What is the diagnosis?

Flexor tendon laceration. He sustained a laceration to the palmar aspect of his right hand with involvement of the flexor tendons.

Image 2. Ultrasound of the distal palm shows a complete laceration of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons with a defect between the retracted tendons measuring 21 mm. Case courtesy of Maulik Patel, Radiopaedia.org, rID: 76841

What is the mechanism of injury?

A laceration is the tearing of tissue caused by shearing forces or blunt trauma. In the patient’s case, the circular saw caused significant shearing force to the hand resulting in a laceration to the skin as well as deeper structures including tendons.

What physical exam findings are expected?

On initial inspection of the wound, the tendon may or may not be visible depending on the laceration. Regardless, it is important to explore the entire depth of the wound as best as possible without causing further tissue injury. When evaluating the integrity of the flexor tendon we should restrict motion of the metacarpal phalangeal (MCP) joint. If the patient is unable to actively flex the proximal or distal interphalangeal joints this is suggestive of injury to the FDP and/or FDS tendons respectively [2]. Without injury to the neurovascular bundle, the patient should have intact sensation and a normal capillary refill distal to the injury.

• Pearl: Tendinous injuries are diagnosed clinically based on physical exam

• Pearl: The FDP tendon inserts on the distal phalanges and is responsible for flexion at the MCP and DIP joints. The FDS inserts on the middle phalanges and is responsible for flexion at the MCP and PIP joints.

Image 3. Flexor tendon insertions of the palmar hand. Case courtesy of Roberto Schubert, Radiopaedia.org, rID: 14718, https://radiopaedia.org/cases/14718.

What is the management in the ED?

It is important to inspect the wound as best as possible, making note of injuries to underlying fascia or deeper structures such as tendon or bone. When dealing with deep wounds it is important to have a clear view and hemorrhage control is vital to providing that. A tourniquet could be briefly used if needed. Once hemostasis is achieved, a thorough exam of the hand is required to evaluate for neurovascular or tendon injury.

The next step is debridement of any foreign bodies and irrigating the wound. Irrigation is the most important step in reducing the chance of wound infection. In the event of a wound that is suspected to violate deeper structures, extensive irrigation is recommended to ensure adequate washout. Proper irrigation may require pain control with local injection or digital block.

• Pearl: If there is suspected bony involvement, X-ray is recommended to evaluate for open fracture which may be managed differently.

When do you consult a specialist?

If there is concern for a flexor tendon injury, emergent/urgent hand surgery consultation is recommended. This may include orthopedics or plastic surgery. If a hand surgery consultant is not available at a given institution, transfer to another facility where these services are available is warranted.

Further ED management may include loose skin closure and immobilization with a splint to limit proximal tendon retraction. Prophylactic intravenous antibiotics and tetanus vaccination are typically recommended. Depending on system capabilities, patients may be discharged home with urgent follow up for surgical repair within 1-2 weeks, generally the earlier the better. However, not all tendon injuries are created equal and certain nuances lead to differences in operative planning as directed by hand surgery [4].