This is where your thigh (femur) and shin bones (tibia and fibula) meet. The end of each bone is covered with cartilage, which allows the ends of the bones to move against each other nearly without friction. The knee joint has two extra pieces of cartilage called menisci, which spread the load more evenly across the knee. The knee joint is held in place by four large ligaments. These are thick, strong bands which run within or just outside the joint capsule. Together with the capsule, the ligaments prevent the bones moving in the wrong directions and help hold the knee in place. The joint is surrounded by a membrane (the synovium) that produces synovial fluid, which helps to nourish the cartilage and lubricate the joint.
The main muscles that bend or straighten the knee (hamstrings and quadriceps) are attached to your bones by strong tendons. These tendons run on either side of the joint and help to keep the knee stable. When your muscles contract they shorten, and this pulls on the tendon attached to the bone and makes the joint move.
The kneecap (patella) is fixed firmly in the middle of the large tendon that attaches your quadriceps muscles to the tibia bone just below your knee joint at the front of your shin bones. The underside of your kneecap is also covered with cartilage.
Common knee injuries can be broken into 5 sub-categories
1. Trauma
Fracture
It is possible to fracture any of the bones around the knee, the patella (kneecap) is however the most common. Most fractures are the result of high impact trauma; however, this may not be the case if you have poor bone density (as occurs in osteoporosis) in this instance you can fracture a bone with very little force.
Dislocation
This is when one of the bones of the knee is moved out of the normal position: this may be the result of direct force such as a car accident or fall or can be as a result of an inherent deformity in the bony alignment of the joint and typically involves the patella dislocating. This type of dislocation tends to be more recurrent in nature.
Ligament sprains/tears
There are 4 main knee ligaments, the medial and lateral collateral ligaments and anterior and posterior cruciate. These can be injured as a result of sudden overstretching, such as from a fall, sudden twist or direct impact. They can vary from a mild sprain or overstretch, to a complete tear or rupture. The symptoms are pain, swelling and loss of movement, instability and difficulty weight bearing.
Meniscal damage
Can be acute damage as a result of a sudden high force or load eg tackle, twisting injury causing a tear across the meniscus. The symptoms are pain, reduced range of movement, immediate swelling or within 2 hours of injury, feeling of knee giving way, difficulty weight bearing and often to fully straightening the knee joint.
Or it can be degenerative damage with gradual onset of pain, often in a specific area of the knee. Pain tends to be sharp with twisting or turning and present on a deep squat. There may be intermittent swelling and sometimes locking or the knee may feel as if it is giving way.
Muscle strains/tears
This is a muscle pull, strain or tear mainly associated with the quadriceps muscles at the front or hamstrings at the back of the thigh. It is commonly related to sports eg football, cycling, rowing and downhill running, where the muscle becomes overloaded and then more likely to be injured usually through a sudden forced over stretch but can be the result of muscle fatigue. Strains are graded from grade 1 where a few fibres are torn, to a grade 3 with a complete rupture. Symptoms vary between a cramp, tightness, pain on stretch or muscle contraction through to immediate stabbing/burning pain, bruising and swelling, difficulty weight bearing.
Patella tendinopathy is characterised by localised pain and often swelling in the area where the tendon inserts into the tibia just below the knee cap. This tendon takes the force from the quadriceps muscle and uses it to straighten or control knee flexion.
Tendinopathy is generally thought to be caused by a sudden change in tendon loading eg start of training season or increasing training too quickly. So it can be an over-use type problem or more insidiously related to tendon health. Tendon health is thought to be related to age, genetics, general health, previous micro trauma and lifestyle.
The localised pain tends to be worse at the start of a movement eg getting out of a chair, eases with some activity and then worsens as you continue the activity. The area is usually tender to touch.
2. Patellofemoral pain syndrome (Anterior knee pain) is most common in teenagers and young adults and can affect up to 1 in 3 people. There are symptoms of pain, grinding, clicking and sometimes swelling in the front of the knee. These symptoms are usually worse after sport, after kneeling or squatting, sitting for a long time or walking up or downstairs.
It is generally caused by a combination of the following: muscle imbalance of thigh or buttock muscles in length or strength; weight bearing imbalances and altered foot alignment, patella shape/position within the leg.
