Intercondylar Eminence Fractures 

Background

Fractures of the tibial intercondylar eminence (see images below) are observed mostly in children and adolescents, often after minimal trauma; good results are expected with treatment by anatomic reduction.

Although adults also can sustain this type of injury, they will often have additional concurrent knee trauma and, despite anatomic reduction, frequently do poorly.

In 1875, Poncet first described intercondylar eminence fractures. In 1959, Meyers and McKeever surgically addressed only type III fractures.^[1] Since then, techniques have improved and awareness of the importance of anterior cruciate ligament (ACL) integrity has increased. Currently, many authorities recommend anatomic reduction and fixation for fractures displaced to any noticeable degree, including type II fractures.

The Meyers and McKeever classification system in use today is as follows (see image below):

• Type I - Minimal displacement of the avulsed fragment, with excellent bony apposition
• Type II - Displacement of the anterior third or half of the affected bone (with intact posterior hinge), with a beaklike deformity appearing on the lateral radiograph
• Type III - Fragment of bone completely separated from its bone bed in the intercondylar eminence, without bony apposition

Zaricznyj proposed another category, type IV fractures (displacement with a comminuted avulsed fragment).^[2]

Frequency

Determining the exact frequency of intercondylar eminence fractures is difficult. The occurrence of these injuries was initially believed to be rare; however, the incidence appears to be rising, possibly due in part to a greater awareness of the condition among physicians. It may also be related to an increase in sporting activities in early adolescence.

Intercondylar eminence fractures in skeletally immature patients usually result from injuries that would cause ACL tears in skeletally mature patients. Meyers and McKeever reported that a large number of bicycle falls produce this type of injury in children. However, intercondylar eminence fractures can be caused by a spectrum of sporting activities and by motor vehicle accidents.

Anterior displacement of the tibia on the femur (often with a rotational component) leads to stress through the ACL, which causes failure at the incompletely ossified tibial eminence before the ligament itself fails. Some controversy exists as to whether microtearing of the ACL is associated with an intercondylar eminence fracture and results in ACL laxity despite anatomic fixation of the fracture.^[3]

Intercondylar eminence fractures can extend into either of the articular tibial plateaus. Associated meniscal or ligamentous injuries, such as a medial collateral ligament tear, also are possible. These types of complicating injuries are more often observed in adults, who frequently sustain higher-energy trauma (ie, injuries involving a large amount of kinetic energy, such as those suffered in motor vehicle accidents).

Patients with intercondylar eminence fractures present with knee pain and often the inability to bear weight. An effusion caused by the hemarthrosis is present. Although patients may keep the knee in a fixed position, range of motion of the knee should be possible once pain is controlled. The presence of a locked knee (usually determined upon examination under anesthesia) should alert the surgeon to the presence of concomitant knee pathology (eg, a meniscus tear) or to an incomplete reduction of the fracture because of an interposed meniscus or a transverse intermeniscal ligament. Neurovascular status should not be affected, and the skin should be intact.

Although it is difficult to choose a clearly superior treatment option for intercondylar eminence fractures, most sources agree that significantly displaced intercondylar eminence fractures (including type II fractures) require anatomic reduction and fixation and that closed reduction is rarely effective. Arthroscopic reduction causes less morbidity than open reduction and internal fixation.

The choice of fixation for intercondylar eminence fractures is still debated. Meyers and McKeever used sutures to tack the bone fragment onto the anterior horn of the medial meniscus. Zaricznyj reported the use of multiple Kirschner wires (K-wires). Others have reported good results with cannulated screw fixation, which is usually the fixation chosen for such injuries in adults. In skeletally immature patients, screw fixation is secure but may require hardware removal. Whether via open, mini-open, or arthroscopic approach, suture fixation does provide secure fixation but may limit the speed of rehabilitation.

The tibial eminence consists of the eminent confluence of the tibial plateaus and contains 2 spines. The medial spine serves as the attachment of the ACL. The ACL, which has a broad insertion onto the tibial eminence, fans out and coalesces with the attaching fibers of the anterior horn of the medial meniscus anteriorly and the anterior horn of the lateral meniscus posteriorly. These meniscal attachments or the transverse intermeniscal ligament may be interposed between the fracture and its bed, thereby blocking a reduction, although this is controversial.^{[4, 5]}

No true contraindications exist for surgical fixation of intercondylar eminence fractures except for contraindications to surgery in general that relate to systemic medical issues.