Justin Wen, Intellectual Property Consultant, Global Prior Art10.02.17
Since their introduction in the 1960s, knee replacement prosthetics have advanced in technical sophistication, enabling new generations of products to be developed and improved clinical outcomes to be achieved. Despite these improvements, failure rates and patient dissatisfaction remain relatively high. With the number of knee replacement surgeries expected to rise dramatically in the next decade, investing in solutions to address these pitfalls is necessary. In this analysis, the key technological trends driving the orthopedic knee industry are examined and an analysis of patent filings in the field is conducted.
Knee replacement surgeries can be divided up into different groups: total or partial replacement and primary or revision surgery. Total knee replacement consists of replacing all three compartments of the knee—lateral, medial, and patellofemoral. Partial knee replacement consists of replacing just one or two of those compartments. Further, primary knee replacement surgery refers to the initial replacement surgery while revision knee replacement surgery refers to subsequent surgeries to fix or replace a failing component.
In 2010, approximately 4.7 million individuals were living with total knee replacements in the United States—comprising approximately 4.55 percent of all people aged 50 or older in the U.S.1 Annually, approximately 262,000 total knee replacement surgeries were performed in 1999 in the United States., rising to approximately 615,000 in 20082 and projected to increase to 3.48 million surgeries in 2030.3 Analysis of U.S. Medicare data from 1997 to 2004 showed an annual failure rate varying between 0.4 and 0.7 percent for total knee replacements, with a total survival rate of 95.9 percent by the eight-year mark.4 A similar analysis of the National Joint Registry for England and Wales in the United Kingdom for total knee replacements between 2003 and 2012 showed a similar total survival rate of 94.6 percent after eight years. When factoring in non-revision reoperations as a further endpoint, however, the survival rate at eight years drops to 87.2 percent, with partial knee replacement survival rate even lower at 80.4 percent.5 Outside of clinical failures, a study of primary total knee replacements from 2001 to 2005 showed as much as 19 percent of patients were dissatisfied with their replacement after just one year.6
Patient dissatisfaction or the failure of a knee replacement hinges upon a variety of factors. Patient dissatisfaction typically revolves around lingering pain in the knee or inability to perform daily and leisure activities. Clinical failure, however, can be attributed largely to aseptic loosening, instability, or infection. A retrospective review of 844 failed knees operated on at six different orthopedic institutions for revision surgery between 2010 and 2011 showed that 31.2 percent of those surgeries were necessitated by aseptic loosening, 18.7 percent by instability, and 16.2 percent by infection.7
To improve clinical outcomes, knee replacement prosthetic designs have been trending toward customization. In 1974, the Howmedica Total Condylar implant, which was available in three sizes, was introduced. By 1986, the Johnson & Johnson PFC implant was available in six sizes and featured left and right components. Currently, modern knee implants are typically available in eight to 10 sizes for femoral and tibial components.8 Besides customization in the prosthetic components, increased customization is also being pursued in surgical guides and placement jigs, allowing for a level of customization while using standard off-the-shelf prosthetic components.
In such a well-established space, the question remains as to how key players are differentiating themselves and if there are ways new companies can leverage innovation to find space in which to operate. Analysis of patent portfolios in the knee replacement space can yield insights into these questions by identifying the intellectual property strategies employed by different companies. This analysis was limited to U.S. and English-language European (EP) and Patent Cooperation Treaty (PCT) patents and patent applications.
Table 1: Cooperative Patent Classification subgroups. Unshaded subgroups were searched in this analysis, shaded subgroups are provided for hierarchical context.
The search was limited to filings in the past five years and focused on one United States Patent Classification subclass—623/20.14 (prostheses for the knee joint bone)—and 12 Cooperative Patent Classification (CPC) subgroups within the A61B and A61F subclasses (Table 1). The search was further limited by excluding patents with claims focused on surgical jigs/guides/tools, surgical methods, and manufacturing methods. A patent landscape of representative assignees in the field was generated from the collected set of documents. Patent documents relevant to the search focus were attributed for the type of knee replacement prosthetic (total or partial), the component being described (tibial, femoral, or meniscal), and the level of customization (fully customized, not customized, modular components, or multiple sizes/shapes) based on the claims (Table 2).
Table 2: Patents and published applications from top assignees disclosing knee replacement prosthetic designs. Shading is determined by the percentage of each assignee’s portfolio claiming the listed feature, and numbers indicate the number of patents for each feature.
