A 16-year-old gymnast presents to the emergency department after sustaining a right knee injury during a floor routine. She states that she landed awkwardly with her foot planted, her knee slightly flexed, and her torso rotating internally. She felt a popping sensation followed by immediate, severe pain and a sensation that her "kneecap moved out of place." On physical examination, the right knee is held in slight flexion. There is a prominent deformity noted over the lateral aspect of the knee joint. There is significant tenderness along the medial border of the patella and a moderate joint effusion.
Which of the following is the most appropriate next step in the management of this patient?
The correct answer is:
B) Closed reduction via medial pressure on the patella with knee extension
This patient has a classic presentation of an acute patellar dislocation. This injury typically occurs in young athletes due to a non-contact twisting motion (internal rotation of the femur on a fixed foot and flexed tibia) or direct trauma. The patella almost always dislocates laterally due to the natural lateral pull of the quadriceps muscle. The first step in management for an acute dislocation is closed reduction. This is performed by applying gentle medially-directed pressure on the lateral aspect of the patella while simultaneously and slowly extending the knee. This maneuver often results in an immediate reduction and significant relief of pain.
Answer choice A: Application of a knee immobilizer and referral to outpatient orthopedics, is incorrect. While immobilization and follow-up are part of the post-reduction care, the dislocation must be reduced acutely to prevent further chondral damage and alleviate pain.
Answer choice C: Emergent magnetic resonance imaging (MRI) of the knee, is incorrect. While MRI is often performed eventually to assess for associated injuries like medial patellofemoral ligament (MPFL) tears or osteochondral fractures, it is not the immediate next step. Reduction should precede advanced imaging.
Answer choice D: Immediate open surgical stabilization, is incorrect. The majority of first-time, uncomplicated patellar dislocations are managed non-operatively with reduction and physical therapy. Surgery is generally reserved for patients with recurrent dislocations or significant associated intra-articular fractures.
Answer choice E: Weight-bearing as tolerated with a hinged knee brace, is incorrect. This is part of the rehabilitation process after the patella has been successfully reduced and the initial period of acute inflammation has subsided.
Key Learning Point
Patellar dislocation most commonly occurs laterally in young, active individuals. The diagnosis is clinical, often characterized by a lateral deformity and tenderness over the medial patellofemoral ligament. The most appropriate initial management is closed reduction using medial patellar pressure while extending the leg, followed by immobilization and physical therapy.
