MRI Evaluation of Grade III Injury to Posterolateral Corner of the Knee
Abstract & Commentary
Synopsis: MRI imaging of the knee is accurate in anatomic identification of posterolateral corner injuries.
Source: LaPrade RF, et al. The magnetic resonance imaging appearance of individual structures of the posterolateral knee. A prospective study of normal knees and knees with surgically verified grade III injuries. Am J Sports Med 2000; 28:191-199.
Magnetic resonance imaging (mri) scans from seven uninjured and 20 patients with posterolateral corner injuries to the knee were reviewed. The injured knees were prospectively collected over two years. Seven injuries were acute (< 3 weeks from injury) and 13 chronic. A single musculoskeletal radiologist read all MRI scans. All injuries recorded by the radiologist were verified at the time of surgery. The knees were examined with a series of tests specifically for the posterolateral knee, including the posterolateral drawer, dial, varus stress, reverse pivot shift, and external rotation recurvatum tests.
The results identified specific posterolateral structures in all knees with a 90% accuracy (iliotibial band, long and short head of biceps, mid-third lateral capsular ligament, fibular collateral ligament, politeus popliteolfibular ligament, lateral gastrocnemius, and fabellofibular ligament). Excellent pictures of injured and normal anatomy were included in the article.
Comment by James R. Slauterbeck, MD
Posterolateral corner knee injuries are difficult to diagnose and to treat. MRI evaluation must be performed precisely and read by an experienced physician. This article emphasizes the need to image the entire fibular head in order to fully evaluate the posterolateral corner. Under the protocol described in the article, MRI accurately diagnosed injury 90% of the time.
So how does this anatomic study help us in our practice? In my opinion, the role of the MRI is to augment what one can identify on physical exam prior to surgery and to assist with preoperative planning. Many posterolateral corner injuries are associated with other ligament injuries and are often associated with knee dislocations. Following acute injury, it is difficult to perform a complete exam without anesthesia secondary to significant pain or associated injury. The best exam is often performed in the operating room just prior to the surgical reconstruction. MRI evaluation identifies the injured structures and defines which structures need repair. The MRI is a tool that assists the surgeon by defining which tissues need repair, which autograft tissues can be used to reconstruct major ligaments, and what allograft tissue may be needed for reconstructive procedures.
I routinely get an MRI on all multiple-ligament-injured knees to better assess the injuries prior to surgery. The MRI can fully evaluate bone bruises, which may have a role in determining ultimate outcome and may help define the weightbearing status post injury or surgery. Additionally, some patients require nonoperative management for posterolateral knee injury and the MRI can assist the surgeon on how to best brace and weightbear the patient.
This is an excellent anatomic article that defines the important anatomy for the posterolateral corner in injured and noninjured knees. It provides great pictures for comparison. I highly recommend reviewing this article and others by the lead author, LaPrade, when dealing with these difficult injuries.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content