Radial Head Replacement in Grown-ups with Recent Fractures
Updated on November 25, 2020 | by Alex Smith
Generally, the most common fractures of the elbow are radial head fractures. In the case of non- displaced fractures, non-operative treatment is suggested. A direct stable internal fixation that can allow early mobility in the elbow is advisable in maximum other cases. But in the 1970s, the radial head’s replacement was started for critically comminuted fractures as it proved to be more suitable for simple radial head resection, which generally causes instability of the elbow or the forearm, specifically in the case of severe fracture with a consequential lesion in another structure too. Whether it is modular or monoblock and with or without a cap, the contemporary implants provide mechanical mobility as that of the native radial head. Still, it does not provide proper treatment of the consequential lesion. It remains critical in the case of the re-fixation of the radial collateral ligament and distal radioulnar stabilization in the case of Essex-Lopresti fracture.
That is why the selection of radial head implants and radial head instruments is the most important technical aspect in the radial head prosthesis as the extremely high implantation of the prosthetic head produces capitellar overloading, which may result in pain and rigidity, and weakening of the stem. Removal of the implant at a distance from the injury is needed in such a condition. In 60% – 80% of cases, the studies have shown satisfactory results.
Generally, the common reason for radial head fractures is falling with the outstretched arm, specifically with the extended wrist and the pronated forearm.
However, Simple isolated nondisplaced radial head fractures do not require surgical treatment. But almost 80% of displaced fracture requires anatomical reduction, stable fixation, and concomitant lesions repairing. But most of the time-critical comminution does not allow radial head reconstruction. To prevent elbow instability in such cases, radial head replacement is a better option as compared to radial head resection. Initially, it was designed to intercept ectopic ossification. That’s why advancement in the design of radial head implants, radial head instruments, and in the material used in its manufacturing has been made with the up-gradation in the domain of elbow mechanics.
Herein, the main aim is to explain the biomechanical role of the radial head, review the role for radial head implants in the treatment of radial head fractures in adults, and analyze radial complications head prosthesis and the result of this procedure considering the recent facts.
Anatomy and the Biomechanics of the Radial Head
The radial head is at the top of the radius bone that is just below the elbow. It forms the humero-radial joint in articulation with the capitellum. Moreover, the extremity of the radial head articulates with the radial notch of the ulna, which forms the radio-ulnar joint. Thus, the radial head is the basis of the forearm scaffold. The radial head is not circular. The radial head is ellipsoid and conical in shape, and there is an increase in size from proximal to distal. The radial head implants are provided by top orthopedic implants companies in the world.
The longest axis (20–23 mm on average) of the redial head is perpendicular to the ulna’s radial notch in neutral rotation. As a result, when the forearm is in supination, the annular ligament surrounding the radial head becomes slack.