Avascular Necrosis (AVN), also known as osteonecrosis, is a condition where bone tissue dies due to a temporary or permanent loss of blood supply. This lack of blood flow prevents the bone from receiving necessary oxygen and nutrients, causing the structure to weaken. If AVN progresses without intervention, the affected bone may eventually collapse, leading to joint pain and severe arthritis. Whether this damage can be reversed is complex, depending heavily on the timing of diagnosis and the overall severity of the disease.
Why Staging Determines Reversibility
Avascular Necrosis is a progressive disease that worsens over time if the underlying cause is not addressed. True reversal, which involves restoring the original, healthy bone structure, is largely confined to the earliest stages of the condition. Medical professionals use staging systems, such as the Ficat classification, to determine the extent of the damage and guide treatment. The most fundamental distinction is between pre-collapse and post-collapse stages.
Pre-collapse AVN (Ficat Stages I and II) involves bone death without changing the shape of the joint surface. At this point, the structural integrity of the bone is intact, offering the best chance for reversal by promoting new blood vessel and bone growth. Once the disease progresses to post-collapse stages (Ficat Stages III and IV), the weakened bone has fractured and flattened, often referred to as the “crescent sign,” leading to joint deformity. At these later stages, the focus shifts away from preserving the natural joint structure toward managing pain and restoring function through joint replacement.
Non-Surgical Approaches for Halting Progression
When AVN is identified early, before collapse has occurred, the immediate goal is to halt progression using non-invasive methods. A primary intervention involves strict lifestyle modifications, such as eliminating causative factors like excessive alcohol consumption or the long-term use of high-dose corticosteroids. Restricting weight placed on the affected joint, often using crutches for several months, helps reduce mechanical stress on the weakened bone.
Pharmacological treatments are also employed to address underlying causes and improve blood flow. Blood thinners, such as warfarin, may be prescribed to prevent clots that block small vessels supplying the bone tissue. Medications designed to open blood vessels (vasodilators) may increase circulation to the compromised area, aiding in natural repair. Bisphosphonates, certain osteoporosis medications, are used to slow the rate of bone breakdown and stabilize the remaining bone structure.
Joint-Preserving Surgical Interventions
For pre-collapse AVN unresponsive to conservative measures, joint-preserving surgical procedures are the most aggressive attempt at reversal through bone regeneration. The most common procedure is Core Decompression, which involves drilling small channels into the necrotic bone area. This action reduces high pressure inside the bone and creates a pathway for new blood vessels to grow into the dead tissue.
Core Decompression is often augmented with bone grafting or cellular therapies to boost regenerative potential. Bone Marrow Aspirate Concentrate (BMAC) is harvested from the patient and injected into the tunnel. This concentrate is rich in stem cells and growth factors, which stimulate the formation of new, healthy bone cells (osteogenesis) and promote healing.
Another technique involves bone grafting, where a segment of healthy bone is transplanted to provide structural support and a scaffold for new bone growth. This may be a non-vascularized graft, or in complex cases, a free vascularized fibular graft may be used. The vascularized graft includes an intact artery and vein from the patient’s lower leg, providing an immediate, living blood supply to the affected area.
Managing End-Stage Necrosis
When joint-preserving efforts have failed, or if the disease is diagnosed after bone collapse (late Stage III or Stage IV), the strategy shifts from reversal to functional restoration. At this end stage, structural failure and resulting arthritis cause severe pain and limit mobility. The definitive treatment in these cases is Total Joint Replacement, or arthroplasty.
Total Hip Arthroplasty (THA) is the most common procedure, involving the removal of damaged bone and joint surfaces. These surfaces are then replaced with metal, plastic, or ceramic implants. While this is not a reversal of the disease, it is highly effective at eliminating pain and restoring the patient’s ability to walk and perform daily activities. Outcomes are generally excellent, providing many years of relief, though younger patients may require a revision surgery later due to normal prosthetic wear.