16. Arthroplasty Registries: Quantifying Your Revised Knee Experience

Check boxBlog 15 walked us through some of the issues defective joint replacement devices cause and the nefarious role the U.S. FDA’s Fast-Track System plays in bringing implants to market, worldwide, without the benefit of rigorous clinical studies to test their safety and effectiveness. I implored you to do what I did not: know your own make and model so that you can more effectively troubleshoot its weaknesses.  Blog 15 concluded with a list of baseline questions to ask your surgeon before agreeing to a revision knee surgery, having determined, unequivocally, that knowing more about your knee implant than less protects you as best as possible, given that we cannot know exactly how well a device will function until it is in you. But we can also do better at tracking knee implants and their after-shocks than we have in the past.

Let’s clarify:  the ideal revised knee replacement implant will allow for baseline normal activities such as walking some blocks to and from the grocer’s and then putting away the groceries; normal motion such as sitting, getting up, turning around while holding something, or carrying a  (light) basket of laundry. They are not designed to enable you to return full force to contact or high-impact sports. Hypothetically, a revised knee replacement, with significant lifestyle modifications, might or could last a patient’s lifetime, if you are in your late 60’s or 70’s. Right now, younger recipients have more demand on them to adapt more careful lifestyles, to pace themselves even more carefully and acquire the grace to do so in order to side-step depression.  So, additional factors besides make and model of a new device also determines the success of a revised knee implant: body structure (ergonomics), pre-existing physical and bio-chemical conditions, and degree of physical discipline by the patient – these along with access to support services and a manageable home environment, financial (flexible employment) and food security, ready access to family and friends, and to consistent physical therapy: these and probably more contribute to positive, long-term outcomes.

So too does having a tool that collects and assesses the strengths, weaknesses and problems associated with implants, the surgical methods used to secure them into bodies, and the rehabilitation programs supporting the recipient. That tool is oftentimes called a Joint Replacement Registry and relies on quantifiable input from surgeons and patients.  It was Sweden that, in 1975, established the world’s first database registry. Now there are well over 35 different registries worldwide designed with the same aim: to provide evidence-based information to guide physicians and patient’s decision-making, and to improve follow-up care, implant design, and surgical techniques. Or, as the American Joint Replacement Registry succinctly put it: To Improve Orthopedic Care Through Data.

AJRR photo coverThe American Joint Replacement Registry (AJRR) has grown to be the world’s largest registry of hip and knee replacement data by annual procedural count. As of November 1, 2019, the Registry contains data on over 1.8 million procedures from hospitals, ambulatory surgery centers (ASCs), and private practice groups in all 50 states and the District of Columbia, to date. It will also need to accommodate increasing numbers of Total Knee Replacement procedures and their associated Revision procedures.  By 2030, The American Association of Orthopedic Surgeons anticipates an additional 120,000 revision procedures alone. That is a jaw-dropping 190 percent increase from 2019.  Unless Regenerative Medicine offers alternatives to metal on bone procedures soon, these numbers will more than double by 2060 (when Revisions are expected to number 253,000, a 400 percent increase from 2019).  These are numbers we do not need to be proud of.  They do not strictly represent improvements in joint repairs, but how market-driven the American culture of orthopedic health care is to combat bone problems quickly with intrusive metal solutions that do not always ensure safe short-term or long-term successes, especially for revision recipients.

But the capacity of the Registry is helpful.  The AJRR is able to search within its inputted data, run reports, and compare a hospital or clinic’s performance to national benchmarks. It also allows surgeons to develop personalized dashboards to summarize their own procedural, post-operative, and patient care data so they can compare their own performances against national benchmarks.


For those of us living in countries with such registries their value is as strong as the data inputted. I encourage you to determine, before you have surgery, if your surgeon participates in a Joint Replacement Registry. If not, keep searching for a surgeon who does. Once you find her, familiarize yourselves with the patient reported outcome measurement (PROM) tools of the registry available to you. In the case of the American Joint Replacement Registry three patient-focused assessment tools are primarily depended on:

  1. PROMIS-10 GLOBAL assessment tool: This tool was designed to be a “bottom-line” assessment of a patient’s health used for a wide variety of diseases. Is it sufficient for assessing the complexity of a person’s life? Yes and No. Filling out the form as instructed dutifully informs the Registry. But its generalized questions require you to summarize what can be conflicting and contradictory information during your post-surgery follow-up. More on this below.

The PROMIS-10 GLOBAL tool is free and accessible at this site:                    http://www.orthotoolkit.com/promis-10. You can probably even pick one up at your surgeon’s office. Note that you can also complete the assessment online as well as print off an empty one and fill it in with a pen or pencil.

