From the Guidelines
Decreased wrist extension is most commonly caused by fractures, particularly of the distal radius, tendon injuries such as extensor tendon ruptures, and arthritis, which can lead to significant morbidity and impact quality of life if not properly managed. The radial nerve, which controls wrist extension, may be compressed or injured at various points along its path, particularly at the spiral groove of the humerus or the radial tunnel 1. Carpal tunnel syndrome, though primarily affecting the median nerve, can sometimes impact wrist mobility. Muscle weakness affecting the extensor carpi radialis longus and brevis muscles can occur due to disuse, neurological conditions, or systemic diseases.
Some key causes of decreased wrist extension include:
- Fractures of the distal radius (Colles' fracture) or scaphoid bone, which can be diagnosed using radiographs as the first imaging test, and advanced imaging with MRI or CT if necessary 1
- Tendon injuries such as extensor tendon ruptures or tenosynovitis (inflammation of the tendon sheath) commonly affecting the extensor tendons crossing the wrist
- Arthritis, particularly rheumatoid arthritis and osteoarthritis, which can cause joint damage and inflammation limiting wrist movement
- Nerve damage, including radial nerve compression or injury, which can be evaluated using MRI without IV contrast to detect ligament injuries and concomitant soft-tissue injuries 1
Treatment depends on the underlying cause and may include physical therapy, anti-inflammatory medications, splinting, corticosteroid injections, or surgery in severe cases. Early diagnosis and appropriate management are essential to prevent permanent loss of function and chronic pain, highlighting the importance of radiographs as the initial imaging test and the selective use of advanced imaging techniques like MRI or CT based on clinical suspicion and the specific location of pain 1.
From the Research
Causes of Decreased Wrist Extension
- Radial nerve palsy can cause decreased wrist extension, resulting from direct trauma, neuropathies, and fracture over the humerus, malignant tumor, and neuritis 2
- Posterior interosseous nerve (PIN) palsy can also lead to weakness of extension of the fingers and may be confused with extensor tendon rupture and wrist drop due to radial nerve damage 3, 4
- Wrist extensor muscles are prone to certain focal musculoskeletal disorders, and the activation pattern of the extensor carpi radialis (ECR) and ulnaris (ECU) muscles may be important risk factors 5
- In patients with extended upper brachial plexus palsy, motor deficit can be variable, and a patient with only thumb and finger extensors may seem to have active wrist extension because of them secondarily acting at wrist and causing wrist extension 6
- Rheumatoid arthritis can cause PIN palsy, resulting in pain involving the elbow, paralysis or weakness of digit extension, and decreased wrist extension 3, 4