Chapter 34

Tibial Tuberosity Fractures

 

Eric W. Edmonds

 

 

DEFINITION

Tibial tuberosity fractures are rare fractures that predominately occur in adolescents with the onset of proximal tibial physeal closure.

These apophyseal fractures occur almost exclusively in boys, but there are a few cases reported in girls. Most commonly, the injury occurs at the initiation of a jump.

The association with prior tibial tuberosity traction apophysitis (Osgood-Schlatter syndrome) is possible but not always present.

 

 

ANATOMY

 

The tibial tubercle exists in an anterolateral location on the proximal tibia just distal to the physis and develops in four recognized stages5 that are important to understanding potential pathology.14

 

Stage 1: The tubercle is completely a cartilage anlage without a secondary center of ossification.

 

Stage 2: known as the apophyseal stage, occurs between ages 8 and 12 years in girls and 9 and 14 years in boys. The secondary center of ossification is present but not contiguous with the epiphyseal ossification of the proximal tibia.

 

Stage 3: known as the epiphyseal stage, occurs when the apophyseal ossification connects with the epiphyseal bone; commonly occurring between ages 10 and 15 years for girls and 11 and 17 years for boys

 

Stage 4: is identified by complete fusion of the tubercle and closure of the apophyseal cartilage

 

 

Closure of the proximal tibial physis and the tubercle apophysis occurs in a predictable pattern.14 The proximal tibial physis closes in a posteromedial to anterolateral direction toward the tubercle apophysis, which is simultaneously closing in a proximal to distal direction.

 

The patellar ligament (tendon) inserts into the apophysis with a large periosteal insertion distally.

 

It is important to remember the native anterolateral position of the tubercle and therefore the fracture fragment when preoperatively planning the approach for intra-articular visualization.

 

The anterior tibial recurrent artery is at risk to rupture with a displaced fracture. Bleeding from its proximal branches as it retracts into the anterolateral compartment could cause a compartment syndrome.

 

PATHOGENESIS

 

The injury occurs with a forceful quadriceps contraction while the foot is fixed. There is a significant eccentric force of the quadriceps mechanism that overcomes the strength of the apophysis and the surrounding

periosteum.10 A second possible mechanism of injury is sudden passive knee flexion while the quadriceps is contracted.

 

It has been hypothesized that individuals with this fracture may have quadriceps strength that is greater than their peers.8 Thus, the conditions for the fracture are present during jumping and in strong individuals.

 

Many children may have preexisting Osgood-Schlatter syndrome.1, 12, 13

 

The injury usually occurs at a time when the tuberosity is undergoing normal closure,14 and the pattern of normal skeletal maturity results in specific fracture patterns.

 

There have also been reports of associated injuries such as quadriceps tendon injury, cruciate ligament tears, and meniscal injury.3, 6, 7, 9

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Patients usually present acutely with significant pain and an inability to bear weight on the affected leg after sustaining an injury during physical activity. They are usually tender, with significant swelling over the anterior proximal tibia. An effusion may be present, and active straight-leg raise against gravity is often not possible.

 

 

Children with minimally displaced fractures may extend the knee but with obvious discomfort (likely due to intact retinaculum and surrounding periosteum).

 

Neurovascular examination should always be performed, as there is distinct risk of injury with tibia tubercle fractures.

 

There should also be an evaluation for the presence of leg compartment syndrome.

 

Osgood-Schlatter syndrome has a more insidious onset and usually will not have an effusion or result in extensor lag, even though it may be significantly tender over the tubercle.

 

RADIOGRAPHIC FINDINGS

 

Good anteroposterior (AP) and lateral radiographs are often able to make the diagnosis, but they may be limited in the assessing the extent of injury.14

 

The displacement is most obvious on the lateral radiograph.

 

 

Lateral radiographs with about 15 degrees internal rotation can place the tubercle on profile and assist with the assessment of nondisplaced or minimally displaced fractures. Contralateral images can be helpful for comparison and may help confirm the diagnosis.

