surgically implanted osseointegrated fixation.1,4–7

Typically, osseointegrated fixations that are currently commercially available rely either on screw-type or press-fit designs.4,8–12 Surgical implantation of the fixation requires possibly one-stage but usually two-stage surgeries followed by a rehabilitation program lasting between 6 and 12 months.13–15

CLINICAL BENEFITS OF BONE-ANCHORED PROSTHESIS

Both methods of attachment have now been trialed and monitored for over a decade.13,16–18 Acceptance within the communities of interest is growing strongly as scientific evidence revealed that transfemoral BAP engenders major clinical benefits (e.g., quality of life, prosthetic use, body image, hip range of motion, sitting comfort, ease of donning and doffing, osseoperception, walking ability, and sustain extended daily activities) with acceptable clinical risks (e.g., implant stability, rate of infection, effect of a fall, and breakage of fixation parts).13,16,17,19–36

ECONOMIC CONSEQUENCES OF BONE-ANCHORED PROSTHESIS

Authors have often indicated that BAP could potentially reduce some prosthetic, medical, and financial burdens for health service administrators by reducing the treatment of skin-socket interface problems over a user's lifespan. For instance, the regular manufacturing of expensive custom-made sockets that could range from $6,203 up to $20,070 over the first 5 years after primary amputation could be alleviated.18,37

ASSESSING COSTS OF BONE-ANCHORED PROSTHESIS

Untangling the financial benefits of BAP is tedious, given that surgical care, rehabilitation care, prosthetic care, and medical care are intertwined and possibly covered in part or in whole by multiple entities (e.g., public health care, private health fund, insurance, and workers' compensation) and/or the patients themselves (e.g., out-of-pocket expenses and fundraising).

Specific studies looking at the health economics associated with BAP are sparse.38–40 Only Haggstrom et al. (2013) compared the prosthetic costs and service between BAP and conventional suspended transfemoral prostheses. They concluded that patients with BAP “make significantly fewer visits per year to a prosthetic workshop compared with a similar group using [socket] prostheses. Despite the differences in visits for prosthetic service between the groups, the overall prosthetic costs for [BAP] prostheses were comparable with those for [socket] prostheses. We suggest this is due to more sophisticated components that can be used with [BAP].”41(p159) However, this study relied on retrospective analysis and surveys to extract actual costs in a nonprofit prosthetic facility, publicly financed by the Swedish health care system. Sweden is known for providing universal high-quality prosthetic care that could provide top-end, expensive microprocessor-controlled prosthetic knees (MPKs).

PROCEDURES FOR EQUITABLE FINANCIAL ASSISTANCE: NEED FOR MORE DATA

This information is relevant but limited for other organizations with different governmental ethos, structure, and resources (e.g., budget), who are facing a range of challenges in adjusting their procedures to include fair and equitable financial assistance for individuals choosing BAP.41 Clearly, there is a need for more in-depth cost analyses associated with BAP that could potentially help policy makers.

Better understanding of the actual BAP's economic benefits is needed for organizations worldwide like the Queensland Artificial Limb Service (QALS), a state organization located in Brisbane, Australia. This publicly funded administration related to the Queensland Government Minister of Health is responsible for the provision of prosthetic services (e.g., artificial limbs) to eligible residents of the 1.8 million km2 state of Queensland. QALS counts over 7000 registered consumers. Its $5.4 million yearly budget enables provision of regular services to approximately 3000 active consumers annually, including 600 (20%) with transfemoral amputations. More importantly, QALS is currently facing one the strongest influx of consumers opting for BAP as typical Queensland tropical heat and humidity make socket prostheses quasi-impossible to bear.

An initial step into unfolding the economic consequences of BAP is to compare costs that could occur for both BAP and socket prostheses. The assessment of the actual costs for approximately 6 years before and after the procedure corresponding to the socket and BAP fittings expenses, respectively, could provide the most realistic estimations.41,42 However, monitoring a cohort of participants over such extended period of time could be impractical but, more importantly, too long-standing to address the immediate policymakers' needs. Alternatively, a cross-comparison of costs can be simulated while considering typical socket and estimated BAP costs.

OBJECTIVES

The ultimate aim of this study was to share the knowledge and experience recently gained by QALS while comparing costs for provision of transfemoral prostheses with conventional and new types of attachment. The main purpose was to describe the methods used by QALS to simulate and compare itemized costs for provision of BAP over socket prostheses for a 6-year funding cycle. The specific objectives were as follows:

  1. To present the ongoing costs of provision of a typical socket-suspended prosthesis for each of the five functional K-level ranking from K0 to K4;
  2. To estimate costs for the provision of BAP with low-cost, budget, and high-cost fitting options including different MPKs; and
  3. To compare historical costs for provision of socket prostheses with simulated costs for BAP.

