Medial femoral condyle fracture associated with lipohemarthrosis and lateral patellar dislocation
Presentation
Motorcycle accident.
Patient Data
Medial femoral condyle fracture and lipohemarthrosis.
Lytic well-defined eccentric bone lesion located in the distal femoral epiphysis, measuring up to 3.0 cm, sharply defined margins, with apparently internal arch calcifications, and no periosteal reaction. Features are those of a nonaggressive bone tumor.
Right knee CT
Medial femoral condyle fracture associated with lipohemarthrosis. Diffuse subcutaneous edema.
Right knee MRI
There is an undisplaced longitudinal irregular fracture line through the medial femoral condyle and associated with bone marrow edema. Large lipohemarthrosis.
The medial patellar retinaculum is torn and the patella mildly lateral displaced.
Medial collateral ligament is normal.
Adductor tendon is normal but there is injury to the VMO. The menisci are intact. Anterior cruciate ligament is intact. The posterior cruciate ligament is intact. Collateral ligaments are intact.
Posterolateral ligaments are preserved.
The quadricipital tendon and patellar ligament are preserved.
Diffuse soft tissue edema.
Dash line delineating the levels between the hemarthrosis and the lipidic content (blue star), on the MRI it is possible also to note the dependent layering of the cellular component of the hemarthrosis (red star).
Case Discussion
Traffic accidents involving motorcycles can produce a variety of musculoskeletal injuries, sometimes with no clear mechanism of injury.
This case demonstrates a nondisplaced fracture involving the medial femoral condyle associated with a torn medial patellar retinaculum and injured vastus medialis, which together cause a lateral patellar dislocation. Prominent lipohemarthrosis is present and seen in all the images (X-ray, CT, and MRI).