Author: Joseph Friedli, MD
Co Author #1: Tyler K. Drewry, MD CAQSM
Co Author #2: Nobin Kottukapally, MD
Senior Editor: Carolyn Landsberg, MD

Patient Presentation:
A 32-year-old male presented for evaluation of right knee pain.

History:
One week prior to presentation, he planted his right leg while getting onto his motorcycle and felt his right shin laterally dislocate as he turned his torso. He immediately felt a pop that was audible to his friend nearby. The patient reported he reduced his dislocated shin by himself by extending his leg manually with his hands. Since this atraumatic injury, he has been unable to fully extend or flex his right knee. He reported significant pain and swelling. He took ibuprofen and applied ice to his knee without improvement. He was given crutches and referred to a Sports Medicine specialist. Of note, he had a similar injury to his right knee 8 years prior and continued to occasionally feel unstable on his right leg with ambulation.

Physical Exam:
Examination revealed a well-developed adult male, not in acute distress. Vital signs were within normal limits. Inspection of his right knee showed mild suprapatellar swelling without erythema or discoloration. Upon palpation of his right knee, there was tenderness along the medial joint line, medial facet of the patella, and medial femoral condyle. Range of motion was limited to 90 degrees of flexion, and he was unable to fully extend his knee due to pain. Strength was 4/5 for both quadriceps and hamstrings. Sensation and distal pulses were normal. Lachman's and Lelli's maneuvers were equivocal. Patellar apprehension and valgus stress were both positive.

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