New Research: Knee and Hip Osteoarthritis Are Different

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hip vs knee arthritis

We all hear the term “arthritis,” and as a result we believe that knee arthritis and hip arthritis are the same disease, just located one joint apart. However, more than a decade of observation and now recent research has taught me that these are two different processes. Understanding this when using regenerative-medicine treatments, like PRP and stem cells, is critical for success.

What Is Arthritis?

There’s a 30,000-foot answer to this question that hasn’t changed much since the 1970s, and then there’s the real answer. From a big picture, disco standpoint, joint arthritis is loss of cartilage, the growth of bone spurs, and increased pain/stiffness. However, our understanding of this disease has been changing rapidly. For example, we now believe that arthritis involves a dance with the bone, which was not previously understood. Meaning what happens to the bone is often a harbinger of what will happen to the cartilage.

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The Visual Differences Between Knee and Hip OA

Any physician who looks at the MRIs of patients with knee and hip osteoarthritis (OA) will soon conclude that these diseases are different. First, hips almost always progress toward a severe state at the speed of light compared to knees. For example, a knee may smolder for many years, slowly losing cartilage and growing bone spurs. However, many hips can go from mild to severe OA within one to two years.

There’s another curious difference between these two joints—cysts. Knee OA rarely presents with bone cysts, and hip OA almost always has them as the disease advances.

A bone cyst is a fluid-filled cavity that is a void of dead tissue. After a small area of the bone dies off, the body walls this area off almost like it does in an infection. It creates a hard shell around the dead area, which structurally shunts the forces that this part of the bone would normally handle around the dead spot.

The Research Showing That Knee and Hip OA Are Different Animals

A few years ago I blogged on a study that showed that the hip was less able to repair itself than the knee. This difference was believed to be due to the differences in the number or inert ability of the progenitor cells in the two joints (these are similar to stem cells but more specifically tasked with repairing the joint). I went searching for that reference last night and instead happened on a brand-new study by the same author that is basically a newer and reswizzled version of the same study.

The new study used an esoteric biomarker for the chronological age of cartilage to determine cartilage turnover. What’s that? Cartilage is constantly renewing itself, which is a process that involves stem cells and mature cartilage cells that produce the substance in which the mature cartilage cells reside. The composition of this substance (called ECM for extracellular matrix) is important, as too much or too little of a certain component will reduce its ability to protect the cartilage cells, leading to their untimely death and a hole in the cartilage surface.

What the authors found was that in knee OA, the cartilage is constantly repairing itself because the age of the cartilage ECM is younger than in hip OA. Basically, hip OA cartilage components were 30 years older than those found in knee OA! Meaning that cartilage in hip OA has very little ability to maintain itself by creating new cartilage ECM.

The upshot? New research confirms what we have observed for years: knee and hip OA are very different disease processes that have a similar endpoint—the joint is destroyed. This research also fits with our registry data (as well as that I’ve seen from others who have presented much smaller patient numbers), that hip OA results in patients with severe arthritis using a same-day stem cell procedure lag that of knee OA results. In addition, this new model of differences in cartilage ECM turnover may also explain why flooding the severe hip OA joint with many more stem cells (through a culture-expanded procedure) seems to give better results than a same day procedure—the hip needs those extra cells whereas the knee OA, in many circumstances, may not.

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This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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61 thoughts on “New Research: Knee and Hip Osteoarthritis Are Different

  1. Linda Britton

    I have had a hip and a knee replaced in my 50s. Now, I have the other hip shot and a knee on it way. I was considering PRP for the hip, which has been bad for 4 years. Are you telling me that procedure is a waste of time and money? What is the approved procedure that works better on the hip, and how much will it set me back in the bank account? Linda B.

    1. Regenexx Team

      PRP is unlikely to help hip arthritis, especially a hip that’s been bad for 4 years, as was discussed in the blog, hip arthritis escalates much more quickly than knee arthritis. Stem cells would likely be needed. As to what type of stem cell procedure, that would be decided in a Candidacy process. Depending on your knee, PRP might be helpful there. If you would like to see if based on medical history, degree of arthritis and other factors, you are a good, fair or poor candidate for a Regenexx procedure, please submit the Candidacy form:

  2. kay williams

    I would like to know, too, Linda..i have plans for knee and hip Regenexx

    1. Regenexx Team

      Not to worry. If you have a procedure scheduled, you’ve been through the Candidacy process, and were given a candidacy rating of good, fair, or poor. We don’t recommend our same day stem cell procedure, Regenexx-SD for severe hip arthritis, so I am assuming your candidacy for your hip was not rated as poor. Having said that some severe hip OA patients given a “poor” candidacy rating do chose to proceed and some get benefit, but that is much less likely.

