Knee Replacement Rehab [What You Need To Know]

Total Knee Replacement Surgery

Several years ago, when I was a Physical Therapy student, I had the privilege of observing a couple of live surgeries, one of which was a Total Knee Replacement. Simply put, I was blown away at how mechanical the surgeon and his team were during the procedure. The process was precise down to the last detail – the preparation, the cuts, the tools, the measurements – nothing was left to chance. There was no guesswork, just a series of steps that were taken to get the job done.

I’m glad I got to see this surgery in particular because my current workload consists of seeing many patients recovering from Knee Replacements. Over the years I’ve learned a great deal about the rehabilitative process and what it takes to be successful.

Although outcomes are good and success is likely, no one wants surgery – it’s a last resort.

That said, if you struggle with knee pain, there’s good news. There are steps you can take to improve your mobility, strength, and function to delay and, sometimes, bypass surgery altogether.

Let’s take a look at what the knee replacement surgery looks like, who needs one, the outcomes, what the rehabilitation process looks like, and – most importantly – the steps you can take to, hopefully, never have to get one…

What Is a Knee Replacement?

Also known as a Total Knee Arthroplasty, the Total Knee Replacement is a surgery to replace the surfaces of the knee joint. It is most commonly performed for end-stage osteoarthritis of the knee1.

The operation can be a partial or total Knee Replacement. Put simply, the procedure consists of replacing the joint surfaces of the knee with specially designed metal and plastic components that simulate normal knee motion.

Knee Replacements are common. I see them all the time – pretty much every day in the clinic I work at.

How common? In 2008, 650,000 Knee Replacements were performed in the United States2.

Who Needs A Knee Replacement?

The main indication for a Knee Replacement is end-stage Osteoarthritis, which accounts for more than 94% to 97% of the operations3.

Arthritis is common, though, and not everyone who has it requires surgery. 27 million people in the US are diagnosed with arthritis4 and that number is projected to reach 67 million by 20305.

More than 50% of people older than 65 years have arthritis on their x-rays6. Will all of these people need their knees replaced?

I hope not.

By itself, arthritis isn’t enough to warrant surgery. Millions of people have arthritis who have very little pain, if any.

To justify a Total Knee Replacement, in addition to the confirmed arthritis, the patient must have severe pain that limits activities of daily living, especially persistent pain at night or with weight-bearing activities7.

Even if all of this criteria has been met, a Knee Replacement should only be considered after all conservative measures have been exhausted8 for at least 6 months9.

What Are the Outcomes After a Knee Replacement Surgery?

In a nutshell, outcomes are generally good.

One prominent study found that up to 89% of patients are satisfied after a Knee Replacement10, while another study found 75% to be satisfied11. Both of these studies found that the biggest predictor of patient dissatisfaction wasn’t that their levels of function or pain were low – it was that their expectations weren’t met.

Therefore, improvements need to be made to educate people beforehand on what to expect going into the surgery and what to expect coming out.

Even though outcomes are mostly good, there is a potential for failure after knee replacement. Thankfully, incidence of failure is low – about 22,000 revisions annually.

Reasons for failure include your basic wear-and-tear of the prosthesis, loosening, instability, infection, arthrofibrosis, and mal-alignment or mal-position12.

One commonality I see often with my own Total Knee patient’s is that the once “uninvolved knee” now becomes the “involved knee” after surgery. Because of weakness and pain during the rehabilitation process, the uninvolved knee has to compensate and ends up taking the brunt of the weight-bearing load.

It’s been reported that 37% of people who have undergone a Total Knee Replacement will have the other knee replaced within 10 years13.

In my experience, people who have a second knee replaced might have a completely different experience from one knee to the other. Even with all factors equal – the same surgeon, same medication, same therapist – the body can respond differently. Most often, I find the second experience is a little easier because you know what to expect and how much effort you’ve got to put in.

Oh, and in case you thought one Knee Replacement at a time wasn’t enough, you can always elect to have both knees replaced the same day. As crazy as it sounds, most people I’ve seen with bilateral replacements are glad they had them done at the same time (no evidence to back this up, just reporting what I hear).

Knee Replacement Rehabilitation (What To Expect)

What can you expect with rehab after a Total Knee Replacement? In a word: work.

The most successful patients I see, and I see a lot, are the ones that put in the time and effort it takes to regain mobility of the knee and strengthen surrounding muscles.

The general goals for a successful rehabilitation after Knee Replacement are:

  • Improved mobility in the knee to a functional level of at least 0-110 degrees
  • Improved strength in the surrounding muscles of the leg
  • Improved functional capacity to be able to do the things you need to do in your life with minimal impairments

I’m a firm believer in helping you become an active participant in your recovery. I put a strong emphasis on the home exercise program – regularly adapting and progressing it to challenge you to improve.

The good news is that, despite the amount of time and effort it takes, the vast majority of patients are very satisfied with their recovery.

