At some point in our lives we may be unfortunate enough to develop problems with our knee joints.
Along with the pain – fluid or swelling filling up the knee can be another side product of your knee pain.
If you’ve suffered an injury to the knee, had surgery or have just been doing a little bit too much – your knee can develop swelling and fluid.
Whilst this is a natural reaction and your body will try and sort it out for you, sometimes it can hang around for a while and it can make the knee uncomfortable.
Depending on how your knee has become swollen there may be some different options to help reduce the swelling.
A good place to start understanding swelling of the knee is the anatomy
Knee Anatomy
The knee is comprised of 3 different bones.
The femur which is also known as your thigh bone, the tibia which is your shin bone and the patella which is also known as your knee cap.
The femur is the largest bone in the bone and it forms the top of the knee with two femoral condyles which are the 2 rounded parts at the end of the bone.
These 2 condyles are covered in articular cartilage which gives the knee a smooth surface and helps to absorb shock and move without pain.
The tibia is the shin and this is the platform of which the femur sits on to. On top of the tibia there are 2 discs of cartilage known as meniscus.
Meniscus is a form of cartilage and again it helps the knee to move smoothly, with comfort and acts as a shock absorber.
The 3rd and final bone is the kneecap – the patella. This sits in a small groove between the 2 femoral condyles of the femur and as the knee bends the patella glides in the groove – this is also cushioned with cartilage. Underneath the patella is a fat pad which helps to cushion the kneecap further.
Cartilage within our knee is very important to ensure our knee works efficiently and comfortably. Unfortunately – our body isn’t great at regenerating cartilage and it can wear down over time causing pain, discomfort and stiffness.
Ligaments of the knee help to connect all of the bones together. The 4 main ligaments of the knee are:
- ACL – anterior cruciate ligament – connects from the back of the femur to the front of the shin
- PCL – posterior cruciate ligament – located at the back of the femur and tibia and connects the 2.
- MCL – medial collateral ligament – this sits on the inner aspect of the knee joining the femur to the tibia.
- Lateral collateral ligament – this sits on the outside of the knee and connects the femur and the tibia
The muscles of the knee are simple in nature and there are the quadriceps which are the thigh muscles which help to straighten and keep the knee secure.
The hamstrings are the muscles on the back of the thigh and this helps to bend the knee.
The glutes which are all of the muscles around your buttocks and hips also play a major role in rotation of the knee and balance.
Knee Function
Your knee is typically a joint which can just move within 2 directions. Flexion and extension.
In healthy knees the knee should be able to fully straighten and bend.
There is a small amount of rotation in the knee but only around 5 degrees.
When the knee is rotated more than these limits it can cause damage to the internal structures like the cartilage or it can also cause ligament damage by stretching them too much.
Extended Anatomy – Important to Knee Fluid
In relation to fluid developing on the knee there is some extended anatomy which is vital for you to know about.
The knee is surrounded by a structure called a joint capsule – within this capsule we have synovial fluid which is a clear liquid which helps the knee to remain happy and healthy but whenever the knee gets aggravated we can produce more of this fluid to help protect the knee.
Synovial fluids role:
- Shock absorption and protection
- Filters – lets nutrients reach the cartilage, but prevents harmful cells and substances hurting the joint.
- Lubrication of the joint
Why do we develop fluid on the knee?
There are many reasons why we develop excess fluid on the knee – here are a few of them.
- Trauma – any accident to the knee can cause excess fluid to develop. Whenever there is damage to any of the structures of the knee, the body will respond by increasing the amount of synovial fluid to protect the knee and add extra cushioning.
It won’t just be synovial fluid however – there could be blood depending on the trauma but this will always be difficult to tell. There may be times when the knee becomes discoloured.
Ligaments, bone and cartilage when injured will all produce a swelling in the knee. When tissues are impacted with too much force or they are taken past their limit with trauma – damage occurs causing tearing and straining.
This can initiate a bleed in tissues and also produce an inflammatory reaction which will increase the amount of fluid and different chemicals being sent to the knee to initiate a healing response.
