Closed ruptures of the little and ring finger flexor tendons caused by hamate is mostly associated with a fracture or nonunion of the hamate hook. Only one case of a closed flexor tendon rupture caused by osteochondroma in the hamate has been reported. We present a case of hamate osteochondroma as a rare cause of closed flexor tendon rupture.
A 48-year-old man who had been a rice-field farmer for 7–8 hours a day for the past 30 years visited our clinic due to the loss of right little finger and ring finger flexion involving both the proximal and distal interphalangeal joints. The patient was diagnosed with a complete rupture of the ring and little finger flexors because of the hamate and was pathologically diagnosed with an osteochondroma. Exploratory surgery was performed, and a complete rupture of the ring and little finger flexors due to an osteophyte-like lesion of the hamate was observed, which was pathologically diagnosed as an osteochondroma.
Bony structure was excised first. Then we performed staged tendon reconstruction using Hunter rods rather than primary reconstruction considering possibility of re-rupture and anesthesia method. However, tendon reconstruction could not be performed because the patient did not return to the hospital as he was busy with work.
Osteochondroma is a common tumor but rare in carpal bones. But osteochondroma in the hamate should be considered as the cause when dealing with patients with closed ruptures of the finger flexor tendon. We suggest repetitive movements of hand could produce friction between tendons and hamate leading to attrition of both tendons and hamate.
