3-D Printing and the Future of Joint Replacement: “Knee”rly There or Ready For Total Replacement?

What role is 3D printing playing in commercializable knee replacement implants?

The global joint reconstruction and replacement industry is $15+ billion and growing.[1] Among all total replacement procedures, total knee replacements (TKR), indicated for patients with severe osteoarthritis, make up almost 50%; nearly a million total knee replacements are expected to be conducted in the US alone in 2018.[2]

Patient outcomes are excellent—TKR is highly successful in reducing pain and restoring function for patients with severe osteoarthritis. Both patients and surgeons report satisfaction levels of over 90% after 12 months.[3] Implant production is highly concentrated among five major players (Zimmer, DePuy Synthes, Stryker, Biomet, and Smith & Nephew) that collectively hold about 90% of global joint manufacturing market share.[4]

So then why was joint replacement manufacturing startup ConforMIS able to raise $135 million on the day of its 2015 IPO?[5] The answer lies in ConforMIS’s additive manufacturing approach to custom-built implants.

Typically, knee replacement implants are made in standardized sizes. The operating surgeon selects amongst these options weighing considerations including alignment and size.[6]

By contrast, ConforMIS uses a CT scan of the patient’s knee to 3D print a wax mold. An implant is then created on this mold, allowing for total customization of the implant to the patient’s anatomy. In clinical trials, the ConforMIS product demonstrated better rotational alignment and tibial fit without causing overhang of the tibial tray when compared with three standardized sizes of implants.[7]

While the long term implications are s yet to be seen, ConforMIS’s use of additive manufacturing and bespoke implants may shorten recovery times, potentially lowering the cost of TKR. Furthermore, it may lower the cost of a customized implant, putting one within reach of patients who would otherwise be cost-prohibited.[8] In an industry where surgeons, the key decision maker in implant selection, are driven by both product factors and vendor sales rep characteristics, ConforMIS’s unique product offering may differentiate it from the entrenched players, providing a competitive advantage despite its small size.[9]

Furthermore, ConforMIS’s technology is already usable in developing and selling add-on products to its implants, including the iJig Instrumentation kit. Using the same CT scan that is used to generate the wax mold, ConforMIS uses 3D printing to create a fully customized surgical implementation toolkit. The tools are both customized and disposable, eliminating the need for post-op sterilization.[10]

However, given the high success rate of existing implant technology, is customization of joint replacement implants even a big enough need to justify ConforMIS’s investment? Or will customized implants remain a niche market for only the most complicated of cases, and if so, is ConforMIS’s solution customized to the patient’s existing anatomy even the most appropriate given the patient’s level of deviation from the ideal?

To stay at the vanguard of personalized medicine, ConforMIS may need to both continue its development of add-on materials to its customized implants and look to the more complicated issue of 3D bioprinting of biocompatible cartilage. While cartilage regeneration is a key unmet need for osteoarthritic patients, bioprinting of cartilage is still in lab stages, as commercializable biocompatibility is yet to be achieved.[11],[12] To truly be the future of the crowded joint replacement market, however, ConforMIS will need to further disrupt the TKR paradigm.

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[1] Source: “Joint Reconstruction and Replacement: Materials, Technologies, and Global Markets,” via BCC Research, accessed November 2018.

[2] Ibid.

[3] Harris, I. A., Harris, A. M., Naylor, J. M., Adie, S., Mittal, R., & Dao, A. T. (2013). Discordance Between Patient and Surgeon Satisfaction After Total Joint Arthroplasty. The Journal of Arthroplasty, 28(5), 722–727. https://doi.org/10.1016/j.arth.2012.07.044.

[4] Source: “Joint Reconstruction and Replacement: Materials, Technologies, and Global Markets,” via BCC Research, accessed November 2018.

[5] Grunewald, Scott J., “3D Printed Knee Replacement Manufacturer ConforMIS (CFMS) Raises $135M As The Company Goes Public”, 3DPrint.Com, July 2, 2015, https://3dprint.com/78272/conformis-3d-printed-knee/, accessed November 2018.

[6] Burns, L. R., Housman, M., Booth, R., & Koenig, A. (2018). Physician preference items: what factors matter to surgeons? Does the vendor matter? Medical Devices: Evidence and Research, Volume 11, 39–49. https://doi.org/10.2147/mder.s151647.

[7] Martin, G., & Schroeder, L. (2018). In Vivo Tibial Fit and Rotational Analysis of a Customized, Patient-Specific TKA versus Off-the-Shelf TKA. The Journal of Knee Surgery. https://doi.org/10.1055/s-0038-1653966.

