What Is a Bipartite Patella?

The patella, commonly known as the kneecap, is a triangular bone located at the front of the knee joint. A bipartite patella is an anomaly characterized by the presence of two distinct bones that form the kneecap instead of the typical single bone structure. Although this condition affects a small percentage of the population—approximately 1 to 2 percent—it can occur in one or both knees.

Symptoms of a Bipartite Patella

In many cases, individuals with a bipartite patella remain asymptomatic, often unaware of their condition until discovered through imaging techniques like X-rays or MRIs. Symptoms are more likely to arise following an injury to the kneecap, especially in sports that involve significant knee movement. An injury to the synchondrosis—the tissue connecting the two bones—can lead to inflammation and discomfort. Common symptoms include:

• Tenderness around the kneecap
• Pain during knee extension
• Swelling in the knee area
• A noticeable bony ridge on the outer edge of the kneecap
• A sensation of instability in the knee

Causes of a Bipartite Patella

The formation of the patella begins with cartilage and blood vessels during childhood. This cartilage starts to ossify into bone by the age of 3 to 5 years, generally resulting in a united kneecap by around 10 years of age. However, the exact cause of a bipartite patella remains unclear; in some cases, the patellar bones do not fully fuse, leading to the development of this condition. The additional bone typically appears at the upper outer edge or the lower and inner portion of the kneecap.

Diagnosis of a Bipartite Patella

Most individuals with a bipartite patella are not formally diagnosed due to the lack of symptoms. However, if an X-ray or MRI is performed for an unrelated issue, the bipartite characteristic may be identified. While it may initially resemble a fracture on imaging, closer examination will reveal that a bipartite patella lacks the defining jagged edges associated with fractured bones.

Treatment Options

Typically, a bipartite patella does not require intervention. If symptoms such as pain or discomfort occur, management strategies may include:

• Icing the kneecap
• Resting the knee to allow for healing
• Taking over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs)
• Using a knee brace for added support
• Undergoing physical therapy for strength and flexibility

If symptoms persist after about six months of conservative treatment, surgical options may be considered. These could involve:

• Removing the smaller of the two patellar bones
• Reconstructing the connective tissue that links the bones, potentially using screws
• Realigning the tissue that keeps the kneecap centered

A study conducted in 2015 reported that 84.1% of surgical patients experienced a reduction in pain, and 98.3% returned to their pre-surgery activity levels following recovery. Recovery duration varies based on individual factors, including age and surgical method, but most people can expect to resume normal activities within a few months.

Living with a Bipartite Patella

Having a bipartite patella is uncommon, and many are unaware of their condition. For those who experience pain, effective treatment options are available. While a period of rest may be necessary post-treatment, most individuals can look forward to returning to their usual activities once healed.