Intercondylar Eminence Fractures


Background

Intercondylar eminence fractures were first described by Poncet in 1875. In 1959, Meyers and McKeever surgically addressed only type III fractures (see Classification below). [1Since 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.

Fractures of the tibial intercondylar eminence 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.

The future of surgical management of displaced intercondylar eminence fractures is the arthroscopic approach. As arthroscopic skills advance, the need for an arthrotomy to fix these types of fractures will decrease. Another future direction is the use of bioabsorbable implants for fixation of such injuries, which would provide rigid fixation but eliminate the need for hardware removal.

Classification

Intercondylar eminence fractures are commonly classifed according to the Meyers and McKeever classification system (see the image below) as follows:

  • 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
Meyers and McKeever classification of type I, II, Meyers and McKeever classification of type I, II, and III intercondylar eminence fracture injuries.

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

Anatomy

The tibial eminence consists of the eminent confluence of the tibial plateaus and contains two 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, though this is controversial. [34]

Pathophysiology

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. [5]

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 sustained in motor vehicle accidents).

Etiology

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. [1However, intercondylar eminence fractures can be caused by a spectrum of sporting activities and by motor vehicle accidents.

Epidemiology

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

Prognosis

Most studies report good results from the use of open or arthroscopic reduction and fixation of displaced intercondylar eminence fractures, or, in the case of minimal displacement, from the employment of closed treatment. [6Although some studies have demonstrated an increased treatment-related ACL laxity by objective measures, these results do not correlate with patients' symptoms.


History and Physical Examination

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.



Imaging Studies

Plain radiography

Plain radiography of the knee usually suffices for diagnosis of intercondylar eminence fractures. Although the anteroposterior view typically underrepresents the degree of comminution and displacement, the lateral view provides sufficient information. (See the images below.)

Tunnel view of intercondylar eminence fracture. Tunnel view of intercondylar eminence fracture.
Anteroposterior radiograph of intercondylar eminenAnteroposterior radiograph of intercondylar eminence fracture.

Computed tomography

Computed tomography (CT) usually is not necessary in skeletally immature patients unless the fracture is highly comminuted or extends into the weightbearing plateaus. CT is indicated for all adult patients to evaluate the integrity of the plateaus. (See the images below.)

Sagittal computed tomography scan of an intercondySagittal computed tomography scan of an intercondylar eminence fracture.
Sagittal computed tomography scan of an intercondySagittal computed tomography scan of an intercondylar eminence fracture.
Coronal computed tomography scan of an intercondylCoronal computed tomography scan of an intercondylar eminence fracture.
Coronal computed tomography scan of an intercondylCoronal computed tomography scan of an intercondylar eminence fracture.

Magnetic resonance imaging

Magnetic resonance imaging (MRI) usually is not necessary unless concomitant ligamentous or meniscal pathology is suspected.


Approach Considerations

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 with internal fixation (ORIF) does. The choice of fixation for intercondylar eminence fractures is still debated (see Surgical Therapy, below).

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

Medical Therapy

Most authors recommend aspiration of the hemarthrosis and casting for nondisplaced type I intercondylar eminence fractures. This is also the initial management used for displaced fractures. The position of immobilization is controversial. Initially, it was thought that the immobilization should be in full extension so that the fracture fragment is reduced by condylar contact. However, because full extension is the tightest position for the ACL, this method may result in increased tension and displacement at the fracture site.

Surgical Therapy

Although most authors agree that displaced intercondylar eminence fractures must be repaired, the choice of fixation is still debated. Meyers and McKeever used sutures to tack the fragment onto the anterior horn of the medial meniscus. [1Zaricznyj reported the use of multiple Kirschner wires (K-wires). [2Others reported good results with cannulated screw fixation, which is the method usually chosen for adults; in skeletally immature patients, screw fixation is secure but may require hardware removal. [78]

Sawyer et al described an approach to tibial intercondylar eminence fractures that makes use of arthroscopic suture bridge fixation. [9Whether via an open, a mini-open, or an arthroscopic approach, suture fixation does provide secure fixation but may limit the speed of rehabilitation. [1011121314151617]

Keshet et al reported good results with the use of a small medial parapatellar approach with open reduction and percutaneous cross K-wire fixation in eight children with Meyers and McKeever type III avulsion fracture of the intercondylar eminence. [18]

Loriaut et al treated five patients using a double-button suspensory device. [19Clinical and radiologic follow-up over 2 years showed successful bony union and complete functional recovery.

Zhang et al achieved success with 17 patients who underwent arthroscopic fixation using suture anchor and EndoButton. [20All of the fractures healed successfully, showing that the procedure is safe and effective.

The details of intercondylar eminence fracture reduction depend mainly on the approach used. However, the basic steps are the same. The fracture bed is cleared of any hematoma and debris (see the images below). Because the attachments of the medial and lateral menisci also may inhibit reduction, these are retracted out of the way as the avulsed tibial eminence is reduced to its bed. The avulsed tibial eminence can be held by sutures to the medial meniscus or through a drill hole or held by K-wires or a cannulated screw (depending on the degree of comminution).

Arthroscopic photo of intercondylar eminence fractArthroscopic photo of intercondylar eminence fracture.
Arthroscopic photo of intercondylar eminence fractArthroscopic photo of intercondylar eminence fracture after hematoma evacuation.

Postoperative Care

The traditional approach to postoperative care for intercondylar eminence fractures has been long leg casting in extension (or slight flexion) for 4 weeks, followed by a rehabilitation program. Several studies have reported use of early anterior cruciate ligament (ACL) rehabilitation protocols, with excellent results achieved.

Complications

The most devastating complication of open or arthroscopic fixation of a displaced intercondylar eminence fracture is infection. Sterile technique and implants, intraoperative antibiotics, and proper wound closure should keep this complication to a minimum.

Another concern with acute surgery is fluid extravasation, leading to the potential for lower-extremity compartment syndrome. The use of the arthroscopy fluid pump should be avoided in this situation.

The most frequently reported complication is ACL laxity. The cause of this laxity could be fixation in a nonanatomic position (thereby functionally lengthening the ACL) or microtearing of the ACL prior to eminence fracture. Although many studies report an increase in KT1000 knee ligament arthrometer measurements, patients do not report associated symptoms of instability.

Another complication is diminished range of motion, caused by immobilization. Most authors report an extensor lag, which can be minimized by secure fixation and an early, aggressive rehabilitation program.

Long-Term Monitoring

Patients with intercondylar eminence fractures should be monitored at least until bony union is seen radiographically. At that point, hardware may need to be removed. Continued follow-up is warranted as patients resume their preinjury levels of activity, because ACL laxity can become symptomatic.



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