eMedicine Specialties > Orthopedic Surgery > Knee

Tibial Tubercle Fracture

Author: Kelvin Lau, MA, BM, BCh, MRCS, DPhil, Specialist Registrar in Cardiothoracic Surgery, Trent Deanery
Coauthor(s): Manoj Ramachandran, MBBS, MRCS, FRCS, Consultant Trauma and Orthopaedic Surgeon, Barts and the London NHS Trust; Honorary Senior Lecturer, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary's, University of London, UK
Contributor Information and Disclosures

Updated: Nov 3, 2009

Introduction

Problem

Tibial tuberosity fractures are infrequent fractures affecting physically active adolescents. Activities involving powerful contraction of the knee extensors, such as springing and jumping movements, can result in avulsion fractures of the tibial tuberosity apophysis.^1,2,3 This condition should be distinguished from Osgood-Schlatter disease, a chronic apophysitis of the tibial tuberosity due to recurrent traction injury.

Recent studies

Frey et al retrospectively reviewed 20 tibial tuberosity fractures in 19 adolescents (aged 10-19 y; mean, 13.7 y) from 2000-2007 for fracture morphology, mechanism of injury, fracture management, and complications. There were 9 left-sided injuries and 11 right-sided, including 1 patient with bilateral fractures. Mechanism of injuries included 8 basketball injuries, 5 running injuries, 3 football injuries, 2 falls from a scooter, 1 high-jump injury, and 1 fall. Comorbidities included 3 patients with Osgood-Schlatter disease and 1 with osteogenesis imperfecta. All the patients were treated with open reduction and internal fixation, including arthroscopic procedures in 2 cases. Complications included 4 patients with preoperative presentation of compartment syndrome (all requiring fasciotomy), 1 case of postoperative stiffness, and 1 case of painful hardware, which required removal. Range of motion was started an average of 4.3 weeks postoperatively, and return to play was an average of 3.9monthspostoperatively.⁴
 
Chakraverty et al reported on the management of tibial tubercle fractures in conjunction with complex proximal tibial injuries and noted that a stable repair of the tibial tubercle fragment is essential if the extensor mechanism is to be reconstituted. The investigators outlined a technique for such injuries in which the tibial tubercle fragment is stabilized by wiring it directly to the screws of a locking plate. According to the authors, this approach allows for reduction and fixation of the tibial tubercle fragment that is stable enough to allow immediate full active range of motion. Over the past 5 years, the authors have applied this technique in 16 patients, and they reported that their preliminary results have demonstrated a high rate of clinical and radiographic union with near normal return of extensor mechanism function.⁵

Frequency

In the United States, the frequency of this injury is not known, although it occurs infrequently. At 1 major center, 15 cases of tibial tuberosity fractures were diagnosed in 5 years. Tibial tuberosity fractures typically occur in individuals aged 14-17 years. As the growth plate closes in late puberty, it is transiently replaced by fibrocartilaginous elements. These elements predispose the tibial tuberosity to traction injury as a result of its weakened tensile strength.

Internationally, the frequency is not known. As in the United States, the condition occurs infrequently.

Etiology

Injury from violent tensile forces on the tibial tuberosity causes this type of fracture. This is delivered through eccentric contraction of the extensor mechanism of the knee from either (1) violent contraction of the extensors without shortening (eg, springing off when jumping) or (2) forceful flexion of the knee against the powerful contraction of the quadriceps (eg, landing from a jump); in other words, it occurs when sudden acceleration or deceleration of the extensor mechanism occurs.

Patients with Osgood-Schlatter disease may be predisposed to tibial tuberosity fractures.⁶ Similarly, patients with these fractures may have a family history of Osgood-Schlatter disease or a history of fractures of the tibial tuberosity.

Pathophysiology

The proximal tibia has 2 ossification centers, the proximal tibial epiphysis and the tibial tuberosity, which are separated by a cartilage bridge (see Image 1). Before ossification, the tibial tuberosity is composed of fibrocartilage that has good tensile strength. However, during ossification, columnated cartilaginous cells with poor tensile strength replace the fibrocartilage, and it is within this small window between fibrocartilage and ossified matrix that the tibial tuberosity is at risk of avulsion fractures.

As a result of the direction of pull of the patella tendon, the tibial tuberosity along with the proximal tibial epiphysis can be avulsed upward in a fracture in 1 or more fragments (see Image 2).

Watson-Jones classified the fractures into the following 3 types⁷ :

• Type I: The fracture is within the most distal portion of the tibial tuberosity ossification center and usually results in avulsion of the most distal portion.
• Type II: Extension of the fracture line occurs into the proximal end of the tibia through the cartilage bridge but does not involve the articular surface.
• Type III: This is an intra-articular fracture in which the fracture line has propagated into the joint.

Ogden further subdivided each class into types A and B.⁸ Type A fractures are single, and type B fractures are comminuted.

Presentation

History

The patient may have a history of Osgood-Schlatter disease in the affected and/or contralateral knee. This fracture typically is sustained during athletic activity and results in an acute onset of pain and swelling and in difficulty extending the knee.

Physical

The injury is almost invariably closed, with swelling and tenderness over the affected tibial tuberosity. Tibial tuberosity fractures are due to avulsion and not direct impact; therefore, injury to the overlying tissue is rare.

In mild, or type I, injuries, the patient may be able to extend the knee against gravity, but he or she may not be able to extend it against resistance. In severe, or type II and type III, injuries, the patient may be unable to actively extend the knee. Type III (intra-articular) injuries are associated with hemarthrosis, and this manifests as a painful knee effusion following injury.

A high-riding patella is suggestive of tibial tuberosity fracture.

Indications

Nondisplaced type I injuries can be managed conservatively by cast immobilization in a long leg cast in full-knee extension. All other injuries are best treated by open reduction and internal fixation with cast immobilization for 6-8 weeks.

Relevant Anatomy

The extensor complex of the thigh exerts its force through the ligamentum patellae on the tibial tuberosity. During its histogenesis, the tibial tuberosity is an anterior extension of the proximal tibial epiphysis separated from the rest of the tibia by the growth plate. As the growth plate closes in late puberty, it is transiently replaced by fibrocartilaginous elements, which predispose it to traction injury as a result of its weaker tensile strength.

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