 

 

Ogden et al13 described three types of tubercle fractures using only the lateral x-ray:

 

 

Type I: fractures through the apophysis only

 

Type II: fractures that exit between the epiphysis and apophysis

 

 

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FIG 1 • AP (A) and lateral (B) radiographs of a 16-year-old boy who sustained a tibial tuberosity fracture. The fracture is a type III or type C, which enters the knee joint.

 

 

Type III: fractures that propagate into the anterior knee joint under the anterior meniscus attachments (FIG 1)

 

A multiplanar imaging classification scheme has also been described that takes the skeletal development and risk for associated injuries into consideration.14

 

Type A (isolated tubercle, child) is isolated to the ossified tip (seen on x-ray) of the largely cartilaginous tubercle—seen predominately between stages 1 and 2 of development.

 

Type B (physeal) involves both the epiphysis and tubercle that fracture as a single unit off the metaphysis without intra-articular involvement—seen predominately during stage 2 of development.

 

Type C (intra-articular) extends into the intra-articular surface of the proximal tibia—predominately occurring during stage 3 of development.

 

Type D (isolated tubercle, teen) involves only the distal aspect of the tubercle because there has been closure of all the remaining apophysis—predominately occurring between stages 3 and 4 of development.

 

Type A fractures risk apophyseal closure and possible recurvatum, whereas type D fractures carry minimal risk.

 

Type B and C fractures should have computed tomography (CT) or magnetic resonance imaging (MRI) assessment to fully evaluate the extent of injury for preoperative planning.

 

 

Type B fractures carry the greatest risk for associated pathology including neurovascular injury and compartment syndrome.

 

NONOPERATIVE MANAGEMENT

 

Open reduction and internal fixation is indicated for all patients except those with completely nondisplaced fractures, especially type D fractures.

 

A long-leg cast is the nonoperative management for children with nondisplaced fractures that can perform a straight-leg raise.

 

Immobilization is 6 to 8 weeks.

 

Close radiographic follow-up is needed for the first 2 weeks to ensure the fracture does not become displaced.

 

The disadvantage of casting even the nondisplaced fractures is the subsequent risk of stiffness that may not arise with percutaneous screw fixation (that may allow earlier mobilization).

 

SURGICAL MANAGEMENT

 

For fractures with displacement, open reduction and fixation with screws is recommended, whereas nondisplaced fractures can be treated with percutaneous screw fixation.

 

Positioning

 

Patients are positioned supine with the operative leg and knee prepared free.

 

The table should allow good anterior and posterior views to be obtained with fluoroscopy.

 

 

Use of a radiolucent table is imperative, but even partially radiolucent tables can be used if the patient's knee is positioned on the table to confirm adequate exposure for the fluoroscopy (this assessment should be made prior to surgery).

 

A thigh tourniquet can be used to keep the field dry, improving visualization of the fracture fragments and the joint reduction. However, the tourniquet can entrap the quadriceps muscle proximally, thereby limiting excursion and making the fragment reduction more challenging.

 

A bump can be placed under the operative knee to keep it slightly bent during the procedure. This improves visualization by keeping the skin incision on traction and allowing any hematoma or fluid to flow away from the central aspect of the incision.

 

Approach

 

A midline anterior incision is appropriate in most if not all tibial tubercle fractures.

 

The proximal extent is the midpatella, and the distal aspect is a few centimeters distal to the tibial tubercle fracture bed for a full, unimpeded view of the fracture and its reduction. It can be shortened on the proximal aspect if it does not involve the joint.

 

 

Commonly, there is a significant amount of hematoma formation and torn periosteum; thus, the incision length allows the surgeon to define the appropriate anatomy and prepare the fragment for reduction.

 

Because the tubercle and the fracture are on the lateral aspect of the proximal tibia, a lateral parapatellar approach will give better visualization of the fracture and intra-articular reduction.

 

 

The lateral approach also limits any damage to the infrapatellar branch of the saphenous nerve.

 

 

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TECHNIQUES

• Dissection and Fasciotomy

The large hematoma should be evacuated.

Identify the long periosteal flap on the distal aspect of the elevated fracture that is commonly present, and extract it from its intercalary position if it is trapped within the fracture.

