True reversal of avascular necrosis, where dead bone fully regenerates and returns to its original state, is not something current medicine reliably achieves. What is possible, and increasingly well documented, is halting the disease in its early stages, preserving enough of the joint to avoid replacement surgery, and in some cases prompting partial bone repair. The distinction matters: “reversed” implies the bone goes back to normal, while the realistic goal for most people is stopping the damage before the bone surface collapses. That collapse is the dividing line. Before it happens, several treatments can change the trajectory of the disease. After it happens, the options narrow sharply.
What Goes Wrong Inside the Bone
Avascular necrosis (also called osteonecrosis) happens when blood flow to a section of bone is cut off. Without a steady supply of oxygen and nutrients, bone cells die. The hip’s femoral head is the most common site, partly because its blood supply is already tenuous and the joint bears enormous mechanical load. The underlying cause is always ischemia, meaning the tissue is starved of blood, but the routes to that ischemia vary. Blood vessels inside the bone can be blocked by microscopic fat particles, abnormal clotting, sickle-shaped red blood cells, or even nitrogen bubbles in divers. Vessels can also be crushed from the outside by swollen marrow fat or elevated pressure within the bone itself.1Joint Bone Spine. Pathophysiology and natural history of avascular necrosis of bone Research has also shown that in steroid- and alcohol-related cases, bone cells undergo a form of programmed cell death called apoptosis, triggered by direct chemical toxicity rather than blood-flow blockage alone.2The Journal of Bone and Joint Surgery. Apoptosis – a significant cause of bone cell death in osteonecrosis of the femoral head In practice, multiple factors often converge in the same patient.
Why Steroids and Alcohol Top the Risk List
Corticosteroids (like prednisone and dexamethasone) and heavy alcohol use are the two most common non-traumatic causes of AVN, and understanding how they damage bone explains why the disease is so hard to reverse. Steroids push the body’s stem cells to become fat cells instead of bone-forming cells, while also causing existing fat cells to swell. The marrow fills with fat, pressure builds inside the bone, and veins get compressed, choking off blood flow and triggering clotting.3Journal of Translational Autoimmunity. Steroid-induced osteonecrosis The mechanisms behind steroid-induced AVN are not fully understood, but fat buildup, fat particles lodging in vessels, and small clots within the bone all appear to play a role.4PubMed Central. Glucocorticoid-induced avascular bone necrosis: diagnosis and management
Alcohol works through a similar pathway. Chronic drinking disrupts fat metabolism, causing fat cells in the marrow to enlarge and compress blood vessels. The end result is the same: interrupted blood flow, cell death, and eventually structural weakening of the bone.5PubMed Central. Osteonecrosis Related to Steroid and Alcohol Use—An Update on Pathogenesis Inherited clotting disorders also raise the odds. In one study of Indian patients, deficiencies in protein C and protein S were significantly more common among AVN patients than in healthy controls.6PubMed Central. Association of Thrombophilic Factors in Pathogenesis of Osteonecrosis of Femoral Head in Indian Population Sickle cell disease, trauma, and radiation therapy round out the list. In many cases, no cause is ever identified.
Catching It Early Makes All the Difference
If there is one message that runs through the AVN literature, it is that the stage at which you catch the disease determines nearly everything about your outcome. Early-stage AVN often causes no symptoms at all, or only vague groin or hip pain that comes and goes. By the time the femoral head actually collapses and the joint surface crumbles, the damage is irreversible in any practical sense.
