Avulsion of the Tibial Tubercle

- See: Intercondylar Eminence Frx

- Discussion:
    - avulsion frx of tibial tuberosity along w/ a Salter Harris type-III frx of proximal tibial physis;
    - need to distinguish tibial tubercle avulsion from Osgood-Schlatter disease (which has no physeal involvement);
          - where as Osgood Schlatter disease involves the anteiror surface of the tubercle, the true tubercle frx is an avulsion of the apophysis;
   - avulsion fractures tend to occur between ages 12-16 years;
   - developmental anatomy:
          - cartilaginous stage occurs before a secondary ossification center appears in the tubercle
                - in fetus, tibial tuberosity develops from anterior aspect of proxtimal epiphysis;
          - apophyseal stage: secondary ossification center appears: in girls (8–12 years of age) and in boys (9–14 years of age);
          - epiphyseal stage:
                - secondary ossification centers of the proximal tibia and the tubercle merge into a bony tubercle adjacent to proximal tibial epiphysis;
                - this ossification center expands proximally  & by age 17, it blends in w/ ossification center of tibial epiphysis;

- Clinical Presentation:
    - swelling, pain, & tenderness directly over tuberosity;
    - knee is held in 20-40 deg of flexion because of spasm of hamstrings;
    - pts may or may not be able to extend knee against resistance;
    - may sense a freely movable triangular fragment of bone;
    - compartment syndrome may occur in some cases;

- Radiographs:
    - lateral view: patella alta (degree depends on displacement of tuberosity)

- Classification (Watson Jones) & Treatment:

- Type I: (most common)
     - type 1A: incomplete separation of fragment from metaphysis;
     - type 1B: complete separation;
     - additional findings:
           - frx through secondary ossification center;
           - fragment of the tuberosity is avulsed & is displaced proximally;
     - exam:
           - pts usually can actively extend knee - but not against resistance;
     - treatment:
           - lateral radiograph of knee in full extension allows evaluation of reduction;
           - adequacy of reduction can be determined by position of patella compared with that in the unaffected limb;
           - when residual displacement is < 5 mm, treat in cyclinder cast w/ knee extended for 6 weeks
           - ORIF is indicated if > 5 mm of displacement persists;

- Type II:
     - tubercle epiphysis lifted anteriorly & proximally, separating tubercle ossification center as well as partially separating the non articular portion of the proximal tibial epiphysis;
          - hence, the frx occurs thru a cartilagenous bridge between the proximal tibial physis and the tubercle apophysis;
     - type 2A: complete tubercle frx w/o comminution
     - type 2B: complete tubercle frx w/ comminution;
     - exam:
            - pts usually cannot extend knee against resistance;
     - treatment:
            - displaced grade II and III frx usually require ORIF;
            - need to identify any intra-articular involvement since this always requires anatomic reconstruction;
            - treated w/ ORIF w/ cancellous-bone screw placed horizontally through tuberosity into metaphysis;
            - post op:
                  - 4-6 weeks of immobilization in cyclinder cast;
                  - no unprotected activities for 6 months;

- Type III:
    - frx propagates from tuberosity in a proximal and posterior direction so that it involves the articular portion of the proximal tibial epiphysis;
    - type 3A: single displaced fragment;
    - type 3B: comminuted displaced fragments;
    - treatment:
          - displaced grade II and III frx usually require ORIF;
          - articular incongruenty must be restored, and meniscus tears need to be repair;
          - ORIF w/ cancellous-bone screw placed horizontally thru tibial tuberosity into tibial metaphysis;
          - note high incidence of compartment syndrome and so therefore consider need for prophylactic fasciotomy;
          - post op:
                  - 4-6 weeks of immobilization in a cylinder cast;
                  - no unprotected activity for 6 months;
          - references:
                  - Follow-up study of arthroscopic reduction and fixation of type III tibial-eminence fractures.
                  - Lessons learned after second-look arthroscopy in type III fractures of the tibial spine.

Compartment syndrome complicating tibial tubercle avulsion.

Tension band wiring of displaced tibial tuberosity fractures in adolescents.

Fractures of the tibial tuberosity in adolescents.       

Tibial Tubercle Fractures: Complications, Classification, and the Need for Intra-articular Assessment

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, December 10, 2012 2:45 pm