The amount of time a patient spends in surgery versus the amount of time spent recovering from surgery

The amount by which the cost of producing custom replacements has declined with the introduction of the new technique for producing them

The degree to which the use of custom replacements is likely to reduce the need for repeat surgery when compared with the use of ordinary replacements

The degree to which custom replacements produced with the new technique are more carefully manufactured than are ordinary replacements

The amount by which custom replacements produced with the new technique will drop in cost as the production procedures become standardized and applicable on a larger scale