Mechanical Distraction Enterogenesis Using Springs Has Equal Effectiveness in Adult and Juvenile Pigs

INTRODUCTION: Short bowel syndrome is a devastating disease affecting children and adults. We aim to apply our spring-mediated intestinal lengthening technique to both populations. We hypothesized that spring-mediated intestinal lengthening can be achieved in adult and juvenile pigs. METHODS: Adult and juvenile pigs underwent insertion of a compressed encapsulated nitinol spring into the jejunum. Jejunum was plicated just proximal and distal to the capsule to affix it within the lumen, and control jejunum was marked. Pigs were fed a liquid diet for 1 week postoperatively. Spring and control segment lengths were measured and compared using t-test. RESULTS: Three adult pigs weighing 30.4 ± 2.1 kg and 3 juvenile pigs weighing 8.9 ± 1.2 kg underwent spring insertion without complications. Springs were compressed from 7.5 to 2 cm and had average spring constant of 9.7 ± 1.2 N/m in adults and 5.4 ± 1.5 N/m in juveniles. Springs of 1.3-cm diameter were implanted in adults and springs of 1.0-cm diameter were implanted in juveniles. Spring segments lengthened on average by 86 ± 33% in adults (p = 0.04) and 123% in juveniles (p < 0.01) compared with the initial length. There was no statistically significant difference in lengthening between juvenile and adult pigs (p = 0.2). Normal mucosal integrity and muscular thickness were seen on histology (Fig. 1).CONCLUSION: We have demonstrated intestinal lengthening using nitinol springs in adult and juvenile pigs. Intestinal lengthening was feasible in adult pigs but required a higher force for their larger diameter intestine.