Why are pregnant women more prone to tenosynovitis?

Many pregnant women are prone to tendon inflammation in the middle of pregnancy. After it happens, they will feel extreme pain in their wrists, and even their range of motion will be shorter than before. They are also unable to take any medication for fear of damaging the health of the fetus in their womb. This will make pregnant women feel very uncomfortable. In fact, after it happens, you can still use hot compresses to appropriately improve the symptoms.

1. Radial styloid stenosing tenosynovitis

Two tendons pass through the first fibrous bone sheath on the dorsal side of the wrist, namely the tendons of the abductor pollicis longus and the extensor pollicis brevis. After passing through the narrow sheath, the two tendons form a certain angle with the sheath and end at the base of the first metacarpal bone and the base of the proximal phalanx of the thumb, respectively. When the wrist and thumb have a wide range of motion, the angle of the tendon increases. Over time, the local synovium becomes inflamed and thickened, the tendon becomes thicker, the fibrous sheath wall also thickens, and subcutaneous nodules appear at the radial styloid process, making it difficult for the tendon to slide in the sheath, causing symptoms such as pain. Due to endocrine changes in lactating and menopausal women, the synovium is easily affected and this is the main reason why the disease is more common in women.

In addition to the above reasons, there are many anatomical variations that can easily cause the occurrence of this disease. For example, if the belly of the palmaris pollicis longus or the extensor pollicis brevis is too low, part of the belly may enter the sheath; because there are more vagal tendons in the sheath, the number of tendons increases significantly, sometimes with more than ten tendons; there are also hard, thick and tough fibrous septa in the first dorsal wrist sheath, which makes the originally narrow sheath even narrower and the tendons are easily incarcerated. These anatomical variations cause the disease to occur at a younger age and make conservative treatment difficult to be effective.

2. Myosinitis

The radial extensor carpi longus and brevis muscles are located on the deep side of the proximal end of the dorsal carpal ligament, and the extensor pollicis brevis and abductor pollicis longus muscles pass through the superficial side at a certain angle. When muscles are overactive, the muscles, tendons, and the surrounding fascia and peritendinous tissues become congested and edematous. The synovial fibrinous exudate increases, and symptoms such as local redness, swelling, and pain appear.

It often occurs on the thumb, middle and ring fingers, and the age of onset is generally over 40 years old. In the early stage of the disease, snapping and pain occur when the fingers are flexed and extended, so it is also called "trigger finger". Patients often report inflexible joint movement and swollen joints. In severe cases, the joint is locked in flexion or extension, and the joint cannot be straightened or flexed. This disease occasionally occurs in children, with the thumbs on both sides in a flexed position and unable to be actively straightened. In mild cases, the thumb can be straightened through local massage when the child is asleep. In severe cases, the thumb cannot be straightened even passively.