Last week we discussed the elbow, this week we cover the wrist.

The wrist is composed of eight bones, and provides a huge variety of movements to consider. The wrist also provides a key diagnostic area for certain types of arthritis, specifically rheumatoid arthritis. Due to its position, the bones of the wrist are often subject to fracture and dislocation when falls occur.

One of the key issues in wrist fracture is the possibility of the blood vessels which pass along the wrist bones being damaged along with the fracture. The two bones of the wrist most associated with complications are the scaphoid and lunate bone. Both these bones have relatively high rates of complications with injuries due to compromised blood supply. This compromised blood supply can lead to a condition called avascular necrosis, which is a fancy way of saying that the bone does not get enough blood and therefore begins to die.

Avascular necrosis is often very insidious, in that it may take months or years for the lack of blood to cause enough damage to cause significant pain. Once the bone is deprived of blood, the cells that maintain the bone die. The early stages of osteonecrosis show no changes on an X-ray and may require an MRI to see it. Once the bone cells die, the body loses the ability to maintain the bone, which eventually leads to collapse of the bone. At this point the bone will need to be surgically replaced either with a bone graft, or artificial joint. The nerves that pass through the wrist are also subject to concern. The median nerve passes through the center of the wrist, and is the nerve involved in carpel tunnel syndrome.

When the median nerve is compressed in the carpel tunnel, it causes numbness and pain in the thumb and the first two fingers of the hand. Of importance to note, the median nerve also feeds the large muscles at the base of the thumb, and area called the thenar eminence.

When there is compression of the median nerve, the thenar muscles will begin to atrophy, which may occur before any pain. The median nerve begins in the neck, and travels down inside the arm and through the front of the forearm before passing into the wrist. The median nerve can be compressed at multiple areas, not just the wrist. Compression of the median nerve at the neck, shoulder, or elbow can cause almost the exact same symptoms as compression at the wrist, so if you are having pain and numbness in the first three fingers, don’t be too quick to jump to the wrist as the source of the problem.

One interesting diagnostic note, a branch of the median nerve called the palmar cutaneous sensory branch divides from the main median nerve in the forearm, before the carpel tunnel. This branch provides sensory input to the palm of the hand. Which means if you are truly having carpel tunnel issues, you will not have sensory changes to the palm of the hand, only the first three fingers.

Dr. Joseph Fraley D.C. is the owner of Alpha Omega Chiropractic, 106 Alpine Village Road. Contact Fraley at 575-258-5999.

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