Physiotherapy

The knee is a “hinge” type joint that allows the leg to bend and straighten (flex and extend). There are three compartments to the knee joint: an inner and outer compartment located between the thigh bone (femur) and the lower leg bone (tibia), and a knee cap compartment located between the knee cap (patella) and a special groove in the femur.

TYPES OF KNEE INJURY

Bursitis — The knee is lubricated by joint fluid that is produced by the lining of the joint and by six lubricating “bursa” sacs. The bursa sacs can become irritated as a result of injury, excessive pressure, or overuse; inflammation of a bursa is called bursitis. 

Joint effusion — After a knee injury, excessive fluid can accumulate inside the joint. This is called “water on the knee” or a joint effusion.

Arthritis — The cartilage covering the ends of the bones and the undersurface of the knee cap (surface or articular cartilage) can become worn down, irritated, or irregular, a condition known as arthritis.

Meniscal tears — Specialized “shock absorber” cartilage located between the thigh and leg bones (meniscal cartilage) can be damaged, a condition known as a torn meniscus.

Cruciate ligament sprain or tear — The knee joint is held tightly together by four ligaments, the inner and outer fan-shaped hinge ligaments (medial and lateral collateral ligaments) and the crossing ligaments (the anterior and posterior cruciate ligaments.

The collateral ligaments are firmly attached to the sides of the thigh and leg bones, hold the two bones together, and prevent side to side motion. The cruciate ligaments are firmly attached to the middle of the thigh and leg bones and prevent forward and backward motion. Irritation of these ligaments is called a sprain, and rupture is called a tear.

Muscle strain — The quadriceps muscle in the front of the thigh and the hamstring muscles in the back of the thigh support and move the knee joint. Loss of muscle tone from injury or disuse causes instability of the knee joint.

Significant loss of muscle support can cause the knee to “give out,” leading to a fall and further injury. Excessive use or a rapid contraction (ie, from sprinting or jumping) can cause a quadriceps muscle strain or a hamstring pull.

CAUSE OF KNEE INJURIES — Pain in the knee can occur as a result of one or more of the following:

• Acute injuries may be caused by breaks in the bones, torn cartilage, ligament rupture, or increased joint fluid due to a severe knee strain, infection, arthritis, or bleeding. Most acute injuries cause severe pain and swelling.

More subtle injuries, such as partially torn cartilage or tendon, and ligament sprains cause less swelling, pain, and minimal difficulty walking or bending the knee

• Overuse or excessive use of the knee, particularly when the muscles are “out of shape,” can cause painful knee caps, arthritis flares, bursitis, or a knee strain and effusion.

• Wear and tear over time; painful knee caps and arthritis are the two most common causes of knee pain in the noninjured knee.

TREATMENT — Physical therapy is essential to the treatment, rehabilitation, and prevention of many of the conditions that affect the knee joint and its surrounding supporting structures. Physical therapy for knee pain often includes ice and elevation and muscle toning exercises.

Activity limitations — To speed recovery and protect against future knee damage, activities that impact or jar the joint cartilage or twist the supporting ligaments should be avoided temporarily. Activities that involve repetetive bending (particularly beyond 45 to 50 degrees or half-way) should be attempted with caution.

The following positions and activities place excessive pressure on the knee joint and must be limited until knee pain and swelling resolve:

• Squatting
• Kneeling
• Twisting and pivoting
• Repetitive bending (stairs, getting out of a seated position, clutch and pedal pushing, etc.)
• Jogging
• Jazzercize
• Playing stop and go sports (basketball and sports that require the use of rackets)
• Swimming using the frog or whip kick
• Bicycling

The following types of exercise equipment also place excessive pressure on the knee joint and should be limited until knee pain and swelling resolve:

• Stair stepper
• Stationary bicycle
• Rowing machine
• Universal gym utilizing leg extensions

The preferred exercise equipment for the knee should provide smooth motion of the knee, maximal toning of the front and back thigh muscles (quadriceps and hamstring muscles), minimal jarring and impact to the joint, and the least amount of bending to accomplish toning. These activities are acceptable alternatives to the above:

• Fast walking
• Water aerobics
• Swimming using the crawl stroke
• Cross country ski machines
• Soft platform treadmill
• Trampoline

Ice and elevation — Ice is useful for the control of pain and swelling. It is applied to the knee for 15 to 20 minutes as often as every 2 to 4 hours, particularly after any physical activity. A bag of ice, frozen vegetables, or an iced towel cooled in a freezer work well. The swollen knee should be elevated above the level of the heart while icing.

Pain relief — If needed, a pain medication such as acetaminophen (Tylenol®) can be taken to reduce pain; the usual dose of acetaminophen is two 375 mg tablets every four to six hours as needed. No more than 4000 mg of acetaminophen is recommended per day, and anyone with liver disease or who drinks alcohol regularly should speak with their healthcare provider before using acetaminophen.

A nonsteroidal antiinflammatory drug (NSAID), such as ibuprofen (eg, Advil®, Motrin®) or naproxen (eg, Aleve®) can also be used for pain. The dose of these NSAIDs is available in table 1 (show table 1). (See “Patient information: Nonsteroidal antiinflammatory drugs (NSAIDs)”).

Muscle toning exercises — Rehabilitation of the knee begins with gentle toning exercises. Straight leg raising and leg extension exercises are used to strengthen the quadriceps and hamstring muscles, to provide support to the joint, and to counteract the giving out sensation caused by disuse or weakened ligaments. These muscle toning exercises are performed without bending the knee.

Straight leg raises — Sit on the edge of a chair or lie down with the opposite leg bent . Raise your leg 3 to 4 inches off the ground and hold for 5 seconds. Sets of 15 to 20 raises should be performed daily with the leg perfectly straight. As your condition improves, perform straight leg raises with weights at the ankle; begin with a two pound weight and gradually increase to a 5 to 10 pound weight (pennies or fishing weights in an old sock, 2 cans in an old purse, or Velcro ankle weights).

Leg extensions — Lie on your stomach or kneel on all fours. Keeping the leg straight, raise your leg 3 to 4 inches off the ground and hold for 5 seconds. Sets of 15 to 20 extensions should be performed daily with the leg perfectly straight.

As knee pain improves, perform leg extensions with weights at the ankle; begin with a 2 pound weight and gradually increase to a 5 to 10 pound weight. Note that the exercise should be performed lying flat if the knee cap is the source of pain.

If the straight leg raising exercises do not aggravate the underlying condition, weighted leg lifts with a bent knee can begin. Initially these are performed with the legs bent to 30 degrees, using the same amount of weight and number of repetitions as with straight leg raises. The amount of bending is gradually increased as tolerated, in increments of 30 to 45 to 60 to 90 degrees of bending.

Return to activity — Advanced knee exercises and high impact sports can be attempted several months after full recovery of thigh and hamstring muscle tone. Tolerance of these exercises depends upon the underlying injury and the likelihood of recurrence. These exercises are not recommended for people with moderate to severe arthritis of the knee joint, after surgical removal of the meniscal cartilage, or in people with severe ligament injuries causing knee instability.

Advanced knee exercises

• Squats — Squats are excellent for the development of the quadriceps muscles and the gluteus muscles of the buttocks. However, the pressure created in the fully bent position is too great for a person with arthritis in the knee joint or painful knee caps. It is safer to perform a quarter or half squat, bending the knee only half way, to no greater than 45 degrees .

• Aerobic activity — Rope jumping, high impact aerobics, step aerobics, etc. may be acceptable for some but not all conditions. People with arthritis, torn cartilage, and fractures with improper bony alignment should not perform these types of exercises.