In a case of a knee injury with a 'step and twist' mechanism, what is the most likely diagnosis?

• A. ACL Tear
• B. Medial Meniscal Tear
• C. Patellar Tendinitis
• D. Collateral Ligament Injury

Answer: (B)

The mechanism of injury described as a 'step and twist' is commonly associated with a tear in the meniscus, particularly the medial meniscus. When the knee undergoes a twisting motion while bearing weight, it places significant stress on the menisci, which act as shock absorbers and stabilize the knee joint.

A medial meniscal tear often occurs during activities that involve pivoting or sudden changes in direction, making this mechanism a classic presentation for such an injury. The medial meniscus has a relatively limited blood supply and is more prone to injury due to its anatomical positioning and the stress it experiences during dynamic movements.

While an ACL tear can also occur with similar mechanisms, the specific action of 'stepping and twisting' places more focus on the meniscus. Patients with a medial meniscal tear might present with joint line tenderness, swelling, and mechanical symptoms like locking or catching during knee motion, which aligns well with the described mechanism of injury.

This understanding aids in differentiating injuries based on the mechanism and presentation, which is crucial for accurate diagnosis and management in orthopedic practice.