The "Pre-Rotating Dilator Technique" for Optimal Endograft Orientation in Complex Endovascular Aortic Repair.

PURPOSE: To describe a novel technique for optimal orientation and accurate deployment of aortic endografts during complex endovascular aortic repair (cEVAR). TECHNIQUE: After establishing the femoral access in the standard fashion, a long large-bore dilator is inserted before the cEVAR delivery system. The dilator is advanced beyond the renovisceral segment noticing the degree of axial rotation. The endograft markers are verified with fluoroscopy outside the patient in the standard way. Thereafter, the cEVAR delivery system is pre-emptively rotated by the same degree in the opposite direction than the dilator showed upon insertion. The endograft is then advanced into position with the markers ending with the markers roughly in position. Minor adjustments are done before and during deployment if needed as per standard technique. CONCLUSION: The use of long, large-bore dilator before the introduction of the aortic graft allows to proactively minimize the risk of endograft misalignment and malrotation especially in cases with challenging anatomies in both the visceral and iliac segments. This can potentially be used in all cases because it minimizes the manipulation of the delivery system and potentially increases the accuracy of endograft deployment. CLINICAL IMPACT: This report describes a novel technique involving the use of a long large-bore dilator to predict the degree of rotation of the cEVAR delivery system during insertion and thereby enabling a pre-emptive compensation. This facilitates the precise orientation of the main aortic endograft with an easier alignment of any branches and/or fenestrations to their respective target arteries. This approach holds the potential to mitigate several of the difficulties commonly encountered with current cEVAR solutions, especially the challenges posed by small and tortuous access and severe angulation in the iliac and visceral aortic segment.

Preoperative excessive lateral anterior tibial subluxation is related to posterior tibial tunnel insertion with worse sagittal alignment after anterior cruciate ligament reconstructions.

Objective: To investigate whether preoperative lateral anterior tibial subluxation (LATS) measured from magnetic resonance imaging (MRI) can influence tibial insertion and postoperative sagittal alignment after anterior cruciate ligament reconstructions (ACLRs). Methods: 84 patients who underwent single-bundle ACLRs were retrospectively investigated. Among them, 39 patients (LATS of <6 mm) 23 patients (LATS of ≥6 mm and <10 mm) and 22 patients (excessive LATS of ≥10 mm) were defined as group 1, 2 and 3, respectively. LATS, the position of graft insertion into tibia as ratio of anterior-posterior width (AP ratio) and the sagittal graft angle (SGA) were postoperatively assessed from MRI at 2-year follow-up. Following linear regression analyses were employed. Results: The group 3 exhibited the largest preoperative LATS and remained the most postoperative LATS. Moreover, the group 3 possessed the most posteriorly located tunnel insertion with the largest AP ratio and the most vertical graft orientation. Of all included patients, a moderate correlation was demonstrated between pre- and postoperative LATS (r = 0.635). A low correlation was observed between preoperative LATS and AP ratio (r = 0.300) and a moderate correlation was displayed between AP ratio and SGA (r = 0.656). Conclusion: For ACL injuries with excessive LATS (≥10 mm), most posteriorly located tibial insertion was found out, and worse sagittal alignment containing high residual LATS was associated with more vertical graft orientation following ACLRs.

In vivo gait kinematics of the knee after anatomical and non-anatomical single-bundle anterior cruciate ligament reconstruction-a prospective study.