In this analysis, knee replacement prosthetics not customized to an individual patient were the most common, comprising 82.6 percent of all collected documents. These patents were prevalent in the portfolios of traditional orthopedic companies such as Zimmer Biomet (85.4 percent of their collected filings), Johnson & Johnson (97.1 percent), Smith & Nephew (95.5 percent), and Stryker (83.3 percent), while comprising a smaller fraction in the portfolio of ConforMIS (15.8 percent). When considering the varying levels of customization available for knee replacement prosthetics, this analysis found that 26 percent of the collected documents claimed some level of customization with individualized customization to one patient being the most common (15.8 percent) followed by modular components and multiple sizes or shapes (5.1 percent each). Analysis of the type of knee replacement described in the patent shows that specifying either a total or a partial knee replacement was not common—only 13.1 percent of the collected documents specified a total knee replacement and 12.1 percent specified a partial knee replacement. Furthermore, documents claiming details of a femoral (67.8 percent) or a tibial (60.9 percent) component of a knee replacement were far more common than documents claiming details of a meniscal replacement (8.3 percent).
Our analysis also suggests differing IP strategies employed by different companies in the knee replacement space. Johnson & Johnson’s filings remain largely in knee replacements that are not patient customized (97.1 percent) with some that mention utilizing modular components for a level of customization (8.6 percent). Smith & Nephew similarly has filings focused on knee replacements that are not patient customized (95.5 percent). Their filings suggest that, at least in recent years, these two companies have focused on updating non-custom designs rather than innovate in areas of customization. ConforMIS, a relatively new company to the space, is more readily focused on patient customized implants, standing in contrast to Johnson & Johnson and Smith & Nephew. Lastly, Zimmer Biomet’s filings show they are pursuing patent protection for non-customized as well as customized knee replacements. Their strategy addresses updating the designs of traditional non-custom knee implants as well as innovations into fully customized options as well.
Looking at currently available commercial products (Table 3) can further validate the analysis of the IP strategies. Depuy Synthes (subsidiary of Johnson & Johnson) and Smith & Nephew lack any individually customized products, while ConforMIS’ product suite entirely surrounds individually customized knee implants, which closely matches its patent portfolio. An example of Zimmer Biomet’s investment into more customized options is its Gender Solutions suite of prosthetic implants, which have shapes and sizes that are tailored based on gender. Although gender customization is not a feature specifically attributed for in this analysis, when reviewing Zimmer Biomet’s IP portfolio, one granted patent with claims for a gender customized implant (US9173744B2) was discovered. Another patent application in the company’s portfolio has claims directed at implants customized based on ethnic background (US20160000571A1), although that does not currently seem to be a commercially available product.
Table 3: Representative examples of currently available products broken down by company and level of customization.
This analysis of the intellectual property surrounding knee replacements only addresses a fraction of the space, examining patents related to the actual prosthetic but excluding supporting technologies such as surgical guides and tools or advances in converting imaging data to custom components. From this analysis, it is apparent that ConforMIS is actively differentiating itself from competitors by focusing its efforts into individually customized implants while Zimmer Biomet seems to also be exploring opportunities in that space. The other top assignees seem to be sticking with the non-custom options. It is possible that their innovations could be focused more in the areas excluded from this analysis. As the knee implant market continues to expand, these differing strategies employed by the top companies could mark the beginning of a shift in the types of products available. It remains to be seen which of these innovations will prove to be better for patient satisfaction and clinical success.
References
Justin Wen is an IP strategy consultant at Global Prior Art Inc., a Boston, Mass.-based company focused on intellectual property research and analysis. For more than 30 years, Global has served many of the world’s leading companies and law firms, addressing more than 16,000 topics. The author declares no competing interests.
Knee replacement surgeries can be divided up into different groups: total or partial replacement and primary or revision surgery. Total knee replacement consists of replacing all three compartments of the knee—lateral, medial, and patellofemoral. Partial knee replacement consists of replacing just one or two of those compartments. Further, primary knee replacement surgery refers to the initial replacement surgery while revision knee replacement surgery refers to subsequent surgeries to fix or replace a failing component.
