To strengthenthe muscles which attach to the outside of the elbow and the hand which help to extend the hand (the wrists and fingers).
Stand with the affected hand suspended by your side with the palm facing backwards. Grasp a small weight (to be determined by your osteopath e.g. 1kg)
In a slow and in a progressive manner extend the wrist upwards. At the end of range hold for 5-10 seconds. Ensure you keep the elbow fully extended throughout the exercise. Relax your hand and repeat as prescribed.
You can improvise with a narrow bottle of water. If you suffer from connective tissue disease like rheumatoid arthritis ensure that you discuss this exercise with your osteopath.