Erquicia et al. Journal of Journal of Experimental Orthopaedics (2022) 9:124 https://doi.org/10.1186/s40634-022-00562-z Experimental Orthopaedics ORIGINAL PAPER Open Access A lower starting point for the medial cut increases the posterior slope in opening‑wedge high tibial osteotomy: a cadaveric study Juan Ignacio Erquicia1,2* , Sergi Gil‑Gonzalez3, Maximiliano Ibañez4, Joan Leal‑Blanquet1,2, Andrés Combalia5,6, Juan Carlos Monllau4,7 and Xavier Pelfort3 Abstract Purpose: The objective of this study was to evaluate the effects on the posterior tibial slope of different dis‑ tances from the joint line to start the osteotomy and of varying the placement of the opening wedge in high tibial osteotomy. Starting the osteotomy more distally and an incorrect location for the tibial opening wedge were hypothesized to increase the posterior tibial slope. Methods: A cadaveric study was conducted using 12 knees divided into two groups based on the distance from the joint line to the start of the osteotomy: 3 and 4 cm. The preintervention posterior tibial slope was measured radiologi‑ cally. Once the osteotomy was performed, the medial cortex of the tibia was divided into anteromedial, medial, and posteromedial thirds. A 10° opening wedge was sequentially placed in each third, and the effect on the posterior tibial slope was evaluated radiographically. Results: Significant changes were observed only in the 3-cm group (p = 0.02) when the wedge was placed in the anteromedial zone. In contrast, in the 4-cm group, significant differences were observed when the opening wedge was placed at both the medial (p = 0.04) and anteromedial (p = 0.012) zones. Conclusion: Correct control of the posterior tibial slope can be achieved by avoiding a low point when beginning the osteotomy and placing the opening wedge in the posteromedial third of the tibia when performing an opening- wedge high tibial osteotomy. Level of evidence: Controlled laboratory study. Keywords: Anterior cruciate ligament, Cadaveric study, Lateral knee X-ray, Medial starting point, Posterior tibial slope, Opening-wedge high tibial osteotomy, Osteotomy, Proximal anatomical axis Background degeneration and varus alignment of the limb [1]. Due Proximal high tibial osteotomy (HTO) is the most to its particular advantages, opening-wedge high tibial widely accepted treatment for physically active patients osteotomy (OWHTO) has become more widely used with initial stages of medial femorotibial compartment in recent years than lateral closing-wedge osteotomies. Among these advantages, the lack of a need to perform an osteotomy of the fibular head with the subsequent *Correspondence: juanerquicia@yahoo.com risk of neurovascular injury [2] and less surgical expo- 1 Department of Orthopedic Surgery and Traumatology, Althaia sure without muscle detachment have been cited [3]. In Xarxa Assistencial Universitària de Manresa, Carrer Dr. Joan Soler, 1‑3, 08243 Manresa, Spain addition, the effect of OWHTO on the tibial metaphysis Full list of author information is available at the end of the article © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://​creat​iveco​mmons.​org/​licen​ses/​by/4.​0/. Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 2 of 10 comparatively facilitates the performance of future knee errors would influence the measurements [15]. Initially, arthroplasty [4]. each knee was placed extended in the anteroposterior (AP) However, OWHTO is not without potential disadvan- plane, and the image was focused on the centre of the tib- tages, including an increase in the posterior tibial slope ial shaft. One-third of the fibular head was covered by the (PTS) and a decrease in the patellar height (PH) [5]. lateral tibial plateau to ensure a correct AP view. This AP Recently, the effects of the PTS on the biomechan- view was used to measure the width (mediolateral) of the ics and stability of the knee [6, 7] have been described, tibial epiphysis by creating a parallel line that passed 5 mm as well as the tension exerted on both native and recon- distal to the joint space. In addition, the mediolateral size structed cruciate ligaments [8–10]. Clinical and bio- of the tibia was measured 3 and 4 cm from the joint line mechanical studies have reported that the tension on using a line parallel to that described above. the native or reconstructed anterior cruciate ligament Subsequently, a strict lateral knee X-ray, where both (ACL) increases significantly after minimal changes in femoral condyle contours perfectly overlapped, was the PTS of only 2°, increasing the risk of failure [11, 