Knee

The knee joint is the largest joint in your body, and one of the most complex. Because you use it so much, it is vulnerable to injury.

Anterior Cruciate Ligament (ACL) Tear

The Anterior Cruciate Ligament (ACL) is a strong ligament inside the knee that connects the thighbone (femur) to the shinbone (tibia). It may become torn, resulting in instability of the knee.

Common Causes

Falls that cause the knee to twist or pivot. Rapid deceleration or pivoting in sports. Common in skiing, basketball, and soccer.

Symptoms

At the time of injury, many patients recall a ‘pop’ in their knee. Swelling usually develops. The knee may feel unstable, with patients not being able to ‘trust’ the knee, or complain of the knee ‘giving way’. Pain is unpredictable.

Physical Findings

Swelling in the knee, especially at the time of injury. Instability of the knee can be demonstrated on physical exam.

Workup

History and physical examination are the main aids to diagnosis. X-rays are usually necessary to rule out a fracture or other injury. Your doctor may obtain an MR scan as well.

Non-Operative Treatment

Initial treatment includes rest, ice, and elevation. A torn ACL will not heal on its own. Some patients, however, can reduce their symptoms with physical therapy, bracing, and activity modification.

Surgical Treatment

The ACL may be successfully repaired with an arthroscopic ACL reconstruction, using one of several surgical techniques.

Injury Comment

Left untreated, ACL tears do not heal on their own. Persistent knee instability may predispose the knee to early wear, leading to arthritis. Patients with a damaged ACL are at much higher risk for causing additional injury to their knees, including meniscus tears and cartilage injuries.

Meniscus Tear

The meniscus is a ring shaped piece of tissue that acts as a cushion, or gasket between the thighbone (femur) and the shinbone (tibia). It functions as a shock absorber, distributing stress across the knee joint. It also acts to aid in smooth hinge-like knee motion. There are two menisci in the knee joint; one in the inside of the knee (medial meniscus) and one in the outside of the knee (lateral meniscus). Either of these structures may become ripped, or torn.

Common Causes

Pivoting or twisting, squatting or kneeling activities. Often there is some trauma to the knee, but many meniscus tears are ‘degenerative’ or simply occur as part of the aging process.

Symptoms

Pain in the knee, especially with squatting or kneeling, getting up out of a chair, getting in and out of a car, etc. The pain may be sharp, in the back of the knee. Patients may report clicking, or a sense of catching inside of the knee. Frank locking of the knee is highly suspicious of a certain type of meniscus tear. There may be intermittent swelling.

Physical Findings

Tenderness along the joint line of the knee, either medially or laterally. A sense of clicking with the knee flexed and rotated is suspicious for a meniscus tear.

Workup

Often the diagnosis is made solely on history and physical examination. MR scans are fairly accurate in detecting these injuries, if the diagnosis is uncertain.

Non-Operative Treatment

Rest, anti-inflammatory medication, and physical therapy may improve symptoms to a very tolerable level.

Surgical Treatment

An operative arthroscopy, with either trimming of the torn piece of meniscus, or an arthroscopic meniscus repair.

Injury Comment

These are common injuries, especially with sports and in an increasingly active middle-aged population. Not all patients require an arthroscopy, but if surgery is required, the success rate is high.

Collateral Ligament Sprain

The knee has strong ligaments on both the inside of the knee (medial collateral ligament) and the outside of the knee (lateral collateral ligament). These ligaments attach to both the thighbone (femur) and to the shinbone (tibia). These two collateral ligaments provide stability to the knee, especially in resisting medial and lateral forces. If there is sufficient force, however, either of these collateral ligaments may become injured.

Common Causes

Struck in the side of the knee or leg during a football tackle. Rapid pivoting, in soccer or basketball.

Symptoms

Pain in the knee, either in the inside (most common) or outside of the knee. There may be feelings of instability in the knee with weight bearing or walking. There may be swelling or bruising present.

Physical Findings

Tenderness along the injured collateral ligament. Pain with stress testing of the ligament.

Workup

In addition to history and physical examination, x-rays are usually obtained to make sure there is no fracture. MR scans are usually not necessary in an isolated collateral ligament injury.

Non-Operative Treatment

Functional knee bracing until the ligament is healed. This may take months in some cases.

Surgical Treatment

Ligament repair.

Injury Comment

Surgery is almost never required collateral ligament injuries of the knee, and non-operative treatment usually gives good results.

Arthritis of the Knee

The ends of the bones in the knee joint are normally covered with a layer of smooth cartilage. If the cartilage wears out, bone will rub on bone, resulting in a stiff and painful arthritic knee.

Common Causes

Most degenerative knee arthritis is genetic, with a family predisposition. It is probably not activity related, and in fact activity may be helpful in reducing the risk of arthritis. ‘Post-traumatic;’ arthritis develops a long time after a significant knee injury, or as a consequence of a chronic knee injury or instability.