  1. Knee Injury and Osteoarthritic Survey (KOOS): KOOS asks for information specifically about your knee (a similar survey focuses on hips, called HOOS). It strives to capture both your physical and personal experiences adjusting to a damaged knee. Unlike the PROMIS-10 GLOBAL assessment tool, KOOS tries to accommodate changes patients make in their lives to accommodate a damaged or a healing knee joint. Like the PROMIS-10 GLOBAL tool, it does not offer the patient space to clarify or describe exceptions or additional factors informing the generalized answers. KOOS offers long and short forms of Knee Injury and Osteoarthritis Score survey.  They are free and easy to access: koos.nu/koos-english.pdf  and www.physio-pedia.com/Knee_Injury_and_Osteoarthritis_Outcome_Score.
  1. Veterans Rand or VR-12: The questions in this survey correspond to seven different health domains: general health perceptions, physical functioning, role limitations due to physical and emotional problems, bodily pain, energy/fatigue levels, social-functioning and mental health. Answers are summarized into two scores, a Physical Component Score (PCS) and a Mental Component Score (MCS) which then provides an important contrast between the respondents’ physical and psychological health status before and after the surgery. Take a look at this tool at aaos.org/uploadedFiles/Veterans%20RAND%2012%20(VR-12).pdf (Some Registries may link and blend this tool’s scores with the PROMIS-10 GLOBAL above).

Do these patient centered tools capture all the important factors impacting knee revision surgery?

They try. It is important to honor the efforts of the Registries. Without them, we would be riding roughshod into the wild west of joint experimentation while relying only on advertisements to guide us. But it is also important to recognize the limitations of the Registry.  Some hospitals and clinics offer their own cocktails of questionnaires, or none at all: When prepping for my revision surgery in Italy, I received a KOOS but not a PROMIS-10 GLOBAL. For follow-up in Bangkok, I did not fill out any patient assessment form. In the USA, these three patient-centered tools are typically given in tandem but not by all surgeons, hospitals, clinics, and post-surgical centers since participating in the American Joint Replacement Registry is voluntary.


Keep in mind that the trauma generated by a revision knee surgery and the associated medications taken afterwards can easily cloud our ability to recall details. And, since these assessment tools force us to check boxes, they do not include space for patients to add additional text to clarify or detail exactly how or why they answer what they answer. I suggest creating your own space on each assessment and jotting down your pertinent details. By doing this, and keeping copies of your own self-assessments, you can gauge how you are doing before and after your knee replacement without forgetting important facts. Complete an assessment before each doctors’ visit. That way you can remember to articulate what is important to you while also helping your surgeon inform the Registry with information important to your surgery and to your repair.

Keeping copies of your assessments can also be very helpful to your physical therapy center for determining specific exercise protocols tailored to your specific needs rather than to a generalized schedule for all implant recipients, as is often the case in the USA.  This practice may be particularly useful if your therapy center depends on rotating therapists in and out of your sessions.

Keeping copies of your assessments can also help inform your legal team should you need to pursue medical malfeasance (See Blog #15).

The PROMIS-10 GLOBAL, highly relied on by the AJRR, seeks general answers to general questions. Take for example question 7c asking for your level of pain, ‘in general’.  We know that pain shifts from hour to hour and depends on our recent physical activity. It also can be chronic or acute depending on activity, weather, or amplified if pre-existing medical conditions exist such as lupus, osteoporosis, or varicose veins. We also know that pain can be shielded by taking anti-inflammatories. Yet, while the surgeon’s AJRR assessment tool includes identifying pre-existing conditions, none of the patient-oriented assessments asks you how you think those conditions affect your healing.  They also do not ask how often you ingest pain killers. So, to answer how, in general, is your level of pain, you must compress or select the facts, skewing your answer away from full representation of your experience.

Be aware that the KOOS and PROMIS-10 GLOBAL are designed to be complementary but without details from patients, completing one without the other eclipses gathering useful data.  For example, The PROMIS-10 GLOBAL Question #5 asks: In general, how would you rate your satisfaction with your social activities and relationships?  Select: ‘Poor’, ‘Fair’, ‘Good’, ‘Very Good’, Excellent’. The KOOS asks in Q2: Have you modified your lifestyle to avoid potentially damaging activities to your knee(s)?  Select: ‘Not at all’, ‘Moderately’, ‘Severely’, or ‘Totally’. They both try for important data that happen to be codependent, but the details are sacrificed for the ability to check a box.


When I answered the PROMIS-10 GLOBAL with a 4+ (out of 5) and without the benefit of completing a KOOS form, I was in a perky mood because I recently had a social outing and I had just been notified that a piece I wrote was going to be published, so I was feeling very good, ‘in general’.  To give that high ranking I compressed all my actual compensation techniques for managing the ongoing pain the revised knee implant had forcibly created. As an extrovert, I returned to more introverted, singular activities in the confines of my own home so I would not have to challenge the knee more than I should: I invested in more online exchanges rather than meeting in person. I strategized how to use (and pay for) various forms of transportation to get from point A to point B, with plenty of days in between to recover from those trips. I regularly swallowed two, 500 mgs. of Tylenol, sometimes more, to get up and go during the first year following surgery and incorporated more applied ice routines and meditation periods into my daily life. So yes, I gave a positive answer despite the machinations I went through to maintain a healthy lifestyle.  The answer did not reflect the success of the surgery itself but of my capacity to adapt.


