Slope-reducing tibial osteotomy decreases ACL-graft forces and anterior tibial translation under axial load

Abstract

Purpose Posterior tibial slope (PTS) represents an important risk factor for anterior cruciate ligament (ACL) graft failure, as seen in clinical studies. An anterior closing wedge osteotomy for slope reduction was performed to investigate the efect on ACL-graft forces and femoro-tibial kinematics in an ACL-deicient and ACL-reconstructed knee in a biomechanical setup. Methods Ten cadaveric knees with a relatively high native slope (mean ± SD): (slope 10° ± 1.4°, age 48.2 years ± 5.8) were selected based on prior CT measurements. A 10° anterior closing-wedge osteotomy was ixed with an external ixator in the ACL-deicient and ACL-reconstructed knee (quadruple Semi-T/Gracilis-allograft). Each condition was randomly tested with both the native tibial slope and the post-osteotomy reduced slope. Axial loads (200 N, 400 N), anterior tibial draw (134 N), and combined loads were applied to the tibia while mounted on a free moving and rotating X-Y table. Throughout testing, 3D motion tracking captured anterior tibial translation (ATT) and internal tibial rotation (ITR). Change of forces on the reconstructed ACL-graft (via an attached load-cell) were recorded, as well. Results ATT was signiicantly decreased after slope reduction in the ACL-deicient knee by 4.3 mm ± 3.6 (p < 0.001) at 200 N and 6.2 mm ± 4.3 (p < 0.001) at 400N of axial load. An increase of ITR of 2.3° ±2.8 (p < 0.001) at 200 N and by 4.0° ±4.1 (p < 0.001) at 400 N was observed after the osteotomy. In the ACL-reconstructed knee, ACL-graft forces decreased after slope reduction osteotomy by a mean of 14.7 N ± 9.8 (p < 0.001) at 200 N and 33.8 N ± 16.3 (p < 0.001) at 400N axial load, which equaled a relative decrease by a mean of 17.0% (SD ± 9.8%), and 33.1% (SD ± 18.1%), respectively. ATT and ITR were not signiicantly changed in the ACL-reconstructed knee. Testing of a tibial anterior drawing force in the ACLdeicient knee led to a signiicantly increased ATT by 2.7 mm ± 3.6 (p < 0.001) after the osteotomy. The ACL-reconstructed knee did not show a signiicant change (n.s.) in ATT after the osteotomy. However, ACL-graft forces detected a signiicant increase by 13.0 N ± 8.3 (p < 0.001) after the osteotomy with a tibial anterior drawer force, whereas the additional axial loading reduced this diference due to the osteotomy (5.3 N ± 12.6 (n.s.)). Conclusions Slope-reducing osteotomy decreased anterior tibial translation in the ACL-deicient and ACL-reconstructed knee under axial load, while internal rotation of the tibia increased in the ACL-deicient status after osteotomy. Especially in ACL revision surgery, the osteotomy protects the reconstructed ACL with signiicantly lower forces on the graft under axial load.

Posteromedial Ligament Repair of the Knee With Suture Tape Augmentation: A Biomechanical Study

“…The specimens were placed upside down in a testing rig that allowed positioning in 6 degrees of freedom, as previously described (Figure 1). 10 Each condition was tested in 5 knee flexion angles: 0°, 15°, 30°, 45°, and 60°. The tibia was statically fixed, while its position in the coronal plane was adjusted according to the previously determined anatomic medial proximal tibia angle to guarantee a horizontal joint line in full knee extension.…”

“…Prior to each valgus and rotational test, an axial joint compression load of 22 N was applied via the lever arm of the X-Y table to center the joint (start position). 10 The specimens were not moved from the testing rig throughout all testing procedures, including all 4 testing conditions.…”

A real 3D measurement technique for the tibial slope: differentiation between different articular surfaces and comparison to radiographic slope measurement

“…Furthermore, an increased tibial slope was recognized as a risk factor for anterior cruciate ligament (ACL) rupture in native knees [11][12][13][14], whereas a decreased tibial slope could be identified as a risk factor for posterior cruciate ligament (PCL) injury [15]. These findings were used to reduce the forces acting on ACL-grafts and to address instability in ACL-deficient knees by reducing the tibial slope when performing a high tibial osteotomy (HTO) [15][16][17][18].…”

An Arthroscopic Procedure for Restoration of Posterolateral Tibial Plateau Slope in Tibial Plateau Fracture Associated With Anterior Cruciate Ligament Injuries

“…Therefore, in cases of PLTP fracture occurring in the context of a "high-energy ACL" injury, initial recognition and surgical restoration of the anatomic PLTP slope represents a crucial opportunity to prevent failure of the reconstructed ACL. [4][5][6][7][8][9][10] Presently, there is no consensus on the optimal timing or a gold-standard surgical procedure for this type of tibial plateau fractures associated with "high-energy ACL" injuries. 1,11 This necessitates surgical innovation and development of a procedure that maximizes postoperative functional outcome while minimizing the duration of discomfort and morbidity associated with operative management.…”

“…Therefore, in cases of PLTP fracture occurring in the context of a “high-energy ACL” injury, initial recognition and surgical restoration of the anatomic PLTP slope represents a crucial opportunity to prevent failure of the reconstructed ACL. 4 , 5 , 6 , 7 , 8 , 9 , 10 …”