Several factors must be taken into consideration when treating radial head fractures. In addition to the fracture pattern itself, associated ulnohumeral dislocation, ligament disruption and other associated elbow fractures must be considered. Patient characteristics such as handedness, functional status and expectations must also be weighed in determining a specific treatment.
The Mechanical Role of the Radial Head
The radial head along with the medial collateral ligament provide the primary restraints to valgus loading of the elbow. In this role, the radial head is secondary to the medial collateral in function. Attenuation of the MCL, however, increases the role of the radial head in valgus resistance.
Radial head fractures are classified via the Mason system. Type 1 fractures are nondisplaced, type 2 fractures are partial articular with displacement and Type 3 fractures are comminuted fractures involving the entire radial head. (Type 3 are subtyped as III A Fracture of the entire radial neck, with the head completely displaced from the shaft; III B Articular fracture involving the entire head, consisting of more than two large fragments and III C Fracture with a tilted and impacted articular segment.) Type 4 fractures represent fracture of the radial head with dislocation of the elbow joint.
Type 1 fractures of the radial head can be treated nonsurgically. This involves initiating range of motion at one week as tolerated by the patient. Modified weight bearing on the extremity is encouraged for the first 6 weeks.
Many of the Mason Type 2 fractures can also be treated nonoperativly if:
1. there is no bony block to elbow motion (30-130 degrees flexion/extension arc, 70 degrees of pronation/supination);
2. Elbow stability is maintained without fracture fixation.
Typically, functional results are not as good as the nonoperative treatment of Type 1 fractures.
Fewer Type 3 fractures can be managed nonoperativly. Elbow stability is required for this treatment protocol.
Surgical treatment is necessary in Mason Type 2 injuries when the radial head is required for elbow stability of there is a block to motion. Open reduction/internal fixation with miniature lag screws in combination with the use of small plates is often indicated.
Radial Head Excision
Partial excision may be considered when the fragments are relatively small and overall elbow stability is preserved. Complete radial head excision can lead to radial shortening, wrist pain and decreased forearm strength and should be performed with caution.
Radial Head Replacement
Type 3 fractures are often treated with radial head excision with concurrent radial head replacement. Metal implants are favored over silicone. Metal implants are reported to result in increased ROM, decreased radial shortening and decreased elbow arthritis when compared to silicone implants.
The lateral Kocher approach is used for the majority of these injuries. Dissection posterior to the midcapitallum can disrupt the lateral ligamentous complex of the elbow. A 110 degree safe zone for hardware. This zone is described as an arc between the axis's of Listers tubercle and the radial styloid. When the arm is in neutral, the zone is along the anteriorlateral radial head that is visible though the Kocher incision.