The Hip: Preservation, Replacement and Revision

Hawkins Type II Talar Frx

- Discussion:
    - displaced frx of talar neck (no matter how slight) w/ subluxation or dislocation of posterior facet of sub-talar joint;
    - subtalar joint subluxation is usually dorsal;
    - ankle remains aligned;
    - persistent slight displacement will result in malunion (usually in varus) which will produce an unacceptable result;
    - despite posteromedial displacement of body with most type II injuries, posterior tibial neurovascular bundle is usually spared;
           - however, it is manditory to monitor this neurovascular bundle;
    - of greatest significance is high incidence (19% to 28%) of associated (usually medial) malleolar frx w/ this injury;
    - complications include AVN in 30% and post-traumatic arthrosis in the majority of patients (over 2/3 patients);

- Exam:
    - in addition to sig local soft tissue injuries, frxs of both remote & adjacent structures have been reported (64% in Hawkins series);

- Radiographic Evaluation:
    - hawkins sign

- Treatment:
    - in type II injuries caused by destruction of talocalcaneal ligament, it is difficult to perform closed reduction of dorsal & supination deformity;
    - operate if there is > 3-5 mm of dorsal displacement & any rotational deformity;
    - if closed reduction is possible then 8-12 weeks is necessary for healing (trabeculation across the fracture site);

- Closed Reduction:
    - under adequate GEA, gentle traction is applied manually & foot is flexed plantarward to bring head frag into proper relaltion to body;
           - any varus or valgus malalignment should be corrected as well;
    - w/ foot held in equinus, lateral, and anteroposterior x-rays of talar neck should be taken to assess the adequacy of reduction;
    - if an anatomical reduction has been achieved, the foot should be casted, still in equinus, in a short leg non wt bearing cast;
           - this position should be held for 1 month, and then with subsequent casts the foot can be brought out of equinus as long as reduction is maintained;
    - non wt bearing cast immobilization is usually required for 3 months to achieve bony union;
    - varus angulation may occur w/ non operative treatment;
         - occurs due to medial comminution;
         - the main effect of this is to eliminate subtalar motion;

- Open Reduction:
    - if reduction is not maintained,  operative treatment is indicated;
    - consider longitudinal anteromedial incision over talar neck just medial to anterior tibial tendon;
           - this allows direct acces to the fracture site;
    - an anterolateral approach may decrease chance of further damage to blood supply of talus and provides adequate exposure of the fracture;
    - following K wire fixation (and ORIF such as a lag screw) a non wt bearing cast is applied for 8-12 weeks, or until frx is healed;
    - rigid internal fixation may be achieved using AO cancellous screw once fracture is anatomically reduced;
    - when there is comminution of the medial neck, screw compression can produce a varus deformity;
    - placement of the screw from posterolaterally to anteromemdially can help avoid this problem;

- Complications:
    - avascular necrosis and/or degenerative arthitis can be expected in over 1/2 cases

A new look at the hawkins classification for talar neck fractures: which features of injury and treatment are predictive of osteonecrosis?

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

Last updated by Data Trace Staff on Monday, February 10, 2014 11:34 am