For such a small part of the body, the knee is prone to a wide variety of aches, pains, and injuries. Even small repetitive strains have been known to wreak havoc on your tendons and ligaments, but autoimmune conditions such as rheumatoid arthritis are the usual suspects when it comes to knee joint pain. It is for this reason that knee replacement surgery has been one of the verified solutions.
1. When is a knee replacement needed?
Pain and disability are the main reasons behind a knee replacement. Meanwhile, the common condition that requires surgery is osteoarthritis, which is a degenerative disease characterised by the breakdown of joint cartilage. When this happens, knee movement can be excruciating. The knee may also swell, or give way because the joint is not stable.
Replacing the knee is not always the first treatment of choice. In fact, doctors will first consider conservative treatment options such as oral medications, topical ointments or creams, medications injected into the joint, weight loss, exercise and physical therapy, or nutritional supplements. However, if these are not sufficient then knee replacement surgery may be considered.
Knee replacement surgery can also be helpful in the following conditions:
- Rheumatoid arthritis
- Structural problems that cause unusual bone growth (e.g. “knock-knees”)
- Knee Injuries
- Loss of blood flow to the knee bones (e.g. osteonecrosis, avascular necrosis)
2. What is the knee replacement process like?
The process starts with the surgeon preparing the bone. This means damaged bone and cartilage of your thigh bone (femur) and shin bone (tibia) are removed. On this cleaner slate, the metal implants are positioned to replace the cartilage and bone and recreate the joint surface. To secure them, these metal parts are either cemented or “press-fit” into the bone.
Depending on the case, the undersurface of the kneecap will also be resurfaced. Afterwards, a medical-grade spacer made of plastic will be inserted between the metal components to create a smooth gliding surface to complete the new bearing system.
3. Who needs knee replacements?
Since its introduction in 1968, the number of knee replacements has increased by a significant amount. From 1991 to 2006 alone, knee replacement surgeries tripled, due to factors such as an ageing population. By 2030, an estimate of 3.5 million people per year in the United States alone will undergo a knee replacement.
Since arthritis is usually an affliction of the elderly, many who need knee replacement surgery are well into their 60’s. In Singapore, the average age of people getting the surgery is 62 years old. However, knee replacement surgery for younger patients is also on the rise. More people in Singapore between the ages of 18 and 50 years old report suffering from joint problems and arthritis. This pattern is attributed to an increased interest in sports and being active. Ironically, people are burning out their knees faster by chasing after health.
So, if you’re a younger patient whose level of activity and function is really important to you, then a partial knee replacement will be appropriate, provided that the osteoarthritis is limited to that one compartment of your knee. If you are slightly older and what is important for you is that you have one operation that is likely to last you the rest of your life, then a standard knee replacement would be the right approach.
4. What are the kinds of knee replacement surgery?
There are two types of knee replacement surgery: total knee replacement (TKR) and partial knee replacement (PKR). Total knee replacement is more common and recommended for people who suffer from osteoarthritis, as well as other conditions like rheumatoid arthritis that affect the whole knee. Traditionally, most doctors just choose to replace the whole knee due to the joint’s complexity.
With TKR there is quite a bit of bone cutting. In contrast, a PKR leaves some parts of the knee intact. This led to some controversy on which of the two provides satisfying results. A lot of patients found that a PKR proves to be more satisfying because by leaving some unaffected parts intact, the movement feels natural. A PKR allows the doctor to focus only on the part of the knee that is painful or arthritic (unicompartmental knee replacement) without having to add trauma to healthy structures. However, there are also cases where a TKR will be a suitable approach.
Fortunately, knee replacement technology has come a long way since 1968, now providing us with sturdier prostheses and refined techniques. Some surgeons are using custom-made prostheses and computer-assisted procedures to make partial knee replacement efficient and effective. This development is especially significant for younger patients and athletes. Usually in sporting injuries, one compartment of the knee tends to deteriorate faster than the rest.
5. What is revision surgery?
Knee replacement surgery may seem intimidating, but it is proven to be successful. Nearly all patients report less pain and increased mobility after the procedure. The artificial prosthetics themselves are pretty hardy, lasting an average of 15 to 20 years.
But, as mentioned, we put our knees through a lot of wear and tear, especially when it has to bear excess weight or an active lifestyle. Knee replacements can break down. When this happens, patients need to get a corrective procedure or revision surgery. By nature, this is usually more complex than the first, due to scar tissue from the previous surgery and less bone to work with.
Patients who undergo revision surgery may notice less mobility and more stiffness, as knee replacements become less effective each time due to the accumulation of trauma and scar tissue. Complications may also require a patient to get revision surgery long before their replacement gives out. Although rare, contracting an infection from the first surgery is a typical reason for revision.
6. How long is the recovery period?
Patients usually stay in the hospital for 3 to 5 days after the surgery, depending on whether they had a total or partial replacement. Patients who have only had a partial knee replacement recover faster.
Within 12 to 24 hours after the surgery, patients will be able to stand up, with some help from the medical staff. You will need to use crutches until around 6 weeks after the surgery, but it may take up to 3 months for the pain to completely subside. During this period, doctors usually prescribe painkillers to help you manage the pain.
Full recovery takes at least a year, and it may take longer for your artificial knee to feel completely normal.
7. Can I ever come back to sports?
The short answer is, yes. With proper rehabilitation, many athletes are able to go back to the playing field. Doctors have even found that patients who exercise, and avoid “non-recommended” sports showed stronger knee functions than those who avoid exercise and being active after surgery. The reason may be that by exercising, you build up muscles and other structures that support your knee. Athletes are also especially better at correcting their form, and protecting their knee.
While the knee may be back in good form, extra caution is still needed. Some sports, like powerlifting, put too much stress on the knee, and hence these sports or similar activities must be avoided. However, sports like swimming and cycling are recommended by surgeons to help build strength and flexibility. One study found that athletes who underwent TKR were able to return to low impact sports 13 weeks after surgery. Still, it is important to consult with your doctor before going back to any kind of physical activity.
Physical therapy is an important part of recovery. Doctors send patients home with a list of exercises. Sticking to the program is even more important for athletes. Doctors usually tailor an intensive rehabilitation program based on the needs of an athlete.
Knee replacement surgery may seem daunting, but many have had their knees replaced and gone on to live more mobile, active lifestyles. Schedule an appointment with us at the Dr Andrew Quoc Dutton Orthopaedic and Sports Clinic if you have any questions about your treatment options.
Dr Andrew Quoc Dutton is a Harvard Fellowship-trained orthopaedic surgeon with clinical interests in arthroscopic/keyhole surgery for the knee, hip, and shoulder. He also specializes in sports injuries, cartilage regeneration, and arthroscopic ligament reconstruction, among many others.