A 40-year-old man boxer, presented with 1-year history of progressive pain at the dorsal aspect of the right wrist.
On physical examination there was swelling on the dorsoradial aspect of his midcarpal joint.
Radiographs in the anteroposterior and oblique views shows the existence of a bone fragment of 6 mm in maximum diameter, located between the scaphoid, trapezoid and capitate bones (Figure 1).
Multidetector computed tomography (CT) with multiplanar reformation demonstrated a bipartite marked sclerotic smooth triangular ossicle in the dorsal aspect of the joint between the scaphoid, capitate, and trapezoid, indicative of accessory ossicle at this level (os centrale carpi) (Figure 2).
Magnetic resonance (MR) images on T1, T2 and STIR sequences depicts low signal intensity of the ossicle on all pulse sequences (Figure 3).
Most accessory bones of the carpus lack clinical relevance and appear as asymptomatic anatomic variants. The os centrale carpi is a relatively rare finding, and bilateral occurrence is even more uncommon. It is located at the dorsal aspect of carpus between the scaphoid, trapezoid and capitate bones. Phylogenetically it is a remnant of the central row of carpals which are present in more primitive animals. With the exception of humans and some African apes, the os centrale carpi is a normal bone in primates. In the human embryo a cartilaginous os centrale carpi with its center of ossification appears at about 6 weeks, fusing with the scaphoid at 8 weeks, forming part of its distal ulnar portion. In some instances, the os centrale may form a projection from the scaphoid or may rarely fuse with the capitate or trapezoid [1, 2, 4, 5].
This entity should be differentiated from dystrophic soft tissue calcifications as hydroxyapatite deposition disease, CREST syndrome, post-traumatic heterotopic ossification and from other abnormalities involving the scaphoid bone. An avulsion fracture shows noncorticated or irregular margins. Dysplasia epiphysealis hemimelica is rare in the wrist, but when it appears it generates large osteochondromatous-like masses in the carpus. Congenital hypothyroidism causes abnormal ossification of the scaphoid, with multiple ossification centers on its proximal and distal aspects [1, 7].
In some cases the os centrale carpi may cause symptoms due to its mobility within the wrist, causing interference with movements of the other carpal bones. Moreover, the symptoms may be due to osteonecrosis of the ossicle and secondary degenerative changes. In the latter case, radiography and CT usually show an os centrale carpi with a sclerotic and fragmented appearance and articular irregularity and narrowing, while MR images depicts low signal intensity of the ossicle on all pulse sequences. The administration of intravenous paramagnetic contrast agent (gadolinium) may confirm the diagnosis of osteonecrosis because an absence of enhancement implies lack of blood perfusion consistent with severe ischemia and necrosis [1, 2, 3, 6].
Osteonecrosis of the os centrale carpi
The patient is a 40-year-old male and a professional boxer, presenting with progressively worsening pain on the dorsal side of the right wrist, accompanied by local swelling.
Based on the provided wrist X-ray, CT, and MRI images, a small bony fragment can be observed in the dorsal radial side of the proximal midcarpal joint region of the right wrist, located between the scaphoid, trapezoid, and capitate, with a relatively regular lobulated or oval shape.
On the CT images, this fragment has a clear boundary distinguishable from the surrounding bone, without any obvious irregular fracture line or disruption of cortical continuity. MRI shows a relatively homogeneous signal, and it has its own articular surface adjacent to the scaphoid, trapezoid, and capitate. In some slices, mild inflammatory signal response can be seen in the surrounding soft tissue, suggesting local irritation or friction.
Based on the imaging findings and patient history, the following potential or differential diagnoses should be considered:
Considering the patient's age, high-intensity wrist activities (boxing), and imaging findings that clearly show a small bony fragment between the scaphoid, trapezoid, and capitate with smooth boundaries and a regular shape, the most likely diagnosis is os centrale carpi. In some cases, repetitive stress or traumatic irritation can lead to pain and restricted joint function.
Should further clarification of its viability (e.g., potential avascular necrosis) be required, additional evaluation based on symptoms and MRI enhancement can be performed. If clinical symptoms are severe and avascular or degenerative changes are suspected, a specialist consultation or further imaging (e.g., arthrography or additional MRI sequences) may be warranted.
Treatment Strategies:
Rehabilitation/Exercise Prescription (FITT-VP):
This report offers a reference analysis based on the imaging and clinical data currently provided and does not replace in-person consultation or professional medical advice. Treatment and rehabilitation plans should be customized according to the patient’s actual condition, subsequent test results, and professional medical evaluation. If you observe any changes in condition or have any concerns, please seek immediate medical attention.
Osteonecrosis of the os centrale carpi
