What is the value of 3D virtual reality in understanding acetabular fractures?

Acetabular fractures are difficult to classify owing to the complex three-dimensional (3D) anatomy of the pelvis. 3D printing helps to understand and reliably classify acetabular fracture types. 3D-virtual reality (VR) may have comparable benefits. Our hypothesis is that 3D-VR is equivalent to 3D printing in understanding acetabular fracture patterns.

A total of 27 observers of various experience levels from several hospitals were requested to classify twenty 3D printed and VR models according to the Judet-Letournel classification. Additionally, surgeons were asked to state their preferred surgical approach and patient positioning. Time to classify each fracture type was recorded. The cases were randomized to rule out a learning curve. Inter-observer agreement was analyzed using Fleiss' kappa statistics (κ).

Inter-observer agreements varied by observer group and type of model used to classify the fracture: medical students: 3D print (κ = 0.61), VR (κ = 0.41); junior surgical residents: 3D print (0.51) VR (0.54); senior surgical residents: 3D print (0.66) VR (0.52); junior surgeons: 3D print (0.56), VR (0.43); senior surgeons: 3D print (κ = 0.59), VR (κ = 0.42). Using 3D printed models, there was more agreement on the surgical approach (junior surgeons κ = 0.23, senior surgeons κ = 0.31) when compared with VR (junior surgeons κ = 0.17, senior surgeons 0.25). No difference was found in time used to classify these fractures between 3D printing and VR for all groups (P = 1.000).

The Judet-Letournel acetabular classification stays difficult to interpret; only moderate kappa agreements were found. We found 3D-VR inferior to 3D printing in classifying acetabular fractures. Furthermore, the current 3D-VR technology is still not practical for intra-operative use.