Arterial injuries are not commonly seen. Lateral dislocations typically involves damage to the medial collateral, both cruciates and the medial posterior capsule. This injury is occurs when there is a violent abduction force on the tibia against the femur. Arterial injuries are not common. Medial dislocation occurs when there is a significant adduction force on the tibia against the femur resulting in damage to the lateral collateral ligaments, both cruciate ligaments, the posterior capsule and commonly, the peroneal nerve.
Rotary dislocations result from anteromedial or anterolateral force on the anterior tibia.
Clinically, patients with direct tenderness over the superolateral patella should be suspicious for bipartite patellar stress fracture and fibrous nonunion. In nondisplaced fractures, a cast should be placed for 4 to 6 weeks. Knee stiffness, quadriceps atrophy, extensor lag and persistent pain are possible complications of patellar fractures. The most frequently injured are the medial collateral and anterior cruciate ligaments. Avulsion of the tibial spine is associated with anterior cruciate ligament injury.