Bipartite Patella or Split Kneecap

 by Dr Jeffrey R. Carlson, MD

In my role as an Orthopaedic Specialist, I often treat people who are suffering pain from an injury or from a disease or condition that develops over time.  I also treat patients who suffer from congenital disease or whose bone, cartilage or tendons/ligaments do not grow and develop normally.  Bipartite Patella (or split kneecap) is one of those conditions that occur when a person’s kneecap does not develop normally.

In this article, I will discuss what this condition is, what causes it, what the symptoms are and how it is treated.

knee surgeon Dr Jeffrey Carlson in the operating room

Dr Jeffrey Carlson MD

The kneecap or patella is a triangular/circular shaped bone that is connected to the patellar tendon and the quadriceps tendon.  The patella sits on the front of your knee and helps to protect the front of the knee joint.  It articulates or “moves against” the femur and functions to let the knee extend fully.  It is vital in that it helps us walk, run and play sports well.

bipartite patella split knee

Some bones do not fully harden until later in childhood or adolescence.  Starting out as two bones in an infant, the kneecap does not fully harden or “ossify” until 3-6 years of age.  In some individuals, this ossification never fully occurs and the patella can remain in two pieces, known a Bipartite Patella.  There can even be three or more pieces to the Patella.  This condition almost occurs exclusively in men; however, we do not understand why. Even though bone never fully fuses the two (or more) pieces, the bones are usually connected by a fibrous type of tissue.

Often, a person will go their whole life and never know that they have a Bipartite Patella.  Most with this condition will never experience any pain or lack of function.  The condition is usually revealed as the result of an x-ray taken to uncover another problem.

Occasionally, a person with a Bipartite Patella will experience symptoms and will come to me for care.  In most cases, the fibrous connection holding the patella together has been damaged and needs rest to heal.  This means avoiding sports and other activities that cause pain. If rest does not ameliorate the pain, a steroid injection into the fibrous tissue which connects the two pieces of the patella may be done.  Anti-inflammatory medications can also provide a longer term improvement.  Physical therapy also may be effective in promoting proper alignment in the joint.  There are some braces that may be helpful in keeping the patella tracking through the femoral notch and prevent friction in the knee joint.

If conservative methods of treatment fail to work, then surgery may be considered.  This surgery is now done arthroscopically, where the surgeon makes several small incisions, inserts a small camera (through which the patella can be visualized ) and then operates through the other small incisions.  The procedure involves removal of the smaller piece of the patella, shaving off any rough spots and repairing any tears to the tendons which attach to the patella.

Results after the surgery are largely dependent on the adherence of the patient to the recovery protocols, but most patients do extremely well.  The small incisions of the arthroscopically-performed surgery allow the patient to recover much more quickly and to begin rehabilitation of the knee, with Physical Therapy and weight-bearing activities.  Recovery typically takes 6 weeks and should be managed carefully to ensure the patient has optimal results.

Dr. Jeffrey R. Carlson is a Harvard Orthopaedic/Neurosurgical Spine Fellow and is Chief-of-Surgery at Bon Secours Mary Immaculate Hospital in Newport News, VA.  He is the Managing Partner of Orthopaedic and Spine Center in Newport News, VA.  For more information or for an appointment, contact OSC at 757-596-1900 or go to



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