目的：本研究以個案的方式，呈現美國大學一級男子足球選手前十字韌帶 (anterior cruciate ligament , ACL) 手術後決定回場的策略。背景：本運動員的左膝在十二個月內經歷了兩次 ACL斷裂，兩次傷害皆為非接觸性、跳躍落地過程所發生的。兩次傷害透過多位美國 (第一次) 與巴西 (第一與第二次) 的骨科醫師進行理學及磁振照影 (magnetic resonance imaging, MRI) 檢查。治療：第一次受傷後，運動員在美國進行每週兩次次，為期十六週的門診物理治療。第二次手術後運動員返回美國，在隸屬的大學中由運動醫學部門進行每週六天，為期八個月的復健。回場測試：針對ACL 術後是否能回場的傳統評方式為單腳跳躍 (Hop Test) 或等速肌力測試 (Isokinetic Test)。兩種測驗皆為運動醫學領域決定術後運動員回場狀態的評估方法。獨特性：除了以Hop Test和等速測力儀進行膝關節屈/伸力量作為評估回場的一般性測試，本研究同時採用跳躍測驗作為作為雙側不平衡 (bilateral asymmetry) 和表現提升的評估方法，透過不平衡指數 (symmetry index, SI)的計算了解兩腳不平衡的程度。討論與結論：儘管膝關節屈/伸等速肌力和 Hop Test 都能作為決定運動員回場狀態的測量，以跳躍測驗收取SI 的方法同樣能提供臨床工作者，針對需要下肢參與的運動項目復健過程中量測的參考指標。

Purposes: To present the case of a National Collegiate Athletic Association Division I men’s soccer athlete’s anterior cruciate ligament (ACL) reconstruction and the strategies used to determine return-to-play. Background: The athlete sustained two ruptures of the ACL in his left knee in a twelve-month period. Both events were non-contact injuries occurring on the landing phase of a jump. Physical exam and magnetic resonance imaging were performed for both injuries by multiple orthopedic surgeons in the United States (1st rupture) and in Brazil (1st & 2nd rupture). Treatment: Following the initial injury the athlete attended two rehabilitation sessions per week for 16 weeks with an outpatient physical therapy clinic in the US. After the second surgery the athlete returned to the US and received treatment six days per week for eight months with the University sports medicine staff. Return to Play Testing: Traditional return to play testing for ACL reconstruction has been associated with a Hop Test or an Isokinetic Test. Both tests have been used as methods to determine return to play status for all methods of surgical repair. Uniqueness: Along with the hop test and an isokinetic knee flexion/extension test as a general protocol to determine the return-to-play a jumps protocol to assess bilateral asymmetry and performance was also used. The symmetry index score (SI) was used to evaluate the magnitude of asymmetry. Discussion & Conclusions: While the isokinetic knee flexion/extension and hop test have been accepted measures to determine return-to-play status, the jumps protocol using the SI score can also provide the practitioner with an objective measure of a skill that is used in all sports involving the lower extremity.