Foot & Ankle International - June 2017 - 647

Reddy et al

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Table 4. Regression Analysis.

Teaching hospitals (ref: nonteaching)
Minor teaching
Major teaching
Hospital size (ref: small hospital)
Medium hospital
Large hospital
Location (ref: rural)
Urban
Ownership (ref: government)
For profit
Non profit
Region (ref: New England)
Mid-Atlantic
South Atlantic
East North Central
East South Central
West North Central
West South Central
Mountain
Pacific
Orthopedic specialty (ref: nonorthopedic
specialty)
Orthopedic specialty hospital
No. of orthopedic cases per 100
Hospital overall margins
Margin on TAR cases
Data year (ref: 2011)
2012
Observations
Pseudo-R2

Logistic Regression

Poisson Regression

Outcome Variable: Whether or Not the
Hospital Had a TAR Case in 2011-2012

Outcome Variable: No. of TAR Cases
at the Hospital in 2011-2012

Odds Ratio

Standard Error

Incidence Rate Ratio

Standard Error

1.099
1.449*

0.155
0.264

0.831
1.235

0.136
0.385

1.499
2.068**

0.330
0.507

0.461*
0.295***

0.144
0.109

2.465***

0.584

1.064

0.271

0.954
1.103

0.196
0.187

0.724
0.750

0.175
0.196

1.158
1.467
1.974*
0.741
2.047*
1.511
4.437***
2.070*

0.382
0.470
0.617
0.289
0.722
0.514
1.457
0.684

1.250
2.051
1.503
1.355
2.827**
1.969*
2.335**
3.230***

0.325
0.890
0.392
0.491
0.971
0.632
0.745
1.103

4.112***
1.201***
2.365

1.325
0.020
1.348

0.779

0.244

0.937
1.003**

0.476
0.001

1.124
6485
0.219

0.068

1.171***
741
0.127

0.053

Source: KNG Health Consulting Analysis of 2011 and 2012 100% Medicare Claims.
Abbreviation: TAR, total ankle replacement.
*P<.05, **P<.01, ***P<.001.

health systems are performing TAR because of greater
awareness of its benefits and surgeon ability with the
technique.
Our study shows that utilization of TAR varied across
hospitals based on certain hospital characteristics. We found
that TAR surgeries were more likely to take place in large
and major teaching institutions. This result is consistent
with the view that total ankle arthroplasty is a "specialty"
procedure, requiring a significant learning curve in mastering the operative technique.4 Given the technical complexity associated with performing the procedure, it is often
performed in larger, tertiary-care referral, and major teaching institutions where surgeons with such expertise are
likely to be affiliated. This would also hold true in the case

of the need for revision, which may require a greater level
of expertise and resources. In a prior survey of California's
hospital discharge database, SooHoo et al found that ankle
arthroplasty was associated with a higher rate of major revision surgery relative to arthrodesis.21 A more recent study of
the same database determined that short- and long-term
complications have decreased with time despite an increase
in the utilization of the procedure.22 This is likely the result
of improvements in design instrumentation and overall
safety of the procedure as well as increased experience with
the operative technique.
We also found that hospitals with a specialty in orthopedic surgery and those with a higher rate of non-TAR orthopedic cases were more likely to perform TAR surgeries,
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