TIBIAL PLATEAU Fractures

EPIDEMIOLOGY

Tibial plateau fractures constitute 1% of all fractures and 8% of fractures in the elderly.

Isolated injuries to the lateral plateau account for 55% to 70% of tibial plateau fractures, as compared with 10% to 25% isolated medial plateau fractures and 10% to 30% bicondylar lesions.

From 1% to 3% of these fractures are open injuries.

ANATOMY

The tibial plateau is composed of the articular surfaces of the medial and lateral tibial plateaus, on which are the cartilaginous menisci. The medial plateau is larger and is concave in both the sagittal and coronal axes. The lateral plateau extends higher and is convex in both sagittal and coronal planes.

The normal tibial plateau has a 10-degree posteroinferior slope.

The two plateaus are separated from one another by the intercondylar eminence, which is nonarticular and serves as the tibial attachment of the cruciate ligaments. Three bony prominences exist 2 to 3 cm distal to the tibial plateau. Anteriorly is the tibial tubercle on which the patellar ligament inserts. Medially, the pes anserinus serves as attachment for the medial hamstrings. Laterally, the Gerdy tubercle is the insertion site of the iliotibial band.

The medial articular surface and its supporting medial condyle are stronger than their lateral counterparts. As a result, fractures of the lateral plateau are more common.

Medial plateau fractures are associated with higher energy injury and more commonly have associated soft tissue injuries, such as disruptions of the lateral collateral ligament complex, lesions of the peroneal nerve, and damage to the popliteal vessels.

MECHANISM OF INJURY

Fractures of the tibial plateau occur in the setting of varus or valgus forces coupled with axial loading. Motor vehicle accidents account for the majority of these fractures in younger individuals, but elderly patients with osteopenic bone may experience these after a simple fall.

The direction and magnitude of the generated force, age of the patient, bone quality, and amount of knee flexion at the moment of impact determine fracture fragment size, location, and displacement.

• Young adults with strong, rigid bone typically develop split fractures and have a higher rate of associated ligamentous disruption.

• Older adults with decreased bone strength and rigidity sustain depression and split-depression

  fractures and have a lower rate of ligamentous injury.

• A bicondylar split fracture results from a combination of forces.

   

  CLINICAL EVALUATION

Neurovascular examination is essential, especially with high-energy trauma. The trifurcation of the popliteal artery is tethered posteriorly between the adductor hiatus proximally and the soleus complex distally. The peroneal nerve is tethered laterally as it courses around the fibular neck.

Hemarthrosis frequently occurs in the setting of a markedly swollen, painful knee on which the patient is unable to bear weight. Knee aspiration may reveal marrow fat.

Direct trauma is usually evident on examination of the overlying soft tissues, and open injuries must be ruled out. Intra-articular instillation of more than 120 cc of saline may be necessary to evaluate possible communication with overlying lacerations.

Compartment syndrome must be ruled out, particularly with higher energy injuries and/or fracture-dislocations.

Assessment for ligament injury is essential.

ASSOCIATED INJURIES

Soft tissue injury is seen in approximately 90% of these fractures.

Meniscal tears occur in up to 50% of tibial plateau fractures. Medial meniscus tears are highly associated with medial plateau fractures and lateral meniscus tears are associated with lateral tibial plateau fractures.

Associated ligamentous injury to the cruciate or collateral ligaments occurs in up to 30% of tibial plateau fractures.

Young adults, whose strong subchondral bone resists depression, are at the highest risk of collateral or cruciate ligament rupture.

Fractures involving the medial tibial plateau may be associated with higher incidences of peroneal nerve or popliteal neurovascular lesions owing to higher energy mechanisms; it is postulated that many of these represent knee dislocations that spontaneously reduced.

Peroneal nerve injuries are caused by stretching (neurapraxia); these will usually resolve over time; however, these are rare.

Arterial injuries frequently represent traction-induced intimal injuries presenting as thrombosis; only rarely do they present as transection injuries secondary to laceration or avulsion.

RADIOGRAPHIC EVALUATION

Anteroposterior and lateral views supplemented by 40-degree internal (lateral plateau) and external rotation (medial plateau) oblique projections should be obtained.

A 5- to 10-degree caudally tilted plateau view can be used to assess articular step-off.

Avulsion of the fibular head, the Segond sign (lateral capsular avulsion) and Pellegrini–Stieda lesion (calcification along the insertion of the medial collateral ligament seen late) are all signs of associated ligamentous injury.

A physician-assisted traction view is often helpful in higher energy injuries with severe impaction and metadiaphyseal fragmentation to delineate the fracture pattern better and to determine the efficacy of ligamentotaxis for fracture reduction.

Stress views, preferably with the patient under sedation or anesthesia and with fluoroscopic image intensification, are occasionally useful for the detection of collateral ligament ruptures (Fig. 36.1).

Computed tomography with two-dimensional or three-dimensional reconstruction is useful for delineating the degree of fragmentation or depression of the articular surface, as well as for preoperative planning.

Magnetic resonance imaging is useful for evaluating injuries to the menisci, the cruciate and collateral ligaments, and the soft tissue envelope.

Arteriography should be performed if there is a question of vascular compromise (see Chapter 34).

CLASSIFICATION

Schatzker (Fig. 36.2)

Type I: Lateral plateau, split fracture (Fig. 36.2A)

Type II: Lateral plateau, split depression fracture (most common) (Fig. 36.2B)

Type III: Lateral plateau, depression fracture (Fig. 36.2C)

Type IV: Medial plateau fracture (Fig. 36.2D)

Type V: Bicondylar plateau fracture (Fig. 36.2E)

Type VI: Plateau fracture with separation of the metaphysis from the diaphysis (Fig. 36.2F)

Types I to III are low-energy injuries.