  3. kay williams

    How often do they check these questions? I am having my procedure soon

  4. Susan Sherrell

    Where’s the answers please?

    1. Regenexx Team

      Sorry, not sure what your question is. Please check the other answers.

  5. Jed Blaich

    I too would like to know about the hip. I am looking at getting the treatment in the coming months.
    Should I go with same day or go to the Cayman clinic for cultured .
    I am 61 and currently have mild OA of the hip.

    1. Regenexx Team

      With mild hip OA, the same day procedure should work well. But many factors go into a Candidacy rating, and it’s that that determines what procedure is recommended. Please submit the Candidate form, and one of Physcians can answer that question once he’s read your films, taken a medical history and spoken to you about your hip. Candidate form Here: You can alternatively go through the Candidacy process at the time of the actual physical exam. It is the exam which directs the final treatment plan.

  6. Cynthia Gentile

    So it is better to have the hip done in the Cayman’s? That sounds ok with me, but I’m scheduled in May in Chicago… ???

  7. Eileen

    I had stem cells injected into my hip 3 weeks ago. I am 60+ and very hopeful that it helps me avoid a hip replacement for a few years. It is a interesting procedure and so much safer than surgery. I am following the recovery plan, plus nutrition, and vitamin supplements + Regenexx stem cell and joint therapy. So hopeful!

    1. Regenexx Team

      It sounds like you are doing EVERYTHING right! Who did your procedure?

  8. Ben

    Yes…we’re all looking forward to your answers. If the Cayman Cultured approach is really now your only serious option for Hip Stem Cell support…any chance the $17,000 price tag may come down?

    1. Regenexx Team

      It’s not that the Cultured procedure done in Caymans is the only option left for hips. Regenexx-SD, the same day stem cell procedure works well for mild and moderate Hip OA. The issue is that since hip arthritis progresses at a drastically accelerated rate when compared to knee arthritis, patients often develop severe hip arthritis very quickly. I doubt the price will come down as there is a lot more involved, and stem cells are stored for future use.

  9. PS

    We all seem to have the same question about the viability of same day stem cell treatment of hip OA. I’m 53 and trying to decide whether to treat my hip or not.

    Anyone here having done a hip? Could you share your experience?

    Thanks and good luck to all!

    1. Regenexx Team

      At 53, if you have hip arthritis, I’d treat it now. As has been said here in other answers, hip arthritis progresses very quickly, and you’re far too young for a hip replacement. As has also been said, the same day procedure works well in mild to moderate hip OA. If you have very severe hip OA, it’s likely that you’d need the cultured procedure.

  10. James S Stevens , Jr .

    Jamie , have been going down in the hips for @ 3 years have talked to a replacement doctor but still have hope for the more natural Regenex ? I live in WV and there are very few choices ?

    1. Regenexx Team

      Yes, Regenexx is very much more natural as it’s using your own stem cells and platelets in Regenerative injections, rather replacing the joint with a prosthesis. While there are no Regenexx Providers in West Virginia, there are several in the surrounding area: See:

  11. Walt

    Ben’s comment is the only one I hav seen that included a dollar amount, no wonder I get no response to my inquiry about price.

    1. Regenexx Team

      These are medical procedures, and medical procedures are based on exam. Once you’ve gone through the Candidacy process, where a Regenexx physician reads your MRI, takes a medical history, speaks to you by phone about your joint issue, goes over medications your taking etc, and decides based on those things whether you are a good, fair or poor candidate and what type of procedure is needed, a ballpark figure can be discussed. However, in the exam itself, the final treatment plan is determined. Ben was speaking about his particular case. A different patient’s both hips were done at another Regenexx location for several thousand less, as it was a simpler case. Therefore subjective discussions about price are not constructive.

  12. Jim Foster

    Jim Foster, April 20 at 2:40pm
    I am still working with diet and exercise as possibilities for my knees and shoulders to come out of this -with full recovery. Eliminating sugar, alcohol and gluten are my basic route. Mentally I only get upset when raising out of bed .- Otherwise during the day- I don’t really have a problem.Coupled with my brain also growing and thinking with exercise !!
    [email protected]

  13. Chris Centeno Post author

    All, with regard to the outcomes of Regenexx-SD (same day stem cell treatment) for hip OA-
    For mild to moderate hip OA, the same day procedure works well.
    For severe hip OA, the same day procedure is not recommended (the patient is placed in the poor category). Having said that, some patients do report relief in this category with a same day procedure, in particular when combined with capsular distension (the injection of platelet growth factors into the hip capsule to stretch ligaments and restore lost range of motion). In general, for patients with severe hip OA, we generally recommend the Cayman procedure.

