Acute and subacute flexor tendon ruptures are rarely reported in the literature. To our knowledge, there are only 2 other reports of acute flexor tendon rupture2,5 after a distal radius fracture, neither of which involved the FPL. These cases, which involved ruptures of the flexor digitorum superficialis and flexor carpi radialis, were thought to be the result of tendon laceration by a volar bone spike. There is also one report of subacute FPL and flexor digitorum profundus rupture approximately 4 weeks after closed reduction of a distal radius fracture.6 Although sparse, the literature regarding flexor tendon rupture and distal radius fractures suggests that involvement of the flexor digitorum superficialis and the flexor digitorum profundus tendons is most common and that the rupture typically occurs in 1 to 4 months.1
We report a rare case of 2 acute flexor tendon lacerations after a Gustilo-Anderson type II open distal radius fracture, likely caused by the volar spike of bone that created the open injury. This case also was complicated by the development of acute CTS.
To our knowledge, despite a rate of acute CTS reported as high as 5.4% in operatively treated distal radius fractures, there are no established associations between acute CTS and flexor tendon rupture in the setting of distal radius fracture.8,9 In a 2008 retrospective case–control study by Dyer and colleagues,8 fracture translation is the most important risk factor for the development of acute CTS associated with fracture of the distal radius. Although not statistically significant, ipsilateral upper extremity trauma, higher-energy injuries, younger age, and male sex were also associated with the development of acute CTS. Open injuries occurred in only 3 of 50 cases of acute CTS.8
In agreement with published reports, the probability and the timing of tendon rupture are likely related to the severity of the deforming forces applied during the initial insult rather than the resultant stresses.1 Clinicians should have a high suspicion of acute CTS and possible tendon injuries after a high-energy injury with a significantly displaced open distal radius fracture and median nerve paresthesias. A thoughtful and complete preoperative examination of the flexor tendons may prevent the need for reoperation. Concerns for flexor injury and acute CTS should be elevated with the observation of a disrupted pronator. For patients with a volarly displaced fragment after fracture reduction, this concern should be even more elevated.9 Preoperative median nerve symptoms in the setting of the severely displaced fracture should necessitate an acute carpal tunnel release. If 1 flexor tendon is injured, the surgeon should remember that multiple flexor tendons may be involved. We recommend that any injured tendons be repaired primarily, if possible, and the patient started on appropriate rehabilitation.