Blunt injuries to the patellofemoral joint resulting from transarticular loading are influenced by impactor energy and mass

Various impact models have been used to study the injury mechanics of blunt trauma to diarthrodial joints. The current study was designed to study the relationship between impactor energy and mass on impact biomechanics and i njury modalities for a specific test condition and protocol. A total of 48 isolated canine knees were impacted once with once of three free flight ine rtial masses (0.7, 1.5, or 4.8 kg) at one of three energy levels (2, 11, 22 J). Joint impact biomechanics (peak load, loading rate, contact area) gene rally increased with increasing energy. Injuries were typically more freque nt and more severe with the larger mass at each energy level. Histological analyses of the patellae revealed cartilage injuries at low energy with dee p injuries in underlying bone at higher energies.