Knee Pain Overview
Types of Knee Pain
The nerves that provide sensation to the knee come from the lower back and also provide hip, leg, and ankle sensation. Pain from a deeper injury (called referred pain) can be passed along the nerve to be felt on the surface. Knee pain, therefore, can arise from the knee itself or be referred from conditions of the hip, ankle, or lower back. All of the following sources of knee pain arise from the knee joint itself.
In general, knee pain is either immediate (acute) or long-term (chronic). Acute knee pains can be caused by an acute injury or infection. Chronic knee pain is often from injuries or inflammation (such as arthritis) but can also be caused by infection.
Acute Knee Pain
Sprained and Torn Cruciate Ligaments
- Description: An anterior cruciate ligament (ACL) injury is a common sports injury generally caused by a hard stop or a violent twisting of the knee. The posterior cruciate ligament (PCL) is stronger than the ACL and much less commonly torn. The PCL requires strong forces, such as those produced when the dashboard strikes the knee in a car accident, to tear. Due to these severe forces, PCL injury is often associated with other ligamentand bone injuries.
- Symptoms: If you tear your ACL, you may hear a pop. You will also notice your knee give way or become unstable and feel pain that is bad enough that you might feel like vomiting. This will, almost always, be followed by marked knee swelling over the next couple of hours because the ACL bleeds briskly when torn.
- Treatment: Surgical repair is recommended for high-level athletes who demand optimal outcomes. Conservative treatment and knee braces may prove sufficient for those who do not demand quite so much from their knees.
- Description: Both the quadriceps and patellar tendons may rupture partially or completely. A quadriceps tendon rupture typically occurs in recreational athletes older than 40 years (this is the injury former President Clinton suffered while jogging), and a patellar tendon rupture typically occurs in younger people who have had previous tendonitis or steroid injections to the knee.
- Symptoms: Rupture of either the quadriceps or patellar tendon causes pain (especially when trying to kick or extend the knee). Those people with complete ruptures are unable to extend the knee. The patella is also often out of place either upward (with patellar tendon rupture) or downward (with quadriceps tendon rupture).
- Treatment: Tendon ruptures should be evaluated urgently. Tendon ruptures generally require surgical repair. A partial rupture may be treated with splinting alone.
- Description: Injuries to the meniscus are typically traumatic injuries but can also be due to overuse. Often, a piece of the meniscus will tear off and float in the knee joint.
- Symptoms: Meniscal injuries may cause the knee to lock in a particular position, or either click or grind through its range of motion. Meniscal injuries may also cause the knee to give way. Swelling typically accompanies these symptoms although the swelling is much less severe than with an ACL injury.
- Treatment: Meniscal injuries often require arthroscopic surgical repair. A locking knee or a knee that "gives" should be evaluated for arthroscopic repair.
- Description: Knee dislocation is a true limb-threatening emergency. This is also a rare injury. Dislocation of the knee is caused by a particularly powerful blow to the knee. The lower leg becomes completely displaced with relation to the upper leg. This displacement stretches and frequently tears not only the ligaments of the knee but also arteries and nerves. Untreated arterial injuries leave the lower leg without a blood supply. If circulation is not restored, amputation may be required. Nerve injuries, on the other hand, may leave the lower leg viable but without strength or sensation.
- Symptoms: Knee dislocations are severely painful and produce an obvious deformity of the knee. Many dislocations are reduced -- or put back into alignment -- on their own. As this occurs, many will report feeling a dull clunk.
- Treatment: If the knee dislocation has not been put back into place on its own, the doctor will immediately reduce the dislocation. Medical treatment, however, does not stop here. Whether a dislocation reduces by itself or is put back into place in the hospital, it requires further evaluation and care. After reduction, people with these injuries are observed in the hospital where they usually do a number of tests to ensure that no arterial or nerve injury has occurred. If such an injury is found, it must be repaired immediately in the operating room.
Dislocated Kneecap (patella)
- Description: A common injury caused by direct trauma or forceful straightening of the leg, such as an injury that happens when serving in volleyball or tennis. Kneecap dislocation is more common in women, the obese, knock-kneed people, and in those with high-riding kneecaps.
- Symptoms: If you have this injury, you will notice the patella being out of place and may have difficulty flexing or extending your knee.
- Treatment: The doctor will move the patella back into place (reduce the dislocation). Even if the patella goes back into place by itself, however, it needs to be X-rayed for a fracture. After reducing the patella and ensuring the absence of a fracture, the doctors will treat these injuries by splinting the knee for 3 weeks to allow the soft tissues around the patella to heal followed by strengthening exercises to keep the patella in line. This injury often causes damage to the cartilage on the back of the patella.