Abstract
Rib grafts in facial plastic surgery are becoming more frequently used. Small animal models, although not ideal may be used to emulate costal cartilage-based procedures. A surgical characterization of this tissue will assist future research in the selection of appropriate costal segments, based on quantitative and qualitative properties. The objective of this study is to assess the surgical anatomy of the rabbit costal margin and evaluate costal cartilage for use in either in vivo or ex vivo studies and to examine reconstructive procedures. Detailed thoracic dissections of 21 New Zealand white rabbits were performed post-mortem. Costal cartilage of true, false, and floating ribs were harvested. The length, thickness, and width at proximal, medial, and distal locations of the cartilage, with perichondrium intact were measured. Further qualitative observation and digital images of curvature, flexibility, and segmental cross-sectional shape were recorded. The main outcome measure(s) is to characterize, describe, and assess the consistency of dimensions, location, and shape of costal cartilage. In this study, 12 to 13 ribs encase the thoracic cavity. Cartilage from true ribs has an average length, width, and depth of 23.75 ± 0.662, 3.02 ± 0.025, and 2.18 ± 0.018 mm, respectively. The cartilage from false ribs has an average length, width, and depth of 41.97 ± 1.48, 2.00 ± 0.07, 1.19 ± 0.03 mm, and that of floating ribs are 7.66 ± 0.29, 1.98 ± 0.04, and 0.96 ± 0.03 mm. Rib 8 is found to be the longest costal cartilage (49.10 ± 0.64 mm), with the widest and thickest at ribs 1 (3.91 ± 0.08 mm) and 6 (2.41 ± 0.11 mm), respectively. Cross-sectional segments reveal the distal cartilage to maintain an hourglass shape that broadens to become circular and eventually ovoid at the costochondral junction. The New Zealand white rabbit is a practical source of costal cartilage that is of sufficient size and reproducibility to use in surgical research where the long-term effects of operations, therapies, devices, and pharmacologic on cartilage can be studied in vivo.
Highlights
Cartilage grafts obtained from the costal margin are frequently used in facial reconstruction providing durable bulk with minimal resorption as this source provides a large reservoir of accessible cartilage.[1,2,3,4]
A variety of animal models exist for facial surgery, one must make selections based on characteristics that are similar to the object of previous experimentation and that at least grossly approximates what can be expected in humans.[5]
This study demonstrates that the New Zealand white rabbit has ample costal cartilage for in vivo and ex vivo reconstructive experimentation
Summary
Cartilage grafts obtained from the costal margin are frequently used in facial reconstruction providing durable bulk with minimal resorption as this source provides a large reservoir of accessible cartilage.[1,2,3,4] To evaluate new technologies, pharmacologic, and biomedical devices aimed at treating or modifying costal cartilage, studies often require long-term, metabolically active in vivo tissue investigations. Medium-sized animals, in contrast, are more practical alternative to mimic costal cartilage-based procedures, to evaluate new instrumentation, pharmaceuticals, or tissue engineered technologies, they are accompanied with increasing ethical concerns.[6] As dogs and cats are domestic, companion animals, biomedical ethics and negative public perception have limited their use in medical research, attention has been focused on the rabbit as an appropriate medium-sized animal.[7,8]. New Zealand white rabbits have been found to have 12 or 13 ribs based on the individual's genetic makeup.[12] On the basis of their anterior attachment, as described in humans, ribs are classified into three types: true, false, and floating.[13] Ribs 1 to 7 comprise the true ribs, articulating with the sternum at synovial sternocostal joints. The 11th, 12th, and, if available, 13th rib pairs are floating ribs and do not articulate anteriorly
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