This is a continuation of a blog posted Nov. 19, 2014 called The Pleasures and Pains of Knee Replacement Surgery and Rehab.
It started with my personal story and continues into a discussion on the etiology of the disease, how it is treated, and the surgical option of joint replacement. It also includes the main goals of therapy after the surgery which should lead to the ability to proceed to the final stage: independent exercise.
Thus, how to exercise and make the most of your new joint and lease on life:
What is Cartilage: How OA Happens?
Cartilage is a smooth, low-friction cushion made of proteoglycans (heavily-glycosolated (carbohydrate-connected) proteins) and collagen (of which there are many types).
Unlike bone, it is softer, more pliant and, after a certain age, less capable of remodeling itself if damaged. Due to a lack of blood vessels, it gets its nutrients from the squeezing and pumping action of the bones on which it is attached.
Thus, activity and movement are essentially good – no, they are essential – for healthy cartilage.
However, over time, cartilage loses its ability to absorb fluid and gets, for lack of better words, dry and brittle. Add extra weight to it, such as with the weight-bearing joints (ankles, knees, hips and spine), and you get increased forces acting on less pliant tissue leading to little cracks and fissures in it.
Now, add extra movements and suddenly chunks of cartilage are floating around in the joint space. Or injure it acutely and keep abusing it over time – as I did – and the damage accrues over time, too.
As we age, small cracks become bigger, and small chunks start acting like sandpaper over the remaining good areas of cartilage, and soon you have exposed parts of the bone with no protection against the forces acting on that joint.
It’s just a matter of time before it’s so worn out that the space between the two bones is thinner, and bones start rubbing on each other creating osteophytes, or what most of us know as ‘spurs’.
These spurs further wear out the cartilage on the adjacent bone and it’s not long before it hurts to move that joint. This is osteoarthritis (OA) which differs from rheumatoid (RA) and other forms of arthritis in that it is usually the result of injury, pathomechanics (bad alignment of the joint such that inappropriate wear occurs) and/or time and aging
RA and juvenile, as well as other types of arthritis, on the other hand, are
autoimmune disorders, where the body attacks its own cartilage for as-yet unknown reasons. The problem, however, is not simply a bone-on-bone, cartilage-free joint.
The consequent reduction in movement leads to loss of function, loss of muscle strength, increased fatty infiltration within the muscles around the joint, reduced fitness, reduced wellness (from a cardiovascular and metabolic standpoint) and, at some level, reduced quality of life.
At some point, if you live long enough and prefer to have a quality of life beyond sitting in a chair, joint replacement, or arthroplasty, becomes an option.
For simplicity, we will refer to total knee replacements as TKA and total hip replacements as THA.
Who Gets OA and Arthroplasty?
According to the Arthritis Foundation, over 50 million people in America are dealing with arthritis, most – up to two-thirds – being under 65 years of age.
However, arthritis is very democratic with children as young as 6 months to Baby Boomers not yet ready to get their first Social Security check suffering from it.
- In fact, it is estimated that over 300,000 kids have arthritis.
- Arthritis affects people of all races: “more than 36 million are Caucasians, more than 4.6 million are African-Americans and 2.9 million are Hispanic.”
- About 27 million of the 50 million with arthritis have OA.
- “People with arthritis account for 44 million outpatient visits and 992,100 hospitalizations.
- It is estimated 67 million Americans will have arthritis by 2030.
- According to a study in Canada, 10-15% of arthritis patients have OA due to prior injury which generally affects younger, more active people.
The Agency for Healthcare Research and Quality, says about 600,000 knee replacements are done each year in the US.
The American Association of Orthopaedic Surgeons notes that most of these procedures are good for 10 – 20 years, with new technologies and surgical techniques being developed regularly so that people older and younger can benefit from them.
Quick Review of Physical Therapy Goals
It is the purpose of the rest of this essay to discuss, not the surgical procedures or post-surgical therapies for those getting joint replacements, but the kinds of exercises one can do for oneself in addition to the basic therapies. In other words, discuss the post-rehab exercises that will enhance both recovery from surgery as well as quality of life afterward.
First and foremost, in addition to the ever-present prevention of infection which could severely hamper recovery and even lead to catastrophic consequences such as revision (corrective surgery) or death, doctors and therapists strive to get range of motion (ROM) restored.
This is because of three things that have happened.
