Tibial Eminence Fracture: Anatomy, Avulsion Types, Spiking, Width Index and Rehab Protocol

Tibial Eminence Fracture:

• What is Tibial Eminence Fracture?
• Anatomy
• Avulsion Types
• Spiking
• Width Index
• Rehab Protocol

What is Tibial Eminence Fracture?

A Tibial Eminence Fracture—also known as an ACL avulsion fracture—is an injury that occurs when the anterior cruciate ligament (ACL) pulls off a piece of bone from the tibial plateau rather than tearing through the ligament itself. This injury is most common in children and adolescents because their bones are still developing and tend to be weaker than the ligament. The tibial eminence, also called the intercondylar eminence, is the bony prominence on the top of the tibia where the ACL attaches.

Clinically, patients present with knee pain, swelling, and restricted motion following a twisting injury or a fall. It is a unique injury that resembles an ACL tear in adults but is treated differently due to the bone involvement. Diagnosis is typically made using X-rays or MRI, which help determine the fracture type, displacement, and associated soft tissue injury.

Anatomy

The tibial eminence is a raised area between the medial and lateral condyles on the upper surface of the tibia. It serves as the attachment site for the anterior cruciate ligament (ACL), which stabilizes the knee by preventing anterior translation of the tibia relative to the femur. The eminence is composed of cancellous bone and covered with cartilage.

Surrounding structures include the menisci, the intercondylar notch of the femur, and the tibial plateau. The medial and lateral intercondylar tubercles form part of the eminence, giving it its characteristic shape. In children, this area is particularly vulnerable to avulsion injuries because the ligament is stronger than the incompletely ossified bone at its insertion point.

Avulsion Types

Tibial eminence fractures are classified into four main types according to the Meyers and McKeever classification (later modified by Zaricznyj):

• Type I: Nondisplaced fracture; the fragment remains in place.
• Type II: Partially displaced (hinged) fracture where the anterior portion of the fragment is elevated, but the posterior part remains attached.
• Type III: Completely displaced fragment, often involving ligamentous tension pulling it away from the tibia.
• Type IV: Comminuted or rotated fragment, representing the most severe form.

Type I fractures are usually treated conservatively with immobilization, while Types II–IV often require arthroscopic or open reduction and fixation. The goal of treatment is to restore joint congruity and preserve ACL function to prevent chronic instability.

Spiking

Spiking refers to the sharp, pointed appearance of the fractured tibial eminence fragment seen on imaging. This spike can interfere with normal joint movement or cause impingement against the femoral condyles. Spiking is most often observed in displaced or comminuted avulsion fractures and may require reduction or surgical trimming during fixation.

During arthroscopic evaluation, spiking fragments can also cause difficulty in restoring proper alignment of the ACL attachment. Addressing these spikes is important to prevent future restriction of knee extension or residual instability. Careful contouring or anatomical reduction helps ensure smooth joint mechanics after healing.

Width Index

The width index is a measurement sometimes used in evaluating tibial eminence fractures, particularly in research and imaging analysis. It refers to the proportionate width of the fracture fragment relative to the overall tibial plateau width. This index can help quantify displacement severity and predict the likelihood of residual instability.

A larger width index may indicate greater bone loss or displacement, potentially affecting surgical decisions and prognosis. Although not routinely used in clinical decision-making, it is a valuable measurement in biomechanical studies and pediatric orthopedic assessments where fracture size correlates with long-term knee stability.

Rehab Protocol

Rehabilitation following a tibial eminence fracture depends on the type and treatment method (conservative or surgical). For nondisplaced fractures treated with casting or bracing, the knee is typically immobilized for 4–6 weeks, followed by gradual range-of-motion exercises and strengthening. Weight-bearing is introduced progressively as healing is confirmed radiographically.

For surgically managed fractures, early controlled motion is encouraged once fixation stability is confirmed. The rehab protocol generally includes:

• Weeks 1–2: Immobilization in extension, isometric quadriceps exercises.
• Weeks 3–6: Gradual knee flexion exercises, avoiding stress on the ACL.
• Weeks 6–12: Progress to full range of motion, strengthening, and balance training.
• 3–6 months: Return to sport-specific training once full motion and strength are restored.

Close follow-up with imaging ensures proper bone healing and ligament function. With appropriate treatment and rehabilitation, most patients achieve excellent functional recovery without residual instability.