Thumb MP Joint Fusion

Thumb Anatomy

The bones in the hand are called metacarpals and the bones in the finger are called phalanges. The joint formed by the finger bones and the hand bones are called metacarpophalangeal joint (MP joint) or knuckle. The MP joints help your fingers move in many directions, straighten, bend, move together and spread apart, and are important for pinching and gripping actions.

MP Joint Arthritis

Arthritis is an inflammatory condition of the joints. Arthritis at the MP joint commonly occurs in the index finger and thumb because of the stress of pinching action.

There are several types of arthritis; the most common type is osteoarthritis or wear-and-tear arthritis that affects the joint at the base of the thumb. Thumb arthritis is more common in women than men, and usually occurs after the age of 40 years. Arthritis of the fingers may cause swelling, pain, stiffness and malformation; all of which interfere with the use of your hand.

Treatment Options for Thumb Arthritis

Non-surgical treatment methods for relieving pain in an arthritic joint include activity modification, pain medications, and use of splints and steroid injections.

Indications for Thumb MP Joint Fusion

Surgery is usually considered in the following cases:

  • Non-surgical treatments fail to provide relief
  • Joints are severely damaged
  • There is limited mobility
  • Damage to the surrounding ligaments and tendons
  • Failed previous arthroplasty
  • When heavy manual use is expected

Thumb MP Joint Fusion Procedure

A fusion, also called an arthrodesis, involves the removal of the joints and fusion of the bones of the joint using metal wires or screws.

The surgery is performed under local or general anesthesia and usually takes about 2 hours to complete. A cut is made over the back of the thumb MP joint and the soft tissues and nerves are carefully moved aside to expose the damaged joint. The damaged articular cartilage on the ends of the bones is removed. Next, a hollow is created in the bones and prepared to accept the prosthesis. The prosthesis is then inserted into the hollowed ends of the bones, ensuring a snug fit. A ligament nearby is then wrapped around the prosthesis to provide even more stability. The soft tissues are then stitched back together, and the hand is placed in a cast until the bone is fully healed.

Postoperative Care for MP Joint Fusion

Following the surgery, your hand will be placed in a cast for six weeks to allow the fusion to heal. You will be instructed to keep your arm propped up to avoid throbbing and swelling. You will be prescribed medication to control any pain and discomfort. A follow up appointment will be made with your surgeon five to seven days after the surgery to assess your progress.

Your surgeon will order physical or occupational therapy to help in your recovery. You will start with heat therapy, massage and other therapies to reduce pain and muscle spasm. Following this, you will be started off on range-of-motion and strengthening exercises.

Risks and Complications for MP Joint Fusion

As with any major surgery, there are potential risks involved. Some of the risks and complications following MP joint fusion include:

  • Infection
  • Nerve damage or nonunion (failure to heal) of the finger joints
  • Repeat surgery if joint movement from a nonunion causes pain