What are the other Names for this Condition? (Also known as/Synonyms)

• Arthroscopy-Associated Knee Osteonecrosis
• Osteonecrosis of the Knee after Arthroscopic Surgery
• Post-Arthroscopic Knee Osteonecrosis

What is Post-Arthroscopic Osteonecrosis of the Knee? (Definition/Background Information)

• Osteonecrosis (or avascular necrosis) is a serious bone disorder characterized by the temporary or permanent disruption of blood supply to the bone, which causes cells and tissues within the affected bone to die. In many, osteonecrosis affects the ends of the long bones in the body and the knee is a common location
• Post-Arthroscopic Osteonecrosis of the Knee is a highly uncommon form of knee osteonecrosis. The condition is more often diagnosed in middle-aged adults who have undergone invasive procedures for various knee conditions
• It is reported that the knee surgery may bring about a change in the strength and function of the knee making it vulnerable to insufficiency fractures (fractures that occur when weak bones are subjected to normal stresses)
• Individuals, who develop Post-Arthroscopic Osteonecrosis of the Knee, begin to experience pain within the affected bone/joint, following 6-8 weeks of surgery. This may be accompanied by tenderness, swelling, and reduced range of knee joint movement
• Treatment associated with Post-Arthroscopic Osteonecrosis of the Knee includes both nonsurgical and surgical methods. With early diagnosis and adequate treatment, the prognosis of the condition may be improved

Who gets Post-Arthroscopic Osteonecrosis of the Knee? (Age and Sex Distribution)

• Post-Arthroscopic Osteonecrosis of the Knee is observed in individuals who have undergone arthroscopic knee surgery. The incidence rate of the condition is reported to be about 4%
• Most cases are reported in individuals in the 40-50 years’ age group
• Both males and females are affected
• All racial and ethnic groups are at risk and no predilection is observed

What are the Risk Factors for Post-Arthroscopic Osteonecrosis of the Knee? (Predisposing Factors)

Post-Arthroscopic Osteonecrosis of the Knee may be described as an iatrogenic condition that occurs following arthroscopic knee (surgical) procedures. The following knee joint procedures are known to increase the risk for the condition:

• Anterior cruciate ligament reconstruction procedure
• Arthroscopic knee surgery
• Chondroplasty
• Meniscectomy, including laser-assisted meniscectomy

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Post-Arthroscopic Osteonecrosis of the Knee? (Etiology)

The exact mechanism of development of Post-Arthroscopic Osteonecrosis of the Knee is not well-established. The onset of symptoms occurs after 1-2 months (usually within 8 weeks) following surgery to the knee.

• A weak bone from invasive bone procedures is prone to breakage on application of normal stresses; such fractures are termed insufficiency fractures. The subchondral bone is the bone layer lying immediately beneath the cartilage that is generally affected
• Post-Arthroscopic Knee Osteonecrosis is reported to develop following a change in knee bone/joint function and strength following arthroscopic surgery resulting in increased susceptibility to (subchondral) bone insufficiency fractures
• Due to such insufficiency fractures, there is a collection of fluid around the bone marrow and consequently, reduced blood supply to the region. This results in cell and tissue death and osteonecrosis

What are the Signs and Symptoms of Post-Arthroscopic Osteonecrosis of the Knee?

The signs and symptoms of Post-Arthroscopic Osteonecrosis of the Knee may be mild or severe and can vary from one individual to another. The signs and symptoms may include:

• Noticeable pain and tenderness in the affected bone
• The pain increases when weight/pressure is applied to the bone
• The pain may be either dull or sharp and shooting
• Swelling of tissue around the affected kneecap or knee joint
• Decreased range of motion of the affected joint/bone
• During the later stages, osteophytes or bony projections may form around the affected knee region. These lesions may range in size from 2-5 cm or may even be larger
• The condition may develop at the knee end of either the femur (thigh bone) or tibia (shin bone)

How is Post-Arthroscopic Osteonecrosis of the Knee Diagnosed?