MATERIALS AND METHODS

RESEARCH TEAM

This study was led by a committee including the QALS management team, a researcher in health economics, and three qualified and experienced prosthetists, referred to as prosthetic service providers (PSPs), working in private settings in two states (i.e., New South Wales and Queensland).

STUDY DESIGN

This primary research aiming at comparing historical costs for socket prostheses with simulated costs for BAP from a health care perspective was designed as an observational study. More precisely, this study was designed like a typical routine-data-based study at an individual level commonly applied in epidemiology.

COST ESTIMATION

An overview of the key factors influencing the typical fixed and ongoing costs of prosthetic care pathways for socket and BAP fitting options that were considered in the proposed cost estimation and comparison analyses is presented in Figure 1.

Figure 1
Figure 1:
Overview of key factors influencing prosthetic care for sockets and bone-anchored prosthesis considered in analyses of cost estimation and comparison.

The typical prosthetic care pathway for individuals with a transfemoral amputation starts with fixed costs for initial socket fitting and an interim prosthesis when possible after amputation, followed by ongoing costs for fitting of so-called definitive prostheses over the individual's lifespan. Individuals opting for a bone-anchored prosthesis then experience a treatment for the implantation of osseointegrated fixation involving fixed costs for following postoperative prosthetic care and light prosthesis enabling safe load bearing prior to being fitted with the definitive prosthesis.

Previous studies indicated that fixed costs for an interim prosthesis were less than $2000 in Australia.43 The authors have estimated that the fixed cost for BAP was $3300, which corresponded to 22 hrs of PSP's labor for preoperative (2.5 hrs, $375), surgical (2.5 hrs, $375), and postoperative (17 hrs, $2550) activities. Further considerations for fixed costs for both attachments were deemed outside the scope of this study. Consequently, only ongoing costs were considered in further estimations and comparisons.

All unit costs per single limb were derived from internal QALS sources. In principle, QALS relies on PSPs to design definitive prostheses on a case-by-case basis depending on individual consumer needs. However, allowable labor and parts expenses, increasing with a consumer's level of amputation, functional classification using four K-levels (i.e., K1, K2, K3, K4), and body mass (i.e., under or over 100 kg), are regulated by QALS' formal “Schedule of Allowable Hours” and “Limb Build Average Estimates,” respectively.44 Furthermore, PSPs can only fit parts included in QALS' approved parts database at prenegotiated price with suppliers. Consequently, a set amount and type of parts will be reported here rather than particular brands and models.

The overall ongoing costs for provision of any type of prosthesis were systematically reported with two complementary breakdowns. First, costs for either labor or physical parts were reported as initially recorded using QALS's financial system. Then, costs for parts and labor were also split between specific costs for attachment (e.g., liner, socket, and connector) or components (e.g., knee and foot) to better differentiate both methods of attachments (Figure 2). The number of units for all labor-related expenses corresponded to PSP hours at the fixed hourly rate of $150.

Figure 2
Figure 2:
Schematic representation of the residuum and parts included or excluded of the cost comparisons of the definitive prosthetic limbs for an individual with transfemoral amputation fitted with socket or bone-anchored prosthesis.

The total ongoing cost of an item was the product of a single unit cost by number of units required over a 6-year duration. In fact, this period of funding included two consecutive 3-year subcycles. Each one corresponded to the typical manufacturer's warranty for more expensive prosthetic components. A 6-year duration is commonly deemed relevant by QALS and other national supporting schemes for reasonable cost predictions with stable unit prices for labor and parts.42 Altogether, the total cost for the provision of a given prosthesis corresponded to the sum of all costs for the whole funding cycle. All costs are expressed in 2016 Australian dollars.

SOCKET

Ongoing labor and parts costs for provision of definitive socket prostheses were extracted from QALS' regulatory documentation listed previously, last updated in 2014. No information was tabulated for K0 classification, including consumers who are unable to wear a socket (e.g., skin problems and short residuum) and therefore incur no costs for provision of prostheses. Typical costs in each of the other K-levels were selected for consumers with transfemoral amputation under 100 kg fitted with liner and ischial containment sockets. The labor costs included PSP hours for designing, fitting, and maintaining sockets, liners, prostheses, and cosmetic covers (e.g., foam). Consumers classified as K1 or K2 were allocated a single-axis friction, single-axis stance-locking, or modular single-axis knee and dynamic response foot units depending on walking ability. Those classified as K2, K3, or K4 were allocated a polycentric or single-axis cadence-responsive knee and energy-storing foot, also depending on walking ability and lifestyle. In all cases, top-end costs were purposely selected in this study for the sake of conservative cost comparisons.

