Ernest L. Sink
DEFINITION
Tibial tuberosity fractures are relatively rare fractures in adolescents. They commonly occur in the later years of skeletal growth before physeal closure.
The fracture mainly occurs in boys, but there are a few cases reported in girls.
The injury occurs while jumping, such as while playing basketball.
There may be a history of prior tuberosity apophysitis.
ANATOMY
The tibial tubercle develops in four stages.5
In the first stage the tubercle is completely cartilage before a secondary center of ossification forms.
The second, or apophyseal stage, occurs at age 8 to 12 years in girls and 9 to 14 years in boys. The secondary center of ossification forms, but it is not connected to the epiphysis of the proximal tibia.
The third, or epiphyseal, stage is when the “tongue” of the apophysis and the epiphyseal bone are continuous. The ages for the third stage are 10 to 15 years for girls and 11 to 17 years for boys.
In the final stage the physis is completely fused and becomes bony.
The patellar ligament inserts into the proximal portion of the apophysis. There is a broad insertion into the periosteum distal to this. The insertion is lateral to the midline; thus, the fracture fragment is centered lateral to the midline.
This is important when considering the approach for intra-articular visualization.
The anterior tibial recurrent artery may tear after a displaced fracture. Bleeding from its proximal branches as it retracts into the anterolateral compartment may lead to compartment syndrome.
PATHOGENESIS
The injury occurs with a forceful quadriceps contraction while the foot is fixed. There is a significant force that the quadriceps mechanism is able to generate, and this overcomes the strength of the epiphysis and the surrounding periosteum.
The other 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 then their peers.8 Thus, the conditions for the fracture are present during jumping and in strong individuals.
Many of the patients have pre-existing Osgood-Schlatter disease.1,11,12
The injury usually occurs at a time when the tuberosity is undergoing normal closure.
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 are usually very tender, with significant swelling over the anterior proximal tibia.
In the more displaced fractures (type II and III) there is usually no possibility of active extension against gravity. There may also be patella alta in the more displaced fractures.
Patients with minimally displaced fractures may extend the knee, but with obvious discomfort.
A good neurovascular examination should be performed.
The clinician evaluates for the presence of leg compartment syndrome.
In the acute fracture there is a sudden onset of pain and it is difficult to ambulate. This is unlike Osgood-Schlatter disease, in which the onset is more chronic and there may be radiographic findings of a chronic condition such as calcification anterior to the secondary center of ossification.
RADIOGRAPHIC FINDINGS
Good anteroposterior (AP) and lateral radiographs are often able to make the diagnosis.
The displacement is most obvious on the lateral radiograph. If it is a nondisplaced fracture or the separation is minimal, a contralateral comparison radiograph may help confirm the diagnosis.
Ogden described three types12 :
Type I fractures are through the apophysis.
Type II fractures exit between the epiphysis and apophysis.
Type III fractures propagate into the anterior knee joint under the anterior meniscus attachments (FIG 1).
NONOPERATIVE MANAGEMENT
Open reduction and internal fixation (ORIF) is indicated for all patients except those with completely nondisplaced fractures.
In nondisplaced fractures where patients can perform a straight-leg raise, a long-leg cast may be used for treatment.
Immobilization should be for 6 to 8 weeks.
Close radiographic follow-up is needed for the first 2 weeks to ensure the fracture does not become displaced.
Even in the nondisplaced fractures, percutaneous screw fixation may allow earlier immobilization and prevent 6 to 8 weeks of casting.
SURGICAL MANAGEMENT
For fractures with more displacement, open reduction and fixation with screws is recommended.
FIG 1 • A. Lateral radiograph of a 13-year-old girl who sustained a tibial tuberosity fracture. The fracture is a type III, which enters the knee joint. B. Lateral radiograph of a displaced type III tibial tuberosity fracture in a 14-year-old boy.
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.
The tourniquet can be used to keep the field dry, allowing for good visualization of the fracture fragments and the joint reduction. The tourniquet, however, may prevent the quadriceps from being freely mobilized and may make reduction more challenging.
Approach
A midline anterior incision is made.
The proximal extent is the midpatella and the distal aspect is a few centimeters distal to the tibial tubercle fracture bed.
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.
Since 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.
TECHNIQUES
DISSECTION AND FASCIOTOMY
The large hematoma should be evacuated.
There is commonly a long periosteal flap of the proximal tibia seen with the elevated fragment that needs to be extracted from the fracture.
A prophylactic anterior compartment fasciotomy is performed.
The distal, medial, and lateral extent of the fracture should be surgically defined with sharp dissection.
