Four to 6° Is the Target Posterior Tibial Slope After Tibial Deflection Osteotomy According to the Knee Static Anterior Tibial Translation

The influence of tibial length on radiographic posterior tibial slope measurement: How much tibia do we need?

PURPOSE

The purpose of this study was to determine whether significant differences exist when comparing posterior tibial slope (PTS) measured using increasing lengths of the tibia to determine the anatomical axis.

METHODS

Patients with full-length weight-bearing tibial radiographs were retrospectively identified from 2014 to 2022 at a single institution. Patients were excluded if there was any previous history of lower extremity fracture or osteotomy. The anatomical axis of the tibia was determined using the full length of tibial radiographs, and the "reference PTS" was measured using this axis. Using the same radiograph, the PTS was measured using four different anatomical axes at standardized tibial lengths. While the center of the proximal circle remained constant at 5-cm below the tibial plateau, the center of the distal circle was drawn at four points: a) overlapping circles; b) 10-cm distal to the tibial plateau; c) 15-cm distal to the tibial plateau; d) half the length of the tibia, measured from the tibial plateau to the tibial plafond. Bivariate correlation and frequency distribution analysis (measurements >2-degrees from reference PTS) were performed between the reference PTS and PTS measured at each of the four other lengths.

RESULTS

A total of 154 patients (39.8 ± 17.4 years old, 44.2% male) were included in the final analysis. Measurements at each of the four tibial lengths were all significantly different from the reference PTS (p < 0.001). The correlation strength improved with increasing tibial length (overlapping: R = 0.681, 10-cm: R = 0.821, 15-cm: R = 0.937, and half-tibia: R = 0.963). The number of PTS measurements >2-degree absolute difference from the reference PTS decreased with increasing tibial length (overlapping: 40.3%, 10-cm: 24.0%, 15-cm: 26.0%, and half-tibia: 18.8%).

CONCLUSION

Assessment of PTS is dependent on the length of the tibia utilized to obtain the anatomical axis. Accuracy and precision of PTS measurements improved with increasing length of tibia used to determine the anatomical axis.

STUDY DESIGN

Case series.

Evaluation of Anterior Tibial Translation Under Physiological Axial Load After ACL Reconstruction With Lateral Extra-articular Tenodesis

Background

Postoperative laxity correlates with negative clinical outcomes after anterior cruciate ligament reconstruction (ACLR). The influence of lateral extra-articular tenodesis (LET) on anteroposterior translation is unclear.

Purpose/Hypothesis

This study aimed to evaluate the reduction in radiographic static anterior tibial translation (SATT) and dynamic anterior tibial translation (DATT) after LET as an adjunctive procedure to ACLR. It was hypothesized that adding a LET procedure would have no effect on postoperative SATT and DATT.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients who underwent primary ACLR with hamstring tendon autografts between 2020 and 2022 were reviewed, and those who underwent ACLR and LET as an anterolateral associate procedure were paired 1 to 1 with those who underwent isolated ACLR (control) based on age, sex, preoperative SATT, and posterior tibial slope (PTS). The indications for LET were age <18 years and anterolateral rotary instability (grade ≥2 pivot shift). A previously validated technique was used to measure SATT, DATT, and PTS on lateral weightbearing and lateral stress knee radiographs. Preoperative and 9-month postoperative radiographs were compared between the 2 groups.

Results

A total of 72 patients were included in the analysis (n = 36 patients in each group). The inter- and intraobserver reliability of the SATT, DATT, and PTS measurements was excellent (intraclass correlation coefficients, 0.88-0.99). The mean pre- and postoperative SATT in the ACLR+LET group was 2.44 ± 2.90 mm and 2.44 ± 2.38 mm, respectively, compared with 2.60 ± 2.99 mm and 2.12 ± 2.74 mm, respectively, in the control group. The mean pre- and postoperative reduction in side-to-side DATT in the ACLR+LET group was 5.44 ± 4.65 mm and 1.13 ± 2.95 mm, respectively, compared with 5.03 ± 3.66 mm and 2 ± 3.12 mm, respectively, in the control group. There was no pre- to postoperative difference in SATT (P = .51). However, the side-to-side DATT was reduced by 3.66 ± 3.37 mm postoperatively (P < .001), without significant differences between groups (P = .24).

Conclusion

Including a LET procedure for patients undergoing ACLR did not reduce SATT; that is, it did not decrease the amount of tibial translation due to physiological axial load.

Anterior cruciate ligament zoobiquity: Can man's best friend tell us we are being too cautious with the implementation of osteotomy to correct posterior tibial slope

Anterior cruciate ligament (ACL) reconstruction (ACLR) is used to treat clinical instability post ACL rupture, however, there is a high rate of incomplete return to sport and rerupture. There is increasing interest in posterior tibial slope as an intrinsic risk factor for ACLR failure and persistent instability. Zoobiquity describes the collaboration between the human and veterinary professions in order to advance the scientific understanding of both fields. Given the cranial cruciate ligament (CCL) in dogs is synonymous with the anterior cruciate ligament in humans, functioning to control internal rotation and anterior translation, but osteotomies, rather than ligament reconstruction, are the mainstay of treatment for CCL rupture, this editorial sort to gain insights into this form of treatment from the veterinary world. Level of Evidence: Level V, evidence.

