How do posterolateral corner injuries occur?
As well, a noncontact injury in which the knee hyperextends and the tibia twists outward may tear these tissues. High-energy trauma, such as that sustained in a motor vehicle accident, is another common cause of PLC injury.
Assessing the integrity of the posterolateral corner
At my Center, we do the following:
First, we take a thorough history, carefully determining to the best of the patient’s ability how the injury occurred, if swelling was noted immediately, if walking was tolerated, and other factors.
Then we examine:
- the patellofemoral joint
ie. how far the kneecap moves side-to-side, crepitus on movement, pain
- tibiofemoral crepitus, joint line pain, compression pain
- varus recurvatum, standing and lying down
ie. knee joint bowing outwards and hyperextendable, that is bending backwards
- gait, or walking pattern (looking for severe hyperextension on walking)
We perform all ligament tests:
Reverse pivot shift for PLC
- Lachman, pivot shift tests for ACL
- posterior drawer, 90° flexion for PCL
- KT-2000 20° flexion, 134 N for ACL
[This article was published in Noyes’ Knee Disorders: Surgery, Rehabilitation, Clinical Outcomes, Noyes FR, Barber-Westin SD (eds.), Copyright Saunders, 2009 - Noyes FR, Barber-Westin SD: Primary, double, and triple varus knee syndromes: Diagnosis, osteotomy techniques, and clinical outcomes, pages 821-895.]
We order imaging:
- Lateral, 30° flexion
- Posteroanterior, weight bearing, 45° flexion
- Patellofemoral axial
- Lateral stress, neutral tibial rotation
- For PCL ruptures: posterior stress
- Varus malalignment (see Figure on right): Full standing radiographs, mechanical axis and weight bearing line
For dislocated knees, a lower extremity venous ultrasound is obtained in knees that have swelling and soft tissue damage. An initial delay before any surgery is considered for 5 to 7 days to allow for observation of the neurovascular status, soft tissue swelling, skin integrity, and some clearing of hemorrhage in soft tissues in the injured extremity.
The treatment of these injuries depends on the degree of damage. First and second degree injuries do not require surgery, but are treatment with rehabilitation and bracing in some cases, as discussed in Part 4. The third degree injury patterns require much more extensive treatment, as I will discuss in Parts 4 and 5.