12]. performed at 30° of flexion. This projection was used to It is believed that the triangular cross-section of the tibia measure the PTS. at this level as well as the way the osteotomy gap is pro- duced highly influence the increase in the PTS [13, 14]. Radiological PTS evaluation However, the inclination of the osteotomy plane has not The medial and lateral tibial plateaus were initially been investigated. identified to establish the PTS. The mean between the The objective of this study was to evaluate the effect inclinations of both plateaus was used as previously on the PTS of modifying the distance from the joint line published [16]. In measuring both tibial plateaus, the where the osteotomy begins in the medial cortex of the existence of osteophytes was excluded. In the same tibia and of varying the placement of the opening wedge lateral view of the knee, the longitudinal component from posterior to anterior. of the PTS was established by following the proxi- An increase in the PTS was hypothesized to be observed mal anatomical axis of the tibia. For this analysis, two both when distalizing the point where the osteotomy points were identified at 5 and 15 cm distal to the joint begins and when anteriorizing the tibial opening wedge. line. The midpoint of these levels, namely, the distance between the anterior and posterior cortex of the tibia, Materials and methods was identified. These midpoints were connected with For this analysis, 12 cadaveric human knees were used, a line that determined the longitudinal axis mentioned stored at a temperature of − 18 °C, and thawed at room above and are shown in Fig. 1 [17, 18]. The same proto- temperature for 24 to 36 hours prior to the procedure, col was used for the radiographic technique and meas- during which they were wrapped in gauze moistened urement of the PTS after osteotomy. with saline solution. Each knee included the distal All radiographic measurements were performed by two two-thirds of the femur and the proximal two-thirds orthopaedic surgeons using the picture archiving and of the tibia and fibula. The knees were macroscopi- communications system (PACS) (Centricity Enterprise cally evaluated and showed no signs of having under- Web V3.0; GE Healthcare). gone surgery. In addition, prior to use, the absence of local radiographical bone lesions or any significant Osteotomy technique bone malformation that might affect the anatomy was A 6- to 8-cm longitudinal skin incision was made in confirmed. the anteromedial and proximal area of the leg midway The knees were randomly divided into two groups between the anterior tuberosity and the posteromedial based on the distance from the start of the osteotomy to edge of the tibia. After dissecting the subcutaneous the joint line: 3 and 4 cm (cm). All surgical procedures tissue, the tendons of the pes anserinus were incised were performed by the same team of two senior ortho- longitudinally in a single plane at the level of the ante- paedic surgeons. rior margin of the medial collateral ligament. Both The study was approved by the clinical research eth- structures were carefully retracted posteriorly with ics committee of our institution (protocol number the help of a Hohman retractor. The patellar tendon PR260/21-CSA PR22/2021). was identified and protected with a retractor. After the metaphyseal-diaphyseal transition zone of the tibia Radiographic technique was identified, according to the randomization group Prior to performing the osteotomy, the radiographic pro- (namely, 3 or 4 cm) (Fig. 2), a 2.4-mm Kirschner wire cedure was standardized to achieve greater reproducibil- was introduced under fluoroscopic control (C-ARM ity of the technique and to ensure that no magnification Fluoroscopy 4400, FM Control, Alava, Spain) in the Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 3 of 10 Fig. 1 Tibial slope measurement on lateral radiographs. The tibial proximal anatomic axis (TPAA) is drawn connecting the midpoints between the anterior and posterior tibial cortex at five and 15 cm distances to the joint line. A reference line is drawn perpendicular to this at the level of the tibiofemoral joint. The mean between the inclinations of both plateaus is also shown. The angle of this line to the reference line is defined as the posterior tibial slope (PTS) medial cortex aiming posterolaterally towards the prox- of the tibia were identified, the same 10° opening wedge imal end of the fibular head. The tip of the wire was was placed in each third (Fig. 3), and radiographic projec- located 1.5 cm distal to the joint space and 1 