Optimal chest wall prosthesis: comparative study of mechanical and functional behaviour

OBJECTIVES Chest wall resections are most commonly performed for tumours, infection, radiation necrosis and trauma. Defects in the anterior chest greater than 5 cm, posterior defects more than 10 cm or resection including more than 3 ribs, independently of the location, require skeletal prosthetic reconstruction. The aim of this paper was to evaluate the strength of prostheses that reproduced the normal human anatomy using different materials subjected to the most dangerous loading conditions. METHODS The biomechanical behaviours of different prosthetic materials under critical rib fracture conditions were analysed using the finite element method and then validated through mechanical testing of 3-dimensional polymethylmethacrylate ribs as a prosthesis reproducing the native anatomy of the human ribcage. RESULTS The prosthetic materials and the polymethylmethacrylate prosthesis were tested under 3 load conditions: sternal load (an anterior–posterior load applied at the third rib); lateral load (strength applied at the lateral arch of the fifth rib) and vertical load (vertical load applied at the first sternocostal junction) and showed the same results in terms of failures compared to the results from the finite element method model simulation (same location and number of fractures were detected). Although the displacement error between the finite element method and experimental test was up to 5% overall, no other microcracking was observed. CONCLUSIONS This experimental study demonstrated that all prosthetic materials currently available for human use show optimal mechanical behaviour in term of resistance and organ protection. Specifically, polymethylmethacrylate was a good candidate as a prosthetic material in term of lightness, resistance and prosthetic weight.