- First, the reduced ROM sufferers have developed as their disease progressed and movements were hampered.
- Second, after surgery, there is a tendency for muscles to contract to protect the joint as they don’t want to allow excessive movement at the joint.
- Finally, there is inflammation and the swelling around the joint causes tightness of the surrounding tissues, from the inner joint capsule to the skin, further hampering full motion.
Nowadays, patients are given drugs to reduce swelling so as to permit better motion, and to minimize pain, both surgical as well as during the imposed movements therapists encourage.
These serve another purpose, however: by reducing inflammation, which shuts down nerve impulses to the muscles around the joint, they allow those muscles to be voluntarily (by conscious decision) to ‘fire’ so that they can start doing their jobs quickly.
This reduces the typical post-surgery atrophy that would be mounted on top of the significant atrophy most OA sufferers have simply from lack of use. Thus, along with working to restore ROM, therapists encourage immediate use of these muscles as patients start along the road to full recovery.
The sooner they are jump-started, the more likely full function will be restored. Hence, simple isometric contractions are encouraged for the
- quadriceps (quads = front thigh muscles)
- hamstrings (hams = back thigh muscles)
- glutes = buttocks muscles
- gluteus medius
- glute med = the muscle on the side of the hip that pulls the thigh away from the other thigh sideways
These valiant efforts by the therapists come during the most fearful time for the patient, and when the patient is very likely to believe if not truly experience both pain and drug-related lethargy. But they are essential to rapid and full recovery.
When you start physical therapy (PT) outside the hospital, more aggressive measures will be implemented to restore ROM, especially for TKA; the hip has very good and very normal ROM immediately, if normal gait is all you seek. (Some athletic types, especially former dancers, martial artists, etc, may wish to resume some level of previous activity mandating higher ROMs. This should be cleared with the surgeon as there are typically restrictions given, to be followed for at least a few months while the capsule heals and in some cases for life, that warrant caution.)
In order to achieve life-style related motion such as for sitting, the knee has to bend at least 90 degrees, although 120 is preferred. Therefore the quads need to be stretched.
Since the post-surgical knee is swollen, this is challenging and requires some hearty efforts by both PT and patient. For the most part, after a THA, unless there is concomitant knee OA, this ROM is intact.
However, with one major concern being subluxation or dislocation of the prosthetic hip, usually flexion beyond 90 degrees (bringing the thigh to perpendicular to the trunk) is not permitted; furthermore, doing so while also adducting the leg (crossing the midline) is also taboo.
As noted above, since THA rarely requires efforts to increase ROM, this part of the discussion will stick to TKA.
In order for the quads to work efficiently, to straighten the leg, the hams have to be supple enough to allow the knee to extend fully. There are various methods to reinforce this capacity immediately post-surgery, from a passive movement machine to which your leg is strapped to a removable cast that does not let your knee flex even in your sleep, which it would love to do.
In therapy, though, all kinds of stretching techniques are applied to get the knee straight and inflammation and fear play into resistance to stretch for these muscles, too.
- As for hips/glutes, unless there is concomitant hip OA, normal range is intact in those with knee OA; however, normal function is not, but this takes us into the strengthening realm, below.
- Early in therapy, though, glute exercises such as ‘tightening your butt’, ‘squeezing your cheeks together’ or ‘pushing your heel into the bed’ are encouraged.
You can see that these early, post-surgical exercises are ones that can be done in the hospital or residential bed and should be done frequently throughout the day to ensure rapid recovery even as it could be weeks or even months before full recovery is noted.
Of course, since ambulation – a fancy word for walking – is a primary goal for anyone wishing to live independently, the PTs will get you up and about, initially with a walker to ensure your safety, progressing to crutches, then to one crutch, then a cane or nothing if you have good control of your body such that you won’t fall.
They will also work on getting you to think about how you walk, to engage your glute med (side hip muscle) so that your hip does not shift outward with each step you take on the surgical leg. This is more of an issue with THA patients but TKA patients, due to many years of limping, are also programmed wrong and need to re-program those muscles.
PT can go on as long as:
- Your insurance covers it
- You are willing and able to afford it on your own
- You are released due to successful restoration of basic function.
From this point on, you could stop doing all your exercises and lead a fairly normal though not vigorous lifestyle; or you could take the bull by the horns and proceed to the next section to learn what exercises to do on your own, at a gym or at home, with or without supervision, that apply to both TKA and THA patients.