The first carpometacarpal joint
This one of the few joints affected by osteoarthritis in which the response to steroid injection is rewarding – the other joint responding well to steroid injection is the acromioclavicular joint. This type of osteoarthritis is commonly described as ‘washerwomen’s thumb’, as it follows the repetitive chores undertaken in the course of domestic work.
Presentation and diagnosis
The patient commonly complains of aching around the joint, and examination reveals pain on passive backward movement of the thumb in extension. Often osteophytes are present, noted on X-ray examination. These may render injection into the small joint space difficult.
This joint is the articulation of the first metacarpal with the trapezium bone of the wrist. Extension and abduction of the thumb causes pain and there is deep tenderness in the ‘anatomical snuffbox’ at the joint line, which is more easily palpable when the subject flexes and tucks the thumb into the palm. The joint space, although small, will accept an injection of about 0.5 ml of steroid solution.
The patient tucks the thumb as far into the palm as possible and holds it there with the index and middle fingers. Palpate the joint line dorsally and then inject from the lateral aspect, taking care to avoid the abductor pollicis tendon as it marks the border of the snuffbox. Use a 1.6cm needle and inject up to 0.5ml triamcinolone acetonide. No lidocaine is required, although some doctors prefer to use an equal quantity of lidocaine 1% plain.
This extract is taken from Joint and Soft Tissue Injection 5th Edition, by Dr Trevor Silver which is now available to purchase from Radcliffe Publishing.
– Confidently diagnose conditions of the joints and soft tissue.
– Understand the benefits and pitfalls of steroid injections.
– New content – sports physiotherapy, elbow joint, iliotibial band syndrome and updates on greater trochanter pain syndrome.
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