Radiographic Investigation of Coronal Plane and Patellar Height and Changes Following Tibial Deflection Osteotomy for Correction of Tibial Slope in Combination With ACL Reconstruction

BACKGROUND

A tibial deflexion osteotomy (TDO) is performed to decrease the sagittal tibial slope to reduce the relative risk of anterior cruciate ligament (ACL) reconstruction (ACLR) graft failure. Given that coronal plane osteotomies can cause consequential changes in the sagittal plane to patellar height and tibial slope, potential changes to coronal plane alignment and patellar height can result after a sagittal plane osteotomy.

PURPOSE

To compare preoperative and postoperative coronal plane alignment after TDO, as well as to analyze the effect of the osteotomy on patellar height.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study was conducted on a consecutive series of patients with primary and revision ACLR with concomitant TDO between 2011 and 2022. Inclusion criteria were 1-stage autograft ACLR combined with supratubercular TDO with pre- and 3 months postoperative radiographs of sufficient quality. Indications for TDO were anterior instability requiring ACL revision surgery and a posterior tibial slope (PTS) >9° or a PTS >14° in the primary ACL surgery patients. Anteroposterior and lateral knee radiographs were reviewed, and the medial proximal tibial angle (MPTA), PTS, Caton-Deschamps index (CDI), and modified Insall-Salvati ratio were measured directly from the radiographs by 2 independent reviewers.

RESULTS

A total of 68 patients were included in this study. Pre- and postoperative radiographs were performed 1 month before and 3 months after surgery, respectively. There was a significant increase in the mean MPTA of 0.95° varus (SD, 2.1°; range, increase of 4.23° valgus to increase of 7.74° varus; P < .01), a decreased PTS of 8.86° (SD, 3.03°; P < .01), and an increased CDI of 0.08 (range, decrease of 0.27 to increase of 0.64) (P < .01; SD, 0.17) in patients undergoing TDO. Insall-Salvati ratio measurements showed no difference. There was good intra- and interobserver reliability, with intraclass correlation coefficients of 0.97 and 0.91 for MPTA, 0.97 and 0.87 for PTS, 0.87 and 0.93 for CDI, and 0.88 and 0.76 the Insall-Salvati ratio.

CONCLUSION

This study, the largest series on TDO for ACLR, demonstrates that the TDO can be performed safely without large changes to coronal alignment or patellar height. The tibial slope was reduced by a mean of 8.86° (range, 2.3°-11.5°; P < .01). The TDO produces a small statistically significant change to coronal alignment, inducing a mean increased varus of <1° and an increased patellar height of 0.1 CDI. Therefore, TDO can be performed safely without dramatic changes to coronal alignment or patellar height, this study highlights technical aspects to minimize iatrogenic varus.

Radiographic Investigation of Differences in Static Anterior Tibial Translation With Axial Load Between Isolated ACL Injury and Controls

BACKGROUND

Static anterior tibial translation (SATT) is radiographically measured to show the amount of tibial translation during the single-leg stance, and thus it is representative of the physiological axial load subjected to the anterior cruciate ligament (ACL) during the stance. Increased SATT has been associated with increased posterior tibial slope (PTS) and is also associated with increased graft failure.

PURPOSE

To compare the SATT value in a control population with that in a population with an isolated ACL injury, as well as to compare the effect of tibial slope on SATT between the 2 groups.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A consecutive series of patients without ligamentous or meniscal injuries between 2019 and 2022 was reviewed. A matched consecutive cohort of patients with nonacute ACL injuries (surgery between 6 and 12 weeks after injury) without concomitant pathology was reviewed. Preoperative SATT and PTS were measured with a previously validated technique on lateral weightbearing knee radiographs. The SATT value was determined, and regression analysis was performed to investigate the relationship between SATT and PTS.

RESULTS

In total, 101 controls and 115 patients with an ACL injury were included in this study. The mean SATT was 1.31 mm (SD, 2.44 mm) and the mean PTS was 10.61° (SD, 3.28°) in the control cohort. The SATT was larger (mean, 2.27 mm; SD, 3.36 mm) in the ACL-injured cohort despite the tibial slope measurement being less in the ACL-injured cohort (mean, 9.46°; SD, 2.85°; P = .016). Linear regression analysis showed that for every 1° of increase in PTS, there was a 0.34-mm increase in SATT in the control cohort; however, there was a greater increase of 0.5 mm for every 1° of increase in PTS in the ACL-injured cohort. We found no significant differences in SATT when the cohorts were compared by age (P = .26) or sex (P = .10).

CONCLUSION

The present study reports a reference SATT value of 1.31 mm (SD, 2.44 mm) in a non-ACL-injured cohort, which was lower than in the ACL-injured cohort (mean, 2.27 mm; SD, 3.36 mm). The effect of slope on weightbearing anterior tibial translation was greater in the ACL-injured population than in the control cohort.