Knee Bursitis

Anatomy

The bursae of the knee are found in areas where tendons glide over bone or soft tissue. Often it is difficult to differentiate bursitis from other conditions of the knee.

The pes anserine bursa lies beneath the pes anserine tendons on the anteriomedial aspect of the inferior portion of the knee. The pes anserine tendons are composed of the confluence of the gracilis, sartorius, and semitendinosus. Beneath the pes anserine bursa lies the tibial attachment of the medial collateral ligament. The infrapatellar bursa is composed of a superficial and a deep component. The superficial infrapatellar bursa lies superficial to the proximal portion of the patellar tendon. The deep infrapatellar bursa lies deep and just proximal to the insertion of the patellar tendon on the tibia. The prepatellar bursa is a large bursa that lies directly superficial to the patella. And last, the tibial collateral bursa lies beneath the medial collateral ligament directly over the medial meniscus.

Causes

Any bursitis can be acute, chronic, or septic. Most common in athletes are the acute and chronic forms. The septic form is usually seen in older individuals, those who are immunocompromised, and those who have had trauma; it can also be iatrogenic, resulting from injection of a nonseptic bursa.

Acute bursitis is often caused by trauma, repetitive stress, gout, or rheumatoid arthritis. Chronic bursitis is often seen following single or repeated episodes of acute or septic bursitis. In addition, overuse injuries or minor repetitive trauma can also lead to this condition.

Prepatellar bursitis and superficial infrapatellar bursitis are seen in individuals who are on their knees frequently. Superficial infrapatellar bursitis, or “vicar's knee,” is usually caused by kneeling in the upright position, whereas prepatellar bursitis, or “housemaid's knee,” is caused by kneeling in the bent-over position. It is also more common in sports that are at risk for a direct blow to the knee, such as football and rugby. Pes anserine bursitis is often seen in individuals with an abnormal gait or knee alignment. It is also commonly seen in patients with arthritis of the knees. And last, athletes with hamstring tightness can be at increased risk for this disorder.

Symptoms

In acute or septic bursitis, the symptoms are similar. Patients will often complain of pain and swelling over the affected bursa. They may even notice increased warmth over the bursa. In addition, the patient will often have pain and limited range of motion when the tendon overlying the bursa is active. For example, with prepatellar bursitis they will have pain and limited range of motion with flexing or extending the knee. With septic bursitis, the pain with range of motion is often more pronounced and is often associated with fever and chills.

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