MRI is the gold standard for early detection. It can pick up changes in bone marrow, like swelling and hardening, well before anything shows up on a standard X-ray.7PubMed Central. The role of imaging in diagnosis and management of femoral head avascular necrosis It is sensitive enough to detect AVN in hips that look completely normal on radiographs and in patients who have no symptoms yet.8PubMed Central. The Application of Magnetic Resonance Imaging in the Early and Accurate Diagnosis of Hip Joint Avascular Necrosis Advanced MRI techniques that measure blood flow within the bone can detect perfusion changes even before the standard MRI markers appear, potentially catching the disease at its very earliest stage.9PubMed. Relationship of idiopathic osteonecrosis of the femoral head to perfusion changes in the proximal femur by dynamic contrast-enhanced MRI Bone marrow blood flow can be reduced in patients who simply carry risk factors for AVN, even before overt disease develops.10PubMed. Quantitative dynamic contrast-enhanced MRI of bone marrow perfusion at the proximal femur: influence of femoral head osteonecrosis risk factor and overt osteonecrosis
Bone marrow swelling visible on MRI is worth paying attention to as a clinical marker. In one study, it was present in about a third of hips during follow-up, and virtually all of those hips (96%) were painful, with the swelling strongly correlated with worsening symptoms.11PubMed. Relationship between bone marrow edema and development of symptoms in patients with osteonecrosis of the femoral head For people on long-term steroids, those with sickle cell disease, or anyone else at elevated risk, there is a strong argument for proactive MRI screening before hip pain ever starts.
Non-Surgical Treatments for Pre-Collapse Disease
Once AVN is diagnosed before the bone has collapsed, several non-surgical options can slow or halt its progression. None of these is a guaranteed cure, but for early-stage disease, the evidence is genuinely encouraging.
Hyperbaric Oxygen Therapy
Hyperbaric oxygen therapy (HBOT) involves breathing pure oxygen in a pressurized chamber, which floods the blood and tissues with far more oxygen than normal breathing delivers. The idea is to rescue struggling bone cells by restoring oxygen supply and promoting the growth of new blood vessels into the damaged area. In a 30-year retrospective review at one center, roughly two-thirds of treated femoral heads showed stable or improved MRI findings after treatment, and about seven in ten patients reported good outcomes.12PubMed Central. The use of hyperbaric oxygen for avascular necrosis of the femoral head and femoral condyle: a single centre’s experience over 30 years Another study found that about four in five patients treated with HBOT had satisfactory hip function at one year, with results comparable to core decompression surgery, leading the authors to describe it as a promising non-invasive alternative for pre-collapse AVN.13Annals of Medicine and Surgery. The outcome of hyperbaric oxygen therapy versus core decompression in the non-traumatic avascular necrosis of the femoral head: Retrospective Cohort Study A separate study of early-stage patients treated with HBOT reported significant pain improvement and an average hip function score well into the satisfactory range, though about a quarter of hips did eventually progress to collapse.14PubMed Central. Hyperbaric oxygen therapy for the treatment of Steinberg I and II avascular necrosis of the femoral head: a report of fifteen cases and literature review
These numbers are encouraging but come with caveats. The studies are small and mostly retrospective, meaning they looked back at patients already treated rather than randomly assigning people to HBOT or a control group. HBOT also requires dozens of sessions in a specialized facility, making it impractical for some patients. Still, for someone with early-stage disease who wants to avoid surgery, the data suggest it is a reasonable option worth discussing.
Medications
A vasodilator drug called iloprost, which widens blood vessels and boosts tiny-vessel circulation, has shown good results in early AVN. Studies evaluating iloprost as a conservative treatment have demonstrated benefits particularly in patients presenting with early-stage disease.15PubMed Central. Long-term Clinical Results after Iloprost Treatment for Bone Marrow Edema and Avascular Necrosis Extracorporeal shockwave therapy, which sends focused pressure waves into the bone from outside the body, is another non-surgical approach. Research suggests it may promote new blood vessel growth around the necrotic area and improve bone remodeling in the surrounding tissue.16PubMed. Dosage effects of extracorporeal shockwave therapy in early hip necrosis
The Bisphosphonate Debate
Bisphosphonates are drugs that slow bone breakdown by inhibiting the cells that normally dissolve old bone. In theory, this should help AVN patients by preventing the weakened femoral head from crumbling under body weight. Some long-term clinical data supports this. A 20-year study found that both oral alendronate alone and combination bisphosphonate therapy slowed disease progression, reduced the rate of femoral head collapse, and lowered the need for joint replacement surgery.17PubMed Central. A Paradigm Shift in Osteonecrosis Treatment with Bisphosphonates: A 20-Year Study The same research group reported that combining oral alendronate with intravenous zoledronic acid outperformed alendronate alone in preventing collapse.18PubMed Central. Bisphosphonate combination therapy for non-femoral avascular necrosis
But the picture is not as clear as those results suggest. A recent review noted that while bisphosphonates improved bone remodeling in animal experiments, meta-analyses of clinical trials have not shown them to be better than a placebo for AVN patients, and serious side effects have been reported in some cases. The disconnect between the promising animal data and the disappointing human results remains unresolved.19Journal of Orthopaedic Translation. Hip joint-preserving strategies for treating osteonecrosis of the femoral head: From nonoperative to operative procedures This is one of those areas where two bodies of evidence genuinely conflict, and a patient reading about bisphosphonates will find enthusiastic advocates alongside skeptics. The most balanced read of the data is that bisphosphonates may help some patients in early stages but should not be treated as a proven solution.
