From the Guidelines
Flexor pollicis longus (FPL) rupture is primarily caused by trauma, particularly penetrating injuries to the hand or wrist, and fractures of the distal radius or scaphoid, as well as non-traumatic causes such as rheumatoid arthritis and mechanical irritation from hardware following surgical procedures 1.
Causes of FPL Rupture
The causes of FPL rupture can be categorized into traumatic and non-traumatic causes. Traumatic causes include:
- Penetrating injuries to the hand or wrist
- Fractures of the distal radius or scaphoid Non-traumatic causes include:
- Rheumatoid arthritis, which can weaken the tendon over time due to inflammation
- Mechanical irritation from hardware following surgical procedures, such as volar plate fixation for distal radius fractures
- Steroid injections in the wrist, which can weaken the tendon and contribute to rupture
- Infection, which can degrade tendon integrity
- Congenital anomalies that predispose to tendon weakness
- Repetitive microtrauma from occupational activities requiring forceful thumb flexion, leading to tendon degeneration and eventual rupture
Diagnosis and Imaging
MRI is ideal for evaluating tendon injuries, including FPL rupture, and helping with surgical planning 1. It can accurately depict the pulley system, particularly the A2 and A4 pulleys, and diagnose injuries to the central slip or the extensor hood.
Treatment
Prompt surgical repair is typically required to restore thumb function, as the FPL is crucial for pinch grip and fine motor activities involving the thumb.
From the Research
Causes of Flexor Pollicis Longus (FPL) Rupture
The causes of FPL rupture can be attributed to various factors, including:
- Friction between the distal edge of a volar locking plate and the FPL tendon after distal radius fractures, as reported in studies 2, 3
- Entrapment of the FPL tendon by the volar locking plate itself, leading to rupture 3
- Trigger thumb preceding FPL tendon rupture after distal radius volar plate fixation, suggesting a potential warning sign for impending FPL rupture 4
- Scaphoid nonunion, where the FPL tendon can abrade on sharp mobile volar scaphoid osteophytes, leading to rupture 5
- Tendolipomatosis, a condition characterized by degenerative changes associated with lipid deposits in the tendon tissue, which can cause spontaneous FPL tendon rupture 6
- Attrition of the flexor tendon by the prominent volar plate or theoretical injury to the tendon during the initial injury, as suggested in study 4
Risk Factors and Complications
Risk factors for FPL rupture may include:
- Previous distal radius fractures and subsequent fixation with a volar plate
- Scaphoid nonunion
- Trigger thumb
- Tendolipomatosis Complications of FPL rupture can include loss of thumb function, reduced grip strength, and decreased range of motion, highlighting the importance of early diagnosis and treatment 2, 5, 6