The patient presented with a painful wrist following a fall onto the outstretched hand. Plain radiographs of the wrist showed no bony injury, but revealed an incidental finding.
The patient presented with a painful wrist following a fall onto the outstretched hand.
Plain radiographs of the wrist showed no bony injury, but revealed an incidental finding of complete lunotriquetral coalition.
Carpal coalition is a relatively common anomaly, which most frequently involves isolated fusion of the triquetrum and lunate bones. This occurs in about 0.1–1.6% of the general population, and is seen more frequently in men and in the Afro-Caribbean population. It is bilateral in 60% of cases. Widening of the scapholunate interosseous space radiographically with an intact scapholunate interosseous ligament is a common finding. Fusions have been described sporadically in all possible combinations including involvement of more than two bones. Less common fusion anomalies include trapezium-trapezoid, capitate-hamate, and hamate-pisiform.
Carpal fusion can occur as an isolated finding or as part of a congenital malformation syndrome. In such cases massive fusion and fusion involving proximal and distal rows is more common. Associations include acrocephalosyndactyly syndrome, arthrogryposis, diastrophic dwarfism, Ellis-van Creveld syndrome, Holt-Oram syndrome, otopalatodigital syndrome, Turner's syndrome and symphalangism.
The aetiology of the condition relates to failure of segmentation of the primitive cartilaginous canals and absence of joint formation. Radiographically, continuous trabeculae can be traced from one bone to the next with an occasional residual cleft detectable.
Lunotriquetral coalition is almost always discovered coincidentally and patients are commonly asymptomatic. The fusion also can be incomplete, however, resembling a pseudarthrosis, and these patients can become symptomatic. Lunate-triquetral coalitions can be subdivided into four types according to the degree of union. Symptomatic Type 1 fusions representing minimal fusion can be treated with lunotriquetral arthrodesis.
Lunotriquetral coalition
The patient is a 25-year-old female who underwent a wrist X-ray after a fall, during which she used her hand to brace herself upon impact. No obvious fracture line or bony destruction is observed on the images, and there are no significant abnormalities noted in the distal radius or distal ulna. Notably, the PA and oblique views of the wrist depict partial fusion between the lunate and triquetrum, shown by an indistinct or absent joint space and continuous trabecular structures extending from the lunate to the triquetrum.
A mild widening is observed in the scapholunate space, but there is no definite evidence of ligament tear or disruption. No apparent soft tissue swelling is noted.
Considering the above differential diagnoses, congenital fusion of the lunate and triquetrum (lunotriquetral coalition) is most consistent with the imaging features in this case.
Taking into account the patient’s age, clinical presentation (fall on the wrist without obvious signs of fracture), and radiographic findings (continuous trabecular structure crossing between the lunate and triquetrum), the most likely diagnosis is:
Lunotriquetral Carpal Coalition (Congenital Fusion of the Lunate and Triquetrum)
This condition is often an incidental finding and generally asymptomatic. If further confirmation is needed, imaging of the contralateral wrist for comparison or a 3D CT reconstruction can provide clearer visualization of the extent of fusion.
No special treatment is typically required for lunotriquetral coalition, particularly in asymptomatic or mildly symptomatic cases. Current wrist pain is more likely attributable to soft tissue contusion or mild ligamentous stress from the fall, which can be managed conservatively.
Surgery (lunotriquetral arthrodesis) could be considered for the rare instances where patients experience consistent pain, restricted motion, or have a “pseudo-joint” appearance (type 1 lunotriquetral coalition) that produces symptoms. In this case, if pain is mild and injury-related, no surgical measures are typically necessary.
Once wrist pain subsides, patients can gradually begin functional exercises to prevent joint stiffness and muscle atrophy:
Throughout the rehabilitation process, exercise intensity and load should be dynamically adjusted according to the patient’s fitness level and changes in pain symptoms. If the patient has osteoporosis or other joint diseases, a progressive and careful approach is essential, ideally under the guidance of a professional rehabilitation therapist or physician.
Disclaimer: This report provides a reference analysis based solely on imaging and currently available clinical data. It cannot replace an in-person consultation or the assessment of surgical indications. If you experience persistent pain or functional impairment, please consult a professional orthopedic or sports medicine specialist promptly.
Lunotriquetral coalition