cm medial tions were taken as explained previously (Fig. 4). to the lateral cortex. Following wire insertion, the oste- Internal fixation was not performed with plates since the otomy was performed, and special attention was paid objective of the study was to evaluate the possible variations to maintaining perpendicularity with respect to the in the tibial slope and not the stability provided by an implant. sagittal long axis of the bone. Initially, the procedure was started with a saw and continued with a calibrated Statistical analysis osteotome, with particular focus on completion of the A descriptive analysis of the study variables was per- osteotomy in the posterolateral region of the tibia and formed. Radiographic parameters were measured twice preserving one cm of bone in the lateral tibial cortex, by two independent orthopaedic surgeons at 6-week which acts as a hinge [14, 19]. Subsequently, a lamina intervals. The inter- and intrarater reliability for the radi- spreader was used to verify a sufficient opening to pro- ographic measurements was assessed by calculating the gressively place a 10° opening wedge (Newclip Technics, intraclass correlation coefficients (ICCs). The ICC values Haute-Goulaine, France). were interpreted as follows: ICC < 0.40, poor agreement; After the anteromedial, medial and posteromedial 0.4 > ICC < 0.75, fair to good agreement; and ICC > 0.75, (AM, M and PM, respectively) thirds of the medial cortex excellent agreement [20, 21]. Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 4 of 10 Fig. 2 Medial starting point. Anteromedial view of the right knee. (a) Kirschner wire located at the level of the joint line and measurement of the site where the osteotomy will begin. JL, joint line. (b) The methodology is graphed according the sites where the osteotomy will begin according to randomization. PT, patellar tendon (c) Two 2.4-mm wires are introduced at 3 and 4 cm, which will serve as a guide for performing the osteotomy for the 3 and 4 cm groups, respectively. A wide dissection of skin and subcutaneous tissue is performed to facilitate understanding of the image. TT, tibial tuberosity Fig. 3 Anteromedial view of the right knee, 4 cm case. The placement of the opening wedge in the M third of the tibia generates a parallel gap (a). In contrast, when the wedge is located in the PM third of the tibia, the result is an asymmetric gap. The extent to which the medial collateral ligament (MCL) may hinder the posterior placement of the opening wedge is also shown (b). PT, patellar tendon; AM, anteromedial; M, medial; PM, posteromedial The chi-square or Fisher’s exact test was used to com- different sites where the opening was performed and the pare categorical variables, and the t test was used for starting point of the osteotomy. continuous variables. Pearson’s correlation coefficient The sample size was calculated a priori. With six sub- was calculated to compare the PTS measurements at the jects per group (n = 12), a statistical power of 80% was Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 5 of 10 Fig. 4 Radiographic control in a left knee, 3 cm case. Anteroposterior view (a) and lateral knee projection (b) with an opening wedge in the PM third location. AM, anteromedial; M, medial; PM, posteromedial obtained to detect a difference ≥ 2° between the different Global measurement of the PTS (n = 12) tests [22], accepting an alpha risk of 0.05 and a beta risk The mean preoperative PTS was not significantly differ- of 0.2 in a bilateral comparison. ent from the postoperative value when placing the open- Because this is a cadaveric study, a loss to follow-up ing wedge at the PM level (preoperative 7.0 ± 2.3° and rate of 0% was estimated. All data were analysed with postoperative 7.2 ± 2.5°, p = n.s.). On the other hand, SPSS Statistics (v 21; IBM), with statistical significance placement of the opening wedge at any other site resulted was established for p < 0.05. in significant changes at both the M and AM levels (post- operative M 8.7 ± 2.8°, p = 0.02 and postoperative AM Results 11.2 ± 3.3°, p < 0.0001). The remaining results from the Eight of the knees were obtained from women and global analysis and the relative differences are presented four from men. Six were right knees, and six were left in Table 2 and Fig. 5. knees. The mean age was 65.3 ± 13.3 years. The overall descriptive analysis is presented in Table 1. PTS in the 3 cm group Based on the analysis of the 3 cm group, placing the Table 1 Descriptive statistics opening wedge in the PM (p = n.s.) or M (p = n.s.) zone N Minimum Maximum Mean SD ML 12 77.6 mm 97.8 mm 88.6 mm 5.3 mm ML 3 cm 12 68.8 mm 84.9 mm 77.3 mm 3.3 mm Table 2 Comparison of preoperative and global (3 & 4 cm, n = 12) postoperative PTS ML 4 cm 12 54.3 mm 65.8 mm 59.6 mm 5.1 mm PTS preop. 