BONE-ANCHORED PROSTHESES

Ongoing labor and parts costs for provision of definitive BAPs were estimated for three fitting options. The ongoing labor costs allocated for the care of the fixation as well as fitting and maintaining prosthesis were the same for all options. The costs were determined by QALS after consultations with clinicians and PSPs as well as a review of literature (e.g., number of visits).13,41 All options provided a whole new limb without cosmetic covers at the beginning of each 3-year funding subcycle, including specific connector attaching the percutaneous part of the fixation to MPK units. We also considered that the connector part included a fixation-specific protective device to prevent excessive loads.20–22,32–34,45–53

The provision of costly MPKs followed the recommendations provided in acknowledged clinical and prosthetic care guidelines for patients with BAP.13–15 A hydraulic knee joint controlled by an onboard computer was deemed essential as it provides required stance phase stability and swing phase responsiveness.54–62 In principle, these features can contribute to preventing falls and avoiding excessive loading that are ultimately critical to protect the fixation and alleviate adverse events (e.g., periprosthetic factures, breakage of fixation parts, and injuries to hip joint).21,22,33,34,50,53 Altogether, consumers can capitalize on both direct attachment (e.g., hip range of movement, easy attachment, sitting comfort, and osseoperception) and MPK's biomechanical benefits to sustain high functional level safely.

Costs varied between options depending on the performance of knee and foot units. The low-cost option included a single-axis friction knee and a dynamic foot. The budget option included a package combining a single-axis cadence-responsive knee, a shock absorption adapter, a tube adapter, and a dynamic foot. The high-cost option included a top-of-the-range single-axis cadence-responsive knee and an energy-storage foot.

COST COMPARISON

Total costs with breakdown for labor hours and costs in dollars as well as parts after a 6-year funding cycle were cross-compared using a matrix including five rows for socket fitting in each K-level and three columns for BAP options. For each given outcome, the difference was calculated by BAP option minus socket fitting. Thus, a negative, close to zero, and positive difference indicated that the BAP option was cost-saving, cost-neutral, and uneconomical compared with socket fitting, respectively.

RESULTS

COST ESTIMATION FOR SOCKET

The total costs over a 6-year funding cycle with yearly costs allocated to labor and parts for provision of socket prostheses in relation to K-level classification are provided in Table 1.

Table 1
Table 1:
Total costs over 6-year funding cycle with yearly breakdown for costs allocated to labor (number of items corresponding to PSP hours) and parts for provision of socket prostheses in relation to K-level classification

The costs allocated for K1, K2, and K3 were 58%, 72%, and 85% of total cost allocated to K4, respectively. The total costs for labor and parts corresponded to 46% and 54%, 38% and 62%, 32% and 68%, as well as 27% and 73% of the total costs for socket fitting at K1, K2, K3, and K4, respectively. The total costs for attachment and components corresponded to 57% and 43%, 47% and 53%, 39% and 61%, as well as 33% and 67% of the total costs for socket fitting at K1, K2, K3, and K4, respectively.

COST ESTIMATION FOR BONE-ANCHORED PROSTHESIS

Total costs over 6-year funding cycle with yearly costs estimated for labor and parts for provision of BAP with three fitting options are provided in Table 2.

Table 2
Table 2:
Total costs over 6-year funding cycle with yearly breakdown for costs estimated for labor (number of items corresponding to PSP hours) and parts for provision of bone-anchored prostheses with three fitting options including low-cost, budget, and high-cost limbs

The costs estimated for low-cost and budget options were 72% and 91% of total cost estimated for high-cost option, respectively. The total costs for labor and parts corresponded to 32% and 68%, 25% and 75%, as well as 23% and 77% of the total costs for BAP fitting with low, budget, and high-cost options, respectively. The total costs for attachment and components corresponded to 10% and 90%, 8% and 92%, as well as 7% and 93% of the total costs for BAP fitting with low, budget, and high-cost options, respectively.

COST COMPARISON BETWEEN SOCKET AND BONE-ANCHORED PROSTHESIS

Raw differences in labor, parts, and total costs over 6-year funding cycles between each BAP and K-level socket fitting options are detailed in Table 3. Relative differences in total cost were also expressed in percentage of socket fitting option and presented in Figure 3.

Table 3
Table 3:
Differences in total costs over 6-year funding cycle for labor and parts between each bone-anchored prosthesis and K-level socket fitting option
Figure 3
Figure 3:
Differences in total costs over a 6-year funding cycle between each bone-anchored prosthesis and K-level socket fitting option expressed in percentage socket options.

The labor and attachment costs were reduced by 18% and 79% for all BAP options compared with any socket fitting, respectively.

For BAP low-cost option, the cost of parts was 53% more expensive than fitting for K1, as well as 7%, 18%, and 35% more economical than fitting for K2, K3, and K4, respectively. The cost of components was 153%, 65%, and 21% more expensive than fitting for K1, K2, and K3, respectively, but 6% more economical than fitting for K4.

