Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

Sandro Hodel; Carlos Torrez; Andreas Flury; Benjamin Fritz; Matthias R Steinwachs; Lazaros Vlachopoulos; Sandro F Fucentese

doi:10.1186/s12891-022-05218-8

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

BMC Musculoskelet Disord. 2022 Mar 18;23(1):262. doi: 10.1186/s12891-022-05218-8.

Authors

Sandro Hodel¹, Carlos Torrez², Andreas Flury², Benjamin Fritz³, Matthias R Steinwachs⁴, Lazaros Vlachopoulos², Sandro F Fucentese²

Affiliations

¹ Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland. sandro.hodel1@gmail.com.
² Department of Orthopedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
³ Department of Radiology, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
⁴ SportClinic Zurich Hirslanden Clinic, Witellikerstrasse, 40, 8032, Zurich, Switzerland.

Abstract

Background: Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.

Methods: The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.

Results: ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient. Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0-2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54-0.85) (p = 0.03) and an accuracy of 79%.

Conclusion: ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.

Study design: Cohort study; Level of evidence, 3.

Keywords: ACL, anterolateral complex; Anterior cruciate ligament; Anterolateral ligament; Pivot shift.

MeSH terms

Anterior Cruciate Ligament* / diagnostic imaging
Anterior Cruciate Ligament* / surgery
Biomechanical Phenomena
Cohort Studies
Humans
Range of Motion, Articular
Retrospective Studies