1 Note on illustrations topenlarge
Throughout this treatment option illustrations of generic fracture patterns are shown, as four different types:
A) Unreduced fracture
B) Reduced fracture
C) Fracture reduced and fixed provisionally
D) Fracture fixed definitively
2 Principles of hinged external fixation topenlarge
The elbow joint closely approximates a simple hinge. Its axis of rotation lies at the centers of the trochlea and capitellum. A guide wire placed along this axis orients the fixator’s hinge(s).
Details of external fixation are described in the basic technique for application of modular external fixator.
Specific considerations for the hinged elbow fixator and the elbow are given below.
3 Pin insertion (humerus/forearm) topenlarge
For safe pin placement make use of the safe zones and be familiar with the anatomy of the humerus and the forearm.
The pins in the ulna should be placed distal to the coronoid and away from fractures and fixation.
Elbow axis guide wire insertion
The guide wire can be placed percutaneously, or through an open surgical wound, if it is present. Remember the ulnar nerve medially.
Precise wire placement is essential. Slight misplacement of the hinge significantly affects hinge behavior.
Anatomically, the axis landmarks are slightly anterior and distal to the medial epicondyle, and just distal to the lateral epicondyle. The wire is placed on one of these points, confirmed fluoroscopically, and advanced slowly with repeated imaging. It must follow the axis. On the lateral view it should be central within the capitellum and trochlea.
For a unilateral hinge, the wire needs to be advanced from lateral to medial only far enough to ensure a perfectly coaxial location and adequate stability. For a fixator with bilateral hinges, the wire must be exposed both medially and laterally.
Soft tissue dissection
Blunt dissection of the soft tissues and the use of small Langenbeck retractors will prevent damage to muscular, vascular and neurological structures.
Prepare a channel for insertion of the pin, using a blunt clamp down to the bone. If there is any doubt an incision should be made big enough to prove that the drill sleeve (for the humerus a must) will have direct contact with the bone.
4 Frame construction (hinged elbow fixator) topenlarge
Placement of hinge
Place the hinge over the guide wire, which must not be bent. With the elbow reduced concentrically, attach the hinge to the proximal and distal partial frames with rods and rod-to-rod clamps. Tighten all clamps.
With image intensifier, confirm reduction of the elbow throughout a gentle range of motion. Adjust the reduction as needed. Finally confirm that all clamps are securely tightened.
Once the hinge is securely attached to the external fixator structure, the guide wire can be removed.