Chicken or the thumb? Comparing chicken femora with human metacarpals

Introduction While the gold standard for simulation training in hand surgery is cadaveric hands, ethical issues and cost limit their use. Chicken thighbones have been utilised to replicate human metacarpals but there is a lack of literature to validate such a model. The aim of this study was to determine whether chicken femurs are morphologically similar to human metacarpal bones. Methods Computed tomography imaging was obtained of hands undertaken at our institute between 1 January and 31 December 2015. A total of 114 chicken thighs were also scanned. Bones with previous trauma or incomplete imaging were excluded. Bone length, distance to isthmus, radius of curvature, medullary canal diameter and cortical thickness were compared between the groups. Statistical analysis was conducted using Student’s t-test or the Mann-Whitney U test, with statistical significance implied with a p-value of < 0.05. Results A total of 146 human CT scans were identified, of which 36 were included in the study, resulting in 158 human metacarpals in 5 female and 31 male patients, with an average age of 39.5 years (range: 16–77 years). Of 114 chickens scanned, 101 were suitable for analysis. Mean length, distance to isthmus, radius of curvature, medullary canal diameter and cortical thickness were 57.3mm (standard deviation [SD]: 8.7mm), 32.9mm (SD: 8.2mm), 68.8mm (SD: 19.5mm), 9.3mm (SD: 1.6mm) and 1.7mm (SD: 0.4mm) respectively in human metacarpals, compared with 66.7mm (SD: 5.1mm), 34.1mm (SD: 6.4mm), 89.1mm (SD: 15.1mm), 6.4mm (SD: 0.6mm) and 1.6mm (SD: 0.1mm) respectively in chicken femurs. There was no significant difference in bone geometry between the groups, with p-values of >0.05 for all parameters described. Conclusions The chicken thigh model provides an anatomically suitable and more cost effective alternative to human cadaveric metacarpals in simulation training for hand surgery.