Spontaneous flexor tendon ruptures of the hand are uncommon and the current understanding of these ruptures is incomplete.

The purpose of this study is to report five cases of spontaneous flexor tendon rupture in the hand, and to contrast the findings to those in the literature.

A retrospective review of patients with flexor tendon injuries referred to our hand surgeons identified five patients who sustained a spontaneous rupture of the flexor digitorum profundus tendon. A literature search found a total of nineteen articles describing spontaneous tendon ruptures that met our criteria.

We report five cases of spontaneous rupture involving the flexor digitorum profundus tendon. One case involves an abnormal intertendinous connection between the ring and small finger profundus tendons and another involves a lumbrical muscle variant. To our knowledge, the latter has not been reported in association with spontaneous tendon rupture. In reviewing the literature for spontaneous flexor tendon ruptures, a total of fifty spontaneous ruptures in forty-three cases was found. The majority involve the profundus tendon of the small finger in the palm. The ruptures most often occur during periods of peak strain, but can also occur without identifiable trauma.

This study provides a detailed overview of spontaneous flexor tendon ruptures in the hand not found in the literature. The pathogenesis of spontaneous tendon ruptures is still unclear and is likely multifactorial. Although spontaneous flexor tendon ruptures of the hand are uncommon, these ruptures occur more often than one might recognise.