Effect of Slope and Varus Correction High Tibial Osteotomy in the ACL-Deficient and ACL-Reconstructed Knee on Kinematics and ACL Graft Force: A Biomechanical Analysis

Abstract

Background: Correction of high posterior tibial slope is an important treatment option for revision of anterior cruciate ligament (ACL) failure as seen in clinical and biomechanical studies. In cases with moderate to severe medial compartment arthritis, an additional varus correction osteotomy may be added to improve alignment. Purpose: To investigate the influence of coronal and sagittal correction high tibial osteotomy in ACL-deficient and ACL-reconstructed knees on knee kinematics and ACL graft load. Study Design: Controlled laboratory study. Methods: Ten cadaveric knees were selected according to previous computed tomography measurements with increased native slope and slight varus tibial alignment (mean ± SD): slope, 9.9°± 1.4°; medial proximal tibia angle, 86.5°± 2.1°; age, 47.7 ± 5.8 years. A 10° anterior closing-wedge osteotomy, as well as an additional 5° of simulated varus correction osteotomy, were created and fixed using an external fixator. Four alignment conditions—native, varus correction, slope correction, and combined varus and slope correction—were randomly tested in 2 states: ACL-deficient and ACL-reconstructed. Compressive axial loads were applied to the tibia while mounted on a free-moving X-Y table and free-rotating tibia in a knee testing fixture. Three-dimensional motion tracking captured anterior tibial translation (ATT) and internal tibial rotation. Change of tensile forces on the reconstructed ACL graft were recorded. Results: In the ACL-deficient knee, an isolated varus correction led to a significant increase of ATT by 4.3 ± 4.0 mm ( P = .04). Isolated slope reduction resulted in the greatest decrease of ATT by 6.2 ± 4.3 mm ( P < .001). In the ACL-reconstructed knee, ATT showed comparable changes, while combined varus and slope correction led to lower ATT by 3.7 ± 2.6 mm ( P = .01) than ATT in the native alignment. Internal tibial rotation was not significantly altered by varus correction but significantly increased after isolated slope correction by 4.0°± 4.1° ( P < .01). Each isolated or combined osteotomy showed decreased forces on the graft as compared with the native state. The combined varus and slope osteotomy led to a mean decrease of ACL graft force by 33% at 200 N and by 58% at 400 N as compared with the native condition ( P < .001). Conclusion: A combined varus and slope correction led to a relevant decrease of ATT in the ACL-deficient and ACL-reconstructed cadaveric knee. ACL graft forces were significantly decreased after combined varus and slope correction. Thus, our biomechanical findings support the treatment goal of a perpendicular-aligned tibial plateau for ACL insufficiencies, especially in cases of revision surgery. Clinical Relevance: This study shows the beneficial knee kinematics and reduced forces on the ACL graft after combined varus and slope correction.

Radiographic and clinical outcomes of slope and varus correction anterior closing wedge tibial osteotomy for primary anterior cruciate ligament injuries with steep posterior tibial slope, varus knee deformity, and medial meniscal posterior root tears

“…Recently, Imhoff et al 10 demonstrated that combined varus and slope correction anterior closing-wedge osteotomy can signi cantly decrease the anterior tibial translation and ACL graft forces. The author also found that an isolated varus correction in the ACL-de cient knee can lead to higher anterior translation and internal tibial rotation, resulting in a more unstable knee 10 .…”

“…Slope and varus correction anterior closing-wedge osteotomy (ACWTO) is a new procedure of correcting increased PTS in sagittal plane and varus deformity in coronal plane. Biomechanically, Imhoff et al 10 demonstrated that slope and varus correction ACWTO can signi cantly decrease the anterior tibial translation and ACL graft forces. However, there is no clinical studies reported such combined procedures.…”

A review of role of osteotomy in knee ligament injuries

“…In a recent cadaveric biomechanical study by Imhoff et al, a 10 anterior opening wedge high tibial osteotomy reduced ATT in the ACL deficient and ACL reconstructed knee under axial load; the osteotomy had a protective role for the reconstructed ACL with significantly lower forces on ACL graft. 21 Studies by Agneskirchner et al and Griffin et al have shown that increase in PTS led to a relative anterior shift in the resting position of the knee which is more so in extension and less so during flexion. Anterior translation of tibia (ATT) is seen throughout knee range of motion with slope change.…”

“…There is good clinical evidence that increased PTS is an important risk factor for graft failure after ACL reconstruction. 21,28,36 In a study looking at single revision ACL versus multiple revision ACL reconstruction patients, Winkler and colleagues noted, that a higher medial PTS is observed in patients with multiple compared to single ACL graft failures (12þ À3 versus 9þ À3 ). 46 A cadeveric study by Petrigliano and colleagues looked at the effect of sectioning PCL and PLC on static and dynamic testing, assessing for any change produced by altering the native tibial slope.…”

A 2021 consensus statement on osteotomies around the knee by the UK Knee Osteotomy consensus Group (KOG)

“…A recent cadaveric study [63] demonstrated that an isolated 5 degree varus OWHTO, an isolated 10 degree tibial slope reduction or a combined varus and slope correction led to decreased ACL graft forces under axial loading of the knee joint. However, only a 10degree slope correction, either isolated or combined, resulted in a decrease in anterior tibial translation by 6.2 +/-4.3 mm.…”