12 4.3° 12.1° 7° 2.3° Mean PTS, SD P value Relative difference PTS PM 12 2.9° 12.5° 7.2° 2.4° PTS M 12 4.4° 14.2° 8.6° 2.8° Pre 7 ± 2.3° PTS AM 12 6.9° 17.5° 11.2° 3.3° Post PM 7.2 ± 2.5° Pre vs. post PM 0.7 2.9% ML, mediolateral; ML 3 cm, mediolateral 3 cm from the joint line; ML 4 cm, Post M 8.7 ± 2.8° Pre vs. post M 0.02 24% mediolateral 4 cm from the joint line; SD, standard deviation; PTS, posterior tibial Post AM 11.2 ± 3.3° Pre vs. post AM < 0.0001 60% slope; PM, posteromedial; M, medial; AM, anteromedial Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 6 of 10 Fig. 5 Preoperative vs postoperative PTS (global 3 & 4 cm, n = 12). The red text indicates significant changes. R. D, relative difference; AM, anteromedial; M, medial; PM, posteromedial Table 3 Independent comparisons of preoperative and postoperative Mediolateral measurement PTS in the 3 and 4 cm groups The measured mediolateral size of the tibial epiphysis Mean PTS, SD P value Relative was not correlated with the magnitude of the postopera- difference tive modifications of the PTS. 3 cm Pre 6.5 ± 1.9° Measurement reliability Post PM 6.7 ± 2.2° Pre vs. post PM 0.75 3% The interrater reliability of the pre- and postosteotomy Post M 7.6 ± 2.5° Pre vs. post M 0.12 17% PTS measurements was “excellent” and is shown in Post AM 10.3 ± 2.5° Pre vs. post AM 0.0002 58% Table 4. The intrarater reliability was also considered 4 cm Pre 7.5 ± 2.8° “excellent”, with ICC values ≥0.91 for all measurements Post PM 7.7 ± 2.9° Pre vs. post PM 0.88 3% performed by both evaluators. Post M 9.8 ± 2.9° Pre vs. post M 0.04 31% Post AM 12.2 ± 4° Pre vs. post AM 0.01 63% Discussion SD, standard deviation The most relevant findings of this study reflect the impact on the PTS of distalizing the point where the osteotomy begins, since a greater distance between did not significantly alter the resulting PTS, and a rela- the beginning of the osteotomy and the joint line tive difference from the preoperative values of 3% and results in a greater risk of causing changes in the PTS. 17%, respectively, was observed (Table 3 and Fig. 6). Another finding in this study is the importance of placing the opening wedge in the PM third of the tibia when performing an HTO, since significant changes PTS in the 4 cm group in PTS were not detected in either group (3 or 4 cm) The preoperative PTS was only maintained when after the procedure. The results of the present study placing the opening wedge at the PM level (p = n.s.). confirm the initial hypothesis. Placement at the M (p = 0.04) and AM (p = 0.012) As previously reported, the PTS tends to increase levels generated significant changes in the postopera- when performing OWHTO [5]. This increase in the tive PTS. The relative differences from the preopera- inclination in the sagittal plane is transformed into tive value were 31 and 63%, respectively, as shown in a greater force of tibial displacement towards the Table 3 and Fig. 6. anterior direction, increasing the demand on the Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 7 of 10 Fig. 6 Comparisons of preoperative and postoperative PTS, in the 3 and 4 cm groups. The red text indicates significant changes. R. D, relative difference; AM, anteromedial; M, medial; PM, posteromedial Furthermore, an iatrogenic increase in the PTS not Table 4 Interrater reliability only affects the native or reconstructed ACL but also, as Obs 1 Obs 2 ICC Rodner et al. have shown, generates greater pressure in the posteromedial compartment [33]. PTS Pre 6.9 ± 2.5° 7.2 ± 2.5° 0.82 (95% CI 0.25–0.90) According to the findings from the present study, the PTS Post PM 6.8 ± 2.1° 7.6 ± 2.9° 0.92 (95% CI 0.73–0.98) undesired effects on the ACL and the increased pres- PTS Post M 8.4 ± 3° 9.0 ± 2.8° 0.94 (95% CI 0.81–0.98) sure on the posteromedial compartment observed after PTS Post AM 10.9 ± 3.6° 11.6 ± 3.1° 0.95 (95% CI 0.84–0.99) the increase in the PTS might be avoided by consider- ML 86.6 ± 3.5 90.1 ± 3.1 0.89 (95% CI 0.77–0.91) ing certain technical aspects during the performance of PTS, posterior tibial slope; Pre, preoperative; Post, postoperative; PM, an OWHTO, such as the distance from the joint space posteromedial; M, medial, AM, anteromedial; ML, mediolateral; Obs, observer; where the osteotomy begins and the placement of the ICC, intraclass correlation coefficient opening wedge in the PM