Robyn Jill Kalke MD, Presenter: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Nothing to Disclose

Adnan Mohammad Sheikh MD, Abstract Co-Author: Nothing to Disclose

Marcos Loreto Sampaio MD, Abstract Co-Author: Nothing to Disclose

Allan Liew MD, Abstract Co-Author: Nothing to Disclose

Kawan S. Rakhra MD, Abstract Co-Author: Nothing to Disclose

To evaluate the MRI pattern of soft tissue and osseous injuries in the setting of acute knee dislocations.

Eighteen patients with a known history of knee dislocation who had MRI performed within one week of injury from 2005 to 2012 were studied at 1.5T. The incidences of ACL, PCL, MCL, LCL, tendon, meniscal, contusion patterns and osseous injuries were calculated.

The incidences of full thickness (FT) and partial thickness (PT) tears of various ligaments and tendon structures were: ACL- FT 83%, PT 11%; PCL- FT 39%, PT 33%; biceps tendon- FT 22%, PT 22%; popliteus tendon- FT 11%, PT 39%. The incidence of MCL Grade 3 injury was 33%, Grade 2 injury 28%; LCL Grade 3 injury 33%, Grade 2 injury 39%, Grade 1 injury 6%. The medial and lateral menisci were torn in 56% and 50% of patients respectively. When considering complete tears of the ACL, PCL, MCL and LCL, the number of patients with all four torn was 1 (6%); with three of four, 4 patients (22%); with two of four, 9 patients (50%); and with one of four, 3 patients (17%). All patients had bone contusions. Seven patients (39%) had an ACL bone contusion pattern; 5 patients (28%) had a PCL contusion pattern; 3 patients (17%) had a MCL contusion pattern; 2 patients (12%) had a lateral patellar dislocation contusion pattern; 5 patients (28%) had a combination of bone bruises; and 7 patients (39%) had contusion patterns that did not fit one of the above types. Sixteen patients (89%) had true fractures, all impaction type.

Knee dislocation was associated with a high, but far from invariable, incidence of ACL, PCL, MCL, LCL, biceps femoris tendon, popliteus tendon, medial and lateral meniscal tears, as well as osseous fractures and contusions. Full thickness ACL tears were the most common injury, with the classic ACL contusion pattern being the most frequently seen. Most patients had full thickness tears of two out of four major stabilizing ligaments (ACL, PCL, MCL and LCL). Medial and lateral meniscal tears were roughly equal in incidence and each occurred in approximately half of patients. All patients had osseous contusions, and the majority also had impaction fractures.

Knee dislocations are considered orthopaedic emergencies, and knowledge of the patterns of soft tissue and osseous injuries may help the orthopaedic surgeon plan knee reconstruction.

Kalke, R, Schweitzer, M, Sheikh, A, Sampaio, M, Liew, A, Rakhra, K, A Pattern Approach to Injuries Seen Following Knee Dislocations.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12026189.html