- Osteoarthritis – over time are knee can lose its smooth cartilage surface. This is typically known as arthritis. You won’t always get pain from this type of issue and in most cases it will be painless – but – when it becomes aggravated, which it can do periodically, the knee will swell up to help it heal.
The increased fluid again, much like trauma helps to bring needed protection and nutrients to the knee.
- Infection – if your knee becomes infected then this can cause your knee to become swollen with fluid. Depending on your activity levels and types of activity levels you never get an infection within the knee but it is important to mention as a safety note that knee infections can be very dangerous. If the knee is hot and swollen – proceed to an emergency department immediately or seek the help of your doctor.
Staph infections of the knee can spread to the whole body and can interfere with your body’s function. These are typically contracted through open cuts and grazes but then can penetrate in to the joint of the knee.
It is possible to have mild warmth in the knee and this can be entirely safe as most fluid will have some form of mild warmth, serious infections will be HOT to touch.
- Fat Pad Irritation – this condition can be commonly known as housemaid’s knee. This term was developed as women who would perform a lot of housework would typically get a sore area underneath the kneecap from kneeling.
The knee cap can pinch in to the fat pad then the area will swell up with fluid. This swelling may be more localised and smaller in nature than a knee joint swelling.
The 6 best and latest ways to reduce fluid on the knee
Active Rest
Depending on what caused your knee swelling you need to rest from that specific thing, but not total rest. If excess sport caused it then reduce your workload. If using a lot of stairs or kneeling down caused it then rest from those things. Adapt your habits to keep yourself moving and do things in a different way. Rest your knee from its most irritating movements.
Compression
This is the best way to get rid of your knee fluid. Compressing swelling and fluid of the knee helps it to reabsorb in to the body and reduce. Compressing the knee can be done in many different ways such as using bandage but the most convenient way to get an elasticated Velcro wrap or a knee sleeve which can provide a tight compression. There are also knee supports which can compress and also support the knee if you have suffered an injury.
Exercise
As mentioned before it’s important to keep active in some way but being specific with knee exercises is key to help the swelling reabsorb and also to keep your knee strong. The weaker your knee is the more pain and swelling can develop. Gentle knee exercises such as tensing the thigh muscles and hamstring curls can help to support the knee whilst it has fluid on.
Anti-inflammatory
Medicines such as ibuprofen – if you are able to take them can help fluid to reduce. Check with your doctor before taking but this medication can assist the healing process if there is any extra inflammation of the knee which is causing the problem.
Elevation
Keeping your knee above heart height will help the swelling to reabsorb. Simply lie down and prop your knee up with pillows and let gravity do the rest.
Massage
Gentle massage of the fluid can help to mobilise it and start the reabsorption process. Massage should focus on stroking the fluid back towards the heart, if the massage is performed with the leg elevated this can help also. Seeing a massage specialist who deal with swelling management can be a beneficial option.
Supplements for knee swelling and fluid
The following supplements can help to aid knee health which in turn may have an effect on reducing the chances of fluid developing on the knee. They cannot help with trauma related fluid but for issues such as knee inflammation they may be useful to add to your daily supplementation plan.
Cod Liver Oil – this is one of the most tried and trusted supplements out there for joint health as it can aid cartilage health and keep joints well lubricated and healthy.
Boswellia Serrata – this is the new kid on the block in terms of joint health and has shown some excellent results in clinical trials for reducing joint inflammation and irritation. This is a natural supplement processed from plants.
Turmeric – high strength curcumin (active ingredient of turmeric) has been shown to have positive results on body inflammation. If your knee swelling is being caused by inflammatory problems then adding this may help to assist a reduction in knee fluid.
Glucosamine & Chondroitin – another supplement that helps with joint health and in particular cartilage. Cartilage issues can often be the source of swelling and fluid in the knee. Give your knee the best head start you can by adding the right joint supplements to your diet.
That’s concludes our guide to swelling on the knee, what causes it, the anatomy and how you can try to manage it and prevent it. We hope that you found this useful and if you did please could you share this with someone you know.