France E P, Paulos L E
Department of Bioengineering, University of Utah, Salt Lake City.
Clin Sports Med. 1990 Oct;9(4):823-41.
In an attempt to evaluate the effectiveness of prophylactic knee bracing and to determine the influence of brace design and material characteristics on the protection of knee ligaments, a series of biomechanical studies were completed. The first series of tests were preliminary parametric tests of brace function utilizing cadaver limbs to understand the failure biomechanics of the medial restraints during low- and high-rate valgus-producing knee trauma. Static and dynamic mechanical properties of the braces were also studied. Finally, a limited series of brace/cadaver knee low-rate loading response tests were performed. With the information obtained from preliminary testing, an instrumented surrogate knee was developed and validated for lateral impact responses. The surrogate allowed for the measurement of ligament force time response during a controlled impact. Special impact facilities were constructed to allow the measurement and control of impact momentum. The effectiveness of six different prophylactic braces in preventing MCL and ACL injury was evaluated using the surrogate and impact facility. Impact parameters of mass, velocity, knee flexion angle, and limb restraint were varied to simulate different direct lateral impact conditions of game play. Testing results were normalized and expressed as an impact safety factor to allow for comparison of braces. An ISF of 1.5 (representing a ligament force reduction of 30%) was arbitrarily chosen as the minimum standard for brace performance. The majority of prophylactic knee braces tested proved to be biomechanically inadequate for protecting the MCl from a direct lateral impact. A few, however, appear to protect the ACL preferentially. In the case of a controlled, direct lateral blow, all but a few braces tested provided some beneficial protection to the MCL and ACL, but performed well below the standard 1.5 ISF level. Therefore, based on the biomechanical research, it is our opinion that the concept of prophylactic lateral knee bracing can be effective. We recommend that prophylactic braces not be abandoned, but rather improved, biomechanically validated, and further evaluated through well-controlled prospective clinical studies.
为了评估预防性膝关节支具的有效性，并确定支具设计和材料特性对膝关节韧带保护的影响，完成了一系列生物力学研究。第一组测试是利用尸体肢体对支具功能进行初步参数测试，以了解在低速和高速产生外翻的膝关节创伤中内侧约束的失效生物力学。还研究了支具的静态和动态力学性能。最后，进行了有限的一系列支具/尸体膝关节低速加载响应测试。根据初步测试获得的信息，开发并验证了一种用于测量外侧冲击响应的仪器化替代膝关节。该替代物能够在受控冲击过程中测量韧带力随时间的响应。构建了特殊的冲击设施，以测量和控制冲击动量。使用该替代物和冲击设施评估了六种不同预防性支具预防内侧副韧带（MCL）和前交叉韧带（ACL）损伤的有效性。改变质量、速度、膝关节屈曲角度和肢体约束等冲击参数，以模拟比赛中不同的直接外侧冲击情况。测试结果进行了归一化处理，并表示为冲击安全系数，以便比较支具。任意选择1.5的冲击安全系数（代表韧带力降低30%）作为支具性能的最低标准。测试的大多数预防性膝关节支具在生物力学上不足以保护内侧副韧带免受直接外侧冲击。然而，有一些似乎优先保护前交叉韧带。在受控的直接外侧打击情况下，除少数支具外，所有测试的支具都为内侧副韧带和前交叉韧带提供了一些有益的保护，但性能远低于标准的1.5冲击安全系数水平。因此，基于生物力学研究，我们认为预防性外侧膝关节支具的概念可能是有效的。我们建议不要放弃预防性支具，而应加以改进，进行生物力学验证，并通过严格控制的前瞻性临床研究进行进一步评估。
