Osteonecrosis of All Major Joints

Osteonecrosis

Osteonecrosis, which literally means "bone death," occurs when blood flow to bones in the joints is reduced. The lack of blood causes the bone to break down faster than the body can generate enough new bone. The bone starts to die and can break down. This disease can also be called avascular necrosis (AVN). It occurs most commonly in the hip, followed by the knee and shoulder. Below please find more information specifically about osteonecrosis of the hip and knee.

Osteonecrosis of the Hip 

Osteonecrosis of the hip is a well-described entity in which a portion of the hip wall loses its blood supply and thus the bone underneath the cartilage dies. This oftentimes can cause increases in pressure in the hip joint and if the lesion is large enough, the cartilage above the dead bone will collapse causing arthritis in the hip joint. Hip osteonecrosis is felt to be associated with approximately 10% of all hip replacements done in this country, the majority of which are done on young patients under the age of 50. There are several things that are associated with the occurrence of hip osteonecrosis. They include the use of steroids, excessive alcohol consumption, deep sea diving, subtle coagulopathies, and trauma. The symptoms are similar to that of arthritis of the hip where the patient oftentimes has an achy-type pain which he or she will describe as being deep within the hip joint itself. On X-rays, you oftentimes will not see any joint destruction. Instead, you will see some changes within the substance of the bone on initial presentation. As the osteonecrosis (AVN) progresses, the area of necrosis may collapse and arthritis may ensue. Physical findings are also consistent with hip arthritis in that the patient will complain of pain with internal or external rotation of the hip joint. Their range of motion is not limited. They will have oftentimes full range of motion. They may or may not have a limp and the limp is associated with pain. There is no leg length inequality.

Treatment options include core decompression either with a single coring device or a multiple pin technique. We prefer using the multiple pin technique since it reduces the complication rate of fracture. It also allows the procedure to be done as an outpatient and allows the patient to begin weight bearing or walking immediately after the surgery. With Stage I disease, the success rate with core decompression is reported as high as 90%. Other treatment options include osteotomies, which is a breaking of the bone, and redirecting the bone in a different orientation so that the area of bone necrosis is no longer under the weight bearing aspect of the hip. There are vascularized fibular grafts in which they take the leg bone and put it into the hip. This has been popularized by Dr. Urbaniak. He has reported reasonable results with this technique. There is though a 10% incidence of ankle pain associated with this procedure. There are techniques such as vascularized pedicle grafting done primarily overseas; this has met with marginal success. Another newer technique based on an old idea is the placement of a tantalum rod, which is a new type of metal, into the femoral head in the hopes that this will provide structural support to the area of necrosis. There is limited data on this newer technique. In Italy, they report reasonable results using this technique.

Something that is currently gaining tremendous popularity which we currently are doing under FDA approval, is a resurfacing hip replacement. This is done using a minimal incision and replacing only the area of dead bone with a resurfaced metal onto the femoral head and putting in an acetabular component. The advantage of this technique is that there is a lower dislocation rate and ideally an improved range of motion. It also potentially allows the patient to increase his or her activities and live a fuller life feeling more normal. If a revision operation is necessary, then the revision is potentially an easier one to perform. Other treatment options for hip osteonecrosis include hip replacement. This historically has had excellent results, but not as well as hip replacements performed for osteoarthritis alone.

Osteonecrosis of the Knee

Knee pain has many causes. A relatively common cause of knee pain in older women occurs when a segment of bone loses its blood supply and begins to die. This condition is called osteonecrosis, which literally means "bone death."

In the knee, the knobby portion of the thighbone on the inside of the knee (the medial femoral condyle) is most often affected. However, osteonecrosis of the knee may also occur on the outside of the knee (the lateral femoral condyle) or on the flat top of the lower leg bone (tibial plateau). The exact cause of the disease is not yet known. One theory is that a stress fracture, combined with a specific activity or trauma, results in an altered blood supply to the bone. Another theory supposes that a build-up of fluid within the bone puts pressure on blood vessels and diminishes circulation. More than 3 times as many women as men are affected; most are over 60 years of age.

Osteonecrosis of the knee is also associated with certain conditions and treatments, such as obesity, sickle cell anemia, lupus, kidney transplants, and steroid therapy. Steroid-induced osteonecrosis frequently affects multiple joints and is usually seen in young patients. Regardless of the cause, if the disease is not identified and treated early, it can develop into severe osteoarthritis.

Signs and symptoms

  • Sudden pain on the inside of the knee, perhaps triggered by a specific activity or minor injury
  • Increased pain at night and with activity
  • Swelling over the front and inside of the knee
  • Heightened sensitivity to touch in the area
  • Limited motion due to pain

Development

Osteonecrosis of the knee develops through four stages, which can be identified by symptoms and X-rays:

Stage I: Symptoms are most intense in the earliest stage. Symptoms may continue for 6 to 8 weeks and then subside. Because X-rays are normal, a positive magnetic resonance is needed to make the diagnosis. Treatment at this point is nonoperative and conservative, focusing on pain relief and protected weight-bearing, and in some cases core decompression (see later).

Stage II: It may take several months for the disease to progress to Stage II. At this point, X-rays will show that the rounded edge of the thighbone is starting to flatten out. An MRI or bone scan can be used to diagnose the disease. A CT scan may also be used to measure the affected area of bone area.

Stage III: By the time the disease reaches stage III (3 to 6 months after onset), it is clearly visible on X-rays and no other diagnostic tests are needed. The articular cartilage covering the bone begins to loosen as the bone itself begins to die. Operative treatments may be considered at this point.

Stage IV: At this point, the bone begins to collapse. The articular cartilage is destroyed, the joint space narrows, and bone spurs may form. Severe osteoarthritis results and joint replacement surgery may be necessary.


Treatment options In the early stages of the disease, treatment is nonoperative. If the affected area is small, this treatment may be all that is needed. Options include:

  •  Medications to reduce the pain
  •  A brace to relieve pressure on the joint surface
  •  A conditioning program with exercises to increase the strengthen of the muscles in your thighs
  •  Activity modifications to reduce knee pain

If more than half of the bone surface is affected, you may need surgical treatment. Several different procedures may be used to treat osteonecrosis of the knee. Among the surgical options are:

  •  Arthroscopic cleansing (debridement) of the joint
  •  Drilling to reduce pressure on the bone surface (core decompression)
  •  Procedures to shift weight-bearing away from the affected area
  •  Replacement of one or both joint surfaces

Clinical: Clinical presentation is summarized in the following table.
Table 1. Clinical Presentation of SPONK and Secondary Osteonecrosis

Physical Characteristic SPONK Secondary Osteonecrosis
Age Typically >55 y Typically
Sex(male-to-female ratio) 1:3 1:3
Associated risk factors None Corticosteroids, alcohol, SLE, sickle-cell disease, caisson disease, Gaucher disease, fat emboli, thrombi formation
Other joint involvement Rare Approximately 75%
Laterality 99% unilateral Approximately 80% bilateral
Condylar involvement One (usually medial femoral condyle or either tibial plateau) Multiple
Location Epiphyseal to the subchondral surface Diaphyseal, metaphyseal, epiphyseal
Symptoms Commonly sudden onset of pain and increased pain with weightbearing, stair climbing, and at night Usually long-standing insidious pain; patient may have symptoms and signs of an underlying disorder, such as SLE
Examination Pain localized to affected area; small synovitis or effusion may occur; ligaments are stable; range of motion may be limited by pain or effusion Pain is difficult to localize; ligaments are stable; range of motion is grossly intact but may be limited by pain