Radial head fractures represent approximately one-third of elbow fractures and 1% to 4% of fractures in adults. A few years ago, the radial head was considered of little importance in the elbow anatomy and biomechanics, so its excision was frequently indicated. Laboratory studies and long-term series outcomes have shown undesirable consequences of this method. Associated injuries usually determine treatment and outcomes.
Anatomy and Biomechanics
A 180-degree arch in the pronation and supination is allowed by the articulation of the proximal end of the radius with the distal humerus (capitulum), and with the ulna in the lesser sigmoid cup (trochoid joint). Cartilage covers the radial head except for the anterolateral third that lacks subchondral bone, and it is easily fractured. It has a 40-degree central cavity, and it is oval-size-like. The head and neck are not collinear with the diaphysis and complete a 15-degree offset angle. They are closely related to the lateral ligament complex, mainly the annular ligament and radial collateral ligament.
The physiologic elbow range of movement is zero to 150 degrees of flexion and extension, and 85 degrees of pronation and 75 degrees of supination.
The radial head stabilizes in valgus when the internal ligament complex is injured, and it does not take part when being harmless (secondary stabilizer). Moreover, it is involved in the longitudinal stability. 
The fracture occurs when a patient has direct traumatic to the elbow or falls with the wrist and the hand in extension. The usual signs are pain and functional impotence, there may be blockages in the elbow. In incomplete or nondisplaced fractures, it is necessary to investigate painful spots and the presence of small petechiae. Suspecting possible associated lesions is important. The medial aspect of the elbow (LCI), the interosseous membrane, and the distal ulnar radius joint should be evaluated, especially in complex cases. When there is doubt as to the size and displacement of the fragment, it is useful to test with a local anesthetic injection to determine if it causes mechanical blockages, which indicates the need for surgical treatment.
Most complex injuries have been associated with lateral and medial ligaments injuries and interosseous membrane (Essex Lopresti). It is useful to make the radius climbing and descending in the surgery and to identify it with the intensifier climbing at elbow level and with the distal radioulnar joint to diagnose this type of injury. Capitulum, coronoid, and olecranon are among the most frequent related fractures.
Assessing the elbow, shoulder, and wrist stability is helpful.
Anteroposterior and lateral x-rays are useful. If there is a pain in the wrist and comminuted fractures, it is useful to request x-rays to compare them. CT scans ease planning in complex cases.
Mason is a widely-used classification system. Type 1 is a nondisplaced fracture. Type 2 is displaced with one fragment fracture. Type 3 is a comminuted fracture. Johnston suggests Type 4to be any fracture with elbow luxation. Lately, Morrey has included to the classical description of joint fractures, those of neck, quantifying them to 30% approximately and displacements between 2 mm.
Hotchkiss modifies the types mentioned above with ones by therapeutic criteria. Type 1 fractures are nondisplaced or mínimum displaced fractures (below 2 mm). Type 2 fracture have a partial head displacement that blocks the pronation and supination, and repairable with internal fixation. Type 3 injuries are nonrepairable fractures with internal fixation.
Objectives are to achieve an appropriate range of motion with an early rehabilitation start, elbow and forearm stability, and to avoid immediate and long-term complications (arthritis). Aspects to keep in mind for therapeutical decision are patient-related and include age, bone quality, functional demand, comorbidities, fracture-related extension, location, displacement, and related injuries.
Most isolated fractures. Indication for nondisplaced fractures, displaced with joint step under 2 mm, a joint surface condition under 30%, and angling under 30 degrees. However, some authors extend the indication to all fractures which do not block the joint (test through anesthesia) in spite of their having further displacements that evolve toward non-strengthening, and the fragment is to be dried similarly.
The local anesthesia test is used to search for mechanical occlusion which could determine surgical resolution. The initial immobilization may be carried out by plaster or sling in functional position. It is to be worn for two or three weeks and followed by an x-ray evaluation seven days later.
It is convenient, attempt active elbow flexion and extension while the humerus is on a flat surface.
Radial head excision:. Indication in severe pain in selected cases for instance older adults with a low demand with complex fractures but no associated fractures which compromise stability. One option is the differed excision with the same indication to the mentioned one or to enhance pronation-supination. 
Open or arthroscopic: Fragment excision may be indicated in cases where these can obstruct joints and are too small for osteosynthesis and should not be part of the proximal radio-ulnar joint.
Osteosynthesis:. As regards isolated fractures, it is an absolute indication when they cause a joint blockage. (Mason type 2) Step over 2 mm, joint fragment over 30%, neck fractures with angling over 30 degrees.
Low profile plates and screws implants or cannulated are applied.
Surgical approach: (Kocher) between the anconeus and extensor carpi ulnaris (ECU), it provides good access to the back fragments and safety to the posterior interosseous nerve. Another option is extensor digitorium comunis (EDC) splinting to avoid iatrogenic injuries.
Osteosynthesis should be placed in the safe interval to avoid interference with the proximal radio-ulnar joint which is located 110 external degrees with the elbow in neutral pronation-supination.
In complex fractures, osteosynthesis or prosthesis? It is convenient not to get more than three fragments with no impaction or deformity with enough bone quality and without metaphyseal bone loss to achieve a stable internal fixation. In many cases, these fracture features are determined at surgery time.
Arthroplasty: Indication for non-repairable fractures. A prosthesis-sized appropriate choice is important to avoid articular stiffness. 
Stiffness due to prominent hardware in osteosynthesis or to the oversized prosthesis in arthroplasties.
It can also be found due to capsular contracture and ossification.
Aseptic necrosis and nonunion after osteosynthesis failure. Malunion is less frequent post osteosynthesis than in nonsurgical treatment.Arthritis according to clinical x-ray studies but with no clinical correlation.
Instability is less frequent. It is important to manage injuries to avoid this complication adequately.
Aseptic necrosis and nonunion after osteosynthesis failure. Malunion is less frequent post osteosynthesis than in nonsurgical treatment.
Arthritis according to clinical x-ray studies but with no clinical correlation.
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