Avascular necrosis of the femoral head (AVNFH) is a pathological condition that is otherwise referred to as osteonecrosis of the femoral head or hip osteonecrosis, is more commonly diagnosed amongst individuals aged 20 to 40 and does not tend to subside spontaneously [1].

It is a disorder that usually develops insidiously and does not produce symptoms at the initial stage. Radiating pain that extends to the ipsilateral buttock or knee is frequently reported in symptomatic patients, alongside restricted hip mobility. Particular movements, such as an intense internal rotation, or weight-bearing, can exacerbate the pain. Bilateral participation of the femoral heads has been documented, although the most common presentation involves unilateral involvement [2]. As the disease progresses, pain is aggravated; it eventually appears both when the patient moves and at rest. Limping may be present as well. Accompanying symptoms include tenderness in the region of the hip and a deformed joint with muscle wasting in severely progressed stages. The vast majority of individuals affected by AVNFH who have not received treatment in time appear with a collapse of the head of the femur [3] [4] [5].

• Hip Pain

  A 1-year-8-month-old boy with mucocutaneous lymph node syndrome (Kawasaki disease) complained of left hip pain. Radiographic examination revealed avascular necrosis of the femoral head. [ncbi.nlm.nih.gov]

  Disponible en: https://www.uptodate.com/contents/approach-to-hip-pain-in-childhood?search=approach-to-hip-pain-in-childhood Lespasio MJ, Sodhi N, Mont MA. Osteonecrosis of the Hip: A Primer. [revistamedicasinergia.com]

• Limping Gait

  The clinical manifestations of ANFH, including pain on exertion, limping gait, and discrepancy in leg length, cause considerable disability. [genome.jp]

• Encephalopathy

  A patient with chronic renal failure, a dialysis encephalopathy syndrome and renal osteodystrophy associated with aluminium intoxication developed an avascular necrosis of the left femoral head. [ncbi.nlm.nih.gov]

The workup involved in a potential case of AVNFH includes plain hip radiographs and a magnetic resonance imaging scan (MRI scan) of the area. Laboratory evaluation is of no diagnostic value, and, even though a biopsy can ascertain the diagnosis, it is not commonly required.

The radiographic depiction of the presumably affected hip is the first step in the evaluation process of patients who report pain in the femoral region and are in risk for AVNFH [6]. Plain anteroposterior and frog-leg lateral images are obtained in order to assess a potential AVNFH. Subtle lucencies, sclerotic or cystic lesions do raise suspicion for an osteonecrotic state, in which case an MRI is performed [6]. The latter is more sensitive in the initial phase, when a plain radiograph may be inconclusive [7].

In general, AVNFH is classified with the Ficat and Arlet and the Steinberg University of Pennsylvania systems [8]. The former utilizes radiographs, MRI findings and patient symptoms to categorize the condition [9]. A more recent classification system is that of the Association Research Circulation Osseous (ARCO), which proposes that plain radiographs, MRI scans, and histology should all be used in order to produce an accurate classification status. Computerized tomography scans (CT scans) can be performed in the evaluation process, but not in a diagnostic sense. They are used to facilitate surgical planning and to illustrate the severity of a potential femoral head collapse [6].

• Ischemic Changes

  The period for complete radiographic recovery of group I ischemic changes was between 2 to 4.5 years. Preoperative mean AA values of both groups were similar. [ncbi.nlm.nih.gov]

The larger both volumes are, the more likely it is that treatment will fail. In patients with remaining necrosis of less than 1000 mm(3), no treatment failure was observed. [ncbi.nlm.nih.gov]

More recent data have shown that MR imaging may improve staging, investigate radiologically occult collapse, depict other causes of disability and pain, assess prognosis, and evaluate treatment. [ncbi.nlm.nih.gov]

