Review Question - QID 217945

Phalanx Fractures QID: 217945 (SBQ21H.32)

QID 217945 (Type "217945" in App Search)

Figure A is the radiograph of a 32-year-old male that presents to your office after injuring his finger at work. Due to the unstable nature of the injury and dorsal subluxation of the distal phalanx, the decision is made to proceed with open reduction and internal fixation. With respect to this injury, what is the origin of the structure that most likely contributed to the avulsion fracture seen in the radiographs?

Type & Select Correct Answer

Type in at least one full word to see suggestions list

Anterior medial proximal ulna

41%

368/905

Distal middle phalanx

57/905

Medial epicondyle

29%

259/905

Lateral epicondyle

11/905

Tendons of the flexor digitorum profundus

22%

202/905

Select Answer to see Preferred Response

The patient has an avulsion fracture of the distal phalanx likely secondary to the flexor digitorum profundus (FDP) tendon. The origin of the FDP is the anterior medial proximal ulna.

Distal phalanx base fractures are often unstable. The mechanism of injury can be shearing due to axial load, leading to a fracture involving >20% of the articular surface, or an avulsion due to tensile force of the terminal tendon of the FDP, leading to a small avulsion fracture. The origin of the FDP is the upper three-fourths of the anterior and medial surface of the shaft of the ulna, the medial surface of the olecranon and coronoid processes of the ulna, and the adjacent anterior surface of the interosseous membrane. Indications for operative stabilization of distal phalanx fractures include: (1) displaced or irreducible shaft fractures, (2) dorsal base fractures with >25% articular involvement, (3) displaced volar base fractures with large fragment and involvement of FDP, and (4) non-unions.

Shah et al. reviewed fracture-dislocations of the hand. They reported that the keys to treatment include early recognition, stable concentric reduction, and protected early active range of motion maintaining joint stability. They concluded that with appropriate treatment, residual stiffness and pain can be minimized.

Freilich et al. reviewed the flexor tendon system in the finger. They reported that closed injuries to the flexor tendon or pulley system are not uncommon in high-level athletes. They concluded that flexor tendon avulsions, require prompt recognition and appropriate treatment to prevent permanent disability to the hand and finger.

Figure A is the radiograph of the finger that demonstrate a distal phalanx base fracture with dorsal subluxation

Incorrect Answers:
Answer 2: The volar plate originates from the distal phalanx. However, large fragments like the ones seen in the radiographs are most commonly caused by avulsion from the FDP
Answers 3&4: The medial and lateral epicondyles give rise to several structures of the hand, but not the FDP
Answer 5: The lumbrical muscles originate from the tendons of the FDP