  14. Terry Clarke

    Hello Everyone…I am interested in the same-day treatment for both of my hips. I was quoted around $7500 for one hip and $10K if I do both at the same time. When I went to my initial consultation with the doc’s in the Los Angeles office, He told me that I have a mild-medium case of OA–although at times it feels severe to me. I was told that he could get me possibly 60-70% better with the same-day treatment and that i was a good candidate due to my age 52, and no previous treatments or injections of the hips. He never mentioned better results in the Caymans. I learned about the Caymans through a webinar presentation where the doctor mentioned that they get much better results in Caymans due to the “cultured” procedure which has been outlawed here in the U.S. I called the office in Caymans and they advised that it’s $17K (I think that’s for one hip–not sure) and it’s a two step process which requires two trips to the Caymans. It also does not cover travel fees, room & board. I am still interested in trying the same-day treatment, but I came here to look for comments from others who had already been through the procedure. So far, this looks like a Q&A session with lots of Q’s but no A’s.

  15. Vern

    The orthos have been telling me for over 3 years that I need a knee replacement. But I have found diet, supplementing,and knee excercises have improved my knee. I am 59 and always been very active. What can I expect from regenexx?

    1. Regenexx Team

      If you’re doing well you need no intervention. Research has found that exercise is better than meniscus surgery, a well balanced low glycemic diet is good for joints, and the right supplements can be joint protective. BUT, if your knee arthritis is progressing despite all of the above, intervening to change that direction and give your knee what it needs to go from destroy to repair mode is important.

  16. Fran

    Ths is a great article. In addition to the differences noted about the arthritis and cartilidge differences, the joints themselves are totally different (ball & socket for hip, hinge w/ some rotation for knee), plus the size is totally different. As a result, suer outcomes are more difficult for hips than knees.. That being said, I am currently in the process of a Regenexx-SD procedure for a hip with moderate arthritis. I can tell, post stem cell injection that things are somewhat better. Had my PRP injection today. From my research, I decided that only PRP would not be enough, thus my decision to follow the Regennexx protocol. I know with moderate arthritis my outcome may not be perfect, but if I have to repeat it, I’ll at least have a good base.

    1. Regenexx Team

      There is something compelling about logic…well said!

  17. Terry Clarke

    While I was writing my last post, I see that Chris Centeno replied with some clarification on the same day hip treatment. This gives me hope because it’s a lot of money to spend for a procedure that might not work. So seeing that there are good results with Regenexx-SD for mild hip OA, I feel better. I will definitely go through with it.

  18. Chris Centeno Post author

    Terry, if you have mild to moderate arthritis, the same day procedure in the US is fine. The big differences in outcome are with moderate to severe OA.

  19. Fran

    I wanted to add one more thing and that is after the stem cell injection in my hip, I was told to be non-weight bearing with no more than a toe touch for balance on that leg until my PRP injection and then 24 hours after the PRP. That is a total of about 11 days on crutches and/or rolling chair to get around the house. I had the crutches and chair, but realized after the fact, that a raised toilet seat and shower chair would be helpful. Thanks goodness I live in a neighborhood where there are many 70+ year olds so I was supplied quickly. These would be good suggestions as part of the preparation protocol. Terry, I know people do both hips at once, but I don’t know how I’d handle the non-weight bearing. Again, knees are different as they have off-loading braces to wear. They were not able to offer a hip version to me but was told it was in the works.

    1. Regenexx Team Post author

      Great suggestion Fran!

  20. Matt

    Do we know how long it takes for shoulder arthritis to progress? You guys are doing incredible work, keep it up!
    Best, Matt

    1. Regenexx Team

      It really depends on what’s causing the arthritis. The shoulder has the greatest range of motion of any joint in the body. To make that possible it’s in a very shallow socket which requires a very elaborate system of tendons, ligaments and muscles to keep it in place. That sets the stage for instability if tendons or ligaments are injured, or just become lax over time, all of which can lead to additional wear and tear on the joint and bone spurs. Avoiding Steroid Shots are very important as they can quickly escalate arthritis.

