Knee pain can have a variety of causes and presentations. Here is a list of common causes of knee pain including a description, common causes and risk factors.
Patellofemoral pain syndrome
Patellofemoral Pain Syndrome (PFPS), is caused by chronically tight and overused muscles in the thigh pulling on the knee cap. This condition caused when a tight and inelastic IT Band (the connective tissue band that runs down the outside aspect of the thigh from the hip to just below the lateral knee) and the lateral quadricep muscle (vastus lateralis) pull on the outside aspect of the knee where it attaches to the bone and knee cap (Patella). In general patellofemoral pain syndrome occurs when the patella does not move or ‘track’ in a correct fashion when the knee is being bent and straightened. This movement can lead to damage of the surrounding tissues, such as the cartilage on the underside of the patella itself, which can lead to pain in the region. Pain is increased with activity and deep knee bending on the affected side.
PFPS is often confused with another condition known as Chondromalacia Patella. This is damage to the cartilage which lines the underside of the knee cap. CMP can be a result of PFPS, although it can also occur independently, usually due to damage from an impact.
- Aching pain in the knee joint, particularly at the front, around and under the patella.
- Tenderness along the border of the kneecap.
- Swelling sometimes occurs after activity.
- Pain is often worst when walking up or down hills or stairs.
- A clicking or cracking sound may be present on bending the knee.
- Sitting for long periods may be uncomfortable.
- Wasting (atrophy) of the quadriceps muscles in prolonged cases.
- Tight muscles including calf muscles, hamstrings, quadriceps (especially vastus lateralis on the outside) and iliotibial band.
Risk Factors/Contributing Factors
- Lack of proper stretching pre/post exercise
- Weak medial thigh muscles (vastus medialis and adductors)
- Long-distance running
- Running uphill
- History of a previous knee dislocation
- Overloading – Bending the knee increases the pressure between the patella and the femur. Thus sports such as running, where repeated weight-bearing occurs, may result in PFPS.
- Over pronation- Pronating sometimes exhibited as ‘flat’ feet lead to an increased biomechanical stress on the knee joint. This may affect the alignment of the patella particularly during movement.
- Q-angle – Some people have a larger than normal femoral angle (known as the Q-angle) resulting in a ‘knock-kneed’ appearance (genu valgum). When the person straightens their leg when weight bearing, the patella will be forced to the outside of the knee. With repeated bending and loading, this motion may lead to damage of the underlying structures and cause pain. A larger Q angle is common in women due to their wider pelvis. This is why more women suffer with this condition than men. Strengthening the abductors (Gluteus Medius, Minimus and Tensor Fasciae Latae) and lateral rotators (Gluteus Medius and Maximus) of the hip can be beneficial when a wide Q angle is thought to be a contributing factor.
LIGAMENTOUS SPRAIN/ MUSCULAR STRAIN
The knee and ankle are common locations for sprain and strain injuries. These types of injuries are often seen in sports such as football, hockey and soccer. They are also common in slips/trips when out walking and running. A sprain is damage to a ligament that supports a joint. These include the medial and lateral collateral ligaments (MCL/LCL) and the anterior and posterior cruciate ligaments (ACL/PCL) in the knee. In the ankle, the most commonly injured ligaments are on the outside aspect of the ankle and includes the anterior talofibular ligament, calcaneofibular ligament, talocalcaneal ligament, posterior talocalcaneal ligament and the posterior talofibular ligament. A strain, on the other hand, is a damage to a muscle in the affected area. Both strains and sprains can range from mild tearing to complete rupture and often need to be differentiated from a fracture by a healthcare provider due to trouble weight bearing, excessive swelling and bruising to the area.
- Swelling ranging from mild and localized to severe with a larger area affected
- Possible bruising also ranging in severity
- Pain with active motion
- Pain with passive motion
- Pain with walking and weight-bearing
- Sense of instability or “giving out”
- Blunt trauma to the area (ie tackle, impact)
- Tripping or stumbling
- A quick pivot and change of direction in sport