Etiologies for Avascular Necrosis (AVN) and Mechanisms for Stem Cell Repair

What is avascular necrosis (AVN)?

AVN is a disorder in which the blood supply to a region of a bone has become impaired. This in turn creates a loss of cellular nutrition to that region (loss of oxygen and nutrients) and the region of bone becomes necrotic or dies.

Avascular Necrosis Terms

There are several terms all describing the same medical condition.

Osteonecrosis                                                      Ischemic necrosis

Bone infarction (loss of blood supply)                Aseptic necrosis

Bone infraction ( non displaced fracture)


Risk Factors or Etiologies associated with an increased risk of avascular necrosis (AVN)

Trauma (fractures or significant trauma disrupt the blood supply to the bone)

Idiopathic (unknown causes)

Excessive cortisone (corticosteroids usage)

Rheumatoid arthritis



Excessive alcohol consumption

Sickle Cell Disease

Radiation therapy (impairs blood supply)

Chemotherapy (local cellular changes)

Gaucher’s disease (this is a genetic fat storage disease that can impair blood flow to the bone)

Vasculitis (disorder of the blood vessel)

Embolism (broken clot that occludes blood vessel as in a stroke)

Thrombosis (a blood clot)


High Blood Pressure (may occlude blood vessels)

Caisson’s disease (decompression sickness) also known as the bends.

Potential Causes

A prolonged exposure to great pressure. This may occlude the blood vessels. Occurs in military and commercial divers.

There are multiple theories as to why some medical illnesses result in a greater likelihood or increased incidence of AVN. Trauma is easily understood. Impairment of blood supply due to a fracture or athletic injury can lead to the development of vascular ischemic changes, that occlude blood flow an lead to the development of AVN.

Other disorders such as corticosteroid use, alcohol consumption, and Gaucher’s disease appear to accumulate lipids or fatty tissue in the bone marrow which impairs the blood flow in the bone.

Stem Cells are precursor cells in our bodies. If we need more red blood cells in the body there are stem cells which differentiate and make more red blood cells. If we need more muscle or bone cells we have stem cells for these purposes.

So, the problem exists with avascular necrosis (AVN), that we cannot deliver adequate stem cells to repair necrotic bone for several reasons.

These are:

1) As we age we have fewer stem cells.

2) with avascular necrosis or osteonecrosis, there is a damaged region of bone that lacks blood supply and is necrotic. These factors prevent healing from occurring in many cases, as the reparative stem cells simply cannot get to the damaged site.

Can this damage be overcome to attempt to heal AVN?


By delivering an adequate supply of the patients own stem cells to the site of injury (osteonecrosis or AVN) locally by an injection. This allows the body to directly address the inherent problems with healing AVN due to poor blood supply, as well as the necrotic (dying bone tissue).

Can Stem Cell Therapy work to prevent bone collapse or secondary arthritis?


If addressed early this can occur. The goal is to prevent joint replacement or surgery.

Can Stem Cell Therapy maintain an athletes career?


If repair and regeneration occur to the damaged region of avascular necrosis, the osteonecrotic lesion may resolve. If secondary joint collapse or degenerative arthritis is averted due to treatment, than continued athletic performance may be maintained. Though Bo Jackson’s career was cut short by hip AVN, Brett Favre enjoyed a lengthy professional football career with hip AVN.


Athletes and those afflicted with AVN from medical disorders have been treated by Dr. Dennis Lox.

Dr. Lox is a Sports and Regenerative Specialist with extensive experience in the treatment of avascular necrosis. Dr. Lox has managed many athletes with AVN and continued them playing competitive sports. The goal is maintain a high functional level, continue athletic competition, deter arthritis, and avoid a joint replacement surgery.