A painful defect may be felt in the knee and there may be blood in the joint. Complications
Complications may include injury to the tibia, femur, or knee ligaments. In the longer term, the knee may not regain full movement, pain may persist and there is an increased likelihood of osteoarthritis of the knee. If there is an associated open wound as in an open fracture, complications also include risk of infection, inability of the broken bones to reunite and osteonecrosis. Diagnosis
Diagnosis is based on symptoms and confirmed with X-rays. In children an MRI may be required. Differential diagnosis
Some people have a normal bipartite patella or two-part patella which can appear as a fracture. The fragment is usually seen in the top outer corner of the patella and can be distinguished from a fracture by being present in both knees. Types
The patella can break in various ways depending on the way it is injured, and into two or more pieces. Types include transverse, with one fracture line and is the most common type, marginal, osteochondral and the rare vertical type, or stellate, where a direct compression force gives rise to a comminuted pattern. Patella fractures can be further classified as displaced, where the broken ends of bone do not line up correctly and separate by more than 2mm, or undisplaced and stable where pieces of bone remain in contact with each other.
Several techniques followed and materials used included metal loops, pins, kangaroo tendons and screws. Significant advances in surgery occurred in the 1950s with the development of banding after Herbert A. Haxton and others demonstrated that the patella was not just to protect the knee but important for straightening the leg. Subsequently, the three surgical treatments for displaced patella fractures became tension banding, partial patellectomy and total patellectomy, the decision of which to use tailored to the individual. References


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