A prophylactic anterior compartment fasciotomy is performed, if it is not already been done by the fracture

 

itself.

 

The distal, medial, and lateral extent of the fracture should be surgically defined with sharp dissection.

 

For type C fractures (exiting in the knee joint), the surgeon must visualize the articular surface either through the fracture (to identify concomitant injuries such as the meniscus) or via the lateral parapatellar approach to assist reduction.

• Open Reduction

   

  Next, the fracture is reduced, and this is often aided by leg extension to take tension off the quadriceps muscle.

   

  For type C fractures, the articular surface should be reduced first, followed by the distal aspect of the fracture.

   

   

   

  TECH FIG 1 • A. A 15-year-old boy with a displaced tibial tuberosity fracture that enters the joint surface.

  B. Initial postoperative lateral radiograph after open reduction and internal fixation. Despite initial fluoroscopic views indicating an adequate reduction, the radiographs indicate a poor reduction. C. AP postoperative radiograph indicating a possible poor reduction. D,E. CT scans indicate the joint surface is poorly reduced. F. A repeat open reduction and internal fixation was performed. The lateral meniscus was impeding the prior reduction and it was removed from the fracture site. This allowed a successful reduction, as shown by the lateral radiograph.

   

  Tentative fixation is used, and the reduction is confirmed with both direct visualization and fluoroscopy.

   

   

  If the fracture is not reduced anatomically, it is due to soft tissue interposition or meniscal interposition (TECH FIG 1).

   

• Fixation

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  Once the fracture is reduced in an acceptable position, screw fixation is recommended. Solid screws or cannulated screws can be used.

   

  Provisional Kirschner wire (K-wire) fixation is best to hold the reduction before screw fixation because it is difficult to use clamps without a more extensive posterior dissection.

   

  Standard K-wires can be used if solid screws are planned, and the surgeon should be cognizant to the K-wire placement so as not to interfere with later ideal screw placement. Conversely, guide pins may be used if a cannulated screw system is being used and placement should be at the ideal location.

   

  The screws are placed from anterior to posterior parallel to the joint surface and without crossing the proximal tibial physis, if desired (TECH FIG 2). Bicortical purchase is not necessary, and it is important to prevent vascular injury posterior to the knee joint in this region.

   

   

   

  TECH FIG 2 • Same patient as FIG 1, demonstrating anatomic reduction of both fragments with 4.5-mm cannulated screws and washers placed parallel to the joint surface. A. The AP radiograph shows the screws are lateral to the midline as the fracture is more lateral, and the screws are not directly under the incision, in an attempt to avoid painful screw heads. B. Lateral radiograph demonstrating fixation of both the epiphyseal fragment and the tubercle fragment.

   

   

  Cancellous screws in compression are ideal for this location, and cortical screws can be used to achieve fixation distally in larger fragments.

   

  If there is a large bone fragment, two or three 4.5-mm screws are ideal and may lead to less screw head irritation.

   

  A washer can be used for these smaller screws to resist loss of near cortical fixation.

   

  Alternatively, 6.5- or 7.3-mm screws can be used, although screw head irritation may occur. Washers

  should not be used with these screws.

  The surgeon should avoid placing the screws directly under the incision.

  For type A fractures that involve the very young, screw fixation will guarantee developed recurvatum; therefore, smooth K-wire fixation should be used. These should also be placed parallel to the joint and avoid crossing the proximal physis as well. They can be left out of the skin and pulled after 4 weeks, during a cast change.

   

   

   

  PEARLS AND PITFALLS

   

  Radiographic interpretation

  • Close radiographic evaluation can help the surgeon to recognize the minimally displaced fracture and the possibility of another extensor mechanism injury, such as a sleeve fracture.

  • Advanced imaging can identify intra-articular extension and entrapment of meniscal tissue.

     

    Reduction techniques

    • The impediments to reduction—the periosteum and meniscus (see TECH FIG 1)—should be removed, being sure that the tourniquet is not limiting quadriceps excursion.

    • A lateral parapatellar approach is more direct to the site of injury.

