For certain conditions, the bone may be affected at the upper or lower end such as with avascular necrosis of the femur in the knee joint. When the site is at the joint, report the condition of the joint, not the bone.

Avascular necrosis (AVN) is a condition in which there is death of bone tissue due to a lack of blood supply. When AVN occurs at a site where the bone forms part of a joint, such as the femur in the knee joint or the hip joint, it can lead to joint problems because the joint surfaces are no longer smooth or because the bone may collapse.

For coding and reporting purposes, when avascular necrosis of the femur is present at a joint like the knee or the hip, medical professionals are instructed to report the condition as one affecting the joint rather than just the bone. This is because the clinical management and the implications for the joint function are of primary concern, and procedures or interventions will likely focus on the joint as a whole, not just the isolated bone.

So, if avascular necrosis of the femur is present at the knee joint, for instance, the condition would be reported with a medical code specific to the knee joint. This ensures that medical records accurately reflect the primary clinical issue, and patients receive appropriate care for their joint condition.