Chandler's disease, also known as idiopathic avascular osteonecrosis of the femoral head (ANFH or ONFH), is a rare condition in which the bone cells in the head of the femur (FH) die due to lack of blood. This disease is caused when blood flow is reduced to the part of a bone near a joint. It is specifically unique because the femoral head is for some reason the only affected part of the body and rarely travels down to the main part of the femur. In 1948, F. A. Chandler did a multi-case review and first released his interpretations as Coronary Disease of the Hip. This term is now considered incorrect as it improperly describes the actual disease.
In current practice patients usually present with hip pain on the side with Chandler's disease. Since this is such a rare diagnosis some more conservative pain control methods are seldom used first before in-depth scans are used that lead to the diagnosis. Based on the staging of the dying bone typically dictates the course of treatment. Many of the more conservative treatments do lead to a whole hip replacement in the span of the patient's lifetime but there is promise of saving the dying bone or proper healing if caught early enough. At this time there are little research on curing the disease since it is not directly life-threatening and even the most invasive options lead to a moderate quality of life. Most of the research is more focused on finding if there is a combination of conservative treatments that together can replace more invasive treatment options as the preferred method of treatment in the later stages.
Signs and symptoms Clinical presentation of Chandlers or ANFH typically is asymptomatic in the early stages. As the condition progresses on patients may develop groin pain that can radiate to the knee and/or ipsilateral buttock otherwise known as the buttock on the same side of the body. In the most severe untreated cases the patient may not be able to walk, stand, or sit due to the increased exposure of nerves to the dead parts of the bone. On physical examination, patients usually present with a limited range of motion at the hip and complain of pain particularly with forced internal rotation. Many people will not know they have it until further diagnostic scans. Those who have it will get diagnosed unless it spontaneously heals on its own which is uncommon. Patients usually go through a few rounds of treatment and testing before more in depth scans are ordered and a full diagnosis is made. Either that or a repeat scan can show degeneration prompting for more in depth investigation. The signs and symptoms of this condition are so similar to others that the more common conditions are treated for or ruled out first.
Etiology and pathogenesis
The current etiology or origin of this disease is unknown. Some studies theorized that bone remodeling is maintained in a microenvironment in the FH meaning that there is a greater local component to changes to the femoral head than the normal systemic way that bone remodeling is handled throughout the body. As a whole our body goes through bone remodeling using various hormones and glucocorticoids to balance the uptake and output of bone throughout the entire body. The local portion is considered to be controlled partially by inflammatory cells called cytokines and individual growth factors. The theory is that the local bone remodeling is malfunctioning and overpowering the systemic bone remodeling causing the FH to be highly susceptible to necrosis. Studies have determined that there are risk factors that are more than likely associated with the development of the disease but many of them are very broad and include large groups of people for example alcoholics, diabetics, and many other common core morbidities. Unfortunately, most are classified under idiopathic due to being unable to truly narrow down the origin of why it only happens to the head of the femur. What most clinicians observe is that the head of the femur seems to almost have a system of its own somewhat separate from the rest of the femur. There are many theories as to how the head of the femur dies unlike why it is happening.
Non-traumatic mechanisms The main mechanism is through external factors causing micro-emboli in the vessels leading to occlusions to the vessels or anyway that can cause ischemia to the femoral head. External factors that can cause these emboli can include alcohol, lipid circulation, high doses of glucocorticoids, and new increases in bone marrow fat cells. Vascular occlusion can also be caused by disease progressions that increase coagulation and thrombus formation in the vessels. Clotting disorders and red blood cell disorders can also lead to abnormal vessel occlusions. Very rarely seen though is a cause of ischemia from decompression sickness or coming down from high pressured areas too fast causing a gaseous bubble to block blood flow. In an extremely rare case, the patient reports to have a familial trait of developing this condition. Although genetic factors play a role in how ANFH can develop the genes themselves do not tend to be the cause. In this case from Japan the family had a specific autosomal dominant mutation that led to failure of collagen type II and thus led to low bone stability and ANFH. Although this does highlight a specific cause in this case, we are still unsure how or why it contains itself solely to the femoral head.
Traumatic Trauma can be classified as a fracture or dislocation of the FH. This can lead to damage to the extraosseous or outer bone blood supply. This is especially prevalent to fractures in the junction between the FH and the neck of the femur called the sub capital region. Trauma at the sub capital region interrupts the connection or anastomosis between the outer blood vessels on the end of the bone or lateral epiphyseal vessels causing poor blood flow to the FH. Lastly, direct irradiation, chemotherapy, or oxidative stress may lead to cellular malfunction ultimately leading to cellular death.
