Review Question - QID 5944

The chevron osteotomy is performed apex distal, 2cm from the palpable tip of the olecranon. The cancellous screw is driven slightly medially because of the proximal varus angulation of the ulna.

An olecranon osteotomy provides extensile exposure of the distal humerus and elbow joint and exposes more of the articular surface (57%) than the triceps-splitting approach (35%) or the triceps-reflecting approach (46%). Both transverse and chevron osteotomies can be performed. To minimize articular surface disruption, it is recommended that the osteotomy be performed in the bare area of the olecranon. The bare area is described by Morrey as "transverse portion composed of fatty tissue divides the sigmoid notch into an anterior portion made up of the coronoid and the posterior olecranon." The osteotomy can be fixed with K-wires and a tension band construct or a single large cancellous screw. The proximal ulna has a slight metadiaphyseal varus angulation. The intramedullary screw should be long enough to reach the varus angle and should be directed in this direction.

Wang et al. performed an anatomic study with 39 cadaver elbows. They found that on average, the bare area was 0.53cm wide, and located 2.1cm from the palpable tip of the olecranon. The length from the tip of the triceps insertion at the ulnar angle was 7.6cm, and the inner diameter of the medullary canal (at the ulnar angle) was 0.71cm (mediolateral) and 0.74cm (dorsovolar) and could easily accomodate a 7.0 or 7.3mm intramedullary screw. At 1-2cm proximal to the ulnar angle, the canal widened to dimensions larger than the 7.3mm cannulated screw. They recommend using this information when planning olecranon osteotomies and also in fixing simple olecranon fractures with an intramedullary screw.

Elmadag et al. compared the olecranon osteotomy and triceps-lifting (Campbell) approach in 54 patients undergoing ORIF of distal humerus fractures. They found that functional outcomes and range of motion was better in the olecranon osteotomy group. Disadvantages of both approaches include: The olecranon osteotomy carries a risk of nonunion (<10%, higher with transverse osteotomy than chevron osteotomy). The triceps-lifting approach requires 3 weeks of postoperative immobilization for extensor healing.

Illustration A shows the bare area of the ulna and the distance from the olecranon tip. Illustration B shows the Campbell triceps-lifting approach.

Incorrect Answers:
Answers 1, 2, 3, 5: The chevron osteotomy is performed apex distal, 2cm from the tip, and cancellous screw fixation will angle medially because of the proximal varus bend.