A 30-year-old man sustained traumatic amputations of three of his left fingers while at work. A heavy object fell when a supporting chain snapped; although he moved quickly, three of his left distal fingers were caught under the object. He was flown to a hospital for definitive hand care.
During the preadmission history and physical, it was noted that the patient had mild right knee pain in addition to his finger injuries. He had experienced no head injury and no loss of consciousness or other complaints. He did not remember injuring his leg, although he said it might have been struck by the falling object; all he could remember was the injury to his fingers.
On physical exam, the only abnormality other than the man’s traumatic finger amputations was mild right knee edema and a small bruised area medially. Initially, he complained of mild pain on palpation and moderate pain with passive range of motion, but range of motion was intact. His pain was worse at the proximal, medial tibial area, and he had mild lateral mid-calf tenderness though no bruising. Distally, his right lower extremity motor and sensory function were intact, and he had no open wounds or skin breakdown. He had 2+ dorsalis pedis pulse and 1+ posterior tibial pulse. The toes were pink and warm with brisk capillary refill. All compartments were soft and compressible.
Upon review of his plain radiographs (three views of the right knee), the patient was noted to have a severely comminuted medial tibial plateau fracture that extended to the midline in the region of the tibial spine, with mild depression of the fracture fragments measuring about 6 mm (see Figures 1a, 1b, and 1c). This would translate into a Schatzker IV classification type1 fracture (see Figure 22,3).
The man was admitted and underwent emergent surgery on his injured left fingers that night. Further diagnostic knee testing was performed, including CT and MRI (see Figures 3 and 4). Three days after admission, the patient underwent open reduction and internal fixation (plating) of the right medial, proximal tibia (see Figure 5). He has done very well since without issue.
DISCUSSION
Fractures of the tibial plateau occur along the articular, or joint, surface of the proximal tibia. The plateau consists of lateral and medial condylar surfaces. These concave structures function as an articulation point for the cartilaginous menisci and the femoral condyles.4 The medial plateau and condyle are stronger than those of the lateral side, and therefore are less commonly fractured. An elevated intercondylar eminence divides the lateral and medial plateaus, providing an attachment site for the cruciate ligaments.3
The Schatzker classification system1 is most commonly used to describe the types of tibial plateau fractures (as seen in Figure 22,3). Schatzker et al1 divided these injuries into six categories, according to the impact of increased energy exerted onto the bone; the rising classification numbers indicate an increase in complexity and severity and usually a worsening prognosis.
The type I fracture represents a split fracture of the lateral plateau. Typically, a fracture of this type has depression or displacement measuring less than 4 mm.
Type II tibial plateau fractures, the most common Schatzker injury, are lateral plateau fractures with depression noted at the split. Not always evident on plain radiographs, this depression can often be overlooked, and the injury mistaken for a type I fracture. The depression is measured vertically from the lower edge of the medial plateau to the lowest depression point of the lateral plateau.5
Type III fractures, the least common among the Schatzker injuries, are described as pure depression fractures of the lateral plateau. These fractures do not have an appreciable “split” along the plateau and are usually found in older patients with osteopenia.2
The Schatzker type IV injury is a medial fracture with displacement or depression to a portion of the plateau. The fracture may be split or comminuted and may originate in the intercondylar area.
Type V fractures, also known as “bicondylar fractures,” affect both the lateral and medial plateau. An inverted “Y” pattern is frequently seen, and there may be additional involvement of the intercondylar eminence. Type V fractures differ from type VI injuries in that there is no disturbance of the metaphyseal-diaphyseal connection. Thus, type VI fractures also include a transverse component that separates the condyles (metaphysis) of the bone from the shaft (diaphysis). Wide variation is seen among type VI fractures.5
Assessment and Diagnosis
Originally termed “fender fractures” due to their frequent association with automobile injuries, fractures of the tibial plateau account for 1% of all fractures and 8% of fractures in elderly patients.6 Tibial plateau fractures occur when varus or valgus force is combined with axial loading. The fracture itself occurs when the femoral condyle is driven into the lateral or medial plateau. Bicondylar injuries occur when rigorous axial force is sustained in a fully extended knee.