Tibial Tubercle Fractures

Key Points:

  • Tibial tubercle fractures result from eccentric loading of the knee extensor mechanism or resisted jumping
  • Tibial tubercle fractures frequently require ORIF
  • Three dimensional imaging may help guide treatment but is not always necessary
  • Compartment syndrome following tibial tubercle fractures may be caused by injury to the anterior tibial recurrent artery

Description:

  The tibial tubercle is the secondary ossification center of the proximal tibia. The primary ossification center is the tibial epiphysis, and the tibial tubercle extends distally from the anterior aspect of the proximal epiphysis and serves as the point of attachment of the patellar tendon. The tubercle often appears fragmented on radiographs during its development and the ossification centers eventually coalesce in the mid-teen years. Tibial tubercle fractures commonly occur in adolescent boys near the end of their growth. Physeal closure occurs from posterior to anterior and proximal to distal in the tubercle apophysis.  Concurrently, it is closing from medial to lateral in the coronal and axial planes. 

Epidemiology:

  Tibial tubercle fractures most commonly occur in adolescent boys aged 12-16 years.   They account for only 1% of pediatric fractures (Pandya, 2012).

Clinical Findings:

  Patients usually have a history of injury and pain in the anterior knee.  There may or may not be associated deformity.  Hemarthrosis may be present in more severe fractures with intraarticular involvement.  An extensor lag or extensor deficiency is present in more severe injuries.  It is important to appreciate the amount of soft tissue damage and periosteal stripping that can be associated with these injuries (Wiss, 1991). Compartment syndrome and vascular injury can occur after a tibial tubercle fracture; therefore, a careful physical exam, including detailed neurovascular exam, is essential. Extended observation is frequently recommended to ensure a compartment syndrome does not develop.

Imaging Studies:

  The initial work up for a suspected tibia tubercle fracture includes AP and lateral radiographs of the knee.  Three dimensional imaging (CT and MRI) may be utilized to better characterize these fractures and provide the treating surgeon with information that may alter the surgical approach, including the need for concomitant arthroscopy or open arthrotomy (Pandya, 2012).  CT or MRI may also be useful in the diagnosis of Type 1 fractures, especially in those patients with pre-existing Osgood-Schlatter's disease.

Etiology:

  Tibial tubercle fractures are commonly produced by eccentric loading of the knee extensor mechanism while landing, or resisted jumping.  These injuries are most often associated with jumping and landing sports, such as basketball.

  Ogden et al proposed classifying these injuries according to the site of failure based on plain lateral radiographs; through the tubercle (Type I), at the level of the proximal tibial physis (Type II), or extending through the anterior tibial epiphysis and into the joint (Type III).  This classification was then modified in 1985 to include avulsion of the entire proximal tibial epiphysis (Ryu, 1985) and again in 1990 to include a periosteal sleeve avulsion of the extensor mechanism (Frankl, 1990).  Fractures that extend through the physis to the posterior tibia metaphysis have been evaluated with regards to surgical treatment (Pace, 2013). A recent publication proposed an entirely new classification system based on 3D imaging of physeal closure, where Type A are tubercle fractures in youth, Type B are physeal fractures, Type C are intra-articular fractures, and Type D are tubercle fractures in adolescents (Pandya, 2012). 

Treatment:

  Nondisplaced fractures may be treated in extension with a brace, cylinder cast, or a long leg cast for 4-6 weeks. Displaced fractures require operative treatment, with screw fixation of the fragment to the tibial metaphysis, although suture fixation via drill holes or suture anchors may be necessary if there is substantial fragment comminution. With displaced fragments, open reduction and internal fixation is required to obtain an anatomic reduction.  With greater displacement, the patellar tendon insertion and extensor retinaculum can also be disrupted, and additional soft tissue repair may be necessary. 

  With intraarticular involvement, an open reduction with an arthrotomy or arthroscopy is performed in order to assess joint congruity, soft tissue entrapment, and to address any associated intraarticular pathology (eg. meniscal tears). Postoperatively, patients are usually treated in a long leg cast or knee immobilizer for 4-6 weeks with restricted weight bearing and activity, allowing progressive knee flexion based upon fracture characteristics and fixation stability. 

Complications:

  There is a high risk of compartment syndrome due to the potential for avulsion of branches of the anterior tibial recurrent artery at the level of patellar tendon insertion (Pape, 1993). Frequent serial examinations should be performed, and if there is a high suspicion for compartment syndrome, then compartment pressures should be measured and/or a fasciotomy performed. Failure to properly diagnose and treat compartment syndrome can result in severe permanent disability and sometimes amputation.  Rates of compartment syndrome have been reported as high as 20% in tibial tubercle fractures (Frey, 2008). Prophylactic fasciotomy at the time of internal fixation may be performed at the discretion of the surgeon. 

  Because most patients with this injury are approaching skeletal maturity, complications related to subsequent growth are rare. However, genu recurvatum is possible and monitoring with serial radiographs of the knee beyond fracture healing should be considered.  This may occur due to arrest of the anterior proximal tibial physis as the posterior physis continues to grow, thus decreasing the tibial slope (Hresko, 1989).  

  Other complications include symptomatic, prominent implants that may require hardware removal.  Failure to adequately reduce an intra-articular component of the fracture may lead to post-traumatic arthritis.  Knee stiffness may occur following this injury and may be exacerbated by prolonged immobilization.

References:

  1. Christie M, Dvonch V. Tibial tuberosity avulsion fracture in adolescents. J Pediatr Orthop 1981; 1: 391-94. 
  2. Frankl U, Wasilewski SA, Healy WL. Avulsion fracture of the tibial tubercle with avulsion of the patellar ligament.  Report of two cases. J Bone Joint Surg Am. 1990;72:1411-1413.
  3. Frey S, Hosalkar H, Cameron DB et al. Tibial tuberosity fractures in adolescents. J Child Orthop. 2008;2:469-474. 
  4. Hand W, Hand C, Dunn A. Avulsion fractures of the tibial tubercle. J Bone Joint Surg (Am) 1971; 58: 1579-83. 
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  9. Pandya NK, Edmonds EW, Roocroft JH, Mubarak SJ. Tibial tubercle fractures: complications, classification, and the need for intra-articular assessment. Journal of Pediatric Orthopedics 2012; 32(8): 749-59. 
  10. Pace J, et.al. Operatively treated type IV tibial tubercle apophyseal fractures.  J Pediatr Orthop 2013; 33: 791-796.
  11. Pape J, Goulet J, Hensinger R. Compartment syndrome complicating tibial tubercle avulsion. Clin Orthop 1993; 295: 201-04. 
  12. Pretell-Mazzini J, et.al. Outcomes and complications of tibial tubercle fractures in pediatric patients: A systematic review of the literature.  J Pediatr Orthop 2016; 36: 440-446.
  13. Rye RK, Debenham JO. An unusual avulsion fracture of the proximal tibial epiphysis.  Case report and proposed addition to the Watson-Jones classification. Clin Orthop Rel Res. 1985;194:181-184.
  14. Schiller J, DeFroda S, Blood T.  Lower extremity avulsion fractures in the pediatric and adolescent athlete. J Am Acad Orthop Surg 2017; 25: 251-259.
  15. Wiss DA, Schilz JL, Zionts L. Type III fractures of the tibial tubercle in adolescents. Journal of Orthopaedic Trauma 1991; 5(4): 475-9.

Top Contributors:

Jennifer Powers MD