Fracture of a patellar enthesophyte.

Bone spurs are abnormal projections of bone that include both osteophytes and enthesophytes. They differ anatomically as osteophytes form around the joint line, while enthesophytes form at the insertion sites of tendons or ligaments known as entheses. The authors present a case of fracture through a large enthesophyte at the inferior patellar pole that occurred during eccentric loading of the knee and use this to highlight differences in the fracture patterns of osteophytes, enthesophytes and avulsion fracture at the patella. Diagnosis and management strategies are considered. Enthesophyte fractures should be treated using a conservative management approach focused on increasing range of motion, progressive resistance exercises and eccentric loading, alongside strategies to reduce joint strain.