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Figure. Coronal MRI of injured medial collateral ligament.
A 26-year-old man presents with a 1-week history of left knee pain and instability. The injury occurred during a soccer game when an opponent collided with the outside of the patient’s knee. He reports having immediate pain and swelling. He went to an urgent care center where radiographs of the left knee were taken and deemed unremarkable for an acute injury. Magnetic resonance imaging was subsequently ordered, which shows a grade 3 medial collateral ligament sprain with pes anserinus tendon entrapment causing a Stener-like lesion (Figure ).
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The medial collateral ligament (MCL) is the most commonly injured ligament in the knee.1 The MCL is typically injured during athletic activities where the knee is struck from the side or is externally rotated, causing a valgus load to the knee.1,2
Physical examination findings include increased laxity to the MCL with valgus stress at 20° and 30°.2 Comparing knee laxity to the contralateral knee is required to accurately measure an acute MCL injury. Grade 1 MCL injury is less than 5 mm of medial joint line opening in 30° flexion with a firm endpoint, grade 2 is 5 to 10 mm with a firm endpoint, and grade 3 is more than 10 mm with no endpoint to valgus stress.1-3
Grade 1 and 2 injuries should be treated with a hinged knee brace, weight-bearing as tolerated, and physical therapy.1 Treatment of grade 3 injuries remains controversial.1,2 Midsubstance tears have an improved healing rate compared with MCL injuries that avulse off the bone.3 An indication for surgery includes a complete tibial-sided MCL tear with pes anserine entrapment as seen in this patient. The patients’ pes anserine is displacing the distal MCL and preventing contact of the tendon from its native bony insertion, which prevents healing. Surgical repair can be achieved by retracting the pes tendons off the MCL insertion site so the MCL can be tied down with suture anchors.3 If the tendon is no longer viable for a tendon to bone repair, a reconstruction with allograft may be required.1-3
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
References
1. Miyamoto RG, Bosco JA, Sherman OH. Treatment of medial collateral ligament injuries. J Am Acad Orthop Surg. 2009;17(3):152-161. doi:10.5435/00124635-200903000-00004
2. Wijdicks CA, Griffith CJ, Johansen S, Engebretsen L, LaPrade RF. Injuries to the medial collateral ligament and associated medial structures of the knee. J Bone Joint Surg Am. 2010;92(5):1266-1280. doi:10.2106/JBJS.I.01229
3. Corten K, Hoser C, Fink C, Bellemans J. Case reports: a Stener-like lesion of the medial collateral ligament of the knee. Clin Orthop Relat Res. 2010;468(1):289-293. doi:10.1007/s11999-009-0992-6
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