3. Degenerative
Osteoarthrosis
OA, degenerative joint disease or wear and tear is a common cause of knee problems. When a joint develops this, some of the cartilage covering the ends of the bones roughens and thins so the joint doesn’t move as smoothly as it should. This can happen in the main knee joint and in the cartilage behind your patella. All the tissues within the joint become more active than normal; your body is trying to heal itself.
The bone underneath the cartilage can react by growing. Bony outgrowths are called osteophytes.
The symptoms of osteoarthritis can include: pain, stiffness, a grating or grinding sensation when the joint moves (crepitus), swelling (either hard or soft) and heat. Sometimes the knee may either lock or give way when you put weight on it.
You are at more risk of having OA if you are female, over 40, over weight, have had a previous injury or because of certain genetic factors.
Baker’s cyst (Popliteal cyst) is a fluid-filled swelling at the back of the knee. It can be caused by direct trauma, sports related knee damage but is most commonly seen with Osteoarthrosis, Rheumatoid Arthritis or Gout. The tissue behind the knee can be swollen and inflamed and cause minor to severe symptoms of pain in the knee and calf and occasional locking of the knee joint.
4. Inflammation/infection
Bursitis is an inflammation of a bursa. Bursae are small fluid filled sacs that help to reduce friction between tendons and bones. They can become inflamed, painful, swollen and warm due to a sudden injury eg fall or direct blow; from recurrent minor trauma eg kneeling for long periods of time; due to infection eg skin break or as part of Rheumatoid arthritis or Gout.
Any of the bursa in your knee can become inflamed, but knee bursitis most commonly occurs over the kneecap (pre-patellar bursitis) or on the inner side of your knee below the joint (pes anserine bursitis).
Knee bursitis can also be caused by an infection, (Septic bursitis). In this instance, as well as having bursitis symptoms, there is also likely to be signs of an infection; such as feeling sick, tired, and feverish.
Infection can occur post-surgery, causing swelling, loss of range of movement and pain.
5. Post-surgery
Total Knee replacement/Partial Knee replacement
This surgery involves replacing a damaged, worn or diseased knee with an artificial joint. Replacement surgery may be indicated if you have severe pain, swelling and stiffness in your knee joint and your mobility is reduced and if your knee pain is so severe that it interferes with your quality of life and sleep. The most common reason for knee replacement surgery is osteoarthritis. A smaller operation called a partial knee replacement tends to be performed on younger people.
Ligament repairs
Ligaments are strong, fibrous rope-like bands that hold the three bones of your knee joint together. The medial collateral ligament (MCL ligament) is on the inner side of your knee, and the lateral collateral ligament (LCL ligament) is on the outer side of your knee. They control sideway motions. The MCL ligament is one of the most frequently injured ligaments that can require repair.
If you tear the anterior cruciate ligament (ACL) in your knee, you may need to have reconstructive surgery. The ACL is a tough band of tissue joining the thigh bone to the shin bone at the knee joint. It runs diagonally through the inside of the knee and gives the knee joint stability and helps to control the back-and-forth movement of the lower leg. ACL injuries are one of the most common types of knee injuries. During surgery the ACL can be reconstructed by removing what remains of the torn ligament and replacing it with a tendon from another area of the leg, such as the hamstring or patellar tendon.
Arthroscopy
This is a surgical procedure and involves a tiny camera being inserted into the knee via a small incision. This then allows the surgeon to see what is happening inside the joint and determine the likely cause of the problem. During an arthroscopy, as well as determining the problem, the surgeon can also perform washouts, removal of loose bodies and trim the cartilage.
Tissue release
Lateral release is a procedure performed to help realign the kneecap and prevent partial dislocations.
Knee treatments
Your physiotherapist will access you and determine what the likely cause of your knee pain is. They may feel that additional investigations are necessary such as X-rays or scans and can contact your doctor to request these as appropriate.
Your treatment programme will be tailored to you but is likely to include some of the following strategies.
Advice, strengthening, stretching and proprioception exercises, management strategies, mobilisations- soft tissue, joint mobs, Acupuncture, PNF, taping
What next?
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