Tibial Tubercle Fracture 

Updated: Oct 24, 2018
Author: Kelvin Lau, BM, BCh, MA, MRCS, DPhil, FRCS(CTh); Chief Editor: Thomas M DeBerardino, MD 

Overview

Background

Tibial tuberosity fractures are infrequent fractures affecting physically active adolescents.[1, 2, 3, 4, 5, 6]  Activities involving powerful contraction of the knee extensors, such as springing and jumping movements, can result in avulsion fractures of the tibial tuberosity apophysis.[7, 8, 9]  This condition should be distinguished from Osgood-Schlatter disease, a chronic apophysitis of the tibial tuberosity due to recurrent traction injury.

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 (ORIF) with cast immobilization for 6-8 weeks. (See Treatment.)

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.

Pathophysiology

The proximal tibia has two ossification centers, the proximal tibial epiphysis and the tibial tuberosity, which are separated by a cartilage bridge (see the image below). 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.

Ossification centers and epiphyseal cartilages of Ossification centers and epiphyseal cartilages of the proximal tibia and tibial tuberosity.

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 one or more fragments (see the image below).

Classification of tibial tuberosity fractures. Classification of tibial tuberosity fractures.

Watson-Jones classified the fractures into the following three types[10] :

  • 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 modified this classification by adding the subtypes A and B,[11] with A representing single fractures and B representing comminuted fractures.

Etiology

Tibial tubercle fracture is caused by injury from violent tensile forces on the tibial tuberosity. The force is delivered through eccentric contraction of the extensor mechanism of the knee from either of the following:

  • Violent contraction of the extensors without shortening (eg, springing off when jumping)
  • 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.[12] Similarly, patients with these fractures may have a family history of Osgood-Schlatter disease or a history of fractures of the tibial tuberosity.

A few cases of tibial tubercle fracture occurring after bone–patellar tendon–bone (BPTB) autograft for anterior cruciate ligament (ACL) reconstruction have been reported.[13]

Epidemiology

In the United States, the frequency of tibial tubercle fracture has not been determined, though the injury is known to occur infrequently. At one 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.

Prognosis

Pretell-Mazzini et al systematically reviewed the English-language literature from 1970 through 2013 (23 studies; 336 fractures; mean follow-up, 33.56 months [range, 5.7-115 months]) in order to determine the following with regard to tibial tubercle fractures in pediatric patients (mean age at surgery, 14.6 years)[14] :

  • Frequency and type of associated injuries
  • Frequency of concomitant Osgood-Schlatter disease
  • Methods of treatment
  • Functional and radiologic outcomes according to fracture type
  • Complications

The most common fracture reported was type III (50.6%). The rate of associated injury was 4.1% overall and was highest for type III fractures (4.7%).[14] ​ Compartment syndrome occurred in 3.57% of cases. ORIF was performed in 98% of surgical cases. Regardless of the type of fracture, 98% of patients were able to regain their preinjury activity and knee range of motion, and 99.4% achieved fracture consolidation. The overall complication rate was 28.3%; removal of an implant because of bursitis (55.8%) was the most common complication, followed by tenderness/prominence (17.9%) and refracture (6.3%).

 

Presentation

History

The patient may have a history of Osgood-Schlatter disease in the affected knee, the contralateral knee, or both. 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 Examination

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

In mild (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 (type II or 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.

 

Workup

Laboratory Studies

Laboratory studies are not indicated unless other diagnoses are being evaluated. Preoperative investigations are requested as required.

Imaging Studies

Radiography of the knee is the main imaging study. Findings are diagnostic of the condition. The tibial tubercle is imaged on a lateral radiograph with the leg in slight internal rotation. Oblique views of the proximal tibia may help reveal the extent of the fracture. Radiographs of the contralateral knee may show evidence of Osgood-Schlatter disease.

Other forms of imaging are not performed routinely; they are requested as required if alternative diagnoses are being considered.

 

Treatment

Medical Therapy

Medical therapy typically involves analgesia for pain control and thromboprophylaxis. The patient's discomfort can be controlled with acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs). If the pain continues, a narcotic analgesic can be added.

Surgical Therapy

The surgical procedure is determined by the type of fracture.[15, 16] The preoperative assessment is designed to identify the fracture, its displacement, and any associated injuries.

Type IA injuries are treated conservatively with cast immobilization in full extension, followed by gradual rehabilitation of the quadriceps. Type IB, type II, and type III injuries are treated with open reduction and internal fixation (ORIF).[17] Type III injuries may also require exploration of the knee joint for meniscal and ligamentous damage, with accurate reduction of the intra-articular surface.

In ORIF, the fracture is approached from an anterior or lateral parapatellar incision. Interposed soft tissue is cleared to promote accurate reduction. The tibial tuberosity is reduced and fixed to the tibia by using one or two screws.[18] Arthroscopy or arthrotomy may be required to repair damaged menisci and to refashion a smooth articular surface, particularly in type III injuries.

Postoperative Care

Analgesia is required for control of postoperative pain.

Physiotherapy is also part of the patients' postoperative care. Progressive rehabilitation of the quadriceps is required after cast immobilization. Physiotherapy and progressive weightbearing exercises can be performed soon after ORIF is completed. Early mobilization attenuates joint stiffness and weakness due to prolonged immobilization.

The prognosis is excellent, and most patients recover full function within 1 year. An orthopedic surgeon should follow patients to ensure that the fracture is healing correctly and that any complications are managed.

Complications

Complications are rare and include those related to trauma (eg, thromboembolism) or effects specific to the fracture. The latter includes meniscal damage in type III injuries, bursitis over metalwork, malunion, nonunion, recurrence, early degenerative change, genu recurvatum, and leg-length discrepancy.

Frey et al retrospectively reviewed 20 tibial tuberosity fractures in 19 adolescents (mean age, 13.7 years; range, 10-19 years) for fracture morphology, mechanism of injury, fracture management, and complications.[19] There were nine left-side injuries and 11 right-side injuries; one patient had bilateral fractures. Injury mechanisms included basketball (n = 8), running (n = 5), football (n = 3), fall from a scooter (n = 2), high-jumping (n = 1), and fall (n = 1). Comorbidities included Osgood-Schlatter disease (n = 3) and osteogenesis imperfecta (n = 1).

All 19 patients were treated with ORIF, including arthroscopic procedures in two cases.[19] Complications included preoperative presentation of compartment syndrome (n = 4, all requiring fasciotomy), postoperative stiffness (n = 1), and painful hardware that required removal (n = 1). Range of motion was started an average of 4.3 weeks postoperatively, and return to play was an average of 3.9 months postoperatively.