
The Knee
Examples of Conditions Treated
Ligament damage
Ligaments are strong bands of connective tissue that run from bone to bone. A ligament offers stability to the joint. When a ligament stretches or tears, the degree of disruption to the tissue is classified as follows:
Grade I: Stretching of the ligament or a very mild tear, with little to no instability at the joint.
Grade II: More serious but still incomplete tear.
Grade III: A completely torn or ruptured ligament. This is not a broken bone, but can feel like one since it is often impossible to put weight on the joint or use the affected limb
Anterior Cruciate Ligament
The anterior cruciate ligament runs from the back of the thigh bone across the space within the knee joint and attaches at the front of the lower leg bone. It controls how far forward the lower leg can move under the thigh bone. Injury is typically caused in a non contact deceleration situation that involves twisting. An example of this would be when an athlete lands on one leg and quickly pivots in the opposite direction. A forced “over straightening” (hyperextension) of the knee can also stress it. Symptoms vary in an ACL rupture. Some patients report hearing or feeling a pop. There will be swelling and there may be immediate feelings of instability.
Posterior Cruciate Ligament
The posterior cruciate ligament is the primary stabilizer of the knee and the main controls how far backward the lower leg bone moves under the thigh. If the shin bone moves too far back, the posterior cruciate ligament can rupture. More recent research has shown us that this ligament also prevents side-to-side and rotatory movements. The posterior cruciate is stronger than the anterior cruciate and injured less frequently. High impact injuries that occur with the knee bent and the lower leg bone being forced backwards (eg: hitting the dashboard in a car accident) can cause the posterior cruciate ligament to rupture.
Medial and Lateral Collateral Ligaments
The ligaments on either side of the knee are there to limit side to side motion, but they also work with the posterior cruciate ligament to prevent excessive backward movement of the lower leg under the thigh bone.
The medial collateral runs down the inside of the knee (the side of your knee closest to the midline of your body) and the lateral collateral runs down the outside. If an injury causes these ligaments to stretch too far they may tear. The tear may occur in the middle of the ligament or it may occur at either end of the ligament where it attaches to the bone. If the force from the injury is great enough, other ligaments and cartilage may also be torn at the same time.
Patella Tendonitis
The quadriceps are a group of four muscles that attach to the front of your thigh. They are connected to the top of your shin bone by a strong band of tissue called a tendon. In the tendon sits the knee cap (the patella). This tendon is therefore known as the patella tendon.
Tightening the quadriceps pulls on the patella tendon with its attachment to the lower leg bone and straightens the leg. The patella tendon can become inflamed due to stresses placed on it and the supporting structures of the knee.
These stresses can be:
- Repetitive Action
- Over Training
- Muscle imbalance anywhere along the leg and into the hip
- Leg length discrepancy
- Tracking abnormalities of the patella
- Foot posture
Meniscal Dysfunction
The menisci are wedge shaped pieces of cartilage that sit in the knee joint between the thigh bone (femur) and the lower leg bone (tibia). There are two menisci. The medial meniscus is closest to the midline of your body, and a lateral one closest to the outside.
The menisci have some important functions:
- Shock absorption. They transmission 50% to 70% of the loads across the knee joint. In their absence, these loads are directly transmitted to the articular cartilage on the ends of the bones.
- Joint lubrication and nutrition
- Joint stability: They are secondary stabilisers of the knee in most movements, but if a patient was to damage their anterior cruciate ligament they become the primary stabiliser of the tibia under the femur in certain movements.
Most injuries to the meniscus are caused by trauma, usually compression and twisting of the knee. Because aging tends to break down the inner tissues of the meniscus, minor trauma (such as squatting) can injure the meniscus in an older person. Symptoms of a torn meniscus include pain, locking or giving way and tenderness around the joint line of the knee.
Bursitis
A bursa is a fluid filled sac that exists in the body where tissue needs to glide over bone. They are friction reducing cushions positioned to afford movement and protection. There are a number of bursa in and around the knee and they all have the potential to be irritated through overload, trauma and infection. They can swell and feel painful.
Prepatellar bursitis: Inflammation of the bursa that sits in between the front of the knee cap and the skin covering the knee cap. Sometimes called housemaids knee.
Suprapatellar bursitis: Inflammation of the bursa that sits behind the kneecap and extends upwards in between the thigh bone and the quadriceps muscle. Can feel painful at the top of the kneecap in bursitis.
Infrapatellar bursitis: Inflammation of the bursa that sits below the kneecap, in between the shin bone and the patella tendon. Can feel painful below (not behind) the kneecap and is associated with patella tendonitis. Sometimes called clergyman’s knee.
Popliteal bursitis: Inflammation and distension of the bursa that sits behind the knee. Can feel painful and grinding behind the knee at the back of the leg. Sometimes called baker’s cyst.
Iliotibial bursitis: Pain and swelling on the lateral aspect of the knee under the insertion of the iliotibial band.