Extending the Life of Joint Prostheses

(Australia—Australian Family Physician, November 1999, p. 1109.) Most conventional joint prostheses are made of metal and plastic and are fixed to the skeleton with polymethylmethacrylate cements. Wear and cement breakdown can cause these devices to deteriorate. Because of these shortcomings, cementless fixation has been the subject of study. Cementless fixation depends on prosthesis design plus ingrowth and overgrowth of bone to biologically bind the prosthesis to the skeleton. The prosthesis and the receptor site have to be accurately prepared to ensure excellent fit in cementless fixation. The surfaces of the prosthesis are textured to maximize surface area and are often coated with substances such as hydroxyapatite to encourage active colonization of the prosthesis by new bone. Another approach to improving durability has been the development of metal-on-metal articulations. Although the rate of wear is reduced, the potential effects of microscopic metal particles on local tissues and the systemic circulation remain a concern.

When to Measure Prolactin Levels

(New Zealand—New Zealand Family Physician, October 1999, p. 12.) The hormone prolactin is secreted by the anterior lobe of the pituitary gland. In normal adults, prolactin secretion increases within 90 minutes of falling asleep and peaks between 4 a.m. and 7 a.m. Prolactin levels are elevated by physiologic conditions such as pregnancy, exercise and stress. Certain pathologic conditions—principally pituitary diseases, hypothyroidism, renal failure and severe liver disease—can also contribute to elevated levels. Prolactin stimulation may also occur as a side effect of drugs such as estrogens, dopamine antagonists and verapamil. In women, chronic hyperprolactinemia produces galactorrhea in 30 to 80 percent of patients and may also induce menstrual disorders, dyspareunia and changes in glycemic control. Men with hyperprolactinemia may experience loss of libido and impotence. As prolactin levels fluctuate during the day, repeated testing may be indicated.

Preventing Suicide in a Family Practice

(Canada—Canadian Family Physician, November 1999, p. 2656.) A Canadian review estimates that family physicians encounter up to 15 suicidal patients per year. Up to two thirds of persons who commit suicide contact their family physician in the month prior to their death; psychiatric reasons are given as the motivation for this contact in nearly one half of the cases. The strongest predictor of suicide risk is a previous attempt. Older age (especially for men), depression, substance abuse, impulsive personality disorders, relationship problems and difficulty in dealing with problems are also risk factors. Environmental factors that increase risk of suicide include access to the means of suicide, social isolation, unemployment and recent losses. Interventions aimed at the patient, family and environment may be necessary to protect a patient from suicide. Physicians should consider a “no-suicide” contract, active treatment of psychiatric and other illnesses, supportive counseling of patient and family, and practical advice about limiting access to means of suicide. Medication should be specific to the needs of each patient; fluoxetine reduces impulsive aggression, and paroxetine may reduce suicidal behaviors.