OBJECTIVE To review 13 years of experience using fused crystalline tes
tosterone implants for androgen replacement therapy in order to identi
fy pattern of usage (including continuation rates) and adverse events
emerging during therapy and factors associated with adverse events inc
luding implant extrusions. DESIGN Retrospective review of prospectivel
y collected data on characteristics of patients and implant procedures
performed as well as adverse events reported during routine follow-up
, PATIENTS Over 13 years 973 implant procedures using fused crystallin
e testosterone implants were performed in 221 men. MEASUREMENTS Contin
uation rates and adverse events such as extrusions, bleeding, infectio
n or others were recorded and analysed in relationship to characterist
ics of the patient and the implant procedure performed. RESULTS Overal
l rate of adverse events (108/973, 11.1%) was significantly related to
increased numbers of implants (4.2 +/- 0.1 vs 4.0 +/- 0.03, P = 0.031
) and higher levels of physical activity at work (P = 0.030). The most
common adverse effect was extrusion (83/973, 8.5%) which was related
to occupational classification (P = 0.033) and increasing work activit
y (P = 0.044) and occurred more frequently than by chance in multiple
(16 vs 3.3 expected) rather than single (65 vs 76.1 expected) episodes
. Bleeding (22/ 973, 2.3%) was significantly associated with an increa
sed number of implants (4.5 +/- 0.2 vs 4.0 +/- 0.03, P = 0.020) but ev
en in the worst cases (3/22) it was of minor clinical importance. Infe
ction was rare (6/973, 0.6%) but occurred more among thinner men. The
overall continuation rate was 92.7% increasing from 86% after the firs
t implantation to >99% after the tenth implant. CONCLUSIONS This study
demonstrates the very satisfactory clinical acceptability of testoste
rone pellet implants for androgen replacement therapy within a single
unit with experienced operators. The only regular adverse effect is ex
trusion, which may be related to mechanical factors such as habitual w
ork activity but also possibly procedural factors. Other adverse effec
ts such as bleeding, infection and fibrosis were rare, An improved met
hod of implant delivery would enhance this old but durable technology.