Article Review

Stress Radiographs for Ligamentous Knee Injuries

Nicholas N. DePhillipo, Ph.D., A.T.C., O.T.C., Patrick W. Kane, M.D., and Lars Engebretsen, M.D., Ph.D.

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 37, No 1 (January), 2021: pp 15-16

Stress radiographs have demonstrated reliability and validity in the diagnosis of knee ligament injuries and can provide an objective, quantifiable assessment.

Commonly utilized techniques include varus, valgus, and posterior stress radiographs which can be used to augment findings on physical examination and magnetic resonance imaging.

The authors provide an infographic depicting knee stress radiographic examples along with diagnostic criteria.

Related Cases

Lateral radiograph of the knee shows fragmentation (arrow) at the tibial tuberosity with thickening and irregularity (arrowhead) of the patellar tendon consistent with Osgood-Schlatter disease. Osgood-Schlatter disease is in apophysitis of the tibial tuberosity. It represents a chronic injury related to repetitive microtrauma. It is incredibly common in active adolescents. Patients present with knee pain and swelling over the tibial tuberosity. This is typically a clinical diagnosis. Radiographs are typically not indicated.

Sagittal T2 weighted MR of the knee in an adolescent shows disruption of the anterior cruciate ligament (arrow). ACL injuries typically occur when an athlete pivots and a valgus stress is applied to the knee in flexion. ACL injuries are more common in boys when the physis is not completely closed (as in this case). #MSKMonday

AP and lateral radiographs of the knee show a small avulsion fragment along the lateral aspect of the tibial epiphysis and a large knee effusion. This type of fracture represents an avulsion of the lateral collateral ligament and is known as a Segond fracture. It is important to recognize as it is almost always associated with an ACL injury. #MSKMonday

Lateral radiograph of the knee (image 1) shows an avulsion fracture (arrow) of the posterior aspect of the tibia epiphysis and a large knee effusion (arrowhead). Sagittal CT image (image 2) shows the avulsion fragment (arrow). Sagittal T2 weighted MRI (image 3) highlights the avulsion fragment (arrow) and the large hemarthrosis (arrowhead). The proton density MRI (image 4) highlights that the avulsion fracture is connected to the posterior cruciate ligament (arrow). Posterior cruciate ligament avulsion fractures are uncommon. They typically occur after motor vehicle collision. However it can also occur as a jumping injury where the individual lands on a plantarflexed foot with the knee in flexion.