However, some patients suffer neurologic deficit; such as weakness, incontinence, or develop spinal instability. The cause of severe symptoms often determines the type of surgery needed. For example, it may be necessary to surgically remove bone spurs or disc tissue compressing spinal nerves or causing spinal cord compression. Depending on the extent of the surgery, spinal fusion to stabilize the spine may be necessary. Fortunately, newer minimally invasive spine surgical techniques greatly benefit patients. Minimally invasive spine surgery enables patients to return to normal activities sooner.
The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine .