Accessory ossicles are supernumerary and inconstant structures that are not caused by fractures. Derived from unfused ossification centers, accessory ossicles were first described by Vesalius in 1543. For centuries, they were believed to be asymptomatic.

Os radiostyloideum (or persistent radial styloid) is an accessory ossicle of the wrist located adjacent to the radial styloid process and lateral to the mid-portion of the scaphoid.

The radial styloid process is a projection of bone on the lateral surface of the distal radius bone. It extends obliquely downward into a strong, conical projection. The tendon of the brachioradialis attaches at its base, and the radial collateral ligament of the wrist attaches at its apex.

Brachioradialis
The lateral surface of lower extremiity of radius is prolonged obliquely downward into a strong, conical projection, the radial styloid process, which gives attachment by its base to the tendon of the Brachioradialis, and by its apex to the radial collateral ligament of the wrist-joint.

Accessory ossicles are well-corticated bony structures found close to bones or a joint. They result from unfused ossification centres and are frequently congenital. They may, however, also be the result of prior trauma.

The os peroneum syndrome (sometimes termed painful os peroneum syndrome (POPS)) refers to a wide spectrum of conditions associated with an os peroneum at the lateral aspect of the foot. It can result in tenosynovitis and/or discontinuity of the peroneus longus tendon.Ordibe

The radial styloid process projects obliquely downward from the distal end of the radius. It serves as the point of attachment for the brachioradialis muscle and the radial collateral ligament. Laterally, the tendons of extensor pollicis brevis and abductor pollicis longus run in a flat groove.

The real cause of radial styloid tenosynovitis is not known. However, repetitive activities and movements of the hand or wrist will result in radial styloid tenosynovitis. Lifting things, working in the garden, playing golf or tennis can lead to the development of De Quervain’s tenosynovitis.

Muscles that Radially Deviate the Wrist

• Flexor Carpi Radialis.
• Extensor Carpi Radialis Longus.
• Extensor Carpi Radialis Brevis.

Ununited ossicle. Osgood-Schlatter disease is one of the most common causes of knee pain in adolescents. Although the symptoms disappear in most patients after the closure of the growth plate,1 they may persist in some cases, affecting sporting activities and climbing stairs through adult life.

The radial styloid process is a projection of bone on the lateral surface of the distal radius bone.

Reference article, Radiopaedia.org. (accessed on 14 Sep 2021) https://radiopaedia.org/articles/54802 The os styloideum is an accessory ossicle of the wrist, situated between the 2 nd and 3 rd metacarpal bases.

The lateral surface is marked by a flat groove for the tendons of the abductor pollicis longus and extensor pollicis brevis. Breakage of the radius at the radial styloid is known as a Chauffeur’s fracture; it is typically caused by compression of the scaphoid bone of the hand against the styloid.