Knee Genicular Nerve Injection & Radiofrequency Ablation

Nature of procedure

The injection targets the sensory nerves (genicular nerves) supplying the knee to provide pain relief.

It is a 2-step procedure:

1. A diagnostic trial injection of the knee is done first and the amount and duration pain relief is evaluated.

2. If successful, radiofrequency ablation (RFA) of the genicular nerve can be offered for “a” longer pain relief duration

Who is suitable

• Those who have not decided or are not keen for knee surgery

• Those who have medical conditions that make “knee surgery” high risk

• Interim pain control or diagnostic treatment for knee pain before “knee” surgery

Knee osteoarthritis (OA) Knee pain results from the degeneration of the knee cartilage.

In Singapore, the national prevalence of knee OA is estimated at 11% with a higher prevalence among women than men. The prevalence of knee OA also increases with age, affecting 19.7% of those aged 60 years and above, compared to 8.6% of those between 18 and 59 years old.

Common risk factors

• Elderly women

• Women

• History of bone deformities

• Previous knee joint injuries/ stress from sports/work

• Obesity

• Family history of osteoarthritis

• Diabetes

Radiofrequency ablation is the next step in treatment

Aims to “burn” the sensory nerves of the knee, leading to longer pain relief period of 6-12 months.

Potential risks/complications of procedure

The overall risks of genicular knee injections are low. Some rare complications that can occur are:

a. Allergic reactions to X-ray contrast, steroid or to the local anaesthetic injectate

b. Bleeding may occur superficially and cause bruising. The risk may be increased if you have underlying bleeding disorders or are on blood thinners

c. Infection: Minor infections may occur, but severe infections are rare

d. Discomfort at the point of the injection or worsening of pain symptoms. These symptoms are usually mild and short lived. Long lasting increases in pain are rare

e. Leg weakness - This is rare but can occur of there is spread of local anaesthetic to the nerves that supply the knee. The strength will recover once the local anaesthertic wears off

f. Local anaesthetic toxicity: - This is extremely rare

Additional risks/complications related to radiofrequency ablation:

a. Aggravated pain/soreness over the next 1-2 weeks: This is common due to damage of the surrounding tissues from the RFA process

b. Bruising at the injection site: This may occur due to the use of larger needles and needle adjustment

c. Permanent numbness: This may be an inadvertent side effect of ablating sensory nerves

d. Permanent weakness: This is rare and may occur due to ablation of a motor nerve. This is avoided through the use of motor testing prior to ablation

Potential side effects of steroid use

a. Facial flushing, headache

b. Elevated blood sugar

c. Elevated blood pressure, fluid retention

d. Skin thinning/ bruising, weight gain

e. Suppression of hypothalamic pituitary axis (impaired stress response)

f. Impaired immunity (increased infection)

g. Neuropsychiatric effects e.g. mood changes, irritability, confusion, insomnia

h. Bone/ muscle effects e.g. osteoporosis, avascular necrosis, muscle weakness

i. Gastrointestinal effects e.g. gastritis, ulcer, gastrointestinal bleeding

j. Eye effects: cataract, increased eye pressure (worsening of glaucoma)

k. Cortisone flare

If you have further questions regarding genicular nerve injection and radiofrequency ablation, check with your chronic pain doctors during your visit.

Khoo Teck Puat Hospital • (65) 6555 8000 • www.ktph.com.sg

Yishun Community Hospital • (65) 6807 8800 • www.yishuncommunityhospital.com.sg

The information is correct at the time of printing and subject to revision without further notice.