Intratendinous rupture of the flexor digitorum profundus tendon in zones II and III.

Spontaneous flexor tendon ruptures are rare. Thirteen patients who had spontaneous intratendinous rupture of the flexor digitorum profundus tendon are described. Twelve of the ruptures occurred in zone III at the level of the lumbrical origin, and one occurred in zone II distal to the A2 pulley. All patients were involved in an activity that required flexion against resistance. Time from injury to treatment averaged 5 weeks. Surgical exploration and subsequent histologic evaluation did not show any pathologic condition to explain the rupture. Surgical treatment was dependent primarily on time from rupture and on the location of the injury; seven patients had direct repair, five had tendon grafting, and one was treated with tendon transfer. Postoperative follow-up time averaged 36 months. All patients regained good-to-excellent active range of motion and returned to work. Patients who had early direct repair of the tendon had better functional results than those who were treated with tendon grafting or tendon transfer.