Bipolar radiofrequency in the human meniscus. Comparative study between patients younger and older than 40 years of age

Radiofrequency energy on cortical bone and soft tissue: a pilot study

BACKGROUND

Radiofrequency-generating energy devices have been used clinically in musculoskeletal procedures to provide hemostasis and capsular shrinkage (thermal capsulorrhaphy). However, the dose-effects are not well known.

QUESTIONS/PURPOSES

We therefore determined dosage effects of radiofrequency energy on bone, skin incisions, and joint capsule in sheep.

METHODS

Five mature sheep had six 2.5-cm(2) tibial periosteal defects and six 1.0-cm skin incisions assigned to six treatments varying by watts and fluence (f = watts . seconds/cm(2)): (1) untreated control, (2) 50 W for 9.5 seconds (190f; n = 5), (3) 110 W for 4.3 seconds (190f; n = 5), (4) 170 W for 2.8 seconds (190f; n = 5), (5) 170 W for 5.6 seconds (380f; n = 5), or (6) 170 W for 8.4 seconds (570f; n = 5). Outcomes included hemostasis, contraction, healing, and histomorphometry for inflammation and necrosis at 2 weeks.

RESULTS

Radiofrequency energy application on skin at 190f or greater had more than 80% hemostasis and dose-dependent contraction, inflammation, and necrosis. Radiofrequency energy application on bone had good (70%) hemostasis at 190f and complete (> 95%) hemostasis at 380f and 570f, without histologic or clinically detectable necrosis.

CONCLUSIONS

Hemostasis can be achieved with radiofrequency energy at 190f in skin and bone. Bone necrosis was not detected at up to 570f. Using fluence greater than 190f in skin achieved dose-dependent necrosis and incisional contraction.

CLINICAL RELEVANCE

Radiofrequency energy can be used on bone and skin for hemostasis, but potential incisional complications, such as necrosis and an atypical firm and desiccated surface, should be expected.

Ablation of bull prostate using novel bipolar radiofrequency ablation probe

PURPOSE

We describe the use of a novel bipolar radiofrequency (RF) system for the destruction of prostate tissue in an ex vivo model.

MATERIALS AND METHODS

A bipolar RF delivery system (Trod Medical, France) was linked to a 500 kHz generator. Eight lesions were created in an ex vivo bull prostate model using 7-mm (n = 4) and 10-mm probes (n = 4). Ablation was performed for 150 seconds. Temperature was recorded at the center of the lesion (Tc) and at the periphery (Tp) of the prostate. Tissue damage, both within and without the intended destruction zones, was assessed. The distance from Tc to Tp was recorded.

RESULTS

All lesions created with either the 7-mm or 10-mm bipolar RF ablation (RFA) probes demonstrated complete tissue destruction only within the intended zone. Using the 7-mm probe, the mean Tc was 82 degrees C and the mean Tp 34 degrees C. The mean distance from the edge of the lesion to the periphery was 5 mm. Impedance was 62 Ohm, and power was 4 watts during ablation with the 7-mm probe. With the 10-mm probe, the mean Tc and Tp were 70 degrees C and 41 degrees C, respectively. The mean distance from the edge of the lesion to the periphery was 5 mm. Impedance was 78 Ohm, and power was 4.5 watts during ablation with the 10-mm probe.

CONCLUSIONS

In an ex vivo model, bipolar RFA is capable of producing lesions with precise margins. Spread of heat is limited, evidenced histologically and by significant temperature drop off. This technology holds promise in the management of benign and malignant urologic diseases.