CT scan (Figure 5) confirmed extensive bony synostosis at the
proximal radioulnar joint. She was again offered a multitude of treatment options, including surgical resection, and family chose nonsurgical management with physical therapy.
Ligamentous constraints include the annular ligament and radial (lateral) collateral ligaments which provide stability to the proximal radiocapitellar and
proximal radioulnar joints and to resist varus stress.
More recent case series have included floating elbow variants including ipsilateral diaphyseal humeral fracture with proximal ulna fracture, and
proximal radioulnar joint disruption (Monteggia fracture); ipsilateral diaphyseal humeral fracture, elbow dislocation, and diaphyseal ulna and radius fracture; and distal humerus fractures with intraarticular fractures of the olecranon or radial head [5,7].
Normal development of the elbow depends on the maintenance of the anatomic relationship between all three components of the elbow joint (ulnohumeral, radiocapitellar, and
proximal radioulnar joint).
The IOM tethers the radius and ulna at the
proximal radioulnar joint and along the length of the forearm.
The three articulations are the ulnotrochlear joint, the radiocapitellar joint, and the
proximal radioulnar joint. Anteriorly, the coronoid process of the proximal ulna articulates with the coronoid fossa of the distal humerus.