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From a bowler’s precise throw to a yogi’s graceful mudras, the wrist’s bones and muscles work in tandem to produce a whole range of movements. In particular, the biomechanics provided by the joints of the wrist allow for a whole range of motions that make even the most complicated movements effortless and mundane.
However, in extremely rare circumstances, wrist, or carpal, bones may sometimes fuse, compromising hand mobility. In a first instance of bilateral carpal fusion in a high-level athlete, Houston Methodist physicians have reported an extremely rare case of coalition of the scaphoid and trapezium wrist bones. Further, the condition did not cause any overt hindrance for the player to pitch the ball.
The case report on the bilateral scaphotrapezial fusion is published in The Journal of Bone and Joint Surgery.
“Pitching involves a lot of flexibility from your wrist and hands,” said Kourosh Jafarnia, MD, assistant professor of clinical orthopedic surgery. “There are several cases of carpal fusion in the literature, but never in an athlete, let alone a baseball pitcher.”
The prevalence of carpal coalition ranges from 0.1% in people of European origin to 1.6% in people of African origin. When the carpal fusion is in isolation, it is often in one hand, on the side of the ulnar bone and between the carpals belonging to the same row, that is, between the lunate and triquetrum bones or the capitate and hamate bones of the wrist. In some cases, these coalitions cause pain and reduced hand mobility, particularly in the forward-backward and sideward directions.
Kourosh Jafarnia, MD
Assistant Professor of Clinical Orthopedic Surgery
Houston Methodist
Image courtesy of Kourosh Jafarnia, MD
In contrast, scaphotrapezial coalitions, arising from carpal bones on different rows, are even rarer, generally unilateral and often a part of congenital syndromes. And thus, Jafarnia said the discovery of a bilateral scaphotrapezial coalition in a collegiate baseball athlete with no prior symptoms or difficulty in pitching was very serendipitous.
The patient, the researchers reported, came to the clinic as a follow-up appointment after a fracture to the index finger was addressed using a plate and screws. When the clinicians X-rayed the hand with the injury, they observed the scaphotrapezial coalition, which was in itself very unusual. But they were even more surprised to find that the uninjured hand had the same carpal fusion. Further, both of his parents had normal hand X-rays and did not have either congenital conditions or a history of wrist or hand complaints, suggesting that the trait was not directly inherited by their son.
“This patient is the only high-level athlete shown to have this condition,” said Jafarnia. “We generally look at X-rays just to see the trauma and these incidental findings go unnoticed. But now that we've observed it, we can update the existing literature on this very rare condition.”
Wininger AE, Jafarnia KK. Incidental Bilateral Scaphotrapezial Coalition in a High-Level Throwing Athlete: A Case Report. JBJS Case Connect. 2021 May 17;11(2). doi: 10.2106/JBJS.CC.21.00027. PMID: 33999866.
Vandana Suresh, PhD, April 2022
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