Ineffectiveness of acute scalp expansion

The aim of this study was to test thr ex vivo biomechanical properties of a cutely expanded scalp flaps to quantitatively assess the efficacy of acute scalp expansion. A total of 14 fresh male cadavers were used for the study. In each cadaver, a rectangular (4 x 10 cm), later-ally based flap was desi gned on each side of the scalp, starting from the superior margin of the ex ternal auditory canal. One randomly selected nap per scalp underwent acute intermittent expansion (a 3-minute expansion/3-minute rest cycle was perfor med three times with the maximum expansion achievable) the contralateral fl ap sen ed as a control. After the expansion process, the acutely expanded n aps were measured to assess whether applied biomechanical stress caused any changes in flap dimensions. The biomechanical properties (stress/strain ra tio, mean stiffness) of both expanded and control flaps were then assessed by means of a dynamometer and a force transducer. The obtained data showed that the biomechanical benefits provided by acute scalp expansion were not statistically different (p < 0.05) from those obtained by simple subgaleal undermining. No change of length nor gain in compliance was observed in the acutely expanded flaps as compared with control scalp flaps. In the author s' opinion, a possible explanation (to be further validated) for the lack o f effect of acute scalp expansion might be that the inelastic galea aponeur otica did not allow mechanical creep to exploit the inherent elastic proper ties of the overlying scalp skin.