In 2010, approximately 4.7 million individuals were living with total knee replacements in the United States—comprising approximately 4.55 percent of all people aged 50 or older in the U.S.1 Annually, approximately 262,000 total knee replacement surgeries were performed in 1999 in the United States., rising to approximately 615,000 in 20082 and projected to increase to 3.48 million surgeries in 2030.3 Analysis of U.S. Medicare data from 1997 to 2004 showed an annual failure rate varying between 0.4 and 0.7 percent for total knee replacements, with a total survival rate of 95.9 percent by the eight-year mark.4 A similar analysis of the National Joint Registry for England and Wales in the United Kingdom for total knee replacements between 2003 and 2012 showed a similar total survival rate of 94.6 percent after eight years. When factoring in non-revision reoperations as a further endpoint, however, the survival rate at eight years drops to 87.2 percent, with partial knee replacement survival rate even lower at 80.4 percent.5 Outside of clinical failures, a study of primary total knee replacements from 2001 to 2005 showed as much as 19 percent of patients were dissatisfied with their replacement after just one year.6
Patient dissatisfaction or the failure of a knee replacement hinges upon a variety of factors. Patient dissatisfaction typically revolves around lingering pain in the knee or inability to perform daily and leisure activities. Clinical failure, however, can be attributed largely to aseptic loosening, instability, or infection. A retrospective review of 844 failed knees operated on at six different orthopedic institutions for revision surgery between 2010 and 2011 showed that 31.2 percent of those surgeries were necessitated by aseptic loosening, 18.7 percent by instability, and 16.2 percent by infection.7
To improve clinical outcomes, knee replacement prosthetic designs have been trending toward customization. In 1974, the Howmedica Total Condylar implant, which was available in three sizes, was introduced. By 1986, the Johnson & Johnson PFC implant was available in six sizes and featured left and right components. Currently, modern knee implants are typically available in eight to 10 sizes for femoral and tibial components.8 Besides customization in the prosthetic components, increased customization is also being pursued in surgical guides and placement jigs, allowing for a level of customization while using standard off-the-shelf prosthetic components.
In such a well-established space, the question remains as to how key players are differentiating themselves and if there are ways new companies can leverage innovation to find space in which to operate. Analysis of patent portfolios in the knee replacement space can yield insights into these questions by identifying the intellectual property strategies employed by different companies. This analysis was limited to U.S. and English-language European (EP) and Patent Cooperation Treaty (PCT) patents and patent applications.
Table 1: Cooperative Patent Classification subgroups. Unshaded subgroups were searched in this analysis, shaded subgroups are provided for hierarchical context.
The search was limited to filings in the past five years and focused on one United States Patent Classification subclass—623/20.14 (prostheses for the knee joint bone)—and 12 Cooperative Patent Classification (CPC) subgroups within the A61B and A61F subclasses (Table 1). The search was further limited by excluding patents with claims focused on surgical jigs/guides/tools, surgical methods, and manufacturing methods. A patent landscape of representative assignees in the field was generated from the collected set of documents. Patent documents relevant to the search focus were attributed for the type of knee replacement prosthetic (total or partial), the component being described (tibial, femoral, or meniscal), and the level of customization (fully customized, not customized, modular components, or multiple sizes/shapes) based on the claims (Table 2).
Table 2: Patents and published applications from top assignees disclosing knee replacement prosthetic designs. Shading is determined by the percentage of each assignee’s portfolio claiming the listed feature, and numbers indicate the number of patents for each feature.
In this analysis, knee replacement prosthetics not customized to an individual patient were the most common, comprising 82.6 percent of all collected documents. These patents were prevalent in the portfolios of traditional orthopedic companies such as Zimmer Biomet (85.4 percent of their collected filings), Johnson & Johnson (97.1 percent), Smith & Nephew (95.5 percent), and Stryker (83.3 percent), while comprising a smaller fraction in the portfolio of ConforMIS (15.8 percent). When considering the varying levels of customization available for knee replacement prosthetics, this analysis found that 26 percent of the collected documents claimed some level of customization with individualized customization to one patient being the most common (15.8 percent) followed by modular components and multiple sizes or shapes (5.1 percent each). Analysis of the type of knee replacement described in the patent shows that specifying either a total or a partial knee replacement was not common—only 13.1 percent of the collected documents specified a total knee replacement and 12.1 percent specified a partial knee replacement. Furthermore, documents claiming details of a femoral (67.8 percent) or a tibial (60.9 percent) component of a knee replacement were far more common than documents claiming details of a meniscal replacement (8.3 percent).
Our analysis also suggests differing IP strategies employed by different companies in the knee replacement space. Johnson & Johnson’s filings remain largely in knee replacements that are not patient customized (97.1 percent) with some that mention utilizing modular components for a level of customization (8.6 percent). Smith & Nephew similarly has filings focused on knee replacements that are not patient customized (95.5 percent). Their filings suggest that, at least in recent years, these two companies have focused on updating non-custom designs rather than innovate in areas of customization. ConforMIS, a relatively new company to the space, is more readily focused on patient customized implants, standing in contrast to Johnson & Johnson and Smith & Nephew. Lastly, Zimmer Biomet’s filings show they are pursuing patent protection for non-customized as well as customized knee replacements. Their strategy addresses updating the designs of traditional non-custom knee implants as well as innovations into fully customized options as well.
