What is causing my knee pain?
When you have a sore knee it is usual to think that the knee itself is the cause. Actually knee pain can originate from a multitude of sources. The knee itself is made up of two main parts, the patello-femoral joint (behind the knee cap) and the tibio-femoral joint (where your thigh bone meets your lower leg). Either of these can cause knee discomfort. Knee pain can also be referred from the hip or low back. Each type of knee pain requires a different treatment approach.
Patello-Femoral joint Pain (PFJP):
PFJP is usually felt at the front of the knee. Typically it feels worse with loaded activities like walking down stairs, jumping, squatting and running down hills. Once PFJP starts it can ache even at rest and may swell. This kind of pain can start traumatically with a blow to the front of the knee, or it can build up over time with repeated activity. Physiotherapy has been shown to greatly benefit this condition (Crossley, 2002)
The tibio-femoral joint has two compartments, medial (inner side of knee) and lateral (outer side of knee). Pain in the tibio-femoral joint is usually felt as a pain deep within the knee or on either side of the knee. Sustained standing, walking, running, squatting or twisting can worsen tibio-femoral joint pain. This kind of pain can start with an injury or can be associated with age related change in the knee joint.
Soft tissues in and around the knee:
- The knee is a hinge joint which is supported by ligaments in and around the knee. These ligaments can be damaged by injuries which cause them to be overstretched. Ligament injury usually leads to pain which is easily located to the injured tissue. Commonly ligament injury can lead to a sense of giving way or instability.
- Tendons attach the muscles to the bones around the knee joint. Trauma or repeated muscle loading can cause injury to the tendon. Tendon pain is usually felt directly at the injured part.
- The tibio-femoral joint contains two moon shaped cartilages called menisci which act as shock absorbers within the knee. They are attached to the bone below by tiny ligaments. Over time repeated loading can cause damage to the menisci. The menisci can also be injured traumatically with loaded bending or twisting movements. Meniscal pain is often felt deep in the knee or to the side of the knee. An injured meniscus can cause your knee to click or lock.
The hip joint commonly refers pain to the knee joint. The location of referred pain is usually difficult to locate. The knee usually is not painful on movement or loading. Activities which load the hip, like squatting, may cause knee pain. As not all people with hip referred knee pain feel pain in the hip, this problem can be difficult to accurately diagnose.
The low back can refer pain to the knee. This kind of referred pain can be accompanied by other sensations like pins and needles or numbness. If the lumbar nerves are affected your leg may feel weak.
Other causes of knee pain:
Other parts of the body like blood vessels, bursas, fat pads or nerves can also cause knee pain.
With so many possible causes of knee pain, effective treatment depends on accurate diagnosis. If the pain is from a local knee joint problem Physiotherapy treatment may involve:
- Mobilization to improve movement and reduce pain
- Exercise to improve co-ordination, strength or balance
- Braces or sports tape to support the knee
- Foot orthotics to support the leg and improve biomechanics
- Cold therapy to reduce pain and swelling
- Physiotherapy with acupuncture to reduce pain and improve muscle control
- Advice and education
What to do if you have a painful knee
Make an appointment with your physiotherapist or medical doctor for a thorough assessment of the cause of your knee pain. You may be referred for further investigations such as an x-ray, MRI scan, ultrasound or blood test, to clarify the cause of the problem. It is important that you commence treatment early as research shows that once some knee conditions become persistent treatment is less effective (Collins, 2010).
APMA would like to thank the Fortus Health for permission to reprint this information.
Yang K, Saris D, Dhert W, Verbout A. Osteoarthritis of the knee: current treatment options and future directions Original Research Article. Current Orthopaedics, Volume 18, Issue 4, August 2004, Pages 311-320
Collins N, Crossley K, Vicenzino B. Characterising anterior knee pain using baseline data from participants in a randomised clinical trial. Journal of Science and Medicine in Sport, Volume 12, Supplement 2, January 2010, Pages e165-e166
Collins N, Crossley K, Darnell R and Vicenzino B. Predictors of short and long term outcome in patellofemoral pain syndrome: a prospective longitudinal study. BMC Musculoskeletal Disorders 2010, 11:11
Crossley K, Bennell K, Green S, Cowan S, McConnell J: Physical therapy for patellofemoral pain: a randomized, double-blinded, placebo-controlled trial. Am J Sports Med 2002, 30(6):857-865.