The distribution of heat in bone during radiofrequency ablation of an ex vivo bovine model of osteoid osteoma.

Osteoid osteoma is treated primarily by radiofrequency (RF) ablation. However, there is little information about the distribution of heat in bone during the procedure and its safety. We constructed a model of osteoid osteoma to assess the distribution of heat in bone and to define the margins of safety for ablation. Cavities were drilled in cadaver bovine bones and filled with a liver homogenate to simulate the tumour matrix. Temperature-sensing probes were placed in the bone in a radial fashion away from the cavities. RF ablation was performed 107 times in tumours < 10 mm in diameter (72 of which were in cortical bone, 35 in cancellous bone), and 41 times in cortical bone with models > 10 mm in diameter. Significantly higher temperatures were found in cancellous bone than in cortical bone (p < 0.05). For lesions up to 10 mm in diameter, in both bone types, the temperature varied directly with the size of the tumour (p < 0.05), and inversely with the distance from it. Tumours of > 10 mm in diameter showed a trend similar to those of smaller lesions. No temperature rise was seen beyond 12 mm from the edge of a cortical tumour of any size. Formulae were developed to predict the expected temperature in the bone during ablation.

[Induction of spermatogenesis in patients with non-obstructive azoospermia after antegrade sclerotherapy]. / Induktion der Spermiogenese nach antegrader Varikozelensklerosierung bei Patienten mit nicht-obstruktiver Azoospermie.

PURPOSE: The aim of this study was to prove the efficacy of antegrade sclerotherapy for varicocele testis in patients with azoospermia and in patients with cryptozoospermia (less than 0.1 million spermatozoons/mL ejaculate). We have investigated the induction of spermatogenesis in patients with non-obstructive azoospermia after antegrade sclerotherapy. MATERIALS AND METHODS: 20 consecutive patients who had been trying to beget a child over a period of one year or longer were chosen for this study. All patients suffered from non-obstructive azoospermia or from cryptozoospermia. We produced a control spermiogram for each patient before, 3 and 6 months after antegrade sclerotherapy. The postoperative spermiogram was done according to WHO criteria and was then compared to the preoperative data. RESULTS: 15 patients (75 %) were found to suffer from azoospermia preoperatively and 5 patients (25 %) from cryptozoospermia. Out of the 15 patients with initial azoospermia 8 (53 %) showed cryptozoospermia (OAT/OT syndrome) after antegrade sclerotherapy. Out of the 5 patients with the initial cryptozoospermia 3 (60 %) showed an improvement in the sperm count and motility criteria. CONCLUSIONS: Antegrade sclerotherapy for varicocele testis is a valid treatment option to isolate the spermatozoons from the ejaculate for extracorporeal fertilisation in patients with non-obstructive azoospermia. Complete normalisation of the spermiogram parameters, i.e., sufficient for natural child conception, cannot safely be achieved by this method.