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.
Other interactions
The avoidance of alcohol is recommended due to increased risk of CNS depression as well as an increased risk of liver toxicity. In addition, the herbal supplement St. Johns wort may decrease the serum levels of zileuton. Overdose/toxicology
Symptoms
Human experience of acute overdose with zileuton is limited. A patient in a clinical study took between 6.6 and 9.0 grams of zileuton immediate-release tablets in a single dose. Vomiting was inducted and the patient recovered without sequelae. Zileuton is not removed by dialysis. The oral minimum lethal doses in mice and rats were 500-4000 and 300–1000 mg/kg, respectively (providing greater than 3 and 9 times the systemic exposure (AUC) achieved at the maximum recommended human daily oral dose, respectively). In dogs, at an oral dose of 1000 mg/kg (providing in excess of 12 times the systemic exposure (AUC) achieved at the maximum recommended human daily oral dose) no deaths occurred but nephritis was reported. Treatment
Should an overdose occur, the patient should be treated symptomatically and supportive measures instituted as required. If indicated, elimination of unabsorbed drug should be achieved by emesis or gastric lavage; usual precautions should be observed to maintain the airway. A Certified Poison Control Center should be consulted for up-to-date information on management of overdose with Zyflo CR. See also
Lipoxygenase inhibitor

References
External links
Zyflo (manufacturers website)
Zyflo (patient information)
https://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm