Knee osteoarthritis (OA) is a common condition, affecting approximately 1 in 10 people over the age of fifty (3). OA is a degenerative condition which is caused by thinning and roughening of the cartilage within a joint, known as ‘wear and tear’. It can occur across the body but commonly occurs in the more weight bearing joints such as the hips and knees as here the joints are subjected to an increased level of stress. The knee consists of two main joints: the tibiofemoral joint and the patellofemoral joint. Knee OA can occur in either one or both of these joints and can occur in either one or both knees. Over time, as the cartilage degenerates, it can lead to knee pain, inflammation, swelling and stiffness (2). Generally, the medial compartment of the knee joint is more likely to be affected as this area of the knee is subjected to increased loading. Consequently, knee OA pain can often be felt on the inner knee but this doesn’t mean that the lateral or posterior knee are not affected.
Knee OA risk factors exist which can predispose an individual to developing the condition (3). Particular risk factors include age, being female, obesity and a family history of the condition. Obesity in particular can play a significant role in knee OA. Injury and a previous history of trauma to the knee can also increase the chances of developing knee OA. Furthermore, health conditions such as cardiovascular disease, cancer and diabetes are also risk factors (2).
A thorough patient history together with a thorough examination of the knee can help to provide a sound clinical diagnosis of knee OA. However, an absolute diagnostic picture can be obtained via a knee x-ray to assess for any changes within the cartilage and knee joint space. This can provide a good indication of whether the cartilage change is mild, moderate or severe and can also be used to monitor knee OA progression over time (3). It can also be used to detect the presence of osteophytes or bone spurs within the knee (2, 3). However, notably, the changes seen on an x-ray do not always correlate to the level of knee pain experienced by an individual. Therefore, whilst an x-ray can diagnose knee OA it does not always form a full picture of the symptoms someone can have.
Signs and Symptoms
Knee OA is normally relatively typical in its presentation. Pain is a key feature which often begins somewhat gradually with no specific cause and can worsen over time. Stiffness can also develop within the knee, particularly in the mornings or after sustained periods of rest and there can also be a reduction in function. Swelling can occur at the knee together with clicking or crepitus. The knee may also have a reduced range of movement. Knee pain tends to be worse during weight bearing activities and can increase particularly when going up or down hills and stairs (2).
On examination, pain is often elicited on palpation of the tibiofemoral joint, often at the inner or medial knee joint line. Pressure placed on top of the knee cap can also elicit pain in the patellofemoral joint if this joint is also affected. Knee range of motion may also be reduced into both flexion and extension.
Management of Knee Osteoarthritis
Knee OA is normally treated conservatively to begin with and includes the use of physiotherapy, pain relief and patient education. The aim of treatment is to help restore knee range of movement, improve strength, improve function and reduce pain (3).
Addressing lifestyle factors can also be extremely important in managing knee OA. Increased weight or obesity can greatly increase the level of pain experienced at the knee. Therefore, changes to diet and advice regarding weight loss can help significantly. Meanwhile, less weight bearing exercise such as swimming and cycling are advocated for knee OA as both of these activities help to reduce the level of load placed through the knees. Generally, high impact sports such as running or jumping and landing on hard surfaces should be avoided if the knee is particularly painful (3).
Changes in footwear, orthotics and a knee brace can also help to improve function in knee OA by helping to address lower limb biomechanics and by helping to reduce the level of load placed through the affected knee (3).
Meanwhile, research advocates the use of physiotherapy to help strengthen the lower limb muscles. This includes strengthening of the hamstrings, quads, calves and glute muscles to help increase stability at the knee joint and to help reduce knee OA pain (3).
Non-steroidal anti-inflammatory drugs (NSAIDs) can also be used to help reduce knee OA pain and inflammation (3). Icing of the knee, particularly if it is swollen can also help to have an analgesic effect and can be used to help reduce oedema.
Surgery for Knee OA
If conservative measures fails to improve things, or if knee OA progresses and becomes more severe and disruptive over time, then surgery can be considered.
Typically, an arthroscopy procedure is normally the first surgical technique to consider as it is a minimally invasive technique, performed via keyhole surgery. The technique is used to trim or debride the cartilage within the knee joint and can be particularly useful if a patient has symptoms such as locking or a meniscus tear. However, whilst this form of surgery can be extremely beneficial at reducing knee OA pain it doesn’t always provide long-term results as the underlying pathophysiology of knee OA is still present (3).
Knee OA can result in knee replacement surgery. This can either be a half knee replacement known as a unicompartmental knee arthroplasty (UKA) or a full knee replacement known as a total knee arthroplasty (TKA) (1). Whilst the former is a shorter surgery, has less blood loss and has a shorted rehab time post-surgery, it does not always achieve as good a result as a TKA. This is because a UKA has a higher revision and failure rate in comparison to a TKA, often attributed to bearing dislocations, mechanical loosening, replacement wearing, impingement or infection (1).
As a result, a TKA is better supported by the research and can give a far more successful and longer lasting result (3). However, as with all surgical interventions, complications can occur. Research indicates that TKA has a complication rate of 5% of patients. This is often attributed to infection (1.5%) or a blood clot in the legs or lungs (1-3%) (3). However, overall, a TKA is the most effective and reliable surgical procedure and tends to have good satisfaction and success rates (3).
Overall, knee OA is a relatively common condition and can be diagnosed clinically and via an x-ray. Conservative measures are appropriate for managing and treating knee OA and normally consist of physiotherapy, pain relief, education and lifestyle changes. However, if quality of life or function are severely diminished by knee OA then surgical intervention can be of benefit.
- Campi, S., Tibrewal, S., Cuthbert, R., & Tibrewal, S. B. (2017;2018;). Unicompartmental knee replacement – current perspectives. Journal of Clinical Orthopaedics and Trauma, 9(2), 17-23. doi:10.1016/j.jcot.2017.11.013
- Heidari, B. (2011). Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Caspian Journal of Internal Medicine, 2(3), 205.
- Hussain, S., Neilly, D., Baliga, S., Patil, S., & Meek, R. (2016). Knee osteoarthritis: A review of management options. Scottish Medical Journal, 61(2), 7-16. doi:10.1177/0036933015619588
- Umeda Con. (2018). Tricompartmental Osteoarthritis Knee. Retrieved from http://produtos-para-emagrecer.info/tricompartmental-osteoarthritis-knee.html\
- Trackactive.co. (2017). Exercises. Retrieved from https://app.trackactive.co/practices/1011/exercises