IS Case 145: Schatzker III Tibial Plateau Fracture with Lipohemarthrosis

Jacinto Camarena III, MD


Imaging Sciences URMC 2008
Publication Date: 2009-05-21

History

A 31-year-old restrained front passenger was involved in a 45 mile per hour head on motor vehicle collision and sustained trauma to the right knee. The patient’s airbag was deployed.

Findings

Initial radiographs of the right knee demonstrated asymmetric increased density of the lateral tibial condyle at the level of the plateau (Fig. 1) with suprapatellar fat-fluid and hematocrit levels (Fig. 2). Subsequent MRI confirms a lateral tibial plateau depression fracture (Fig. 3) and large lipohemarthrosis (Fig. 4).

Diagnosis

Schatzker III Tibial Plateau Fracture with Lipohemarthrosis

Discussion

When a suprapatellar fat-fluid level is the only finding appreciated on radiographs, a diligent search for a subtle distal femoral or tibial plateau injury should follow. It has been shown that lipohemarthrosis is virtually always associated with an intra-articular fracture. Extrusion of marrow fat and blood into the joint space may settle to form fat-fluid layers visible on various radiologic imaging. Utilizing proton density MRI (Fig. 4), the fat layer floats to the top and demonstrates high-signal intensity (arrowhead) while the hemorrhagic layer may separate into low-signal serum (white arrow) and intermediate-signal cellular components (black arrow). Tibial plateau fractures are most often accompanied by hemarthrosis.

The mechanism of tibial plateau injury may involve laterally directed forces, twisting stresses and most commonly axial loading. The lateral plateau is more commonly fractured due to mechanics of the knee and the strength of the medial plateau. Ligamentous, meniscal, peroneal nerve and popliteal artery injuries may be associated.

The Schatzker classification may be used to categorize tibial plateau fractures as follows: Type I is a split fracture involving the lateral plateau; Type II is a combined split and depression fracture involving the lateral plateau; Type III is a depression fracture involving the lateral plateau; Type IV is a fracture involving the medial plateau; Type V involves both medial and lateral plateaus (bicondylar); Type VI consists of a plateau fracture and a transverse or oblique fracture of the proximal tibia such that separation of the metaphysis from the diaphysis occurs.

References

  1. Barrow BA, Fajman WA, Parker LM, et al. Tibial plateau fractures: evaluation with MR imaging. Radiographics. 1994 May;14(3):553-9. [PMID: 8066271]
  2. Lee JH, Weissman BN, Nikpoor N, Aliabadi P, Sosman JL. Lipohemarthrosis of the Knee: A Review of Recent Experiences. Radiology. 1989 Oct;173(1):189-91. [PMID: 2781006]
  3. # Sorenson SM, Gentili A, Masih S. Tibial plateau fractures. Emedicine, Jan 24, 2007. http://emedicine.medscape.com/article/396920-overview

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