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Knee Replacement

Knee Replacement

Knee replacement surgery, also known as arthroplasty, is generally regarded as an effective treatment for end-stage knee arthritis. It results in an improved knee function and significantly relieves severe pain caused by degenerative joint diseases.


All knee replacement procedures are generally divided into 2 major groups, depending on whether the knee is replaced totally or partially. A knee joint is often compared to a hinge which allows to flex, extend and limitedly rotate the lower leg. Structurally it resembles three separate joints: slightly rounded end of the thigh bone forms 2 separate articulations with a slightly hollow end of the shinbone which has a mobile kneecap on top. The most common indication for total knee replacement is severe osteoarthritis that affects all surfaces of these synergic joints and causes pain which is unresponsive to medical management.

  • During the procedure, the patella is laterally subluxed and the knee is exposed in flexion. 
  • The affected joint tissue is surgically removed and replaced by a knee prosthesis which consists of three separate components. 
  • The end of a thigh bone is replaced with a femoral component made out of metal plate which corresponds to the natural shape of the bone.
  • The tibial component, which consists of a metal tray covered with a layer of plastic that moves against the surface of the femoral segment, replaces the top surface of the lower leg bone. 
  • Patellar component covers the back part of the kneecap and is made out of plastic for it to glide over the front of the knee. Due to this reason the patients are advised not to kneel on the operated knee as the plastic covering of the patella may resurface.

These significant structural changes are directly responsible for the main complaint after knee replacement surgery, which is stiffness and a lingering sensation of a foreign body placed inside the joint. All in all, a total knee replacement is one of the most successful examples of innovative surgery and has resulted in substantial quality-of-life gains for people with severe joint problems.

What is a partial knee replacement?

In comparison to a total knee arthroplasty, partial knee replacement may be defined as a less invasive surgical approach for patients with only moderate knee joint diseases. A great majority of degenerative joint diseases primarily affect the medial compartment of the knee joint. This is because a fibrous cartilage between the surfaces of the medial tibiofemoral articulation, also known as a medial meniscus, is relatively thinner and experience greater pressure while walking etc. The damaged component of the knee is replaced using the same method as in the total knee arthroplasty but without affecting the healthy parts of the joint. However, as flawless as partial knee replacement may sound, its biggest potential drawback is incomplete pain relief. The success of the surgery depends entirely on choosing the right candidate and carefully evaluating the extent of disease.


Preparation for surgery

Careful preparation for knee replacement surgery is an important part of the procedure itself as it determines the success of the surgery and the quality of post-op recovery. Here are the main recommendations to be followed:


Is there an age or BMI limit for the surgery? 

Increased body weight would, intuitively, be expected to lead to a poorer outcome after joint replacement as the knees are directly strained by overweight. A significant positive correlation has been observed between the wear damage seen on the components of knee prosthesis and the BMI of the postoperative patients. However, some recently published studies have proven that the perioperative complication rate in patients with BMI over 40 wasn’t dramatically higher than the rate in patients with lower BMIs. Moreover, it is now known that obese patients have relatively good pain relief and positive functional outcomes after the surgery. Therefore, a simple answer to the question about BMI limit is negative. Looking from a medical point of view, obesity is associated with many other comorbidities that affect one’s everyday life and well-being. That is why overweight should not be tolerated, and if a patient is able to lose weight they most definitely should do that.


The age limit for knee replacement patients is also of a debatable significance. Although the older patients require a relatively longer hospitalization time and have higher complication rates, the improvements in their quality of life are very similar to those of younger patients.


Hospitalisation and what to expect during the first days after surgery

After the surgery a patient is expected to stay in the clinic for 2 to 3 days. If a patient underwent general anaesthesia, it is absolutely normal to experience some mild side effects on the first day after the procedure. On the following day a postoperative patient is encouraged to start moving and walking with a walker or crutches. In the beginning, it requires a lot of will and effort to start walking again, but it will pay off in the form of faster recovery. Upon discharge from the hospital, a patient should be able to take short walks, bend one’s knee up to 90 degrees and climb up and down a few steps with some extra help.


The importance of physiotherapy

It could be said that half of the success of a knee replacement surgery depends on the post-op physical therapy. Physiotherapy exercise routine may be either home-based or monitored by the health professionals in rehabilitation facilities. Studies have shown that light to moderate regular exercises show short-term improvements in patients’ physical function, whereas more intensive ones have positive long-term outcomes. In order for a certain therapeutic approach to give good results the right combination of physiotherapy methods should be selected  for each patient individually.


Physical activity after the surgery

The positive effects of physical activity are particularly important for patients undergoing knee replacement, as osteoarthritis predisposes them to metabolic and functional decline. Light physical activity such as walking, climbing the stairs, jogging etc. is an attractive and convenient form of exercise as it can be self-managed and performed on a daily basis with low cost and minimal equipment. In addition to that, there are several types of exercises which target specific muscle groups of the lower body and may be performed every day:


  • Stretches – Exercising muscles of the thigh improves knee flexion. This may be achieved by light stretches of hamstrings.
  • Tension Creating Exercises – Muscles in the front of the thigh are responsible for knee extension. In order to strengthen them any light tension creating exercises, such as half squats done while holding on to a handrail or straightening the leg while sitting on a chair in highly advised.
  • Exercises Performed While Lying – In the early-operation period there is a great variety of light exercises that should be performed while lying down. This includes bending the knees by sliding the heel towards the buttocks, repeatedly adducting the operated leg.
Wound care and Staple removal


  • Dressing – After the knee is totally or partially replaced, the midline incision across the front of a knee is closed and tightened up with staples or stitches. In order to prevent the wound from getting infected, a waterproof dressing is applied. It is highly recommended to keep the dressing for up to 7 days after the procedure unless it moves out of place or becomes fully saturated. If so, it should be changed by a qualified nurse, if possible, or a patient may do it by themselves.
  • Showering – When it comes to showering, it is allowed as long as the dressing is kept as dry as possible, for it may fall off if the skin becomes too moist.
  • Stiches – The stiches or staples are usually removed in 10 to 21 days after the surgery. If during the postoperative period a leakage, bruise or swelling is observed and the incision site becomes painful, you should consult a doctor immediately as the wound might get infected.
Driving after surgery

The candidate for knee replacement are often hesitant about the surgery as there is a common misconception that driving is prohibited once the surgery is performed. In fact, the postoperative patients may already resume driving 4 weeks post-operation or when they feel comfortable and confident about the flexibility of the knee.


Sports after a knee replacement

Based on a general opinion among the medical society low-impact sports, such as hiking, swimming, running, and cycling etc. after knee replacement are most certainly welcome and encouraged. However, strenuous activities that put a lot of pressure om the knees are a topic of discussion. It is observed that the patient who played sports before their surgery are more likely to return to sports because of the willingness and motivation. All in all, due to the improvements in surgical technique and the growing knowledge about post-operative management of knee prosthesis, knee replacement surgery has even less impact on the activity level of post operative patients.