Joint-Preserving Surgery
When non-surgical options are not enough but the bone has not yet collapsed, or has only just begun to, several surgical techniques aim to save the natural hip joint.
Core Decompression
Core decompression is the most commonly performed joint-preserving procedure. A surgeon drills one or more channels into the femoral head to relieve the elevated pressure inside the bone, which in turn allows blood vessels to grow into the damaged area and begin the process of tissue repair.20PubMed Central. Survival Analysis after Core Decompression in Association with Platelet-Rich Plasma, Mesenchymal Stem Cells, and Synthetic Bone Graft in Patients with Osteonecrosis of the Femoral Head On its own, core decompression has a mixed track record. A systematic review found that about 42% of patients eventually needed a hip replacement after core decompression alone, but that rate dropped to about 30% when orthobiologic materials like stem cells or growth factors were added to the procedure.21Journal of Hip Preservation Surgery. Surgical management techniques for avascular necrosis of the femoral head: a systematic review
Stem Cell Augmentation
Adding concentrated bone marrow, which contains stem cells capable of forming new bone, to the decompression procedure has shown promise in slowing or stopping progression. The approach aims to seed the area with cells that can rebuild bone tissue from the inside. Research has found it holds particular value for younger patients, potentially sparing them from hip replacement during the most active decades of their lives.22PubMed Central. Stem cell treatment for avascular necrosis of the femoral head: current perspectives In one case series using drilling combined with bone marrow injection, about 86% of patients showed no signs of collapse or disease progression on follow-up X-rays, and hip scores improved significantly after surgery.23Journal of Orthopaedic Reports. Drilling and bone marrow injection in avascular necrosis of femoral head: A case series
Vascularized Fibular Grafts
This is a more involved procedure in which a surgeon removes a segment of the patient’s fibula (the thin bone in the lower leg) along with its blood supply, and transplants it into the femoral head. The living bone graft provides both structural support and a new source of blood flow to the damaged area. A systematic review and meta-analysis found that about 69% of patients treated with vascularized grafts had good to excellent clinical results, compared to 25% of patients treated with other methods. The rate of conversion to hip replacement was substantially lower as well: about 17% for vascularized grafts versus roughly 43% for other approaches.24PubMed. Vascularized fibular grafts in patients with avascular necrosis of femoral head: a systematic review and meta-analysis One long-term study found that 90% of patients maintained their native hips for at least eight years after receiving a vascularized graft.25PubMed Central. Vascularized fibular grafts for avascular necrosis after slipped capital femoral epiphysis: is hip preservation possible? Clinical results of vascularized grafts have consistently outperformed non-vascularized versions of the same procedure, underscoring the importance of bringing a live blood supply along with the structural bone.26Acta Orthopaedica et Traumatologica Turcica. Comparison of early results of vascularized and non-vascularized fibular grafting in the treatment of osteonecrosis of the femoral head
The downside is complexity. Vascularized fibular grafting is microsurgery with a longer recovery, and it is not available at every hospital. It also works best when the femoral head has not yet fully collapsed. Among the joint-preserving surgical options reviewed in the literature, vascularized bone grafting had the lowest conversion rate to hip replacement at roughly 10%, compared to about 42% for standard core decompression.21Journal of Hip Preservation Surgery. Surgical management techniques for avascular necrosis of the femoral head: a systematic review
When the Femoral Head Has Already Collapsed
Once the bone surface has crumbled and the joint is deformed, preserving the natural hip becomes much harder. Total hip replacement is the standard treatment for advanced AVN, and it generally delivers strong results. In one study of patients under 30 who received hip replacements for AVN, the overall implant survival rate was 100% at five years and 94% at 15 years. When only mechanical loosening of the implant was considered as a failure endpoint, the survival rate was 100% even at 15 years.27PubMed. Total Hip Arthroplasty in Patients Under 30 Years Who Have Osteonecrosis of the Femoral Head: Mean Follow-Up of More than 120 Months Broadly, about 83% of patients report significant pain relief and roughly seven in ten achieve good to excellent functional outcomes after hip replacement for AVN.28TAJ: Journal of Teachers Association. Long-Term Outcomes of Total Hip Arthroplasty in Young Bangladeshi Patients with Avascular Necrosis of the Femoral Head
Hip replacement does not reverse AVN. It replaces the damaged joint entirely. For younger patients, the concern is that artificial joints wear out over time and may need revision surgery decades later. That is precisely why so much research focuses on catching AVN before collapse and trying everything reasonable to preserve the natural joint.
