Executive Editor: Peter Trafton

Authors: Kodi Kojima, Steve Velkes

Proximal forearm 21-B3.1 Arthroplasty

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Glossary

1 Preliminary remarks top

Anatomical reduction and stable fixation of both fractures are desirable for 21-B3.1 fractures. Begin by exposing both fractures. Usually, the ulnar fracture will be fixed first. Difficulty in reducing either fracture may be caused by malreduction of the fracture in the other bone.

Rare type IV Monteggia variant fractures (complete dislocation of the radial head relative to capitellum) must be recognized, since open reduction will be necessary for both dislocation and fracture.

The fixation of each fracture is presented separately. The specific fracture fixation is determined by the character of each fracture.

2 General considerations top

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Indications

Stable restoration of radial length is usually important for elbow or forearm stability. If this cannot be achieved with ORIF, a proximal radius prosthesis will be necessary.

Prosthetic replacement for unreconstructable radial head fractures is indicated

  • when the elbow joint is unstable
  • with an unstable coronoid fracture
  • with medial collateral ligament insufficiency or ulnohumeral instability
  • after radial head excision with evidence of medial collateral ligament insufficiency or ulnohumeral instability
  • with associated interosseous membrane injury (Essex-Lopresti injury)

Correct prosthesis size

Select the right prosthesis size to avoid over- or underfilling of the radiocapiteller joint which can cause restricted range of motion (too large and/or long prosthesis) or elbow instability (too small and/or short prosthesis).

Pearl
Reconstruct the radial head with the excised fragments and choose the size of the prosthesis accordingly.


Cemented or uncemented prosthesis

The surgeon must choose between cemented and uncemented prosthesis, the latter being easier, but perhaps less stable.

3 Resection of the radial head top

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Resect radial head fragments

Carefully resect all radial head fragments. Preserve the annular ligament for repair, if possible.


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Trim the radial neck

Trim the radial neck to fit the prosthesis with of a small rongeur.

4 Replacement top

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Opening the medullary canal

Carefully open the medullary canal with an awl to fit the prosthesis stem.


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Trial insertion of the prosthesis

Insert the chosen prosthesis. Assess its length and stability. Cementing the prosthesis may be necessary for optimal stability, and can be determined now.


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Avoid lengthening or shortening

To avoid lengthening and overstuffing of the radiocapitellar joint, or shortening and instability, the prosthesis should fit as follows:

The articular surface of the radial head prosthesis should be at the level of, or slightly proximal to, the lateral edge of the coronoid articular surface.

The radius with prosthesis should match radiographs of the opposite (intact) forearm, to ensure correct length.


Assessment

Check tracking of the prosthesis in flexion, extension, pronation and supination.

Cement the prosthesis in place, if desired, and if its size and position are satisfactory.

If the annular ligament is ruptured, repair it with non-absorbable sutures.


Final assessment

Following repair of the ulnar fracture, replacement of the radial head and repair of ligaments, assess elbow stability through a full range of flexion-extension. Radiocapitellar and ulnohumeral joints should remain located.

Also check supination and pronation. Fixation should be stable. Crepitus or restricted motion should be absent. Check fractures and fixation with image intensifier or x-ray.

If elbow instability or dislocation are identified, it is essential to maintain elbow alignment. This can be done with temporary hinged external fixation. If a hinged external fixator is not available, the significantly unstable elbow should be bridged with a non-hinged external fixator.

v1.0 2016-10-24