OBJECTIVEThe study was to investigate the influence of maintenance period of expansion upon skin tension and immediate stretch-back rate of the expanded skin.

METHODS30 expanders (240 ml) were implanted in six adult dogs, which were divided into four groups: group A with 2-week saline injection of the expander; group B with 6-week injection; group C with sham-operation and group D as the blank control group. The first two groups were subdivided into three groups respectively according to different maintaining times of one week, two weeks and four weeks. When full inflation was finished, a 4 cm x 7 cm expanded flap was created and in vivo skin tension and stretch-back ratio of the flap were measured. The Comparison was made in terms of in vivo skin tension and immediate stretch-back ratio between different injection and different maintenance periods.

RESULTSWith expansion maintenance time increasing, the in vivo skin tension and immediate stretch-back ratio decreased. After the capsule of the expand skin flap was removed, the in vivo skin tension and immediate stretch-back rate significantly reduced. Based on the experimental results, 16 patients were treated with implantation of 23 expanders. Their average expander injection time was 14 days and the average maintenance time was 25 days. All expanders obtained good results except one extrusion.

CONCLUSIONIn skin and soft tissue expansion, in vivo skin tension and immediate stretch-back ratio can be reduced through prolonged maintenance of expansion and capsule removal from the expanded skin flap.