... still you may run into problems. Some afflictions just turn up when bass technique is perfect, Some problems with hands, arms and shoulders have little or nothing to do with playing the bass guitar. Lack of knowledge about these might urge players to either change their technique or their hardware to no avail.
A trigger finger is one that snaps back from a bent position. In a bad case, it may get locked completely.
Trigger finger is caused by the repetitive strain from gripping movements that may occur even with correct technique. Mild cases of trigger finger may be cured completely by exercise. Consequently, trigger finger may be prevented by hand and finger stretching exercises.
Ganglion cysts are permanent swellings on joints or tendon covers. They can hardly be related to bass guitar technique. If, however, the cyst is located at the inside of the wrist, it might compromise the median nerve that is directing the motions of thumb, index and middle finger. See a doctor before things get worse.
Nodes are bony formations caused by osteoarthritis of the joints of fingers (and toes) that show up at middle age. They are unlikely to be caused by bass playing, since in the way most of us play, the finger joints are kept in a rather immobile, neutral position. However, if you experience sudden swelling and pain, it is better to see a doctor and stop playing till the pain stops.
Rheumatism is a connective tissue inflammation with a wide variety of causes. There is no direct connection with bass guitar playing, unless a rheumatic inflammation is caused by one of the repetitive strain injuries we already dealt with, such as the carpal tunnel syndrome. In case of swollen hands, pain or loss of sensitivity, stop playing and see a doctor. Only resume playing once the inflammation has been cured.
Dupuytrens Contracture is the shrinking of a layer of tissue under the skin of the hand palm causing lumps, dimples or a bending of the fingers. Causes are unclear, most probably genetical. There is no causal relation to bass playing. Treatment in an early stage is necessary for full recovery. Even then, the disease may return.
Entrapments of nerves, muscles and blood vessels are a serious threat to the bassist. Quite a few of these entrapments are not caused by playing, but due to other kinds of repetitive strain or bad posture. Spine and bone conditions as well as long forgotten injuries may contribute also. If you feel tingling or pinching, lack of muscle strength or suspect low blood flow in your arm, see a doctor right away. Irreparable damage is looming. A common example is thoracic outlet syndrome (TOS), an entrapment of the arm nerves (90% of cases), muscles or veins. You may get it from long or repeated work with the arms above the head or from computer work keeping the keyboard extremely low. Again, problems arise where people go to the limits of what a joint can take. Bass guitar playing is a highly improbable cause for TOS, but may well may well be impaired by it.
Cubital tunnel syndrome may result from keeping the elbow fully flexed for a long time, like when on the phone or sleeping on your arm. The connection with bass playing is unclear, though some sources say that repetitive flexing of the elbow in combination with pressure better be avoided. This could occur if the neck of the bass is kept very close to the shoulder. As the cubital tunnel syndrome is easily confused with some common neck and shoulder problems, see a doctor before taking any measures.