Spontaneous rupture of the flexor digitorum superficialis tendon of the index and middle fingers: “The pen sign”

Unusual rupture of the middle finger flexor digitorum superficialis tendon in a climber: Biomechanical analysis

“…In the literature, there are several case reports of FDS tendon rupture during activities other than climbing [22][23][24][25][26][27][28][29]. Boyes et al [30] performed a literature review of spontaneous flexor tendon rupture and found that 12% of reported ruptures involved only the FDS tendon (n = 9/80); 10% occurred in the middle finger.…”

Spontaneous Rupture of a Flexor Digitorum Profundus Tendon at Two Levels in Zones II and III in a Child

“…They tend to present late and may be underdiagnosed, possibly because there is little functional limitation. Martinache et al [20] described the so-called pen sign as an altered finger posture when using a pen if the FDS tendon is not functioning in the index finger.…”

“…O'Sullivan et al [29] presented a case of bilateral, but not simultaneous FDP tendon rupture in the index fingers at the junction of zones II and III. Isolated spontaneous ruptures of the FDS tendons have been reported less frequently as isolated case histories [2,20,24,33]. They tend to present late and may be underdiagnosed, possibly because there is little functional limitation.…”

Spontaneous rupture of the flexor superficialis tendon of ring finger: a case report and review of literature

“…In 2009, Martinache et al [6] described a spontaneous FS injury of index and long finger, clinically as ''pen sign'', underlined as difficulty of patient to use the pen; injury was confirmed by MRI, and no surgical treatment was suggested for the poor disability.…”