third of the tibia. Consistent with the data published by Rubino et al., performing the opening in the PM third of the tibia suc- native ACL [23]. Likewise, evidence also supports the cessfully avoids modifications in the PTS. The findings impact of the PTS on the ACL postreconstruction of our study show that as the opening wedge is moved [24, 25]. to the M and AM thirds, the increases in the PTS are A greater lateral PTS in patients who suffered early progressive (Table 3), similar to the study by Rubino failure after ACL reconstruction versus those who had et al. In their study, the placement of the wedge at the satisfactory results after the same reconstruction was level of the M third also showed significant changes in shown by Christensen et al. [26, 27]. the TS, although the authors did not specify the dis- The role of the medial PTS as a predictive factor for tance from the joint line where the osteotomy began ACL reconstruction failure is more controversial [28, [34]. According to the results obtained in our study, the 29]. However, different studies [30–32] are consistent height where the osteotomy begins plays a relevant role with those published by Webb et al. [10]; in their study, in the resulting PTS, since no significant differences in a medial PTS > 12° was stated to increase the risk of the PTS were observed when the opening was created failure after ACL reconstruction. in the medial third in the 3 cm group (preoperative PTS Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 8 of 10 of 6.5 ± 1.9° vs. postoperative PTS of 7.6 ± 2.5°, relative Recently, in another cadaveric study [19], the effect difference 17%, p = n.s.). However, a significant increase on the PTS of an OWHTO in which the lateral hinge in the PTS was observed when the osteotomy began was located 1 cm distal to the standard position was 4 cm from the joint space and the opening was estab- analysed [1, 33, 40]. The authors of this study con- lished at the level of the M third (preoperative PTS of cluded that the distalization of the lateral hinge gen- 7.5 ± 2.8° vs. postoperative PTS of 9.8 ± 2.9°, relative erated an increase in the PTS compared to the site difference 31%, p = 0.04). defined as a standard to locate it. This distalization The findings presented in our study may be related of the hinge not only affected the PTS but also gener- to the three-triangle method published by Noyes et al. ated a greater number of fractures in the lateral cor- in 2005 [35]. In that study, the medial cortical tibia was tex of the tibia. These aforementioned changes were established to have an angulation of 45° in the axial attributed by the authors to the decrease in the axial plane, and when creating the opening, the anterior gap size of the tibia at that level. In our study, cases of frac- was suggested to be half of the posterior gap. According ture were not observed when the standard height of to their published data, assuming a medial cortex of the the lateral hinge was chosen. However, when the oste- tibia measuring 40 mm, a 10° increase in the PTS would otomy was started 4 cm from the joint space, which be generated by an error of 5 mm in the size of the ante- represents a smaller ML distance, changes in the PTS rior gap. It was concluded by the authors that as a general occurred more easily, similar to the results published rule, for a 40-mm medial cortex, each millimetre altera- by Jo HS et al. [19]. tion in the opening gap results in a 2° increase in the PTS. This study is not without limitations. Because it was It was also established that if the size of the medial cortex a cadaveric study, the number of subjects was limited. decreases to 20 mm, then each millimetre of error in the However, the number of specimens used is consistent anterior opening gap generates a 4° increase in the PTS. with other cadaver studies focused on the analysis of According to the data from this study and the existing the tibial slope, whose range is 8–16 knees [1, 13, 19]. differences in the mediolateral distance at 3 and 4 cm in Due to the characteristic bone quality of this sample, our series (Table 1), when selecting a distal site to begin we did not propose the creation of openings of differ- the osteotomy, a smaller medial cortical bone is assumed, ent amplitudes. These limitations were minimized by which is associated with a greater risk of producing selecting the degree of opening based on the protocols increases in the PTS after minimal changes in the place- used in other studies that analyse the PTS when per- ment of the opening wedge [36]. forming an OWHTO [13]. In addition, because the Different authors mention the site they chose to begin specimens did not include the ankle joint, the PTS was the osteotomy, but to our knowledge, these different measured on a lateral radiograph of the knee according levels have not been compared with each other to date. to the proximal anatomic axis of the tibia [41]. How- Matar et al. preferred the metaphyseal-diaphyseal junc- ever, with this methodology, no significant differences tion area, distal to the capsular insertion and 3 cm from in the PTS should be observed if it is measured accord- the joint space, considering this site as the safest since ing to the complete anatomical axis of the tibia on full- they managed to place a retractor and protect the poste- length lateral radiographs [42]. Similarly, varus/valgus rior neurovascular structures [37]. In contrast, Noyes FR alignment could not be evaluated due to the lack of a et al. prefer starting at 3.5 cm [38], and other authors have complete limb and the impossibility of performing radi- started at 4 cm from the joint space [39]. ographs in the standing position [43]. The findings from the present study have an even more Finally, and when also presenting the amputation in relevant implication for those cases where simultaneous the proximal third of the femur, the possible relation- ACL reconstruction associated with OWHTO is pro- ship between the different changes produced in the posed. In these cases, it was suggested by Cantivalli et al. PTS and the patellar height could not be studied due to that OWHTO should begin 4 cm from the joint space to the interruption of the extensor apparatus. create a tibial tunnel of sufficient length and prevent it In terms of the clinical relevance of this work, both from starting within the osteotomy gap [39]. The lower the site where the opening is performed and the cor- starting point suggested by these authors could generate responding wedge is placed and the distance from the a clear undesired effect on the PTS if the surgeon does joint line where the osteotomy will begin must be con- not maintain strict placement of the opening wedge at sidered by the orthopaedic surgeon prior to surgery. the PM level. In this context, the opening at the level of In cases requiring an OWHTO associated with ACL the M third would generate an increase in the PTS > 2°, reconstruction, the distalization of the site where the with all the consequences that this change would impose osteotomy begins potentially exerts a relevant effect on on the recent reconstruction of the ACL [10, 11]. the PTS. Erquicia et al. Journal of Experimental Orthopaedics (2022) 9:124 Page 9 of 10 Conclusion References 1. 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J Orthop Surg (Hong Kong) 29(3):9–12 also want to thank María Angela Zumel, Ph. D, Marta Banque, Ph. D, and Gaston 6. Dai Y, Cross MB, Angibaud LD, Hamad C, Jung A, Jenny J-Y (2018) Pos‑ Rodriguez Granillo, M. D, Ph.D, for assisting in the statistical analysis. Finally, they terior tibial slope impacts intraoperatively measured mid-flexion anter‑ thank the institutional support from Newclip Technics (Haute-Goulaine, France), oposterior kinematics during cruciate- retaining total knee arthroplasty. who provided the instrumentation required for completion of this study. Knee Surg Sport Traumatol Arthrosc 26(11):3325–3332 7. Kang K-T, Kwon SK, Son J, Kwon O-R, Lee J-S, Koh Y-G (2018) The increase Authors’ contributions in posterior tibial slope provides a positive biomechanical effect in JIE designed the study and draft the manuscript. SG and JIE carried out the posterior-stabilized total knee arthroplasty. Knee Surg Sport Traumatol osteotomies. SG and MI performed the radiographic measurements. JCM and Arthrosc 26(10):3188–3195 JLB co-analyzed the data and were major contributors in writing the manu‑ 8. Bernhardson AS, DePhillipo NN, Aman ZS, Kennedy MI, Dornan GJ, script. AC and XP co-designed the study and helped to draft the manuscript. LaPrade RF (2019) Decreased posterior tibial slope does not affect post‑ All authors read and approved the final manuscript. operative posterior knee laxity after double-bundle posterior cruciate ligament reconstruction. Am J Sports Med 47(2):318–323 Funding 9. Bernhardson AS, DePhillipo NN, Daney BT, Kennedy MI, Aman ZS, LaPrade No funding of whatever form was provided for this study. RF (2019) Posterior tibial slope and risk of posterior cruciate ligament injury. Am J Sports Med 47(2):312–317 Availability of data and materials 10. 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