Abstract:
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Purpose: To recognize posterior joint capsule edema as a secondary sign of injury of the posterolateral stabilizers and cruciates of the knee.
Methods and Materials: Reports of 572 consecutive knee MR examinations for 18 month period were retrospectively reviewed. Cases imaged more than 3 months after injury or for tumor or infection were excluded. Imaging was performed using 1.5 T magnet, and T1-spin echo,T2-FSE fat saturated sequences. 111 MR imaging exams with posterior joint capsule edema were then retrospectively reviewed for the characterization of extent of edema and for ligament and tendon injury. Posterior joint capsule signal abnormality was assessed on sagittal and axial images and characterized as Grade 1 if the signal did not extend to the PCL's femoral attachment site. Grade 2 signal was defined as extension between the PCL's femoral attachment site and the gastrocnemius muscle attachment. Grade 3 signal extended proximal to the gastrocnemius attachment site to the level of distal femoral diaphysis. Partial or full thickness tears of the anterior and posterior cruciate ligaments, medial and lateral collateral ligament complex and popliteus tendon were assessed. Arthroscopic or surgical reports were reviewed to confirm the tendon, ligamentous injuries.
Results: Grade 1 signal was present in patients with isolated rupture of the ACL (n=28), PCL (n=5) or combined ACL and PCL partial tears (n=3). Grade 2 signal was present with ruptured ACLs and PCLs (n=4), complete tears of lateleral collateral ligament (n=11), biceps femoris tendon (n=6), popliteus tendon (n=4), rupture of ACL or PCL with partial tear of at least one posterolateral ligament or tendon (n=12) and partial tear of ACL or PCL with full thickness tear of at least one posterolateral ligament or tendon(n=16). Grade 3 signal was present with rupture of the ACL or PCL with full thickness tear of at least one posterolateral tendon or ligament(n=22). There were no cases of isolated MCL injury that had associated posterior capsule edema.
Conclusion: Posterior joint capsule edema is a secondary sign of combination injuries of one or both cruciate ligaments and posterolateral ligaments. The greater the extent of edema, the greater the extent of injury to cruciates and posterolateral stabilizers.
Kaushik MD, S,
Posterior Joint Capsule Edema: A Secondary Sign of Injury of Cruciate Ligaments and Posterolateral Stabilizers. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108491.html
