Effects of Muscle Fatigue on Shoulder Proprioception

OBJECTIVE: To investigate the changes of shoulder proprioception in normal subjects, according to the direction of the evoked fatigue on the shoulder muscle group. METHOD: 20 healthy volunteers (14 males and 6 females, age 20~35 years) with entirely normal shoulders participated in this study. Before fatigue exercises, the proprioception tests were performed during active reposition (ARP) and passive reposition (PRP) of dominant shoulder, using isokinetic dynamometer, System 3 Pro (Biodex medical system, New York, USA). Three trials each of active and passive repositioning (2degrees/sec) were recorded. We also estimated the results of the peak torque shoulder movements. The subjects performed maximal efforts with five repetitions on the direction of flexion, abduction, internal rotation and external rotation. The mean values of maximal concentric voluntary contraction (MVC: peak torque of each muscle group contraction) were recorded. We repeated fatigue exercises until the peak torque dropped to 30% three times consistently, then retested the proprioception of shoulder joints. We compared the proprioceptive changes of the shoulder with pre-fatigue test and post-fatigue test on the direction of shoulder movements. RESULTS: There were significant differences of shoulder proprioception between pre-fatigue test and post-fatigue test of ARP in shoulder abduction and external rotation (p<0.05). CONCLUSION: In our study, the proprioception of shoulder joint decreased more prominently on external rotation and abduction movements under severely provoked muscle fatigue around the shoulder joint.

The Effect of Knee Osteoarthritis and Unilateral Total Knee Arthroplasty on Balance

OBJECTIVE: To assess the effect of knee osteoarthritis (OA) and unilateral total knee arthroplasty (TKA) on balance. METHOD: Fifteen patients with bilateral knee OA and fifteen patients with unilateral TKA and fifteen healthy adults were assessed by computerized dynamic posturography. The posturography test was performed 3 times at 6 different simulated conditions. We evaluated anteroposterior sway of center of gravity and strategy score of OA group, TKA group and healthy adults group. We compared the equilibrium scores of each group with normal data reported previously. We also compared strategy scores of each group. RESULTS: Patients with bilateral knee OA and unilateral TKA showed lower equilibrium scores than normal one at the condition 4, 5, 6. But patients with unilateral TKA did not show significant equilibrium score difference as compared with bilateral knee OA patients. Patients with bilateral knee OA and unilateral TKA showed significantly lower strategy scores than normal one at the condition 4, 5, 6 (p<0.05). But patients with unilateral TKA did not show significant strategy score difference as compared with bilateral knee OA patients. CONCLUSION: Patients with bilateral knee OA showed deficit of dynamic postural control due to proprioceptive dysfunction. And TKA did not affect proprioceptive change in knee osteoarthritis.

The Effect of GivMohr Slings on Shoulder Subluxation in Hemiplegic Patients

OBJECTIVE: To compare the radiological corrective effect for shoulder subluxation among GivMohr & other slings in hemiplegic patients. METHOD: Fifteen hemiplegic patients with flaccid upper limb were included. The vertical distance (VD), horizontal distance (HD) & joint distance (JD) on the plain AP views of the shoulders were measured. GivMohr sling was compared with 2 conventional slings, which were forearm cuff type extension sling and Bobath sling, in the effects of correction. RESULTS: The mean values of VD and JD of hemiplegic shoulder increased compared to unaffected side, but those of HD was not different between them. In Bobath sling, VD was significantly reduced and HD was not changed. However, JD was increased as other studies. GivMohr sling and forearm cuff type extension sling showed corrective effect in VD and JD (p<0.05). When compared with these two slings, there were no significant differences in VD and JD. CONCLUSION: The results show that GivMohr sling reduces shoulder subluxation as other slings. This new sling is helpful for patients with flaccid upper limbs to reduce shoulder subluxation.