Looking at currently available commercial products (Table 3) can further validate the analysis of the IP strategies. Depuy Synthes (subsidiary of Johnson & Johnson) and Smith & Nephew lack any individually customized products, while ConforMIS’ product suite entirely surrounds individually customized knee implants, which closely matches its patent portfolio. An example of Zimmer Biomet’s investment into more customized options is its Gender Solutions suite of prosthetic implants, which have shapes and sizes that are tailored based on gender. Although gender customization is not a feature specifically attributed for in this analysis, when reviewing Zimmer Biomet’s IP portfolio, one granted patent with claims for a gender customized implant (US9173744B2) was discovered. Another patent application in the company’s portfolio has claims directed at implants customized based on ethnic background (US20160000571A1), although that does not currently seem to be a commercially available product.
Table 3: Representative examples of currently available products broken down by company and level of customization.
This analysis of the intellectual property surrounding knee replacements only addresses a fraction of the space, examining patents related to the actual prosthetic but excluding supporting technologies such as surgical guides and tools or advances in converting imaging data to custom components. From this analysis, it is apparent that ConforMIS is actively differentiating itself from competitors by focusing its efforts into individually customized implants while Zimmer Biomet seems to also be exploring opportunities in that space. The other top assignees seem to be sticking with the non-custom options. It is possible that their innovations could be focused more in the areas excluded from this analysis. As the knee implant market continues to expand, these differing strategies employed by the top companies could mark the beginning of a shift in the types of products available. It remains to be seen which of these innovations will prove to be better for patient satisfaction and clinical success.
References
- Kremers, Hilal Maradit, Dirk R. Larson, Cynthia S. Crowson, Walter K. Kremers, Raynard E. Washington, Claudia A. Steiner, William A. Jiranek, and Daniel J. Berry. “Prevalence of Total Hip and Knee Replacement in the United States.” The Journal of Bone and Joint Surgery-American Volume 97.17 (2015): 1386-397. Web.
- Losina, Elena, Thomas S. Thornhill, Benjamin N. Rome, John Wright, and Jeffrey N. Katz. “The Dramatic Increase in Total Knee Replacement Utilization Rates in the United States Cannot Be Fully Explained by Growth in Population Size and the Obesity Epidemic.” The Journal of Bone and Joint Surgery-American Volume 94.3 (2012): 201-07. Web.
- Kurtz, Steven, Kevin Ong, Edmund Lau, Fionna Mowat, and Michael Halpern. “Projections of Primary and Revision Hip and Knee Arthroplasty in the United States from 2005 to 2030.” The Journal of Bone and Joint Surgery (American) 89.4 (2007): 780-85. Web.
- Slover, James D., Harry E. Rubash, Henrik Malchau, and Joseph A. Bosco. “Cost-Effectiveness Analysis of Custom Total Knee Cutting Blocks.” The Journal of Arthroplasty 27.2 (2012): 180-85. Web.
- Liddle, Alexander D., Andrew Judge, Hemant Pandit, and David W. Murray. “Adverse outcomes after total and unicompartmental knee replacement in 101 330 matched patients: a study of data from the National Joint Registry for England and Wales.” The Lancet 384.9952 (2014): 1437-445. Web.
- Bourne, Robert B., Bert M. Chesworth, Aileen M. Davis, Nizar N. Mahomed, and Kory D. J. Charron. “Patient Satisfaction after Total Knee Arthroplasty: Who is Satisfied and Who is Not?” Clinical Orthopaedics and Related Research 468.1 (2009): 57-63. Web.
- Schroer, William C., Keith R. Berend, Adolph V. Lombardi, C. Lowry Barnes, Michael P. Bolognesi, Michael E. Berend, Merrill A. Ritter, and Ryan M. Nunley. “Why Are Total Knees Failing Today? Etiology of Total Knee Revision in 2010 and 2011.” The Journal of Arthroplasty 28.8 (2013): 116-19. Web.
- Slamin, John, and Brian Parsley. “Evolution of customization design for total knee arthroplasty.” Current Reviews in Musculoskeletal Medicine 5.4 (2012): 290-95. Web.
Justin Wen is an IP strategy consultant at Global Prior Art Inc., a Boston, Mass.-based company focused on intellectual property research and analysis. For more than 30 years, Global has served many of the world’s leading companies and law firms, addressing more than 16,000 topics. The author declares no competing interests.