[8] Spaeth, Dennis, “3D Printing is Changing the Face of Multiple Industries,” ECN: Electronic Component News 61, no.9 (October 2017): 21-23.

[9] Burns et. al., Medical Devices: Evidence and Research, Volume 11, 39–49.

[10] Source: ConforMIS website, https://www.conformis.com/custom-made-knee-implants/products/ijig/. Accessed November 2018.

[11] Chen, H., Malheiro, A. de B. F. B., van Blitterswijk, C., Mota, C., Wieringa, P. A., & Moroni, L. (2017). Direct Writing Electrospinning of Scaffolds with Multidimensional Fiber Architecture for Hierarchical Tissue Engineering. ACS Applied Materials & Interfaces, 9(44), 38187–38200. https://doi.org/10.1021/acsami.7b07151.

[12] Jammalamadaka, Udayabhanu and Tappa, Karthik. Recent Advances in Biomaterials for 3D Printing and Tissue Engineering. Journal of Functional Biomaterials, 9(1), 22. https://doi.org/10.3390/jfb9010022.


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Student comments on 3-D Printing and the Future of Joint Replacement: “Knee”rly There or Ready For Total Replacement?

  1. I am interested to understand whether the improved clinical results are due to the customized shape of the implant or the material used by ConforMIS. As you mentioned in the analysis, if the customized shape is their competitive advantage (and the results are not significantly better than TKRs using traditional technology) that may not be enough for the industry to shift. However, if the material used also results in improved outcomes, ConforMIS can capitalize on that opportunity while experimenting with bioprinting. Do you think the real value of additive manufacturing is in the ability to quickly/efficiently build custom products or in the future potential of manufacturing with previously hard to mold materials?

  2. I really enjoyed reading your insightful piece about TKR and additive manufacturing. As you have clearly demonstrated in your evidence, this is an area of great need (with 1M TKRs performed this year in the US alone). Personalized 3D printed joints, I believe, will fundamentally change patient outcomes and satisfaction. I wonder if you know how many of those million TKRs are repeat TKRs? Despite this being quite a routine procedure, my guess is that there is a not insignificant number of repeat TKRs every year, due to poorly fitting replacements, infections, etc. I think this would offer further evidence toward a need for personalized replacements. I also would wonder what the price point is, and how this company is thinking about using this model for additive manufacturing in rural or underserved settings where you could print a joint in the middle of Nebraska, for example, where you might not have easy access to the best supply chain from Stryker, etc. Thanks for an interesting commentary!

  3. This is a really interesting usage of additive manufacturing. I suspect that, as the entire joint replacement market advances and patient outcomes improve, bespoke replacements will become even more important and poorly fitting replacements will no longer be tolerated. I would be interested to hear how this has developed over the past 10 years as these methods have come into play.

  4. This was a very informative and interesting post. I have read a bit about the benefits of 3D printing in the medical device sector, so it was very interesting to learn more about a real example. My main question would be about the real driver of adoption of this technology in this space given that patient outcomes are already so high. If the existing technology is already working well, what is the motivate to invest in expensive 3D printing capabilities?

  5. I think this has a huge potential going forward. Unfortunately my aunt is in the 10% of total knee replacement patients who has not gained full mobility of her joint 12 months post-surgery (this might also serve to answer the above comment as to why it is still necessary to invest in improving the technique). I think that if she had been able to use this technology and have a customized knee replacement she could have had a better outcome. My biggest hope is that as the technology matures the price of the service will go down making this a plausible solution for all patients.

  6. I found this article very interesting. I think that ConforMIS offers high value proposition for the unique, critical cases. Unfortunately, my mom is one person who has had multiple TKRs and hip replacements over the course of her life, and has not regained full flexibility of her knee. Given this personal experience, I think that a custom ConforMIS implant plus 3-D printing of bio-compatible cartilage could be very attractive to those patients like my mom who have tried the standard procedures to no avail. To widen its target market, could ConforMIS use its 3-D printing technology for other kinds of implants as well? Before patients are willing to undergo another surgery, however, ConforMIS needs to guarantee that the 3-D printed product has the same longevity as the traditional implants.

  7. This topic is really relevant and close to home as I’ve had orthopedic surgeries. It’s true that existing knee replacement implants are already very successful – yet the surgery is still very challenging to recover from. I think there must be a balance between spending as much money as necessary to find a perfect solution vs. taking a more conservative medical treatment approach and being satisfied with “good enough.” Another key question is what the long term impact is of using 3D-printed implants, as no longitudinal studies have been done given how new the technology is. As you mention, cartilage would be an even bigger game-changer, as it could be shaped into the ideal form to promote healing.

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