For tissue to remain healthy and function normally, it requires a healthy blood (vascular) supply. Patients can develop a rare condition in their subchondral bone (bone beneath and supporting the joint surface) called avascular (“without blood”) necrosis (“death/dying”), or AVN, where the bone loses blood supply, dies, and then fractures and eventually collapses without proper treatment. AVN usually affects bone just under the joint surface and can lead to collapse of the joint surface and painful arthritis.
There are two types of AVN: traumatic and atraumatic. Traumatic AVN may occur following an injury such as a dislocation, while atraumatic can happen with certain diseases, blood disorders, or taking medication such as corticosteroids. Occasionally, it can develop for no discernible reason.
The goal of treatment is to re-vascularize the bone, bone graft, protect it from loading until it heals, maintain or restore the joint surface to prevent arthritis, and regain range of motion and function. Outcomes depend on the stage of the AVN. Early recognition affords us the opportunity to stimulate re-vascularization (new blood supply) and healing of the bone or bone graft lost bone before it compromises the joint surface.
If detected early by MRI, some AVN lesions can heal with rest and activity restriction. Gentle physical therapy can help to maintain motion during the rest period and restore strength and motion once the injury is healed.
More often surgery is required to stimulate, re-vascularize, and repair the avascular necrosis. Dr. Chudik can perform arthroscopic surgery to evaluate the AVN lesion. The surgical method is determined by the size and condition of the AVN lesion. Small loose fragments can be simply removed, and the surface of the bone is stimulated to promote a healing response. Large lesions can be drilled, bone grafted to stimulate healing, or replaced.
The surgery is performed under light intravenous sedation and with local anesthetics. Patients will be required to be non-weight bearing for six weeks post-operatively to allow the bone time to heal. Physical therapy is begun two days following surgery to restore range of motion while protecting the healing bone. If AVN is severe and the integrity of the joint surface is compromised, a knee replacement may be required.