1 General considerations topenlarge
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 neck fractures is indicated:
- When the elbow joint is unstable
- With an unstable coronoid fracture
- With medial collateral ligament insufficiency or ulnohumeral instability
- With associated interosseous membrane injury (Essex-Lopresti injury)
Reduction and fixation of 21-A3.2 / A3.3 fractures
Anatomical reduction and stable fixation of both fractures are desirable for 21-A3 fractures. Begin by exposing both fractures. Usually, the ulnar fracture will be fixed first. Malreduction of the first of the fractures will usually impede reduction of the other. The specific fracture fixation is determined by the character of each fracture and is discussed below. Rare type IV Monteggia fractures (complete dislocation of the radial head relative to capitellum) must be recognized, because both dislocation and fracture must be reduced.
Determination of the correct prosthesis size
Select the right prosthesis size to avoid over- or underfilling of the radiocapitellar joint which can cause restricted range of motion (too large and/or long prosthesis) or elbow instability (too small and/or short prosthesis). For comminuted radial neck fractures, determining the correct length of prosthesis may be difficult. Comparison with an x-ray of the opposite (intact) elbow may be helpful for preoperative planning.
Reconstruct the radial head and neck 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.
2 Resection of the proximal radius topenlarge
Resect radial head and neck fragments
Carefully resect all radial head and neck fragments. Preserve the annular ligament for repair, if possible.
Trim the radial neck
Trim the radial neck to fit the prosthesis with of a small rongeur.
3 Replacement topenlarge
Opening the medullary canal
Carefully open the medullary canal with an awl to fit the prosthesis stem.
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.
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.
Check tracking of the prosthesis in flexion, extension, pronation and supination.
Check elbow stability.
If the elbow is stiff or unstable, change the size of the prosthesis accordingly.
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.