- prognosis: - in general, patients with confirmed AVN have a 70-80% chance of collapse after 3 years; - in the series of 72 hips (general population) w/ MRI changes c/w AVN (followed by Ito H, et al (1999)), 64% became symptomatic; - necrotic lesions [wheelessonline.com]

In most cases, however, the etiology is unclear and generally described in the orthopedic literature in ambiguous terms. Radiologically, the femoral head ossification center may be condensed, deformed or fragmented. [ncbi.nlm.nih.gov]

Etiology Several traumatic and atraumatic factors are known contribute to the etiology of osteonecrosis, all of which contribute to changes in blood supply. [amboss.com]

Epidemiology References: [1] Epidemiological data refers to the US, unless otherwise specified. [amboss.com]

Introduction Clinical definition reduced vascular sup ply to the bone resulting in progressive and painful degeneration of the bone also termed osteonecrosis Epidemiology incidence typically occurs in the anterolateral femoral head demographics dependent [medbullets.com]

Osteonecrosis ICD-9 : 733.42 (head of femur), 733.41(head of humerus), 733.44(talus), 733.43(medial femoral condyle), 733.40(unspecified), 733.49(other) Osteonecrosis Etiology / Epidemiology / Natural History Most commonly adults 20-50yrs old, 60% bilateral [eorif.com]

ANFH is a common disease in China [3], but accurate epidemiological data are unavailable. This disease frequently occurs in adult patients between the ages of 20 and 50 years old [4]. [journals.plos.org]

Epidemiology Frequency United States AVN of the femoral head is a debilitating disease that usually leads to osteoarthritis of the hip joint in relatively young adults (mean age at presentation: 38 y). [emedicine.medscape.com]

The temporal association in this instance implicates a pathophysiologic relationship between the development of ALL and necrosis. [ncbi.nlm.nih.gov]

The pathophysiology of avascular necrosis of the femoral head has not been completely accounted for. In some patients there has clearly been a direct cause (trauma, radiation,..), while in others the pathophysiology is still uncertain. [physio-pedia.com]

On this basis, we propose to study the pathophysiological mechanism(s) of inherited and sporadic ANFH. [clinicaltrials.gov]

Osteonecrosis of the femoral head: pathophysiology and current concepts of treatment. [revistamedicasinergia.com]

[…] and secondary degenerative joint disease Causes: fracture, dislocation, corticosteroids, nitrogen bubbles in dysbarism, vasculitis, radiation, vascular compression, venous hypertension, thrombosis (sickle cell disease), Gaucher’s disease, alcoholism Pathophysiology [pathologyoutlines.com]

Because hip arthroplasty in the younger population is prone to early wear and failure, it is paramount to prevent collapse once osteonecrosis is detected. [ncbi.nlm.nih.gov]

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3. Mont MA, Jones LC, Hungerford DS. Nontraumatic osteonecrosis of the femoral head: ten years later. J Bone Joint Surg Am. 2006;88(5):1117–1132.
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5. Floerkemeier T, Lutz A, Nackenhorst U, et al. Core decompression and osteonecrosis intervention rod in osteonecrosis of the femoral head: clinical outcome and finite element analysis. Int Orthop. 2011;35(10):1461–1466.
6. Murphey MD, Roberts CC, Bencardino JT, Appel M, Arnold E, Chang EY, et al. ACR Appropriateness Criteria Osteonecrosis of the Hip. J Am Coll Radiol. 2016 Feb. 13 (2):147-55.
7. Lieberman JR, Berry DJ, Mont MA, et al. Osteonecrosis of the hip: management in the 21st century. Instr Course Lect. 2003;52:337–355.
8. Musso ES, Mitchell SN, Schink-Ascani M, Bassett CA. Results of conservative management of osteonecrosis of the femoral head. A retrospective review. Clin Orthop Relat Res. 1986;(207):209–215.
9. Jawad MU, Haleem AA, Scully SP. In brief: Ficat classification: avascular necrosis of the femoral head. Clin Orthop Relat Res. 2012;470:2636–2639.