Femoral Osteotomies and Their Limits
Another surgical approach involves cutting and repositioning the bone (osteotomy) to move the dead area of the femoral head away from the main weight-bearing zone. Techniques like the Sugioka transtrochanteric rotational osteotomy were developed with this idea. Long-term follow-up data has been less encouraging, however. One study comparing osteotomy patients with those who went directly to hip replacement found that the hip replacement group had significantly better pain scores and patient-reported outcomes, and osteotomy patients had a notably high rate of eventually needing a hip replacement anyway.29PubMed Central. Evaluation of the long-term patient-reported outcomes after hip arthroplasty or joint preserving with Sugioka femoral osteotomy in patients with femoral head osteonecrosis Osteotomies still have a role in selected cases, but the trend in orthopedic practice has shifted toward core decompression with biologics and vascularized grafting as the preferred joint-preserving strategies.
AVN in Sickle Cell Disease
Sickle cell disease deserves separate mention because AVN is one of its most debilitating complications, and the outcomes are stubbornly difficult to improve. Sickle-shaped red blood cells physically block small blood vessels, making the femoral head especially vulnerable. In a multicentre study tracking sickle cell patients with AVN over a median of roughly nine years, 72% had hip involvement and the majority of those had both hips affected. About 59% of affected hips eventually required total hip replacement. Perhaps most concerning, patients reported moderate to severe impairment in joint function and pain regardless of whether they had surgery, highlighting how challenging this particular form of AVN is to manage.30PubMed Central. Long-term outcomes of avascular necrosis in sickle cell disease using joint-specific patient-reported outcome measures: Results from a multicentre study The disease process is ongoing in sickle cell patients, which means new episodes of vessel blockage can undermine even successful treatments. Researchers continue to emphasize the need for better strategies in this specific population.
The Blood-Flow Puzzle at a Microscopic Level
One of the more interesting findings in recent imaging research is that blood flow within the femoral head is not uniform even in healthy people. The parts of the bone that bear the most mechanical load, like the upper weight-bearing surface, have the least blood perfusion to start with.31PubMed. Assessment of the zonal variation of perfusion parameters in the femoral head: a 3-T dynamic contrast-enhanced MRI pilot study This built-in vulnerability helps explain why the femoral head is so prone to AVN in the first place and why the damage tends to be concentrated right where the bone needs to be strongest. It also hints at why reversal is so difficult: the region with the least blood supply to begin with is being asked to mount a healing response that depends entirely on restoring blood flow. The biology is working against itself.
Researchers using advanced MRI techniques have shown that perfusion changes in the femoral head can precede visible necrosis, and that the area of altered blood flow often extends well beyond the dead zone itself into the surrounding femoral neck.10PubMed. Quantitative dynamic contrast-enhanced MRI of bone marrow perfusion at the proximal femur: influence of femoral head osteonecrosis risk factor and overt osteonecrosis The implication is that even when imaging shows a localized patch of dead bone, the surrounding tissue may already be compromised. This wider zone of impaired circulation complicates any treatment that depends on healthy neighboring tissue to drive repair.