Case 14
History:
15 year old female with left knee injury secondary to sport injury
Findings:
Knee MRI showing bone marrow edema in the medial patellar facet and lateral femoral condyle with joint effusion. There is thickening of the medial patellar retinaculum.
Diagnosis:
Transient Lateral Patellar Dislocation (TLPD)
Discussion:
Transient Lateral Patellar Dislocation (TLPD) is seen in 2-3% of all knee injuries and commonly occurs in athletes. Most occur in teenagers and young adults. More than 50% of these injuries are not initially clinically diagnosed. TLPD is reported to be associated with medial meniscal tear or major ligamentous injury in 31% of cases.
The medial patellar retinaculum, often will show increased signal intensity, thickening, or disruption resulting in a residual patellar tilt is often seen secondary to damage to the medial retinaculum. Associated osteochondral injuries should also be evaluated.
Patients frequently respond to conservative rehabilitation measures, with nonoperative treatment resulting in good or excellent results in up to 75% of patients with no congenital abnormality of the extensor mechanism.
References:
- Kirsch MD, Fitzgerald SW, Friedman H, Rogers LF. Transient lateral patellar dislocation: diagnosis with MR imaging. AJR Am J Roentgenol 1993; 161:109-113.
- General Case of the Day, WR Corse, DJ Flemming, and AC Brower, Radiographics 1994; 14:449-451.
