Quantitative Analysis of Technological Innovation in Knee Arthroplasty: Using Patent and Publication Metrics to Identify Developments and Trends.

Background: Surgery is in a constant continuum of innovation with refinement of technique and instrumentation. Arthroplasty surgery potentially represents an area with highly innovative process. This study highlights key area of innovation in knee arthroplasty over the past 35 years using patent and publication metrics. Growth rates and patterns are analyzed. Patents are correlated to publications as a measure of scientific support.

Methods: Electronic patent and publication databases were searched over the interval 1980-2014 for "knee arthroplasty" OR "knee replacement." The resulting patent codes were allocated into technology clusters. Citation analysis was performed to identify any important developments missed on initial analysis. The technology clusters identified were further analyzed, individual repeat searches performed, and growth curves plotted.

Results: The initial search revealed 3574 patents and 16,552 publications. The largest technology clusters identified were Unicompartmental, Patient-Specific Instrumentation (PSI), Navigation, and Robotic knee arthroplasties. The growth in patent activity correlated strongly with publication activity (Pearson correlation value 0.892, P < .01), but was growing at a faster rate suggesting a decline in vigilance. PSI, objectively the fastest growing technology in the last 5 years, is currently in a period of exponential growth that began a decade ago. Established technologies in the study have double s-shaped patent curves.

Conclusion: Identifying trends in emerging technologies is possible using patent metrics and is useful information for training and regulatory bodies. The decline in ratio of publications to patents and the uninterrupted growth of PSI are developments that may warrant further investigation.