Whilst the knee joint is really one joint and in fact the largest joint in the body, it can be described as having three components. The kneecap or patella articulates with a groove on the front of the femur known as the trochlea and together they form the patellofemoral joint. The end of the femur expands into two condyles the medial and lateral femoral condyles which each in turn articulate with the medial and lateral tibial plateaus forming the medial and lateral tibiofemoral joints respectively.
Damage to the articular surface of the joint may be isolated to one of these components or involve any combination of them. When it involves all three, it is known as tricompartmental arthritis.
Pain is by far the most common symptom in patients presenting for arthroplasty or joint preserving surgery. The location of the pain is important, it may be generalized, anterior (as in behind the knee-cap), medial or lateral. When considering surgery, patients should have tried reasonable conservative or non-operative measures such as simple analgesia, activity modification, a rehabilitation programme and weight loss. If the pain is waking you up from sleep at night or significantly interfering with your ability to perform your normal day to day activities, this is also important in helping to decide the best course of action.
Some patients also report significant difficulty as they cannot fully bend or straighten the knee. A knee with a limited bend makes it difficult to go up and down stairs and get into and out of a car for example. A knee that doesn't straighten out fully will cause your leg to fatigue when you stand for more than a few minutes as the large quadriceps muscles must remain contracted.
As one side of the joint becomes more worn, the leg will start to bow in or out. This can also make it quite difficult to mobilize.
Patients may notice that their knee looks considerably larger than the opposite side or it may feel tight when they bend it. It may be due to a build-up of fluid within the knee (an effusion) or it may be due to inflammation of the tissue lining the knee (synovitis) or a combination of both. Occasionally the swelling in the knee protrudes more to the back of the joint forming a Baker's cyst.
This is the most common form of arthritis and refers to the progressive loss of cartilage from the surface of joints and is characterized by the development of bony spurs and cysts in response.
This refers to the development of arthritis due to a previous injury. For example, a patient may have sustained a previous fracture of the tibial plateau or a previous ligament injury.
This is a group of disorders that occur when the body's own immune system starts to attack its own tissues. The most well known of these is rheumatoid arthritis but the group also includes psoriatic arthritis, ankylosing spondylitis, SLE and inflammatory bowel disease.
In contrast to osteoarthritis, joint swelling and inflammation are usually the predominant symptoms and usually these are worse in the morning time.
When the blood supply to a segment of bone is interrupted, the segment can die and as it weakens will collapse resulting in damage to the joint itself. In the knee especially this phenomenon is poorly understood and it is possible that in many cases the inciting event is a small fracture that causes swelling and pressure in the bone and this then results in death of the bone rather than the opposite way around.
This is a type of acute inflammatory arthritis characterized by the deposition of uric acid crystals in the joint. Recurrent attacks lead to progressive destruction of the articular cartilage.
Simple analgesia such as paracetamol often combined with occasional anti-inflammatories can be be very effective early in the course of the disease. If you are requiring regular anti-inflammatory tablets it is important to note that this has significant health risks due to gastritis, peptic ulcer disease and kidney damage and it may be worthwhile contemplating surgery.
The force going through the knee joint, particularly the patellofemoral joint during activities such as going up or down the stairs or running can reach up to eight times your body weight. Thus, the effect of obesity on knee symptoms is greatly amplified. Likewise however, even losing a relatively small amount of weight can begin to improve knee symptoms.
Weight bearing cardiovascular exercise and a lower limb strengthening programme can greatly improve knee symptoms. It is important to note that short term you may notice some worsening of symptoms e.g more pain that evening but with persistence, symptoms will often dramatically improve. Also exercise therapy is independent to weight loss and when both are combined the effect is combined.
A steroid injection can be a very effective short-term therapy especially for an acute flare-up of symptoms. Relief of symtoms can be somewhat unpredictable but will often last for approximately 3 months. They can be especially useful in patients unsuitable for surgery.
The role of keyhole surgery for arthritis is extremely limited and not recommended without significant mechanical symptoms such as locking of the knee.
Hyaluronic acid injection
Hyaluronic acid forms part of the normal lubricating fluid (synovial fluid) in the knee. This can also be an effective treatment but there is little evidence to suggest that hyaluronic acid injections are superior to steroid injections.
Special unloader braces apply a 3-point pressure to the leg and reduce the force going through the most worn side. Some patients notice significant improvement in symptoms but they are often cumbersome and uncomfortable to wear on a more long-term basis.