The literature on extensor tendon rupture and even chronic flexor tendon rupture after volar plating and distal radius fracture malunion is ubiquitous. However, acute and subacute flexor tendon ruptures caused by distal radius fractures have been reported only in limited case reports. These rare injuries may involve multiple tendons and are associated with high-energy mechanisms. This case report details the involvement of multiple flexor tendon injuries associated with a Gustilo-Anderson type II distal radius fracture and the development of acute carpal tunnel syndrome (CTS) after a motor vehicle collision. The patient provided written informed consent for print and electronic publication of this case report.
Case Report
The patient is a 46-year-old woman who was involved in a motor vehicle collision. She was triaged as a trauma patient via Advanced Trauma Life Support protocol, and treated with antibiotic and tetanus prophylaxis. Radiographs showed an open, comminuted, displaced intra-articular distal radius fracture on the right side (Figures 1A, 1B). The fracture was closed reduced and splinted in the emergency department (Figures 2A, 2B). On initial examination, the patient had diffuse paresthesias in the digits that were most pronounced in the median nerve distribution. Motor examination was limited secondary to pain; however, she demonstrated gentle flexion and extension of the digits. The hand was well perfused, and a palpable radial pulse was present.
After clearance was obtained, she was taken urgently to the operating room. The wound was volar and transverse, approximately 2 cm in length, and approximately 4 cm proximal to the wrist crease. The wound was extended proximally and distally for a standard volar (Henry) approach. The flexor carpi radialis tendon was found to be partially lacerated, comprising 60% of the tendon. The fracture was readily identified because the deep fascia and the pronator quadratus were disrupted. No deep tendon lacerations were identified. The median nerve was found to be in continuity. After satisfactory débridement of the fracture and the wound, reduction and fixation was achieved with a volar locking plate and a single Kirschner wire. The flexor carpi radialis tendon was repaired with a modified Kessler stitch and epitenon repair. The wound was closed primarily in layers (Figures 3A, 3B).
The patient’s immediate postoperative neurologic examination was compromised secondary to the patient having a supraclavicular nerve block for anesthesia. Regional anesthesia was chosen because the patient’s pulmonologist recommended avoiding general anesthesia owing to her history of severe asthma that frequently required corticosteroid treatment. Once the block wore off, she complained of persistent paresthesias in all digits but most pronounced in the median nerve distribution. She was able to flex the interphalangeal joint to the index finger but could not flex the interphalangeal joint to the thumb. Over the course of the night, she was also noted to have worsening pain out of proportion to her injury.
As the paresthesias became denser in the median nerve distribution, she was diagnosed with acute CTS and was taken urgently back to the operating room under general anesthesia. After releasing the carpal tunnel through a separate incision, the original wound was reopened and explored. The median nerve was again visualized and found to be in continuity. All 4 tendons to both the flexor digitorum superficialis and flexor digitorum profundus were identified. The flexor pollicis longus (FPL) was not visualized in the wound. The distal portion of the FPL was retracted in the thumb tendon sheath and retrieved blindly with a tendon passer. The proximal portion was retracted to the mid-forearm. The laceration occurred distal to the musculotendinous junction. The tendon was repaired with a modified Kessler stitch as well as a box suture, resulting in 4 core strands across the tendon. The hand and the wrist were splinted in a thumb spica cast, and the patient was started on a modified Duran protocol 1 week after surgery. Median nerve function improved postoperatively.
Discussion
The rupture of the extensor pollicis longus tendon in nondisplaced distal radius fractures is not uncommon, but occurs in fewer than 5% of nondisplaced distal radius fractures.1 Although less common, chronic complications with flexor tendon rupture after distal radius fracture are well described.1-6 Flexor tendon rupture after distal radius malunion or volar plating is a known complication and is thought to be the result of attritional tendon wear because the flexors rub against protruding bone or plate;3,4,7 however, the initial tendon injury may play a role in those tendons that rupture more quickly.3 When secondary to volar plating, the rupture typically occurs within 1 year of injury,7 but, in both plating and malunion, it has been characterized as a late complication up to 10 years and even 20 years after injury.3,4 Similar to other reports, this rupture was encountered during a volar wrist approach. It has been suggested that, as the incidence of volar plating rises, more acute flexor tendon injuries may be diagnosed because of anatomic exposure,2 but this has not been reported in the literature.