    • The surgeon should make sure that the joint surface is reduced in type B and C or type III fractures. Moreover, preoperative advanced imaging is important for planning purposes.

 

Associated pathology and complications

• The surgeon should be aware of associated injuries (eg, meniscus, anterior cruciate) and look for them.

• A prophylactic anterior compartment fasciotomy should be performed.

• Smaller screw heads (4.5 mm) may lead to less complaints of screw head pain and reduce the risk of return to surgery for implant removal.

 

 

 

POSTOPERATIVE MANAGEMENT

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Postoperatively, a cylinder cast or long-leg cast can be used. A cylinder allows motion at the ankle but may have more skin issues because of that motion. For type A fractures being treated with pins, a long-leg cast that includes the foot must be used to protect the protruding pins.

 

Postoperative immobilization after fixation should be done for 4 weeks. This can be followed by progression into a knee range-of-motion brace to limit activities but promote gentle range of motion if radiographs at that visit demonstrate adequate healing. With less than the ideal bone callus and healing at that 4-week visit, a knee immobilizer can be used for an additional 4 weeks, followed by range of motion and physical therapy, if needed.

 

OUTCOMES

Most of the published series have a small number of patients due to the uncommon nature of this fracture.

 

All studies have been consistent in their conclusion that the fractures heal with success and patients return to normal function. Growth abnormality has not been reported in types C or D4, 9, 12, 13; however, recurvatum due to premature apophyseal closure can occur in types A and B fractures.14

 

 

COMPLICATIONS

Reported complications are few for the treatment of tibial tuberosity fractures, with screw prominence and irritation being the most common.16

Compartment syndrome has been reported, particularly in type B fractures.11, 14, 15 A prophylactic anterior compartment fasciotomy and close observation and recognition may decrease the possibility of this complication.

As mentioned in the Outcomes section, growth disturbance, such as a recurvatum from tibial tubercle arrest, is not of too much concern, as this fracture predominately occurs in adolescents near the end of growth.

Loss of motion or quadriceps muscle weakness is extremely rare but may occur with a malunion or malreduction.2

 

 

ACKNOWLEDGMENT

 

Thank you to Ernest L. Sink, MD, who prepared this chapter for the first edition of this text.

 

REFERENCES

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2. Bolesta MJ, Fitch RD. Tibial tubercle avulsions. J Pediatr Orthop 1986;6:186-192.

    

    

3. Choi NH, Kim NM. Tibial tuberosity avulsion fracture combined with meniscal tear. Arthroscopy 1999;15:766-769.

    

    

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5. Ehrenborg G. The Osgood-Schlatter lesion. A clinical study of 170 cases. Acta Chir Scand 1962;124:89-105.

    

    

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7. Lipscomb AB, Gilbert PP, Johnson RK, et al. Fracture of the tibial tuberosity with associated ligamentous and meniscal tears. A case report. J Bone Joint Surg Am 1984;66(5):790-792.

    

    

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11. Neuschwander DC, Heinrich SD, Cenac WA. Tibial tuberosity fracture associated with a compartment syndrome. Orthopedics 1992;15:1109-1111.

     

     

12. Nimityongskul P, Montague WL, Anderson LD. Avulsion fracture of the tibial tuberosity in late adolescence. J Trauma 1988;28: 505-509.

     

     

13. Ogden JA, Tross RB, Murphy MJ. Fractures of the tibial tuberosity in adolescents. J Bone Joint Surg Am 1980;62(2):205-215.

     

     

14. Pandya NK, Edmonds EW, Roocroft JH, et al. Tibial tubercle fractures: complications, classification, and the need for intra-articular assessment. J Pediatr Orthop 2012;32(8):749-759.

     

     

15. Pape JM, Goulet JA, Hensinger RN. Compartment syndrome complicating tibial tubercle avulsion. Clin Orthop Relat Res 1993;(295): 201-204.

     

     

16. Wiss DA, Schilz JL, Zionts L. Type III fractures of the tibial tubercle in adolescents. J Orthop Trauma 1991;5:475-479.