5 Sports Medicine CASES

CASE                                5                               

A 24-year-old graduate student twists her knee while walking in high heels on a cobble stone street. She has an acute onset of pain and deformity. On presentation to the emergency department, she is uncomfortable and maintains her knee in a flexed position. As her leg is gradually extended, an audible “clunk” is heard, and her knee can rest flat on the stretcher. Moments later, she is able to complete a straight-leg raise.

What structure was most likely injured in her accident?

1. Medial meniscus

2. Medial patellofemoral ligament

3. Anterior cruciate ligament

4. Patellar tendon

5. Medial collateral ligament

 

Discussion

The correct answer is (B). The student sustained a patellar dislocation. With passive extension of the knee, the patella reduced causing an audible clunk. Lateral dislocations are the most common, and the medial patellofemoral ligament is injured as a result. While other intra-articular structures can be injured in twisting injuries, the restoration of function following passive leg extension makes a patella dislocation the most likely.

Radiographs of her knee reveal no fracture. If an MRI were ordered, which of the following is the least likely finding?

1. MPFL rupture

2. Bone edema on the lateral femoral condyle

3. Osteochondral injury to the medial patellar facet

4. Loose body in the medial gutter

5. Lipohemarthrosis

 

Discussion

Correct answer is “E.” In the absence of fracture, a lipohemarthrosis is unlikely. Injury to the medial patellofemoral ligament results from a lateral dislocation. As the medial facet of the patella strikes the lateral femoral condyle, a bone bruise may result along with an injury to the patellar articular cartilage. If injured, a loose piece may be found on the MRI.

After the first event, she undergoes conservative treatment. Unfortunately, she has several recurrent episodes. A CT scan reveals excessive lateralization of the tibial tuberosity. If she undergoes a reconstruction of the medial patellofemoral ligaments, what other procedure should be performed simultaneously?

1. Distal tibial tuberosity transfer

2. Trochleoplasty

3. Femoral/tibial derotational osteotomy

4. Medial tibial transfer

Discussion

The correct answer is (D). Distal tibial tuberosity transfers are indicated with patella alta. Trochleoplasty should be used to address severe trochlear dysplasia. Excessive limb rotation can be corrected with combined femoral and tibial derotational osteotomies, while lateralization of the tibial tubercle benefits from a medial tibial transfer.

 

Objectives: Did you learn...?

 

 

The signs and symptoms of MPFL injury? The imaging findings of MPFL injury?

 

The treatment of MPFL injury?