Thumb CMCJ Replacement Surgery

Thumb CMCJ Replacement Surgery

Patient Information

Hand Therapy Department

• Author ID:             DA
• Leaflet Number:     Tpy 081
• Name of Leaflet:    Thumb CMCJ Replacement Surgery
• Date Produced:     October 2024
• Expiry Date:          October 2026

Introduction

This leaflet is to provide advice and exercises following your Carpometacarpal Joint (CMCJ) replacement surgery. Each person’s operation is individual, and you may be given instructions specific to you that are not contained within this leaflet.

What is a CMCJ replacement?

The CMCJ is the articulation between the trapezium (carpal) bone in your wrist and the first metacarpal bone located at the base of your thumb. This joint is susceptible to osteoarthritis because of its mobility, and the large forces transmitted through this joint when using your hand. The joint surfaces and ligaments wear down, causing pain at the base of the thumb.

A CMCJ replacement involves replacing the painful surface at the base of your thumb with an artificial joint, also known as a prosthesis. Benefits can include reduced pain and thereby improved function of the thumb.

CMCJ replacement implant

CMCJ replacement X-ray

Risks

Your doctor will discuss with you the risks involved prior to this operation.

Specific complications of a CMCJ replacement include: 

• Ongoing pain / swelling / stiffness in the thumb 
• Numbness due to damage of nerves that are situated close to the operation site
• Reduced pinch grip strength
• Risk of intraoperative fractures and conversion to trapeziectomy (removal of the trapezium bone)  
• Dislocation or loosening of the prosthesis in the long-term, requiring a revision operation

General complications associated with surgery include: 

• Bleeding
• Wound infections
• Scarring of the skin over the operation site
• Complex Regional Pain Syndrome

During the operation

The operation is performed as a day case, so you can normally return home the same day. There are different types of anaesthetics that can be used, and the Doctor will discuss the options with you before the operation. Broadly, these are general anaesthetic, where you are put to sleep, or a regional block, where injections are used to numb the arm, and you are awake during the procedure. 

You will have an incision at the base of your thumb. The skin will be closed using stitches and then a bulky dressing or plaster cast is then applied to your hand. This will remain in place for 1-2 weeks. 

After the operation 

Pain

Your hand may cause you some discomfort following the operation. You will be given advice regarding pain relief medication.

Swelling

You should keep your arm elevated intermittently to reduce the swelling. You may be given a sling to rest your arm post-op. Resting your hand using pillows underneath it while sitting in a chair or in bed at night will help.

Rehabilitation

You will get an appointment to see the team within 7-14 days after surgery for removal of your dressing and to check the wound.

Within this time, you will also see the Hand Therapy Team, where you will be given a splint to protect the joint replacement. Your thumb will be immobilised for a minimum of 2 weeks. You will be shown some exercises to maintain the movement in the unaffected joints of the arm and hand, including your shoulder and elbow.

Your Hand Therapist will guide you on exercises to move your thumb when appropriate. An X-ray will be performed within 6 weeks of your operation to check the position of the implant. 

2 - 4 weeks

• Avoid gripping, pinching or lifting anything heavy with your operated hand 
• Continue to wear your splint full-time, apart from when performing your exercises

Exercises

None of the exercises should be painful; however, it is normal to experience some discomfort. You should aim to practise the exercises little and often throughout the day. 

If you feel you have done too many, rest the hand until it feels comfortable, and slowly build up the exercises again. 

Thumb extension: 

Rest your hand on a table on the little finger side, with the thumb relaxed. Lift your thumb (as shown). Repeat 10 times.

Thumb abduction:

Rest your hand on a table on the little finger side, with the thumb relaxed. Move your thumb outwards keeping the end thumb joint slightly bent (as shown). Repeat 10 times.

Thumb opposition:

Rest your hand on a table, with the thumb relaxed. Bring your thumb across to touch the tip of your index finger only. Ensure you make an ‘O’ shape when the fingertips touch, keeping the thumb joints slightly bent (as shown). Do not squeeze. Repeat 10 times.

Scar Care

Once the wound is fully healed, it is important to start scar massage. To do this, you should use unscented moisturising cream.  Apply a gentle pressure to the length of the scar 3 to 4 times a day for a few minutes each time.  This will help the scar to heal, flatten and will reduce any tenderness.

Some people experience increased sensitivity of the scar, which can be unpleasant. To desensitise the area, you should continue with scar massage and practise touching the area with different textures using different pressures.

4 - 6 weeks

• Depending on your pain levels and thumb stability, at this stage you may be given a different splint
• You will be advised on increasing light function as comfort allows, whilst wearing the splint
• Avoid weight-bearing through the hand and wrist and avoid repetitive gripping and heavy lifting
• Continue scar management as appropriate

Exercises

As guided by the Hand Team, you may progress exercises. Repeat these little and often throughout the day:

Thumb opposition: 

Bring your thumb across to touch the tip of each finger. Repeat 10 times.