For the type of fracture that exits the anterior part of the knee joint, the surgeon must visualize the knee joint. This can be accomplished by looking into the knee through the fracture or by a parapatellar approach. Specifically, the surgeon must ensure the meniscus is not injured or interposed in the fracture before reduction.
OPEN REDUCTION
Next, the fracture is reduced; this is aided by leg extension.
Often the articular surface can be first reduced and the distal aspect then reduced into the base.
Reduction is confirmed with both visualization and fluoroscopy.
If the fracture is not reduced anatomically, it is due to soft tissue interposition or meniscal interposition (TECH FIG 1).
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. (continued)
TECH FIG 1 • (continued) 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.
FIXATION
Once the fracture is reduced, screw fixation is recommended.
Provisional Kirschner wires may be placed to hold the reduction before screw fixation.
The screws are placed from anterior to posterior parallel to the joint surface. Bicortical purchase is not imperative due to the thin posterior cortex in this region. It is important to prevent vascular injury posterior to the knee joint in this region.
Cancellous screws in compression are ideal for this location. Cortical screws will achieve fixation as well, especially more distal.
If there is a large bone fragment, two or three 4.5-mm screws are ideal and may lead to less screw head irritation (TECH FIG 2A,B).
We often use a washer for the thinner cortical bone at the distal region of the fracture.
Alternatively, 6.5 or 7.3-mm screws can be used, although screw head irritation may occur.
The surgeon should avoid placing the screws directly under the incision (TECH FIG 2C).
TECH FIG 2 • A. Intraoperative fluoroscopic image after open reduction and internal fixation of the fracture in Figure 1A with two 4.5-mm screws. B,C. Patient in Figure 1B after open reduction and internal fixation. B.Lateral radiograph shows where three 4.5-mm screws were used parallel to the joint surface. C. Anterior radiograph shows the screws are lateral to the midline as the fracture is more lateral. The screws are not directly deep to the incision, in an attempt to avoid painful screw heads.
POSTOPERATIVE MANAGEMENT
Postoperatively, a cylinder cast for 4 weeks is commonly used, followed by progressive range of motion, or a knee immobilizer for 4 weeks, followed by range of motion.
Postoperative immobilization depends on the fixation. Smaller bone fragments will likely require more immobilization than larger bone fragments, where greater fixation can be achieved.
OUTCOMES
Most of the published series have a small number of patients, due to the rare 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.4,9,11,12
COMPLICATIONS
Reported complications are few for the tibial tuberosity fracture. Screw prominence is the most common complication.14
Compartment syndrome has been reported.10,13 A prophylactic anterior compartment fasciotomy and close observation and recognition may decrease the possibility of this complication.
Growth disturbance, such as a recurvatum from tibial tubercle arrest, is not much of a concern as this fracture 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
REFERENCES
1. Bang J, Broeng L. Spontaneous avulsion of the tibial tuberosity following Osgood-Schlatter disease. Ugeskr Laeger 1995;157:3061–3062.
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.
4. Christie MJ, Dvonch VM. Tibial tuberosity avulsion fracture in adolescents. J Pediatr Orthop 1981;1:391–394.
5. Ehrenborg G. The Osgood-Schlatter lesion: a clinical study of 170 cases. Acta Chir Scand 1962;124:89–105.
6. Falster O, Hasselbach H. Avulsion fracture of the tibial tuberosity with combined ligament and meniscal tear. Am J Sports Med 1992; 20:82–83.
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;66A:790–792.
8. Maffulli N, Grewal R. Avulsion of the tibial tuberosity: muscles too strong for a growth plate. Clin J Sport Med 1997;7:129–133.
9. McKoy BE, Stanitski CL. Acute tibial tubercle avulsion fractures. Orthop Clin North Am 2003;34:397–403.
10. Neuschwander DC, Heinrich SD, Cenac WA. Tibial tuberosity fracture associated with a compartment syndrome. Orthopaedics 1992; 15:1109–1111.
11. Nimityongskul P, Montague WL, Anderson LD. Avulsion fracture of the tibial tuberosity in late adolescence. J Trauma 1988;28:505–509.
12. Ogden JA, Tross RB, Murphy MJ. Fractures of the tibial tuberosity in adolescents. J Bone Joint Surg Am 1980;62A:205–215.
13. Pape JM, Goulet JA, Hensinger RN. Compartment syndrome complicating tibial tubercle avulsion. Clin Orthop Relat Res 1993;295: 201–204.
14. Wiss DA, Schilz JL, Zionts L. Type III fractures of the tibial tubercle in adolescents. J Orthop Trauma 1991;5:475–479.