For the BAP budget option, the cost of parts was 112%, 48%, and 14% more expensive than fitting for K1, K2, and K3, respectively, as well as 9% more economical than fitting for K4. The cost of components was more expensive than fitting for K1 by 228%, K2 by 113%, K3 by 57%, and K4 by 22%.

For the BAP high-cost option, the cost of parts was 140%, 68%, and 29% more expensive than fitting for K1, K2, and K3, respectively, as well as 3% more economical than fitting for K4. The cost of components was more expensive than fitting for K1 by 264%, K2 by 137%, K3 by 74%, and K4 by 36%.

DISCUSSION

OUTCOMES

This study considered only the costs for provision of BAP that QALS deemed acceptable on balance with resources (e.g., governmental budget) and anticipated outcomes for consumers. Consequently, considerations for additional expenses (e.g., surgical, rehabilitation, and medical care) that would provide a more holistic view of the cost of BAP were beyond the scope of this study.

However, this study provided new knowledge by estimating and comparing the itemized costs (i.e., labor vs. parts and attachment vs. components) for provision of transfemoral prostheses for K-levels and different BAP fittings. This study revealed that BAPs were more economical by approximately $18,200, $7,000, and $1,600 over 6 years when fitted with low-cost, budget, and high-cost MPK units, respectively, compared with sockets for K4. B.P. fitted with low-cost MKPs were the only more economical fitting compared to all sockets above K2. All the other BAP fitting options were uneconomical compared with socket fittings below K4.

Furthermore, itemized analysis provided some insights into the relative current weight of industry sectors driving the costs for provision of BAP. This study showed the relative importance of the workforce when labor costs were compared with parts costs. As expected, the breakdown of component costs showed that typical manufacturers of conventional prosthetic knees and feet can strongly impact the overall costs. More surprisingly, this study showed that manufacturers of osseointegrated fixations themselves could play a decisive role given the importance of the cost of connectors and protective devices they commercialized. Indeed, significant variations in the costs of these parts could greatly increase the total cost and possibly make all BAP fitting options uneconomical.

However, the financial cost per individual that could possibly be covered by governmental organizations to provide BAP is only one aspect of the overall procedure. For instance, BAP will always cost more for individuals classified as K0 but will provide them with better opportunities to increase functions and possibly will play a socioeconomic role (e.g., employment). Consequently, a more holistic assessment of the overall benefits would require considering how the additional cost could be offset by an increase in quality-adjusted life-years (QALYs). Ultimately, both total cost and QALY would be needed to determine the cost-utility of BAP and, eventually, help decision makers to establish relevant incremental cost-effectiveness ratio.

LIMITATIONS

The generalization of these outcomes must be considered carefully given the typical intrinsic limitations inherent to estimation of costs over time (e.g., simulation for single limb vs. actual cost for cohort of individuals) associated with labor (e.g., no consideration for Consumer Price Index) and prosthetic components (e.g., release of new conventional and BAP-specific components) in a fast-developing clinical field (e.g., development of several osseointegrated devices at various stages of development in United States and Europe, new rehabilitation procedure, and neuroprostheses).63–72

Generalization might also be limited by some contextual determinants that were Australian and, potentially, Queensland state specific (e.g., cost in Australian dollars, policy guiding allowable labor and parts expenses, and cost of prosthetic components). However, the methodology for cost estimation proposed in this study should easily accommodate adjustments required to replicate a similar cost comparison in another jurisdiction elsewhere in the world.73,74

FUTURE STUDIES

A better understanding of the cost comparison proposed here will be facilitated by future longitudinal studies looking at costs estimated for different governmental organizations (e.g., health care systems) and, more importantly, by studies comparing the actual costs for provision of both socket prosthesis and BAP with different types of components for large cohorts over an extended period.42,55,75

Possibilities for additional cross-sectional studies are endless, particularly for the ones associating fixed (e.g., primary vs. secondary intervention) and ongoing costs with all other socioeconomic aspects of the BAP procedure (e.g., out-of-pocket expenses, surgical and medical costs, QALY, cost-effectiveness, cost-utility, and large-scale simulations) as well as clinical benefits (e.g., health-related quality of life and walking ability) and safety (e.g., infection and incidence of fall) for a broader case mix (e.g., single and bilateral transfemoral, transtibial, transhumeral, and transradial amputations).27,32,51,57,61,73,74,76–81

CONCLUSIONS

An attempt on cost cross-comparison for provision of sockets and BAP from a governmental organization's perspective was shared for the first time. This work was an initial effort toward the development of fair and equitable governmental financial assistance programs for individuals choosing BAP. Altogether, this study should be considered as a stepping stone providing a working approach for BAP cost assessments to other organizations worldwide.

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Keywords:

amputation; artificial limb; bone-anchored prosthesis; cost; osseointegrated implants; osseointegration; prosthesis; reimbursement

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