      1. Matt

        Thanks for your response!

  21. Eric Manalansan

    Great article. Dr. Centeno, what is the difference (amount of cells, ability to specialize, speed to proliferate) between stem cells from peripheral blood (PRP) vs and those from bone marrow? Is stem cell from PRP for mild to moderate OA as good as those derived from bone marrow? Can platelets from PRP recruit stem cells from the synovial membrane & cartilage stem cells from the non-weight bearing part of femoral condyle & Tibial plateau? Thanks for sharing your valuable work, you are helping a lot of people.

  22. Marie Butler

    I really like the idea of stem cell replacement (for my hip) but had to give it up because I was a poor candidate–67, OA-severe, and on a statin drug. I was quite disappointed . so, I gave in to hip replacement, which for now has been good. If you have a good surgeon, this procedure is the next best thing you can do for a hip. I wonder if I should be doing a regimen of pills that Regenexx proposes to save the other hip and joints???

    1. Regenexx Team

      So glad to hear your hip replacement went well! That’s the purpose of the Candidacy process. The patient knows, based on our experience, whether we feel this will work for them or not. Thanks for pointing out what impacted your Candidacy, as it will help others. In answer to your question, the Advanced Stem Cell Support Formula is a great way to support joint health. We put a year’s worth of lab research into testing what ingredients positively impact human mesenchymal stem cells. If you’re the type of person who can tolerate a lot of pills, the Bundle is designed to hit the problem from different angles for maximum benefit.

  23. Gaylon

    I’m checking into the possibility of stem cell treatment for both knees My VA clinic state that I’m a candidate to have both knees replaced and they will cover the operations, but will not cover stem cell injections. They will however cover cortisone shots. Has anyone found any insurance companies that cover stem cell shots administered by Regenexx offices? And if so under what circumstances?

    1. Regenexx Team

      The upside down-ness of that is the million dollar question! But importantly, though covered, steroid shots are a very bad idea: We have not heard of any Insurance Companies that cover stem cell procedures, simply because the Insurance Industry itself has chosen not to cover them.

  24. JH

    To all those with questions about the same day procedure for moderated hip OA, I had this procedure done in November and my hip feels perfect. Absolutely no pain. I can’t tell the difference between my two hips. And I wasn’t able to walk down the beach last summer…

    1. Regenexx Team

      Wonderful news..thanks for sharing it! Regenexx SD has been very successful for so many hip arthritis patients! No medical procedures, especially surgery, come with guarantees because the human body presents too many variables. We just feel it’s important to give people realistic expectations. If you find a stem cell clinic, or any doctor for that matter who gives guarantees or promises 100% success rate…RUN!

  25. Joao Manhaes


    Thank you for the post. I will have my evaluation appointment for my hip pain on May 16 and I am a little anxious to find out if I will be a suitable candidate to the SD procedure. I would not be able to afford a $17K procedure in the Cayman’s. If I do the SD, I will make sure to come back here and tell others about the results. I understand now that everybody needs hope..

    1. Regenexx Team

      We’re hoping with you! Which Dr. are you seeing on May 16?

  26. Joanne Banos

    3 months ago I had my left hip SD stem cell procedure… I’m still working at a job on my feet 10 hr shifts…..I am still in a lot of pain and limp pretty bad… I realize now that my hip OA was in the severe stage and probably should of not been told I was a candidate… Now I have no choice but to get my hip replaced …

    1. Regenexx Team

      Sorry to hear you’re in a lot of pain. Everyone is different. Some people feel great at three months and for some it can be 6-9 months before the full effects of the treatment are apparent. It’s really important to be in touch with your doctor as they know better than anyone else what they would expect in your particular case at what point of recovery. Do you need assistance in reaching them?

  27. Terter

    Your article says that hip OA happens much quicker than knee OA. My knee OA went from mild to bone on bone in two years. Is that unusual, and would it indicate a poor response to your processes?

  28. Ben Orbeck

    I’m unclear on the effects of artificial sweeteners on the stem cell treatment.

    1. Chris Centeno, M.D. Post author

      I would stay away from artificial sweeteners for all sorts of reasons, not the least of which is your stem cells. See

  29. Una

    Do you need to go o the same location for the Candidacy process that you would plan on having the treatment? The closest facility to my homes are 2 hours and it seems like you would need someone to accompany you and or drive you.
    It seems that even if you provide the MRI, history etc you still need a physical exam before candidacy is determined.
    Also how long to you need to be on the supplements before the stem cell procedure.
    Are Synvisc injections a deal breaker?
    Questioning procedure for knee.

