By Edward J. Shahady, MD; Willis Paull, PhD; Tanya Evers; and Aarti Patel
Dr Shahady is clinical professor of family medicine at the University of Miami in Florida, an associate faculty member in the Tallahassee Memorial Hospital Family Practice Residency Program, and medical director of the Diabetes Master Clinician Program of the Florida Academy of Family Physicians Foundation in Jacksonville.
Dr Paull is professor of anatomy at Florida State University College of Medicine in Tallahassee.
Ms Evers and Ms Patel are both second-year medical students at Florida State University College of Medicine.
A 12-year-old girl complains of left knee pain and swelling that resulted from a collision with another player while she was playing kickball the day before. Her left foot was planted as she tried to catch a ball, and she was hit on the outside of the left knee. She fell to the ground and was unable to walk on the injured leg; overnight, the knee became more swollen and painful.
Flexion of the left knee is limited to 60 degrees, and there is an extension lag of 10 degrees. Results of a Lachman test are negative, but application of valgus stress to the knee produces some medial laxity and increased pain. Examination of the right leg reveals normal extension (to 0 degrees), flexion to 145 degrees, and no laxity or discomfort during a Lachman test or a valgus stress test.
What is your presumptive diagnosis at this point?
A. Sprained anterior cruciate ligament.
B. Growth plate fracture.
C. Torn medial collateral ligament.
D. Torn medial meniscus.
E. Torn posterior cruciate ligament.
(Answer and discussion on next page)