hta_ knee intro.qxp - Ministero della Salute

5.2.5 Analysis on purchasing price of knee prostheses
The questionnaires provided information about purchasing prices and volumes by knee system
and, in some cases, also for single system’s components.
On the basis of data from our survey we calculated the mean (weighted) price by the number
of models purchased in 2007. From this calculation we obtained a wide price range (€ 2.154,00 to
€ 5.330,00).
The stratification of all the models of prosthesis according to a single parameter may be very
difficult and subjective (see Appendix 1). We decided to privilege the classification based on the
biomechanics of the replaced knee. To allow a suitable biomechanical behaviour some different
concepts have been applied 18 .
We identified 5 classes of prostheses by our survey:
• Multiradius femoral design;
• Single-radius femoral design;
• Medial pivot design;
• Tricondilar femural design;
• Linked, constrained or hinge systems.
Multiradius and single-radius are the most common designs and widely represented on the
market. Medial pivot and tricondylar designs are more recent and less represented (only one
model for each design).
Linked, constrained or hinge systems present an important mechanical connection between
the femoral and the tibial component. Such designs are used when medio-lateral stability is required
and are not frequently used in primary TKR.
From this stratification we obtained the range of “mean weighted price” for all prostheses purchased
by all centers divided into the 5 classes. Table 5.6 shows that multiradius and single-radius
designs have the same mean, minimum and maximum weighted prices. In the multiradius class
we took into account the price of €4.680,00 because the maximum value of € 5.016,00 is out of
the mean distribution. The other classes have a range that could not be taken into account because
of the low representativeness (use) of the model included. All mean weighted prices identified
in the survey are reported by model of prosthesis and by femoral class. Tables 5.5 and 5.6 refer
only to cemented knee systems.
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