Fractures of Radial Head or Head of Radius – The Biomechanics

The radial head  articulates with ulna at its proximal end through  the lesser sigmoid notch. It maintains contact with the ulna throughout forearm pronation and supination.

Radial head fracture is very common in adults. Radial head had been previously excised for fractures of head of radius and fractures of neck of radius.  However a very common complication that occurs with excision of radial head is proximal migration of  the radius bone . It results from loss of strut that used to support and block this when radial head was intact.

Interossoeus Membrane. Click Image To Enlarge

Because relations of ulna and radius bone alter with proximal migration of radius, it results in deformities at wrist. One of the major factors that prevent proximal migration is the interosseous ligament, also known as interosseous membrane.It is a complex structure that connects radius and ulna in their entire length

In most specimens, there is a central thick band and a group of accessory bands.  The central band appears to be the dominant component and is responsible for majority of the stiffness of the interosseous ligament after radial head excision.

Interosseous ligaments shares all the load transferred when radial head is not present. It might get stretched and may migrate proximally,  as noted previously leading to symptoms in the wrist.

When planning for thr treatment of radial head fractures, reconstruction of the radial head is the first prirority. If it is not possible, patient should be explained the likely problems in future and should be kept in follow up for long time.

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1. Radial Head Fractures – Clinical Presentation and Treatment
2. Radial Head Fractures – Treatment Options
3. Mason Type IV Radial Head Fractures – Xrays and Clinical Photographs
4. Xray of Elbow After Excision of Radial Head
5. An Unusual Fracture Of Proximal End Ulna Along With Dislocation of Radial Head