Proprioception, or joint position sense, probably plays an important role in shoulder joint function. In this study, we assessed the effect of muscle fatigue on shoulder proprioception in 20 volunteers with no shoulder abnormalities. Shoulder proprioception was measured as the threshold to first detection of humeral rotation with the joint at 90 degrees of abduction and 90 degrees of external rotation. Subjects were tested while rested, exercised on a isokinetic testing machine until fatigued, and then retested in an identical fashion. Both shoulders were tested, and the order of dominant and nondominant shoulder was randomized. Shoulder proprioception was analyzed for its dependence on arm dominance, direction of rotation, and muscle fatigue. Subjects detected external rotation after significantly less movement than they did internal rotation. Overall, before exercise, motion was detected after a mean of 0.92 degrees of rotation. After exercise, this threshold to detection of movement increased to 1.59 degrees, an increase of 73%. This significant increase occurred with both internal and external rotation. The decrease in proprioceptive sense with muscle fatigue may play a role in decreasing athletic performance and in fatigue-related shoulder dysfunction. It remains to be determined if training can lessen this loss in position sense.
The question of when a surgeon should retire has been the subject of debate for decades. Both anecdotal evidence and objective testing of surgeons suggest age causes deterioration in physical and cognitive performance. Medical education, residency and fellowship training, and technology evolve at a rapid pace, and the older a surgeon is, the more likely it is he or she is remote from his or her initial education in his or her specialty. Research also shows surgeons are reluctant to plan for retirement. Although there is no federally mandated retirement age for surgeons in the United States, surgeons must realize their skills will decline, a properly planned retirement can be satisfying, and the retired surgeon has much to offer the medical and teaching community.
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