COOLIEF® Cooled Radiofrequency is a breakthrough radiofrequency ablation technology in which the electrode is actively cooled by fluid in a closed circuit. This allows a significantly larger and more predictable zone of nerve ablation than conventional RF – translating into longer-lasting and more durable relief in patients with degenerative disease of large joints.

How Does the COOLIEF® Cooled RF Procedure Work?

Cooled RF is liquid-cooled thermolesion. A radiofrequency current (approximately 480 kHz) generated by an 80-watt Avanos console passes through a special needle (catheter) introduced near the sensory nerve supplying the painful joint. Simultaneously, cooled saline is pumped through an internal channel in the needle by a peristaltic pump, cooling the electrode tip.

This seemingly contradictory solution – cooling a needle that is meant to ‘heat’ – is precisely the key to the technology’s effectiveness. In standard RF thermolesion, the temperature at the needle tip rapidly reaches 80–90°C, causing tissue charring (carbonisation) around the electrode. The charred layer acts as an insulator and limits further energy conduction – thereby limiting the lesion size to a small ellipsoid.

The Technological Advantage of Cooled RF

Cooled RF maintains the needle-tissue interface temperature at a controlled level of approximately 60°C, preventing carbonisation. The practical consequences are significant:

  • Energy can be delivered for longer and at higher power – Cooled RF delivers up to 3.7 times more energy than conventional RF
  • A spherical lesion up to 12 mm in diameter is created – significantly larger than in conventional RF
  • The lesion projects >45% beyond the needle tip – allowing access to nerves at varying depths and in non-standard anatomy
  • A larger lesion area means a higher probability of successfully ablating the nerve despite anatomical variation (sacral lateral branches, medial cervical and thoracic branches, sensory branches of the knee and hip joints)

In clinical practice this translates to a significantly higher rate of successful procedures and a longer duration of effect compared to conventional thermolesion – in randomised trials up to 24 months of relief without the need to repeat the procedure.

Indications for COOLIEF® Cooled RF

  • Degenerative disease of the knee joint – especially in patients not qualifying for arthroplasty or deferring surgery
  • Chronic pain following knee or hip arthroplasty (post-arthroplasty pain)
  • Degenerative disease of the hip joint (coxarthrosis)
  • Chronic shoulder pain (e.g. in rotator cuff arthropathy)
  • Sacroiliac joint pain
  • Axial spinal pain originating from facet joints – lumbar, thoracic and cervical spine
  • Patients with contraindications to opioid therapy or seeking a non-opioid alternative
  • Patients who have undergone previous thermolesion procedures
  • Patients with extensive degenerative spinal changes

Procedure Sequence

  • The patient lies on the procedure table and receives local anaesthesia.
  • Under fluoroscopic X-ray guidance (less frequently ultrasound), special COOLIEF® liquid-cooled needles are introduced near the sensory nerves responsible for the pain (e.g. genicular nerves of the knee, nerve branches supplying the hip).
  • Sensory stimulation (50 Hz) and motor stimulation (2 Hz) are performed – the patient confirms the needle position is correct (feels ‘their’ pain with no muscle contraction).
  • Ablation cycle: 60°C for approximately 2.5 minutes, typically 2–4 points per joint. During this time the pump continuously cools the needle tip.
  • After the procedure the patient is observed for 30–60 minutes, then goes home.

Preparation

  • Consultation with a pain medicine physician including review of imaging studies (X-ray, MRI)
  • A prior diagnostic sensory nerve block is usually required – if it provided >50% relief, this is a good predictor of Cooled RF efficacy
  • Discontinuation of anticoagulant medications according to individual recommendation (depends on the preparation)

Effects

Full pain relief develops gradually over 2–6 weeks following the procedure (time needed for nerve activity to subside). Numerous multicentre randomised trials (including Davis 2019, Hunter 2020, Lyman 2022) demonstrate sustained relief:

  • Average pain reduction of 50% or more in the vast majority of patients
  • Duration of effect: 12 to 24 months
  • Significant reduction in analgesic consumption (including opioids)
  • Improvement in physical function and quality of life (WOMAC, Oxford Knee Score scales)

Once the effect wears off, the procedure can be safely repeated. Nerves regenerate functionally, enabling a subsequent ablation of similar efficacy.

Possible Side Effects

  • Transient pain at the puncture site (1–7 days) – managed with paracetamol and ice packs
  • Minor subcutaneous haematoma
  • Very rarely – transient paraesthesia or focal sensory disturbance in the ablation area
  • Occasionally – absence of a satisfactory effect (usually correlates with failure to respond to the diagnostic block)

FAQ – Frequently Asked Questions

Does Cooled RF replace knee arthroplasty?

It does not replace arthroplasty, but is a valuable alternative for patients who cannot or do not wish to undergo surgery – due to age, comorbidities, BMI, fear of surgery or the need to defer the procedure. It can also be used in patients with chronic pain after joint replacement.

How does Cooled RF differ from standard RFA thermolesion?

Cooled RF cools the needle with fluid, enabling delivery of up to 3.7× more energy to the tissue, creating a 4× larger spherical lesion (up to 12 mm in diameter). Conventional RF creates a small elliptical lesion and is less effective in cases of variable nerve anatomy (e.g. the knee joint).

How long until results are felt?

Patients notice the first effects within 1–2 weeks; full relief develops over 2–6 weeks. The maximum effect is then maintained for up to 24 months.