Fig. 6

Force and displacement for two thoracotomies. a No ruptures evident. Retraction to DA = 112 mm over 240 s. Retraction proceeded as eight clicks in the first 60 s, followed by a 60 s pause, and completed with a final six clicks. Each click is evident as a step increase in both traces. After each click, the force decreases due to force relaxation of the viscoelastic tissues. Maximum force was 372 N (38 kgf) at the end of the final click. DB at end of the final click was only 93 mm (19 mm less than DA). b Three ruptures evident (marked by arrows). Retraction to DA = 115 mm over 240 s. Retraction proceeded as nine clicks in the first 60 s, followed by a 60 s pause, and completed with a final clicks. Maximum force was 372 N (38 kgf) at the end of the final click and would have been higher if the ribs had not fractured. DB at end of the final click was only 93 mm (21 mm less than DA)