A 16-year-old male football player presented with a four-month history of diffuse anterior knee pain. He described aching after training, difficulty sitting for prolonged periods and pain walking up and down stairs. He did not have any associated symptoms. He had a near normal knee examination but was noted to have poor single leg stability and pain with patellofemoral compression.
An AP x-ray image shows a type III (supero-lateral) bipartate patella. A subsequent MRI shows that while the bone marrow oedema is slightly more intense adjacent to the synchondrosis there is no separation of the ossicle, fluid in the synchondrosis or cleft in the overlying cartilage. The remainder of the knee appeared within normal limits.
This player was reassured that his patella was ‘normal’ and that he had a common anatomical variant. Given that there was no clear radiological evidence that the synchondrosis had been disrupted, it was uncertain as to whether the bipartate patella had any clinical relevance in this case. The player was given a diagnosis of patellofemoral pain syndrome and started work with a physiotherapist. His symptoms responded well to a rehabilitation programme. This comprised of a period of cross training (using a stationary bike), taping of the patellofemoral joint (PFJ) and strengthening activity directed towards the proximal kinetic chain. He reported a significant improvement over a three-month period. He was able to continue training and playing during this period.
A bipartate patella is a common incidental finding on x-ray imaging. They occur in about 3% of the general population and are bilateral in more than 50% of cases. In young, active patients, a bipartate patella can be a cause of anterior knee pain. This most commonly occurs when the synchondrosis is disrupted after trauma, overuse or in association with high training loads. It is not entirely clear whether having a bipartate patella is a risk factor for PFJ pain. Patients with a symptomatic bipartate patella frequently report pain while squatting, jumping, climbing stairs/hills or with any activities involving quadriceps contractions. MRI scans can be used to try to determine whether the bipartate patella is symptomatic. Most patients improve with non-surgical treatment. Surgery is generally only considered when non-surgical treatment fails. Excision of the fragment is the most common surgical option, however, when the fragment is large and has an articular surface, excision may lead to patellofemoral incongruity and further symptoms.
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