We continually have to update ourselves. One frustration the surgeon faces is that he or she may do an excellent replacement only to be troubled by breakdown of the mechanical parts of the artificial knee. At some point, the plastic just wears out. Each time you take a step during the day, multiplied by 365 days a year, the plastic parts are rubbing against metal. That is millions of cycles.
Nothing lasts forever and that's true for knee replacements.
The orthopedic manufacturers are continually manufacturing more durable plastic, better quality cement and cementing techniques, and improving metallurgy. These changes are encouraging, and slow refinement has continued over the past several decades. By the time I met this patient, a delightful woman in her late 30s, she already had completely stiff, very painful, very debilitating knees. She was just horribly functionally impaired at a young age. She had severe rheumatoid arthritis, and somehow had not had any treatment for her knees for many years.