4Causes
Most cases of patella fracture happen after a direct fall on the kneecap. As a result, there is usually damage to your overlying skin. An open fracture can sometimes occur due to the restricted amount of soft tissue around the knee. Another possible cause is when the quadriceps muscle contracts but the knee joint straightens at the same time. Also known as eccentric contraction, this causes the muscle to pull forcefully and results in a patellar fracture. There are a few situations when your kneecap can be fractured with minor injuries as well. Sometimes, they are pathologic fractures, which are the result of weak bones due to tumors, bone infection, or osteoporosis. [4]