So how long does the rehabilitation process take?

According to a popular protocol, PT visits can range from 16-28 visits14 over the course of 10+ weeks.

Many Physical Therapists have different philosophies. My particular bent is not to follow strict guidelines but to tailor rehabilitation around your functional abilities, your pain level, your response to treatment, your progression, your finances (i.e. if you have a high co-pay and can’t afford to come in 28 times), and your compliance to a home exercise program. Therefore, everyone’s program looks a bit different.

I’ve had a few lucky people come see me once or twice and say, “I think I’m Okay.” Once in awhile I’ll get someone like this come to Physical Therapy a couple weeks after surgery with nearly full range of motion and good strength. I can’t explain it. It’s rare. But it happens.

For the vast majority of people, though, the length of your recovery really depends on your goals and whether or not you’ve met them.

For some, a goal is to be able to walk short distances inside the house. For others, a goal is to be an avid hiker again. Therefore, the rehabilitation process can look dramatically different from person to person.

I usually say the first 3 months are the most important. Why? Because after 3 months it’s unlikely you’ll gain significantly more range of motion in the knee. If you don’t get your knee totally straight, it will be much more difficult to walk. If you don’t get your knee to bend at least 110 degrees, it will be much more difficult to go up and down steps, to sit, and to perform daily tasks.

In general, I say give the overall process a good 6 months. At 6 months post-surgery, assuming there are no complications, your strength and mobility should be at a point to allow you to function well in your everyday life.

How Can You Prevent Getting a Knee Replacement?

As good as the outcomes for the Knee Replacement are, it’s still a major surgery and, hopefully, not at the top of your priority list.

As far as I’m concerned, surgery is always a last resort.

If you’re at a place where you struggle with knee pain, perhaps with mild to moderate arthritis on an x-ray, your status doesn’t have to continue to decline. In fact, it can improve.”

Unfortunately, you can’t reverse the degeneration in your knee without surgery. However, you can delay it. Remember, as I previously stated, arthritis doesn’t necessarily equal pain. Millions of people have arthritis yet don’t have pain and continue to function normally.

So, let’s talk about some alternatives to Knee Replacement.

In 2008, the American Academy of Orthopaedic Surgeons released guidelines for non-operative treatment of patients with knee osteoarthritis. According to their evidence-based guidelines, their highest recommendation was a trial of weight loss with diet and exercise15.

How effective can weight loss be?

A prominent study found that your chances of developing arthritis in the knees was 50% less with a decrease in body mass index (weight in kg/height in meters squared) of 2 points or more16.

It’s also been shown that 5 kilograms (roughly 11 pounds) of weight loss reduces your chances of arthritis by 50%17.

You’ve heard it before, I know – losing weight helps everything, right? Blah, blah, blah…

To put this into perspective, though, the force on each knee per step is equivalent to around 2 to 3 times your body weight. So if you’re carrying an additional 33 pounds of body weight, that’s 100 extra pounds of force on each knee per step.

Assuming you take at least 2000 steps per day, that’s an additional 100 extra tons of force on each knee per day18. So… yeah, 33 pounds of weight loss can make a big difference on your knees.

What kind of exercise is best for knee arthritis?

Meta analysis studies show that aerobic exercise leads to better long-term function in active patients with knee arthritis19. I generally recommend a stationary bike, particularly the recumbent type. One good thing about a bike is that it is low-impact, resulting in very little force on the knees. It also gets the knees moving and, as we PTs often say: “Motion is Lotion.”

Physical Therapy can also help the knees. If you’re lacking range of motion, we can help with mobility. We can also help determine any particular weaknesses you might have that, if strengthened, can take pressure off of the knees.

Strengthening the Quadriceps muscles, even if you do end up having a Knee Replacement in the future, can still be beneficial. It’s been shown that your Quadriceps strength before surgery is predictive of your function 1 year after surgery20 – so start strengthening!

If, by chance, all conservative options fail after at least 6 months of effort and you’re still having severe persistent pain that’s limiting your activities of daily living, surgery might be on the table for discussion.

Let’s talk about your options.

Other than the Knee Replacement, some less invasive surgical options might include Arthroscopy for debridement of the arthritic sections of the knee or a Meniscectomy for meniscus tears.

Arthroscopic Surgery of the knee is controversial. As far as the outcomes, around 50% to 75% of patients will have some relief. However, 15% of these patients progress to a Knee Replacement within 1 year, and only 44% have a significant decrease in functional pain21.

A 2002 study tested the efficacy of arthroscopic knee surgery. Without knowing which, subjects with knee osteoarthritis either had arthroscopic knee surgery or a sham surgery.

Sham surgery isn’t real surgery – it involves getting minor stab wounds but no entry of the surgical equipment into the joint. So, the recipients in the study wouldn’t know whether they actually had the surgery or not.

Early on, both groups showed signs of pain reduction. After two years, though, there was essentially no difference in pain in either group from when they started22.

Meniscectomy is equally controversial and outcomes aren’t any more impressive. A recent study showed that outcomes of the arthroscopic partial meniscectomy were no better than sham surgery immediately after and 12 months after initial testing23 – yikes!

I’m not a surgeon, but the results of these studies speak for themselves.

Another option for surgery – if only one section of the knee has arthritis – would be a Unicompartmental Knee Arthroplasty. Results of this option show 60% less chance of post-op complications. However, the revision rates are 5.4 times higher than a Total Knee Replacement24.

The bottom line is this: if you’re having knee pain and/or functional limitations with or without arthritis, address it now. See a Physical Therapist and determine what you can do to improve.”

Question: What questions do you have about knee arthritis? A Knee Replacement?

  1. Palmer, Simon H. (Jun 27, 2012). Total Knee Arthroplasty. Medscape Reference. ↩︎
  2. Kim RH, Springer BD, Douglas DA. Knee reconstruction and replacement. In: Flynn F, ed. Orthopaedic Knowledge Update. Resomeont, IL: American Academy of Orthopaedic Surgeons; 2011:469-475. ↩︎
  3. Robertsson O, et al. Knee arthroplasty in Denmark, Norway and Sweden. Acta Orthop. 2010;81(1):82-89. ↩︎
  4. Lawrence RC, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States: part II. Arthritis Rheum. 2008;58(1):26-35. ↩︎
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  9. Zhang W, et al. OARSI recommendations for the management of hip and knee osteoarthritis: part II. OARSI evidence-based, expert consensus guidelines. Osteoarthritis Cartilage. 2008;16(2):137-162. ↩︎
  10. Bourne RB, et al. Patient Satisfaction after Total Knee Arthroplasty: Who is Satisfied and Who is Not? Clin Orthop Relat Res (2010) 468:57-63. ↩︎
  11. Noble PC, et al. The John Insall Award: Patient Expectations Affect Satisfaction with Total Knee Arthroplasty. Clin Orthop Relat Res (2006) 452:35-43. ↩︎
  12. Sharkey PF, et al. Why Are Total Knee Arthroplasties Failing Today? Clinical Orthopaedics & Related Research (2002); 404: 7-13. ↩︎
  13. Ritter MA, Carr KD, Keating EM, Faris PM. Long-term outcomes of contralateral knees after unilateral total knee arthroplasty for osteoarthritis. J Arthroplasty. 1994 Aug;9(4):347-9. ↩︎
  14. Delaware Physical Therapy Clinic. Rehab Practice Guidelines for: Unilateral Total Knee Arthroplasty (TKA). Updated 4/2014. ↩︎
  15. American Academy of Orthopaedic Surgeons. Guidelines on the treatment of osteoarthritis (OA) of the knee. American Academy of Orthopaedic Surgeons Web site. ↩︎
  16. Felson DT, et al. The prevalence of knee osteoarthritis in the elderly: the Framingham Osteoarthritis Study. Arthritis Rheum. 1987;30(8):914-918. ↩︎
  17. Felson DT, Zhang Y, Anthony JM, Naimark A, Anderson JJ. Framingham Study. Am J Int Med 1992. ↩︎
  18. Van Manen MD; Nace J; Mont MA. Management of Primary Knee Osteoarthritis and Indications for Total Knee Arthroplasty for General Practioners. The Journal of American Osteopathic Association 2012, (112):709-715. ↩︎
  19. Brosseau L, et al. Efficacy of aerobic exercises for osteoarthritis (part II): a meta-analysis. Phys Ther Rev. 2004;9(3):125-145. ↩︎
  20. Mizner RL, Petterson SC, Snyder-Mackler L. Quadriceps strength and the time course of functional recovery after total knee arthroplasty. J Orthop Sports Phys Ther. 2005 Jul;35(7):424-36. ↩︎
  21. Dervin GF, Stiell IG, Rody K, Grabowski J. Effect of arthroscopic debridement for osteoarthritis of the knee on health-related quality of life. J Bone Joint Surg Am. 2003;85-A(1):10-19. ↩︎
  22. Moseley JB, et al. A Controlled Trial of Arthroscopic Surgery for Osteoarthritis of the Knee. New England Journal of Medicine. 2002;347(2):81-88. ↩︎
  23. Sihvonen, et al. Arthroscopic Partial Meniscectomy versus Sham Surgery for a Degenerative Meniscus Tear, 2013. N Engl J Med 2013; 369:2515-2524. ↩︎
  24. Arirachakaran A1, Choowit P, Putananon C, Muangsiri S, Kongtharvonskul J. Is unicompartmental knee arthroplasty (UKA) superior to total knee arthroplasty (TKA)? A systematic review and meta-analysis of randomized controlled trial. Eur J Orthop Surg Traumatol. 2015 Jul;25(5):799-806. doi: 10.1007/s00590-015-1610-9. Epub 2015 Feb 13. ↩︎
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