Symptoms

Pain when walking, worsened with increased activity and relieved with rest. Difficulty tying your shoes, or putting on socks. Difficulty with stairs. Swelling in the knee joint.

Physical Findings

Tenderness, and swelling in the knee. Loss of motion or deformity may be present.

Workup

History, examination, and x-rays are generally diagnostic.

Non-Operative Treatment

Activity modification, weight loss, physical therapy, and anti-inflammatory medication may be helpful. Corticosteroid injections may bring temporary relief, but should be performed sparingly. Injections of hyaluronic acid may reduce symptoms for a period of time in some patients. Some patients report relief with chondroitin sulfate or glucosamine pills, but scientific studies are inconclusive.

Surgical Treatment

An arthroscopy, with debridement, will remove debris and cartilage fragments from the knee, and can provide relief. Ultimately, a total knee replacement may be necessary.

Injury Comment

Total knee replacement surgery has a high success rate, and great patient satisfaction. Biggest problem is durability of the prosthesis, which wears out or loosens with time. The success rate for a redo, or revision knee replacement is not nearly so high. Therefore, this surgery should be delayed as much as possible, especially in the younger patient.

Patellar Tendonitis

The patellar tendon runs from the kneecap (patella) to the front of the shinbone (tibia). When the thigh muscles (quadriceps) contract, the knee extends, or straightens, by way of the patellar tendon. Overuse may lead to inflammation of the tendon.

Common Causes

Frequent kneeling, squatting, climbing or jumping (frequently seen in basketball players).

Symptoms

Pain in the front of the knee, just below the kneecap. The pain is worsened by kneeling or squatting.

Physical Findings

Tenderness along the patellar tendon, usually near the attachment of the kneecap. Swelling, or thickening of the tendon may be present.

Workup

Diagnosis is made by history and physical examination. X-rays are frequently obtained to make sure there is no other injury.

Non-Operative Treatment

Rest, avoidance of aggravating activities, anti-inflammatory medication and physical therapy are the mainstays of non-operative care.

Surgical Treatment

Debridement of the damaged tissue. Rarely indicated.

Injury Comment

Non-operative care is generally successful.

Chondromalacia Patella / Patellofemoral Pain / Anterior Knee Pain

The kneecap, or patella, rides along a trough or groove at the end of the thighbone (femur), much like a bobsled down a track. The patella is attached to the strong thigh muscles on one end, and is attached via the patellar tendon to the front of the shinbone (tibia) on the other end. Thus, when the thigh muscles contract, they pull on the patella, and the leg straightens. The undersurface of the patella has a thick layer of smooth cartilage, and rides nearly friction free. Damage to the cartilage undersurface of the patella is termed Chondromalacia Patella.

Common Causes

May be due to direct trauma, such as a fall on a flexed knee. Abnormal cartilage wear may develop due to chronic maltracking or subluxation of the patella (see patellar instability). Weight gain, or other increased load on the knee can cause symptoms. Also frequently seen in adolescent girls.

Symptoms

Pain in the front of the knee. Worsened with going up and down stairs, climbing, squatting or kneeling, and prolonged standing.

Physical Findings

Tenderness in the front of the knee, with a positive patellar compression test. Findings are often unimpressive.

Workup

Diagnosis is made by history and physical examination. X-rays are useful to rule out other injury.

Non-Operative Treatment

Anti-inflammatory medication, rest, physical therapy and possible patellar stabilizer knee bracing are the mainstays of treatment for this condition.

Surgical Treatment

Generally not indicated.

Injury Comment

Most cases resolve with appropriate treatment.

Patellar Instability / Patellar Subluxation

The patella, or kneecap, rides along a trough or groove at the end of the thighbone (femur), much like a bobsled down a track. The patella is attached to the strong thigh muscles on one end, and is attached via the patellar tendon to the front of the shinbone (tibia) on the other end. Thus, when the thigh muscles contract, they pull on the patella, and the leg straightens. The patella is supposed to ride in the center of its track. With abnormal patellar tracking, the kneecap can start to ride out of its groove, and can even dislocate.

Common Causes

Twisting injury to the knee, a direct blow to the kneecap. Certain people have a predisposition to this problem, based on their own knee alignment.

Symptoms

Pain in the front of the knee, increased with exercise or activity. A patellar dislocation results in an obvious deformity of the front of the knee, with an inability to move the knee.

Physical Findings

Abnormal patellar tracking on physical examination. Tenderness with compression of the patella, or with attempts to shift the patella to the side.

Workup

History examination, and x-rays. Special x-rays can detail how the patella tracks down the end of the thighbone.

Non-Operative Treatment

Physical therapy, with attention directed on strengthening specific muscle groups. Anti-inflammatory medication is helpful to reduce discomfort. Patellar stabilizing knee braces are effective.

Surgical Treatment

Patellar realignment procedures. These range from an arthroscopic lateral release, to open realignment of the insertion of the patellar tendon on the tibia.

Injury Comment

The majority of cases can be successfully treated with therapy and exercise. Symptoms may be exacerbated during growth spurts in adolescents.