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conditional on other characteristics. This result also supports the notion that a hospital's level of commitment to
orthopedic surgeries and the opportunities it provides to
surgeons in developing their operative skills may be important determinants of a hospital's decision to perform TAR
surgeries. We did not find evidence of a hospital's financial
strength, proxied by the overall hospital margin, limiting a
hospital's decision to perform TAR as the hospital overall
margin was not found to be a statistically significant predictor of a hospital's performance of TAR.
Financial considerations, however, may affect the volume of TAR surgeries a hospital performs conditional on it
performing at least 1 TAR surgery.16,25 We found that among
hospitals that perform at least 1 TAR, the margin on TAR
cases was positively associated with the total number of
TAR surgeries. Our results further revealed that among hospitals that conduct at least 1 TAR, variation in the number of
TAR surgeries was associated with factors that were different from those influencing a hospital's decision to perform
at least 1 TAR. For example, being a teaching hospital, having an orthopedic specialty, and the volume of orthopedic
cases per year were not statistically significant determinants
of the volume of TAR surgeries. This result suggests that
although the substantial operative expertise required to perform TAR may serve as a constraint in TAR utilization
across hospitals, it does not influence the volume of TAR
surgeries performed conditional on performing at least 1
TAR. Finally, among hospitals that had at least 1 TAR, large
hospitals had a lower TAR rate, suggesting that there may
be limits to the adoption of TAR as bed size increases.
Although more institutions were performing TAR, it was
not a profitable endeavor for most, with approximately only
one-third of hospitals being able to demonstrate profitability. Hospitals with an average positive TAR margin were
able to demonstrate lower costs and receive higher payments relative to those with a negative TAR margin. Much
of this difference was related to the difference in prosthesis
costs among institutions, as there was no demonstrable difference in length of stay or the number of TAR cases performed. Specifically, the average prosthesis costs in
profitable hospitals were $2570 and $4031 lower in 2011
and 2012, respectively, than in and nonprofitable institutions (Table 3). Implant costs among centers are variable,
dependent primarily on contracts that are negotiated
between health systems and the individual implant companies. Unfortunately, this raises a potentially difficult scenario for institutions and providers that desire to perform
TARs if it is viewed as a financially prohibitive procedure.
Historically, with respect to total hip and knee arthroplasty,
hospitals have been able to curtail implant expenses.
Currently, some hospitals may be forced to prohibit TAR
because of a negative profit margin. This can further create
an issue with access to care for patients that may have to
travel longer distances to receive an ankle replacement or
potentially handicap providers in performing them. Our

Foot & Ankle International 38(6)
finding that average TAR margin was a determinant of TAR
rate among hospitals with at least 1 TAR surgery further
suggests that a hospital's ability to negotiate or secure better
terms for prosthesis cost and payment for the surgery could
potentially spur the diffusion of TAR across institutions.
Our study has several limitations. First, it only controlled
for hospital characteristics that were observable in the
Medicare claims data; therefore, it did not include other
potential determinants of TAR utilization, such as operative
skills and contractual differences among health systems,
which were not observable in the available data. In addition,
we were limited by the completeness and accuracy of the
Medicare claims data. Second, our analyses are descriptive in
nature and do not necessarily imply causality. Finally, our
study focused on hospital characteristics, which may be considered supply-side factors that are associated with TAR utilization. Future studies should investigate the demand-side
determinants of TAR by investigating patient characteristics.
Author Note
The abstract was presented at 2016 AAOS/AOFAS Specialty Day,
Orlando, FL, March 5, 2016.

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.

Funding
The author(s) disclosed receipt of the following financial support
for the research, authorship, and/or publication of this article: This
study was funded internally and did not have any influence on the
outcome of the study.

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http://www.cms.gov https://www.aamc.org/download/443398/data/september2015evaluatingpaymentaccuracymedicarepatients.pdf https://www.aamc.org/download/443398/data/september2015evaluatingpaymentaccuracymedicarepatients.pdf https://www.aamc.org/download/443398/data/september2015evaluatingpaymentaccuracymedicarepatients.pdf https://data.medicare.gov/Hospital-Compare/Hospital-General-Information/xubh-q36u https://data.medicare.gov/Hospital-Compare/Hospital-General-Information/xubh-q36u

Table of Contents for the Digital Edition of Foot & Ankle International - June 2017