Types IV to VI are high-energy injuries.

Type I usually occurs in younger individuals and is associated with medial collateral ligament injuries.

Type III is usually extremely rare and will only occur in older individuals or those with osteopenia (Fig. 36.2).

Moore (Fig. 36.3)

Type 1 is a split fracture of the medial tibial plateau in the coronal plane.

Type 2 is an entire condyle fracture with the fracture line beginning in the opposite compartment and extending across the tibial eminence.

Type 3 is a rim avulsion fracture; these fractures are associated with a high rate of associated neurovascular injury.

Type 4 is another type of rim fracture, a rim compression injury usually associated with some types of contralateral ligamentous injury.

Type 5 is a four-part fracture with the tibial eminence separated from the tibial condyles and the shaft.

Orthopaedic Trauma Association Classification of Tibial Plateau Fractures (Type 43)

See Fracture and Dislocation Classification Compendium at http://www.ota.org/compendium/compendium.html.

TREATMENT

Nonoperative

This is indicated for nondisplaced or minimally displaced fractures and in patients with advanced osteoporosis.

Protected weight bearing and early range of knee motion in a hinged fracture brace are recommended.

Isometric quadriceps exercises and progressive passive, active-assisted, and active range-of-knee motion exercises are indicated.

Partial weight bearing (30 to 50 lb) for 8 to 12 weeks is allowed, with progression to full weight bearing.

Operative

Surgical indications

• The reported range of articular depression that can be accepted varies from >2 mm to 1 cm.

• Instability >10 degrees of the nearly extended knee compared to the contralateral side is an accepted surgical indication. Split fractures are more likely to be unstable than pure depression

  fractures in which the rim is intact (see Fig. 36.1).

• Open fractures

• Associated compartment syndrome

• Associated vascular injury

Operative treatment principles

• Reconstruction of the articular surface, followed by reestablishment of tibial alignment, is the goal.

• Treatment involves reducing and buttressing of elevated articular segments with bone graft or

  bone graft substitute.

• Fracture fixation can involve use of plates and screws, screws alone, or external fixation.

• The choice of implant is related to the fracture patterns, the degree of displacement, and familiarity of the surgeon with the procedure.

• Adequate soft tissue reconstruction including preservation and/or repair of the meniscus as well

  as intra-articular and extra-articular ligamentous structures should be addressed.

Spanning external fixation across the knee may be used as a temporizing measure in patients with higher energy injuries and limb shortening or significant soft tissue injury. The external fixator is used to keep the soft tissues out to length and provides some degree of fracture reduction until definitive surgery.

Arthroscopy may be used to evaluate the articular surfaces, the menisci, and the cruciate ligaments. It may also be used for evacuation of hemarthrosis and particulate debris, for meniscal procedures, and for arthroscopic-assisted reduction and fixation. Its role in the evaluation of rim disorders and its utility in the management of complicated fractures are limited (Fig. 36.4).

An avulsed anterior cruciate ligament with a large bony fragment may be repaired. If the fragment is minimal or the ligament has an intrasubstance tear, reconstruction should be delayed. Instability is generally not a problem in patients following tibial plateau fracture.

Surgery in isolated injuries may proceed after a full appreciation of the “personality” of the fracture. This delay will also allow swelling to subside and local skin conditions to improve.

Schatzker types I to IV fractures can be fixed with percutaneous screws or a laterally placed periarticular plate. If satisfactory closed reduction (<1-mm articular step-off) cannot be achieved with closed techniques, open reduction and internal fixation are indicated.

The menisci should never be excised to facilitate exposure.

Depressed fragments can be elevated from below en masse by using a bone tamp working through the split component or a cortical window. The metaphyseal defect should be filled with some type of osteoconductive material to support elevated fragments.

Types V and VI fractures can be managed using plate and screws, a ring fixator, or a hybrid fixator. When external fixation is used, limited internal fixation can be added to restore the articular surface.

Percutaneous inserted plating, which is a more biologic approach, has been described. In this technique, the plate is slid subcutaneously without soft tissue stripping.

Use of locked plates has diminished the need for double plating some bicondylar tibial plateau fractures.

Fractures of the posterior medial plateau may require a posteromedial incision for fracture reduction and plate stabilization.

Postoperative care: Patients are kept non–weight bearing with or without continuous passive motion, and active range of motion is encouraged.

Weight bearing is allowed at 8 to 12 weeks.

COMPLICATIONS

Arthrofibrosis: This is common. It is related to trauma from injury and surgical dissection, extensor retinacular injury, scarring, and postoperative immobility. It is more common in higher energy injuries.

Infection: This is often related to ill-timed incisions through compromised soft tissues with extensive dissection for implant placement.

Compartment syndrome: This uncommon but devastating complication involves the tight fascial compartments of the leg. It emphasizes the need for high clinical suspicion, serial neurovascular examinations, particularly in the unconscious or obtunded patient, aggressive evaluation, including compartment pressure measuring if necessary, and expedient treatment consisting of emergency fasciotomies of all compartments of the leg.

Malunion or nonunion: This is most common in Schatzker VI fractures at the metaphyseal–diaphyseal junction, related to comminution, unstable fixation, implant failure, or infection.

Posttraumatic osteoarthritis: This may result from residual articular incongruity, chondral damage at the time of injury, or malalignment of the mechanical axis.

Peroneal nerve injury: This is most common with trauma to the lateral aspect of the leg where the peroneal nerve courses in proximity to the fibular head and lateral tibial plateau. It can be iatrogenic.

Popliteal artery injury: This is rare.

Avascular necrosis of small articular fragments: This may result in loose bodies within the knee.