研究背景與目的：過去文獻報告單側人工膝關節置換手術後之患側膝伸肌肌力兩年後仍有肌力相對於健側較弱之現象。本篇研究探討單側人工膝關節置換手術後之女性病患，其患側與健側之肌力於術後半年間之變化。方法：本實驗共有18位接受單側人工膝關節置換手術之女性患者參與。患者接收患側與健側膝伸肌及屈肌之等張肌力測試。術後6個月重複接受測試。結果：於30度膝屈曲時兩側之等張膝伸肌力(p<0.05)及於30度與60度膝屈曲之等張膝屈肌力(p<0.05)均於術後6個月時較術前有明顯進步，但是於60度膝屈曲時之兩側等張膝伸肌力則無明顯進步。然而，兩側之屈、伸肌力與屈肌／伸肌比值仍有明顯差距(p<0.05)。結論：單側人工膝關節置換手術後，病患患側及健側之膝伸肌於術後6個月時均有顯著進步。兩側屈肌肌力亦出現適應性肌力增加現象。然而，兩側之肌力及屈肌／伸肌比值於術後半年仍未達對稱，顯示在疼痛解除及功能恢復仍存在潛在因素影響患側肌力之恢復，需進一步探討及追蹤。

Background and purpose: Changes in knee muscle strength and flexor/extensor(hamstrings/quadriceps; H/Q)ratio for operated knees have been reported in patients following two years of unilateral total knee arthroplasty (TKA).Whether muscle strength of the kness shows changes in patients before and after TKA remains unclear. This study was to compare the muscle strength and H/Q ratios between the operated and the non-operated knees in female patients before TKA operation and six months after operation. Methods: Eighteen female patients participated. Each patient was tested for maximal torque of knee extensors and flexors bilaterally, at 30°and 60°of knee flexion pre-operatively and six months after operation. Results: The isometric extensor torques of both knees tested at 30°of flexion were increased at six months following operation(p<0.05).The isometric flexor torques of both knees at 30°and 60°of flexion also showed increase at six following operation(p<0.05).However, the muscle strength and H/Q ratio of the two knees remained unequal at six months post-operation (p<0.05). Conclusion: The significant increase in muscle torque of both extensors and flexors might be resulted from gradual reduction of pain and chronic inflammation after surgery. However, significant weakness of the extensor and flexor of the operated knee compared to the non-operated knee at six months post-operation may relate to some other potential factors preventing a full restoration of knee strength after the operation. Further investigation in this area is needed.