    1. Chris Centeno, M.D. Post author

      Many network physicians can do the better part of the candidacy over the phone reviewing history and images, which should save some travel. Most patients take the supplements for about a month before the procedure. SinVisc injections one month or more from the stem cell procedure are fine.

  30. Joanne Banos

    Regenexx team, .. Thankyou for responding to my comment…… I’m now a little but more confused though… You are telling me to give it at least 6 more months to see better results, but my MRI.. Did say Severe OA of my left hip…and the article I read above said Same day stem cell not recommended for severe OA…. Dr. Bowen in NJ did the procedure …he was surprised I’m not getting good results…. I am confused if if I should move forward with a replacement or give it more time… I’m on my feet moving at work and in psin !!!!

  31. Eric Manalansan

    I missed your most recent webcast. I meant to ask the advantage of obtaining stem cells from bone marrow vs peripheral blood (PRP). Thanks for your advise.

    1. Regenexx Team

      Because of the difference in Regenerative Potential. Bone marrow contains the greatest numbers of the different types of stem cells most important in Orthopedic applications like Mesenchymal, Muse, Osteochondroreticular, Hematopoietic, etc. While blood contains some Hematopoietic stem cells, it’s more valuable for it’s platelets which contain growth factors and other natural healing molecules, which are what is concentrated in PRP. We use both Platelets and Stem Cells, the trick is knowing what to use for what.

  32. Joanne Banos

    I would like to make a correction on my earlier post …. I did not have a same day procedure on my severe left arthritic hip. I had Lepogems…because it was in the same day, I thought it was SD stem cell… I wanted to make that correction…. Also Dr. Bowen in N J, is top notch ….

    1. Regenexx Team Post author

      Thanks so much for the update. That’s an easy mistake to make. We continue to wish for the very best for you!

  33. Max

    Thanks for the article! You mentioned the hip ECM is older and presumably hip cartilage doesn’t self-heal. So how does the PRP + stem cell procedure help hip arthritis? Does it only help heal labrum and tighten ligaments and reduce pain or actually create new articular cartilage? I’m a 40 yo very active male with FAI, a labral tear and mild OA in right hip. Trying to understand if I should go for the procedure asap or try extensive PT first. Appreciate your reply to the above questions and any suggestions!

    1. Regenexx Team Post author


      Glad you enjoyed it! Given that the main difference between hip and knee arthritis is that hip arthritis escalates so much more quickly, early intervention with hips is advised. In reference to how stem cells work in a joint, I think this answers your question best: A Regenexx stem cell procedure, however, is not just an injection into the “joint”. All of the issues you mentioned would be treated individually. Please see:

  34. Erin

    Am I a candidate for your stem cell procedure if I have been diagnosed with end stage DJD? Thank you..

    1. Regenexx Team

      Hi Erin,
      Please tell us more…

  35. Sherry

    I had a work related accident in July/2015 from getting up from a chair. I fell on my right side (like a tree in a forest) on thinly carpeted cement flooring. While my lower back was being treated for severe muscle spasms and two bulging disks, my right hip was not, even though I constantly complained about it. MRI showed advanced osteoarthritis last Feb/2018. After relocating my residence, I was assigned a new WC doctor who suggested PT to which I have complied.

    I was an active, extremely fit, individual prior to the accident but have been benched ever since from all my favorite sports.

    I continued with PT with no lasting results. I have extreme flare ups.

    I finally convinced the doctor to do PRP. However, that was 6 weeks ago and I’m still flaring up. He injected my upper thigh and not the hip joint where I believe I have a laberal tear which is connected to my lower back (2) bulging disks. I find that rather odd. After everything I read and researched, I don’t understand why he didn’t inject the joint and around the laberal issue?

    I am concerned about “next steps”. I do not want invasive surgery if at all possible.

    I would appreciate any guidance and hope of a better potential outcome you could offer.

    I am 5’6, 113 lbs, and it great shape for my age (60). I was a paddle boarder, swimmer, dancer, yoga, bike rider, etc.

    I continued PT which ends next week. I often have to pull my pants to move my leg and have extreme difficulty in performing the PT tasks, and my hip clicks and wants to buckle. :(

    Any hope for me RE more PRP/Stem cell?

    Thank you,


    1. Regenexx Team

      Hi Sherry,
      Most Dr’s don’t know how to successfully inject a Hip Labrum tear, , and, don’t take the time to make an accurate diagnosis:

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