This is an images of the hands of a 23 year-old Omani girl who presented to the Family Medicine Clinic of Sultan Qaboos 
University Hospital, Oman, with complaints of 
bilateral wrist pain for the previous four weeks [Figure 
1]. The pain was aggravated by activities especially 
those requiring weight lifting. The history revealed 
no other joint involvement, no previous trauma, 
fever, morning stiffness, or weight loss. On 
examination, she was of average height and weight. 
Her wrist examination showed mild tenderness and 
swelling over the lateral aspect of her wrists proximal 
to the second metacarpal base, especially in her 

left wrist. In addition, her left fourth metacarpal 
was relatively shorter than rest of her metacarpals. 
However, the range of movements at the wrist and 
the metacarpophalangeal joints were full, but were 
associated with pain at the extremes of movement. 
The diagnosis after X-ray was congenital fusion of 
carpal bones.

Fusion or synostosis of various carpal bones is 
possible in different combinations. It can either be 
a part of a syndrome or can occur as an isolated 
anomaly.2 The term ‘fusion’ can be considered 
as a misnomer as it is not truly a fusion of carpal 
bones, rather it is an absence of joint cavitation, 

SQU Med J, December 2010, Vol. 10, Iss. 3, pp. 405-406, Epub. 14th Nov 10 
Submitted 27th March 10
Revision ReQ. 22nd June 10, Revision Recd. 23rd June 10
Accepted 29th June 10

Department of Family Medicine & Public Health, Sultan Qaboos University Hospital, Muscat, Oman.
*Corresponding Author email: nafisa77@squ.edu.om

<ªÜvflπ]<<‹ø√÷]Ê<Í√eÜπ]<‹ø√÷]<∞e<Íœ◊§̌]<t^⁄Çfi˜]


Congenital Fusion of the Trapezium and 
Trapezoid

*Nafisa Samir and Abdulaziz Al-Mahrezi

INTERESTING MEDICAL IMAGE

Figure 1: X-ray of both hands, posterior-anterior view. The upper arrow shows the short left fourth metacarpal while 
the lower arrows show bilateral fusion of the trapezium and trapezoid.



Congenital Fusion of the Trapezium and Trapezoid

406 | SQU Medical Journal, December 2010, Volume 10, Issue 3

and chondrification of the joint interzone. This 
leads to the phenomenon of carpal synostosis which 
becomes apparent only after the bones ossify. Carpal 
fusions occur as normal variations in about 0.1% of 
the population. Lunate-triquetral fusion is the most 
common fusion anomaly of the carpus.2 This bone 
anomaly is mostly bilateral, but more common on 
the left side when unilaterally present.3 Among 
the various population groups studied, the highest 
incidence is seen in people of African descent with  
a with a higher female to male ratio (2:1) and a 
strong familial tendency.

Carpal coalition is usually asymptomatic and 
often discovered incidentally. There have been 
reports of symptomatic pisohamate coalition, 
scapholunate triquetral coalition, and scaphoid 
trapezium synchondrosis.1,2,5 The loss of movement 
between the fused bones leads to a compensatory 
increase in motion at surrounding joints. This 
predisposes the person to recurrent sprains 
causing pain, especially under stressful conditions. 
Occasionally, this may also result in an overgrowth  
of bone called carpal bossing.1,2 Increased demand  
on the joint, especially in high activity level people 
like sportsmen, may lead to progressive stress  
loading and early degenerative arthritis or 
pseudoarthrosis. Generally, isolated carpal fusions 
involve two bones of the same row, while the 
syndrome-associated fusions, such as Ellis van 
Creveld syndrome, Osteochondritis dissecans, 
foetal alcohol syndrome, symphalangia, diastrophic 
dwarfism, gonadal dysgenesis, and Poland 
syndrome, are quite often multiple.1,2 Acquired 

fusion can occur secondary to arthritis, trauma or 
as a result of surgery for joint stabilisation.2

Radiological findings may vary in appearance 
and fusion may present as partial or complete 
union of the carpal bone or there may be narrowing 
of the joint space without adjacent sclerosis or 
osteophytosis.2 For asymptomatic cases, treatment 
is rarely required. Symptomatic treatment might 
be needed for the minority of patients who present 
with symptoms. 

References
1. Terrence JJJ. Congenital fusion of the trapezium and 

trapezoid. Rom J Morphol Embryol 2008; 49:417–9.

2. Singh P, Tuli A, Choudhry R, Mangal A. Intercarpal 
fusion – a review. J Anat Soc India 2003; 52:183–8.

3. Cockshott WP. Carpal fusion. Am J Roentgenol 
Radium Ther Nucl Med 1963; 89:1260–71.

4. Resnick D, Niwayama G. Diagnosis of Bone and Joint 
Disorders, 2nd Ed. Philadelphia: WB Saunders Co., 
1988. pp. 3560–1.

5. Knezevich S, Gottesman M. Symptomatic 
scapholunatotriquetral carpal coalition with fusion 
of the capitatometacarpal joint: Report of a case. 
Clin Orthop Relat Res 1990; 251:153–6.

6. Simmons BP, McKenzie WD. Symptomatic carpal 
coalition. J Hand Surg 1985; 10:190–3.

7. Chouhdry R, Tuli A, Chimmalgi M, Anand M. Os 
capitate trapezoid: a case report. Surg Radiol Anat 
1998; 20:373–5.

8. Friedman T, Reed M, Elliott AM. The carpal fusion in 
Poland syndrome. Skeletal Radiol 2009; 38:585–91.