Diagnosis ANFH can only be diagnosed by MRI of the hip and X-rays of the hip specifically in the anteroposterior and frog-leg lateral poses. Along with these scans an additional bone scan needs to be done which allows doctors to see the activities of bone cells in a body. Once the images that the physician want are obtained, they are then measured through two systematic reviews.
Ficat and Arlet classification system consists of four stages, based on standard radiographs +Ficat and Arlet classification systemStagingRequirementsStage 0Normal x-ray and MRI with no symptomsStage IMinor osteopenia on the x-ray, edema on the MRI, and increased bone uptake on the bone scan Stage IIOn x-ray and MRI there is normal FH contour, but with evidence of bone-remodeling, and sclerotic and cystic changes. Bone scan would still show increased uptake.Stage IIIX-ray and MRI indicates evidence of subchondral collapse, crescent sign, or flattening of the FHStage IVMRI and X -ray show narrowing of the joint space with secondary degenerative changes in the acetabulum, which is the socket portion of the hip that is a part of the pelvis, such as cysts, osteophytes, and cartilage destruction.
Steinberg Classification System expands the Ficat system into six stages and includes quantification of involvement of the FH within each stage. +Steinberg Classification SystemStagingSub StagingRequirementsStage 0Normal x-ray and MRI with no symptomsStage INormal X-Ray but abnormal MRI and/ or Bone ScanStage IA< 15% of FH being involved in abnormal scan considered mildStage IB15% to 30% of FH being involved in abnormal scan considered moderateStage IC30% of FH being involved in abnormal scan considered severeStage IIX rays and/or MRI show a mix of osteopenia and/or sclerosis and/or subchondral cysts, without any subchondral lucencyStage IIA< 15% of FH being involved in abnormal scan considered mildStage IIB15% to 30% of FH being involved in abnormal scan considered moderateStage IIC> 30% of FH being involved in abnormal scan considered severeStage IIIX ray and/or MRI show crescent signStage IIIAMild, Subchondral collapse beneath the FH < 15%Stage IIIBModerate, Subchondral collapse beneath the FH 15% to 30%Stage IIICSevere, Subchondral collapse beneath the FH > 30%Stage IVX ray and MRI showing flattening of the FHStage IVAMild < 15% of FH flatteningStage IVBmoderate 15% to 30% of FH flatteningStage IVCSevere > 30% of FH flatteningStage VJoint space narrowingStage VAMild < 15% of narrowingStage VBmoderate 15% to 30% narrowingStage VCSevere > 30% of narrowing In addition, the Association Research Circulation Osseous (ARCO) suggested a new classification system based on the combination of radiographic, MRI, bone scan and histologic findings. However, apparently these two classifications systems, Ficat and ARCO are still not enough reliable to assess the status of ONFH alone.
Epidemiology ONFH is newly diagnosed 10 to 20 thousand times a year in the US. It is most common in individuals between the ages of 20 and 50 this is roughly what many studies tend to agree upon. Due to being such a rare occurrence and rarely study many studies come with different numbers. Many studies are on populations in Japan, the United States, and other nations. The male to female diagnosis ratio is respectively 5:1 to 2.1:1, meaning it is 2-5 times as likely to happen to a man rather than a woman. Some found a large correlation between those who smoked and contracting later stage ONFH. One study found that of their participants above 30% had an alcohol related risk factor that they believed played a possible factor into the development of the necrosis. Although these statistics can be alarming most of this is done with in the community that has ANFH. It seems to not differ between races or that it is infectious between people. When compared to national and global population this disease effects a minuscule number of people in the world. A great number of people affected by this tend to be sick or already have health problems and the percentage that have it due to hereditary reasons is extremely minuscule compared to all populations.
Analogous diseases Although Chandler's Disease is specific to the head of the femur there are many other diseases that are analogous to the mechanism of Chandler's Disease: Legg-Calve-Perthes syndrome is found only in children and affects the femoral head similarly as in Chandler's disease. Preiser Disease is generally the same problem but found in the scaphoid bone of the hand. Khöler Disease affects the navicular bone of the foot. Keinböck's disease is another disease affecting the hand but rather the lunate bone
Treatment
Non-surgical Conservative treatment of ANFH, which is considered to be non-surgical, may be effective in the earlier stages of the disease and when combined together with other types of treatments outcomes were seen to increase than treatments on their own. +Pharmacological management of AVN Medicine typeUseExamplelipid lowering agentsClear out any lipids blocking vesselsStatinsanticoagulantsStops the formation of clots Enozaparinvasoactive substancesMakes blood vessels wider improving blood flowProstacyclinbisphosphonatesIn bone remodeling it reduces osteoclast activity
Platelet-rich plasma