Gardinier Emily S, Di Stasi Stephanie, Manal Kurt, Buchanan Thomas S, Snyder-Mackler Lynn
School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
Sports Health and Performance Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA Department of Orthopaedics, The Ohio State University, Columbus, Ohio, USA.
Am J Sports Med. 2014 Dec;42(12):2917-25. doi: 10.1177/0363546514552184. Epub 2014 Oct 15.
After anterior cruciate ligament (ACL) injury, contact forces are decreased in the injured knee when compared with the uninjured knee. The persistence of contact force asymmetries after ACL reconstruction may increase the risk of reinjury and may play an important role in the development of knee osteoarthritis in these patients. Functional performance may also be useful in identifying patients who demonstrate potentially harmful joint contact force asymmetries after ACL reconstruction.
Knee joint contact force asymmetries would be present during gait after ACL reconstruction, and performance on a specific set of validated return-to-sport (RTS) readiness criteria would discriminate between those who demonstrated contact force asymmetries and those who did not.
Descriptive laboratory study.
A total of 29 patients with ACL ruptures participated in gait analysis and RTS readiness testing 6 months after reconstruction. Muscle and joint contact forces were estimated using an electromyography (EMG)-driven musculoskeletal model of the knee. The magnitude of typical limb asymmetry in uninjured controls was used to define limits of meaningful limb asymmetry in patients after ACL reconstruction. The RTS testing included isometric quadriceps strength testing, 4 unilateral hop tests, and 2 self-report questionnaires. Paired t tests were used to assess limb symmetry for peak medial and tibiofemoral contact forces in all patients, and a mixed-design analysis of variance was used to analyze the effect of passing or failing RTS testing on contact force asymmetry.
Among all patients, neither statistically significant nor meaningful contact force asymmetries were identified. However, patients who failed RTS testing exhibited meaningful contact force asymmetries, with tibiofemoral contact force being significantly lower for the involved knee. Conversely, patients who passed RTS testing exhibited neither significant nor meaningful contact force asymmetries.
Joint contact force asymmetries during gait are present in some patients 6 months after ACL reconstruction. Patients who demonstrated poor functional performance on RTS readiness testing exhibited significant and meaningful contact force asymmetries.
When assessing all patients together, variability in the functional status obscured significant and meaningful differences in contact force asymmetry in patients 6 months after ACL reconstruction. These specific RTS readiness criteria appear to differentiate between those who demonstrate joint contact force symmetry after ACL reconstruction and those who do not.
前交叉韧带（ACL）损伤后，与未受伤的膝关节相比，受伤膝关节的接触力会降低。ACL重建后接触力不对称持续存在可能会增加再次受伤的风险，并且可能在这些患者膝关节骨关节炎的发展中起重要作用。功能表现对于识别ACL重建后表现出潜在有害的关节接触力不对称的患者也可能有用。
ACL重建后的步态中会出现膝关节接触力不对称，并且在一组特定的经过验证的恢复运动（RTS）准备标准上的表现能够区分出表现出接触力不对称的患者和未表现出接触力不对称的患者。
描述性实验室研究。
共有29例ACL断裂患者在重建后6个月参与了步态分析和RTS准备测试。使用肌电图（EMG）驱动的膝关节肌肉骨骼模型估计肌肉和关节接触力。未受伤对照组中典型肢体不对称的程度用于定义ACL重建后患者中有意义的肢体不对称的限度。RTS测试包括等长股四头肌力量测试、4项单侧跳跃测试和2份自我报告问卷。配对t检验用于评估所有患者中内侧峰值和胫股接触力的肢体对称性，混合设计方差分析用于分析通过或未通过RTS测试对接触力不对称的影响。
在所有患者中，未发现具有统计学意义或有意义的接触力不对称。然而，未通过RTS测试的患者表现出有意义的接触力不对称，患侧膝关节的胫股接触力明显较低。相反，通过RTS测试的患者既没有显著也没有有意义的接触力不对称。
ACL重建后6个月，部分患者在步态中存在关节接触力不对称。在RTS准备测试中功能表现较差的患者表现出显著且有意义的接触力不对称。
当对所有患者进行综合评估时，功能状态的变异性掩盖了ACL重建后6个月患者接触力不对称方面显著且有意义的差异。这些特定的RTS准备标准似乎能够区分ACL重建后表现出关节接触力对称的患者和未表现出关节接触力对称的患者。
