- Technique:
- disimpaction of posterior facet:
- if the posterior facet is impacted down into the cancellous bone, it should be elevated en mass w/ use of an osteotome;
- it is important to elevated the posterior facet along w/ a generous amount of cancellous bone so that the articular fragments do not separate;
- articular reconstruction:
- medial articular fragments are the most difficult to reduce and the most difficult to visualize;
- for this reason, the medial fragment should be reduced first;
- for better exposure, excise fat pad behind posterior facet;
- finger can then be passed behind and around posterior facet to help directly reduce medial fragment;
- medial part of the posterior facet is elevated until it is aligned with the middle facet;
- K wires are inserted from posterior to anterior thru tuberosity fragment and into medial sustentaculum fragment;
- wires can also be inserted from inferior to superior thru the tuberosity fragment into the sustentacular fragment;
- if articlar reduction is difficult, consider pressing the articular fragments up against the undersurface of the talus, in order to mold it into reduction;
- the articular surface of the talus holds the posterior facet in a reduced position;
- articular reduction is maintained w/ K wires;
- hazards:
- avoid medial penetration of the posterior facet:
- be aware that the posterior facet slopes from lateral-superior to medial-inferion, and therefore screws which are inserted in a horizontal direction at the superior margin of the posterior facet will penetrate the articular surface;
- in the report by Jordan C, et al (1999), the authors recommend the following:
- at the anterior aspect of the posterior facet, screws need to be angled 5 deg in a plantar direction or need to be placed 1.5 mm below the edge of the articular surface;
- at the mid portion, screws need to be angled 20 deg inferiorly or 10 mm below the joint edge;
- at the posterior portion, screws need to be angled 32 deg inferiorly or 15 mm below the joint edge
Determining the angle of screw placement for internal fixation of calcaneal fractures.