Base of Thumb Arthritis
What is Base of Thumb Arthritis?
In a normal joint there is a 2mm cartilage lining covering the bones which allows smooth, painless movement and acts as a cushion. When this cartilage lining wears out bone moves on bone. This age-related condition is osteoarthritis. Injury to the joint such as fractures that damage the joint lining or ligament injuries that cause instability can also result in arthritis. Inflammatory diseases such as rheumatoid and psoriatic arthritis also damage the joint and are known as inflammatory arthritis.
The joint at the base of the thumb is called the first carpometacarpal joint. A wrist bone called the trapezium and the first metacarpal bone form this joint. The unique ‘saddle’ shape of these bones allows enormous freedom of movement. Base of thumb osteoarthritis is far more common in women than men, and typically occurs after the age of 50. It is often hereditary.
What are the signs & symptoms?
The earliest symptom of base of thumb arthritis is pain with activities that involve pinch. These include opening jars, door handles, car doors and turning keys. Repetitive grasping activities or heavy lifting may cause aching pain at the base of the thumb. Changes in the weather may also cause pain. As the arthritis gets worse, pinch and grasp become weaker and swelling and deformity of the joint occurs.
How is the diagnosis made?
Most patients will be aware of the signs & symptoms that have been described above. There is usually deformity/prominence of the base of thumb and tenderness. The ‘grind’ test is used to compress the joint and reproduce the pain. It may also produce a gritty sound called ‘crepitus’. This is due to bone contact against bone.
X-ray will demonstrate arthritis however, the severity of the symptoms does not always correspond to the symptoms. Older patients may have severe arthritis on x-ray with no symptoms and younger patients may have very early arthritis and be quite disabled by pain.
Overlap of symptoms from carpal tunnel syndrome & base of thumb arthritis Many patients with base of thumb arthritis will also have carpal tunnel syndrome. The carpal tunnel is narrowed by base of thumb arthritis and carpal tunnel syndrome is very common in women over 50 years of age. The median nerve in the carpal tunnel supplies the sensation (feeling) to the thumb and power to the muscle at the base of the thumb (thenar eminence). So, both conditions may cause thumb pain and aching in the wrist and thenar eminence. An ultrasound of the carpal tunnel may be recommended. Occasionally a trial of a carpal tunnel steroid injection may be recommended to help distinguish which symptoms are from the carpal tunnel versus the base of thumb.
Non-operative treatment
Non-operative treatment is often very effective for base of thumb arthritis and should be trialled before considering surgery. It includes:
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Lightweight splints: Comfort Cool or similar (most pharmacies) Push-brace (hand therapist)
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Panadol Osteo - 2 tablets 2-3 times every day
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Anti-inflammatories - short (5-7 day) courses when symptoms flare up. (e.g. Meloxicam, Naproxen)
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Specific exercises - to strengthen the first dorsal interosseous muscle have been clinically proven to decrease symptoms.
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Activity modification - to minimize irritating the joint.
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Devices to assist with daily activities (e.g. Avant jar opener, Pen again)
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Steroid injections are rarely recommended as they provide only temporary relief. Steroid injections should not be given more than 3 times in the same location due to the risk of cartilage damage.
You may be referred to a hand therapist to assist in managing your arthritis. The aim of non-operative treatment is to provide you with the tools and knowledge to manage your arthritis so that it does not interfere with your lifestyle.
Surgery may be advised when non-operative treatment is not helpful. Active people in the 50–65-year age group are more likely to require surgery. Older people with lower demands often have excellent symptom control with non-operative treatment.
More information about non-operative management of arthritis.
Surgical Treatment
When the symptoms of base of thumb arthritis cannot be adequately controlled with non-operative treatment, surgery may be considered. As this is a significant operation with a 6-12 month recovery, it is best considered when non-operative treatment is no longer effective and functions is significantly affected. he goal of surgery is to decrease pain and keep motion in the thumb. The procedure is called "Trapeziectomy and Suture Suspension Arthroplasty" It is performed under general anaesthetic and most patients stay overnight in hospital for pain relief. The surgery involves removing the trapezium bone (trapeziectomy). Next, a fiberwire suture is woven several times between two tendons at the base of the thumb. This creates a "hammock" to "suspend" the thumb (suture suspension arthroplasty). The space created by removing the trapezium fills with fluid and develops a scar tissue which stabilises the thumb by 3-4 months.
Surgery is performed under general anaesthetic and takes 60-90 minutes. The hand and wrist are immobilised in a bulky dressing with a fibreglass splint to protect the thumb. The splint will reach from your thumb to approximately 10cm below the elbow. Most patients will stay in hospital overnight for pain relief.
What are the risks of surgery?
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Infection < 1% risk of infection
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Nerve injury - there is a very low risk of injury to skin nerves that may leave a small patch of numbness over the back of the thumb/hand. This may also develop into a small neuroma that is tender to touch and causes ongoing pain.
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Proximal migration of the thumb metacarpal <3%. This is when the thumb moves into the space created when the trapezium bone is removed. It can cause pain if it comes in contact with the scaphoid bone. In this situation, further surgery may be required to re-suspend the thumb.
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Carpal tunnel syndrome Base of thumb arthritis narrows the carpal tunnel and means that you are at increased risk of carpal tunnel syndrome. Even if you have had no carpal tunnel symptoms, the swelling that occurs after surgery can put pressure on the median nerve and cause severe pain, swelling and stiffness, compromising your recovery from surgery and requiring a second surgery to perform a carpal tunnel release. You will be assessed for carpal tunnel syndrome prior to surgery and may be advised to have a carpal tunnel release at the time of your base of thumb arthritis surgery.
What about recovery?
Discomfort is expected in the first 3 months and improves with time. No strong grasp or pinch is allowed for 3 months to allow enough healing for stability of the thumb. It will take up to a year for the maximum benefits of surgery to be reached. Pain is greatly improved with surgery, but you may still have some occasional mild discomfort. Strength is usually also improved following surgery.
2 weeks: Bulky bandage & half cast from forearm to hand is removed. Changed to light weight splint.
4 weeks: Splint shortened to wrist level and physiotherapy commenced. Driving, typing, writing may recommence. (Pen Again is helpful for writing.)
8 weeks: Light gardening, golf, bike riding etc with splint. No strong gripping or heavy lifting.
12 weeks: Activities unrestricted but may still prefer flexible splint for more repetitive tasks/sports.
6 -12 months: Maximum strength & pain relief