Composite bone models are often used for fracture studies because of availability, predictable properties and easy storage, with research showing that composite bone can be mechanically similar to real bone in several gross morphological structural properties (Cristofolini et al., 1996, Cristofolini and Viceconti, 2000, Dunlap et al., 2008, Heiner and Brown, 2001, Zdero et al., 2007). While a composite bone as a structure in bending can behave similarly to a whole bone, composite bone may not model every real bone property. Hosseini found that the composite models were “unrealistically stable” compared to cadaveric femurs, may not be reliable models of osteoporosis and did not fail in a mode seen in cadaveric tests (Hosseini Khameneh et al., 2019). Grant studied frictional properties to find that the synthetic bone surfaces were sensitive to lubrication and finish, so care was needed in the study of these interfaces with transverse loading. Quenneville compared synthetic composite to cadaveric tibias for impact and found that synthetic tibias failed with lower forces and in a different mode than normal tibial shaft fractures (Quenneville et al., 2010). Basso in examination of hip fractures found synthetic femurs were much stronger at the bone-implant interface and failed in a different manner than cadaveric models, advising against their use as a substitute in osteoporotic hip fractures (Basso et al., 2014). Elfick compared novel surrogate humeri to cadaveric humeri with plate fixation in three-point bending and screw pull-out with comparable results between the groups (Elfick et al., 2002). Gardner used 3rd generation Sawbones models to simulate osteoporotic bone showing that locked plate and hybrid constructs for transverse humeral shaft fractures were more stable than unlocked constructs in cyclical loading (Gardner et al., 2006). Journals vary in the acceptance of composite bone in research. For example, Journal of Orthopaedic Trauma has no policy and Foot and Ankle International only accepts their use in limited circumstances (FAI, 2023).

Humeral shaft fractures (AO/OTA 12-A3), a fracture type where composite bone could offer a convenient research platform, occur commonly, but functional bracing may not always be the best option depending on the fracture pattern and severity (Ali et al., 2015, Hosseini Khameneh et al., 2019, Sarmiento et al., 2000, Schoch et al., 2017, Virkus et al., 2008). Other options such as open reduction internal fixation (ORIF), external fixation, and relatively newer intramedullary fixation techniques are also available (Dunlap et al., 2008, Hosseini Khameneh et al., 2019).

The purpose of this study was to determine if composite humerus models (CHM) are an adequate substitute for fresh frozen cadaveric humeri (CAD) in modeling mechanical properties of compressive stress, compressive force, and contact area during a compression plate fracture repair. Our hypothesis was that the compressive stress, contact area and compressive force would be significantly different in CHM than in CAD.