The aim of the study was to directly measure graft forces of an anterior cruciate ligament reconstruction (ACLR) and a lateral extra-articular tenodesis (LET) using the modified Lemaire technique in combined anterior cruciate ligament (ACL) deficient and anterolateral rotatory instable knees and to analyse the changes in knee joint motion resulting from combined ACLR + LET. On a knee joint test bench, six fresh-frozen cadaveric specimens were tested at 0°, 30°, 60°, and 90° of knee flexion in the following states: 1) intact; 2) with resected ACL; 3) with resected ACL combined with anterolateral rotatory instability; 4) with an isolated ACLR; and 5) with combined ACLR + LET. The specimens were examined under various external loads: 1) unloaded; 2) with an anterior tibial translation force (ATF) of 98 N; 3) with an internal tibial torque (IT) of 5 Nm; and 4) with a combined internal tibial torque of 5 Nm and an anterior tibial translation force of 98 N (IT + ATF). The graft forces of the ACLR and LET were recorded by load cells incorporated into custom devices, which were screwed into the femoral tunnels. Motion of the knee joint was analysed using a 3D camera system. During IT and IT + ATF, the addition of a LET reduced the ACLR graft forces up to 61% between 0° and 60° of flexion (P = 0.028). During IT + ATF, the LET graft forces reached 112 N. ACLR alone did not restore native internal tibial rotation after combined ACL deficiency and anterolateral rotatory instability. Combined ACLR + LET was able to restore native internal tibial rotation values for 0°, 60° and 90° of knee flexion with decreased internal tibial rotation at 30° of flexion. The study demonstrates that the addition of a LET decreases the forces seen by the ACLR graft and reduces residual rotational laxity after isolated ACLR during internal tibial torque loading. Due to load sharing, a LET could support the ACLR graft and perhaps be the reason for reduced repeat rupture rates seen in clinical studies. Care must be taken not to limit the internal tibial rotation when performing a LET.

中文翻译：

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改良的 Lemaire 肌腱固定术可减少胫骨内扭矩负载期间的前交叉韧带移植力

该研究的目的是使用改良的 Lemaire 技术直接测量前交叉韧带重建 (ACLR) 和外侧关节外肌腱固定术 (LET) 的移植力，用于联合前交叉韧带 (ACL) 缺陷和前外侧旋转不稳定的膝关节和分析由 ACLR + LET 组合引起的膝关节运动变化。在膝关节试验台上，在膝关节屈曲0°、30°、60°和90°的以下状态下测试了6个新鲜冷冻尸体标本：1）完好；2) 切除ACL；3）ACL切除合并前外侧旋转不稳；4) 带有隔离的 ACLR；5) 结合 ACLR + LET。试件在各种外部载荷下进行检查： 1) 空载；2) 胫骨前移力 (ATF) 为 98 N；3) 胫骨内扭矩 (IT) 为 5 Nm；4) 胫骨内扭矩为 5 Nm，胫骨前移力为 98 N (IT + ATF)。ACLR 和 LET 的移植力由装入定制装置中的称重传感器记录，这些装置被拧入股骨隧道。使用 3D 相机系统分析膝关节的运动。在 IT 和 IT + ATF 期间，添加 LET 在 0° 和 60° 屈曲之间将 ACLR 移植物力降低了 61% (P = 0.028)。在 IT + ATF 期间，LET 移植力达到 112 N。在 ACL 缺乏和前外侧旋转不稳定联合后，单独的 ACLR 不能恢复原生胫骨内旋转。联合 ACLR + LET 能够恢复膝关节屈曲 0°、60° 和 90° 的原生胫骨内旋值，同时在屈曲 30° 时减少胫骨内旋。该研究表明，添加 LET 可降低 ACLR 移植物所受力，并减少孤立 ACLR 后胫骨内扭矩负载期间的残余旋转松弛。由于负载分担，LET 可以支持 ACLR 移植物，这可能是临床研究中降低重复破裂率的原因。进行 LET 时必须注意不要限制胫骨内旋。