The revised knee continues to cause problems two years after surgery. But there are no questions in the PROMIS-10 GLOBAL asking about personal resiliency and access to additional resources to adapt.  I swear my Zimmer Biomet NextGen Revision Knee System has a lateral plateau issue. Yet there are no questions asking patients for specific information about where in the joint they experience ongoing pain. I am hard pressed to see how the questions asked by the PROMIS -10 assessment tool communicates strengths and weaknesses of the implant device itself.  How does our (patient) input inform and then influence the design of a device, we ourselves host, if we are not asked direct questions about our experiences with the metal? That I must ask that question raises my concern: what kind of  specific, patient-informed quality-control assessment is used to inform implant designers and their manufacturers? If available, where are they located? As recipients, our ability to communicate to implant device manufactures our experiences of their makes and models is valuable – especially as we continue to serve as guinea pigs.

Without the opportunity for patients to provide full answers to more probing questions, the assessment tools together and separately are inadequate for the purposes of truly ‘improving orthopedic care through data’.  Yet, the responsibility for communicating the realities of our lives to our health care team, and thus the orthopedic industry, is on us, the patients, to ensure complete consideration of the range of effects revision surgeries have on our lives.

However, even if your revision experience is replaced by a numerical figure to communicate your views, your views can matter.  As the AJRR Annual Report 2019 stated, no matter how presumptuously: “Patient Reported Outcome Measurements (PROMs)…are increasingly being utilized to evaluate success of a hip or knee arthroplasty procedure. Many orthopedic stakeholders are finding benefit in capturing this patient perspective to best provide a full picture for surgical outcome evaluation. Recognizing this, AJRR has made a commitment to facilitating capture of this useful data.” Let us help health care providers, manufacturers, and future patients by taking the 5-10 additional minutes needed to complete these summaries by insisting on adding our own clear, raw, therefore important, data.

Other Suggestions to Improve Current Assessment Tools

I am not a statistician nor a physician, but I have been an active patient over the years.  It seems to me that the existing assessment tools, while helpful, could be ‘tweaked’:

  • Assessments are taken within a shorter window of time than the length of dependency on the implant itself. My doctor stopped interviewing me approximately one year after my revision surgery. The worldwide orthopedic industry acknowledges the complexity, no, the severity, of revision surgeries. So, why does the industry stop collecting data after one-year? Two years out from my last surgery, and I am still feeling the effects of this irreversible situation. Why is the registry not formally designed to capture on-going data from this quickly expanding arm of the orthopedic industry?
  • Assessment outcomes are selectively used and communicated. Patient input materials while noted as important do not seem to factor high in the final annual report by the AJRR (2019). For example, to date, the AJRR does not incorporate PROM mental health care outcomes but they are quick to point out the rising numbers of patients ‘satisfied’ with their overall surgical outcome.
  • Assessments are limited in scope. The Revision Arthroplasty Section of the Report does not ask and therefore analyze how pre-existing conditions such as established scar tissue, autoimmune diseases, or osteoporosis impact outcomes.
  • Input from surgeons could be biased. How are surgeon inputs assessed for possible bias in favor of successful surgery outcomes?  It is very possible that doctors skew their input into the Registries to reflect only positive outcomes for themselves or only input negative outcomes due to implant design rather than to dubious surgical procedures.
  • Data is available to patients but you have to look for it.  Go to the AJRR Blog site to initiate ongoing contact with the Registry.  You can even request weekly or monthly updates and input your own responses.  The site: blog.ajrr.net/joint-surgeon-needed-tka . If you want to know the outcomes of your time and effort filling out PROMs, you really must search for their generalized outcomes. And, for now, as recommended above, you must keep your own records and expand on them if you want to keep an accessible ongoing record of your implant experience.
  • Registry guidance is limited. While (for example, the American) Registries are supported by committees that sometimes allow one or two patients to sit on them, globalization of this industry screams for broader patient representation by age, range of implant types, bio-regions, and income-levels.

Are these assessments enough to protect us from medically deficient devices or incapable surgeons? No. We still do not have enough data to determine the best knee replacement implant for someone’s structure.  A surgeon will still favor a familiar make and model, hospitals who purchase the implants will favor cost-effective investments, and fast-tracked devices will still find their way into our bodies unless quickly taken off the market. And, unless a company is sued, (i.e. Zimmer-Biomet, see Blog 15) such devices will more than likely remain on the market for quite some time.

Still, until reliable and less invasive means of managing damaged knee joints are readily available, implants and their associated registries are almost all we have for tracking joint repairs. Let’s make the most of them.

Dr and PT good

BLOG 17, the third in my three-part series, will explore Patient Advocacy Groups and their efforts to help improve knee implant care.



American Joint Replacement Registry: aaos.org/registries/registry-program/american-joint-replacement-registry/

Annual Report, AJRR, 2019: connect.ajrr.net/2019-ajrr-annual-report




http://www.FDA.gov/medical devices





www. aaos-annualmeeting-presskit.org/2018/research-news/sloan_tjr/