K

knee injuries Sprains, strains, CARTILAGE tears,
and fractures involving the structures of the knee.
The knee is a hinge JOINTthat allows the leg to flex
(bend back) and straighten, essential actions of
walking. Unique among hinge joints in the body,
the knee also allows a small amount of rotation.
The knee is vulnerable to both traumatic and repe-
tition injuries. Knee injury is the leading reason for
visits to orthopedic surgeons in the United States.
The knee primarily joins the femur (thigh BONE)
to the tibia (shin bone) and the fibula (small long
bone behind the tibia). It also contains the patella
(kneecap), a small bone that provides added lever-
age for movement of the lower leg. A C-shaped
thick pad of cartilage, the meniscus, cushions the
ends of the bones from each other. Each knee
contains two menisci: the medial meniscus, which
wraps around the inside of tibia, and the lateral
meniscus, which wraps around the outside of the
tibia. Strong ligaments bind the knee from each
side and the center, holding the bones in place.
The most damaging traumatic injuries to the
knee are those that result from a blow or fall that
rapidly stretches the ligaments and causes them to
tear (ligament sprain). Sudden twisting motions in
which the foot plants but the rest of the leg con-
tinues to move also expose the knee to such
injury. The knee takes considerable pounding in
the course of everyday activities that subject it to
repeated impact (such as occurs with walking,
running, and jumping). Repetition or “wear and
tear” injuries of the knee include OSTEOARTHRITIS
and PATELLOFEMORAL SYNDROME.

Symptoms and Diagnostic Path
PAINand swelling are symptoms common to many
kinds of knee injuries. Damage to ligaments and
menisci often result in an unstable knee that feels

“loose” or may not bear the person’s weight. With

a moderate to severe injury the person hears and

feels a substantial “pop” from the knee, which is

the LIGAMENTtearing. Depending on which liga-

ment the injury damages, the knee may feel it

wants to bend too far back, extend too far for-

ward, or slip to one side or the other. A significant

blow to the side of the knee can cause multiple

injuries within the knee, rendering the knee use-

less. Hyperextension and dislocated patella present

characteristic appearances that make the diagnosis

obvious. A fractured patella can cause excruciating

pain and complete inability to use the knee or leg.

The diagnostic path begins with a detailed

accounting of the nature of the pain and descrip-

tion of any precipitating trauma. The doctor will

thoroughly examine both knees. Diagnostic proce-

dures may include X-RAY, especially if the doctor

suspects a FRACTURE, though COMPUTED TOMOGRAPHY

(CT) SCANor MAGNETIC RESONANCE IMAGING(MRI) typi-

cally yield more information about the nature and

extent of soft tissue injuries such as are most com-

mon in the knee. Diagnostic ARTHROSCOPY, a MINI-

MALLY INVASIVE SURGERY, may be necessary to fully

assess the damage and has the advantage of allow-

ing the surgeon to immediately repair the injury.

Treatment Options and Outlook

Ice to the knee and restricting movement are the

most effective immediate treatments for traumatic

injury. Prompt icing can reduce INFLAMMATIONand

swelling to minimize the severity of the injury.

Suspected patella fracture or severe sprain

requires immobilization to prevent further dam-

age. Many knee injuries heal with conservative,

nonsurgical treatment approaches. The doctor

may recommend a knee wrap or brace, depending

on the injury. NONSTEROIDAL ANTI-INFLAMMATORY

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