Diagnostic methods that a physician may use to help diagnose Post-Arthroscopic Osteonecrosis of the Knee include:

• Physical examination and evaluation of medical history (including history of knee surgery)
• Assessment of the signs and symptoms
• Functional evaluation of the affected knee joint
• X-ray of the knee: X-rays can help the physician rule-out other possible causes of knee discomfort. During the early stages of osteonecrosis, it is difficult to locate the appearance of any abnormal bone changes. However, X-rays can usually identify the presence of osteonecrosis during the later stages
• Magnetic resonance imaging (MRI) of the knee joint: An MRI is an imaging technique that creates images of soft tissues and bones, which helps detect any bone abnormalities, during the early stages of osteonecrosis
• Bone scan: A bone scan is a diagnostic method used to identify any bone abnormalities by injecting tiny amounts of radioactive material into the bloodstream
• Computerized tomography (CT) of the knee joint: A CT scan takes a series of X-ray images from several different angles, which are then merged to create cross-sectional images of bones and soft tissues of the body. This allows a physician to examine the bone or joint and its surrounding structures

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Post-Arthroscopic Osteonecrosis of the Knee?

The complications associated with Post-Arthroscopic Osteonecrosis of the Knee may include:

• Further deterioration of the involved bone; if left untreated, the bone or joint may collapse
• Immobility of the affected knee
• Walking difficulties, walking with a limp
• Chronic disability
• Severe emotional stress

How is Post-Arthroscopic Osteonecrosis of the Knee Treated?

The treatment of Post-Arthroscopic Osteonecrosis of the Knee includes non-surgical and surgical methods and may depend on the severity of the condition (mild or severe). A healthcare provider may start with non-surgical treatment methods before adopting surgical procedures and techniques. These include:

• Applying ice to the region can help with pain and reduce swelling
• Avoiding further stress/weight on the involved knee, such as by using a pair of crutches; preventing further bone damage
• Non-steroidal anti-inflammatory oral medications, such as ibuprofen and naproxen, may be used to help decrease pain and swelling
• Use of bisphosphonate medications help in slowing or preventing progression of the condition
• Medications for osteonecrosis may decrease the progression of this condition
• Corticosteroid injections help provide temporary relief of symptoms and in improving the range of motion. It is important to note that corticosteroid injections may only give temporary relief. Prolonged episodes of such injections can injure the joints in the long-run
• Electrical stimulation therapy to aid in the growth of the affected bone
• After the symptoms has decreased, it is important to begin some light motion exercises.  Physical therapy may help restore strength, as well as provide flexibility to the muscles

Surgical treatment measures include:

• High tibial osteotomy: The affected bone is surgically removed/cut and reshaped or realigned; usually, in younger patients
• Cartilage grafting: Cartilage grafting is a surgical procedure to replace the damaged cartilage, which may be damaged due to osteonecrosis or any traumatic injury
• Core decompression: Core decompression is used to treat early-stage osteonecrosis. In this surgical procedure, the pressure within the bone is decreased by removing a part of the bone causing the abnormal pressure
• Bone grafting or osteochondral autografting: It is a technique that involves removing a healthy bone from within the body and replacing the affected bone
• Unicompartmental knee arthroplasty (UKA): An invasive procedure to relieve pain and other symptoms in one of the knee compartment. It has a shorter recovery period and reduced surgical complications
• Total knee arthroplasty (TKA): In total knee arthroplasty, the involved joint cartilage is completely removed. It is then replaced by a metal and plastic prosthetic implant. This surgical procedure is recommended, if the entire joint is acutely affected

How can Post-Arthroscopic Osteonecrosis of the Knee be Prevented?

An accurate diagnosis, identification of appropriate surgical techniques to be used and sustained, vigilance during and after knee arthroscopy may help reduce the risk for Post-Arthroscopic Osteonecrosis of the Knee.

What is the Prognosis of Post-Arthroscopic Osteonecrosis of the Knee? (Outcomes/Resolutions)

• The prognosis of Post-Arthroscopic Osteonecrosis of the Knee depends on the severity of the condition and the complications that arise
• If treated early and adequately, many individuals may show improved outcomes

Post-Arthroscopic Knee Osteonecrosis is a known complication of arthroscopic and other surgical procedures involving the knee. Even when surgical procedures are conducted by experienced surgeons, one may be at risk for this condition. An early recognition and treatment may help your healthcare provider take suitable measures that can help prevent it from getting worse.

Additional and Relevant Useful Information for Post-Arthroscopic Osteonecrosis of the Knee:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/health-topics/orthopedc-disorders/