The knee is a synovial joint that connects the femur (thigh bone) to the tibia (shin bone). The knee is shaped in such a way that lets the normal knee bend (flex) and straighten (extend), while also allowing small amounts of rotating and sliding. The knee is the largest joint in the body.
A number of ligaments stabilize the knee. These include the two cruciate ligaments (ACL and PCL) as well as the two collateral ligaments (MCL and LCL). At the front of the knee is the patellar tendon that connects the tibia to the quadriceps muscle via the patella bone (knee cap), and this arrangement works to straighten the knee. The knee also has the ability to lock itself straight to help you stand up for long periods of time. The ability to straighten the knee is one of the things that is first lost in early arthritis.
The knee is made up of three compartments: the medial (on the inside), the lateral (on the outside), and the patellofemoral (at the front). The compartments are all joined together but there are occasions when problems such as arthritis can exist in only one of the compartments of the knee.
Inside the joint there are also two menisci. These act like shock absorbers to help with the smooth movements of the knee. It is not uncommon for these to become torn. This can then sometimes lead to symptoms of pain, swelling, locking or jamming and the feeling like your knee may give way under you, especially during twisting activities. If symptoms persist, keyhole surgery (arthroscopy) may help.
Covering the bones inside the knee joint is articular cartilage. This cartilage is very smooth and has very low friction, allowing the bones to slide easily over each other to bend and straighten the knee. Loss of this cartilage occurs in knee arthritis.
Knee arthritis is commonly referred to as ‘wear and tear’ inside the knee joint. The knee is one of the more commonly affected joints in the body. Knee arthritis occurs where the cartilage (the smooth lining inside of the knee joint) becomes worn away. When the cartilage is worn away it leaves the hard bare bone surface that may lead to pain and sometimes deformity (such as the bow-leg or knock-knee appearance).
Certain risk factors exist for knee arthritis. These include previous trauma to the knee (breaks, fractures or ligament tears), previous surgery (such as where the whole meniscus has been removed), other diseases that affect the joints (such as rheumatoid arthritis or gout) and being overweight. It can also run in families too.
The symptoms of knee arthritis include pain (especially on walking and going up and down stairs), stiffness, swelling and sometimes clicking or grating.
The NHS links below give further information regarding arthritis, what it is, types of arthritis & treatment.
Arthritis is a common condition that causes pain and inflammation in a joint.
Osteoarthritis is a condition that causes joints to become painful and stiff. It's the most common type of arthritis in the UK.
Knee replacement surgery (arthroplasty) is a common operation that involves replacing a damaged, worn or diseased knee with an artificial joint.
Versus Arthritis help support those with arthritis and along with the carers, researchers, healthcare professionals, family & friends work together to develop treatments, raise awareness & support each other when or wherever it is needed.
The website has lots of information & support materials, including exercises & pain relief you can try at home.
Losing weight if needed & taking more exercise.
Having physiotherapy & occupational therapy (OT). This may include using walking aids likes canes or special insoles.
Treatments to manage pain, including tablets you take by mouth, injections into the joint and self-help support.
Surgery, including total or partial knee replacement, arthroscopy & osteotomy. Surgery is usually for people with severe symptoms who have tried other treatments first.