BACKGROUND: The factors that influence functions of knees after anterior cruciate ligament reconstruction (ACLR) still remains uncertain. The functional restoration of knees after ACLR can be reflected on gait kinematics restoration. The purpose of this study was to evaluate the gait kinematics and clinical outcomes of knees after anatomical and non-anatomical single-bundle ACLR during level walking. METHODS: Thirty-four patients with unilateral primary single-bundle ACLR and 18 healthy people were recruited. Patients were divided into anatomical reconstruction group (AR group; n=13) and non-anatomical reconstruction group (Non-AR group; n=21) according to Bernard Quadrant method. The ACL graft orientations on coronal and sagittal planes were measured on 3D models from medical images. The 6 degrees of freedom (DOF) kinematics of knees and range of motion (ROM) of 6 DOF kinematics were measured with a portable optical tracking system. The comparison of 6 DOF kinematics and ROM of 6 DOF kinematics were performed between the ACLR knees and contralateral knees. The following assessments were also performed including clinical examination, KT-2000 arthrometer measurement, International Knee Documentation Committee (IKDC) and Lysholm scores. RESULTS: All patients reached a minimum follow-up of 6 months (10±4 months). For AR group and Non-AR group, no statistically significant differences were observed in gait kinematics between the ACLR knees and contralateral knees. No statistically significant differences between the ACLR knees and contralateral knees were observed in terms of ROM of 6 DOF kinematics in AR group. However, in Non-AR group, the ACLR knees exhibited significant ROM of anterior-posterior translation by approximately 0.5 cm than contralateral knees (P=0.0080). No statistically significant differences between the two groups were observed regarding IKDC subjective score, Lysholm score and KT-2000 arthrometer test. CONCLUSIONS: The anatomical ACLR can restore close to normal gait kinematics and ROM of 6 DOF kinematics compared with non-anatomical ACLR. The ACL graft after anatomical ACLR simulated native ACL fibers to function in terms of graft orientation.

Impact of graft and tunnel orientation on patient-reported outcome in anterior cruciate ligament reconstruction using bone-patellar tendon-bone autografts.

BACKGROUND: The optimal positioning of anterior cruciate ligament graft is still controversially discussed. We therefore wanted to determine the tunnel-to-joint (TJA), tunnel-to-shaft (TSA), and graft-tunnel divergence angles which would provide the best outcome, determined by the KOOS (Knee Injury and Osteoarthritis Outcome Score). This study evaluated the clinical influence of graft orientation as measured with the KOOS questionnaire in patients with anterior cruciate ligament reconstruction with bone-patellar tendon-bone autografts. METHODS: We designed a prospective cohort study, with a 1 » year recruitment phase from March 2011 to July 2012 and a minimal follow-up period of 1 year. Inclusion criteria were patients ≥ 18 years of age receiving an ACL reconstruction with bone-patellar tendon-bone autografts at our institution after having suffered an acute ACL rupture. The primary outcome was the KOOS. Independent variables were patient age, gender, laterality of rupture, mechanism of trauma, and type of femoral and tibial fixation, as well as sagittal graft-tunnel divergence, TJA, and TSA, the latter two being assessed on coronal slices of magnetic resonance imaging. Equations modeling the relationship between TJA, TSA, and graft-tunnel divergence with the KOOS overall score were fitted, and the optimum angles were mathematically determined. RESULTS: In total, 31 patients were included in our study. Our cohort with a median age of 28 years was predominantly male. The mathematically determined optimal placement of the implant in the coronal plane was a TJA of 74.8°, a TSA of 80.1°, and a graft-tunnel divergence angle of 8.5°. CONCLUSION: With regard to patient-reported outcome, the optimal graft orientation is provided by a coronal tunnel-to-shaft angle of 80° and tunnel-to-joint angle of 75°, respectively. Interestingly, in our series, patients reported best clinical outcomes with a sagittal graft-tunnel divergence. These results should be validated in larger studies.

Knee moment and shear force are correlated with femoral tunnel orientation after single-bundle anterior cruciate ligament reconstruction.

BACKGROUND: Increasing evidence has shown that anatomic single-bundle anterior cruciate ligament reconstruction (ACLR) better restores normal knee kinematics and functionality than nonanatomic ACLR. Whether anatomic reconstruction results in better knee kinetics during daily activities has not been fully investigated. PURPOSE: To assess the relationship between femoral tunnel angle and kinetic parameters of the knee joint during walking after single-bundle ACLR and to compare the radiographic and kinetic results of patients who underwent anatomic ACLR with those of patients who underwent nonanatomic ACLR. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-one patients who underwent unilateral ACLR were recruited, and 20 healthy subjects from a previous study were used as a control group. All surgical procedures were performed by a single surgeon, 11 using the transtibial (TT) technique and 10 using the anteromedial portal (AMP) technique. Femoral tunnel orientation was measured from posterior-to-anterior radiographs. Dynamic knee joint moments and shear forces during gait were evaluated using 3-dimensional motion analysis and inverse dynamics. Relationships between femoral tunnel angles and kinetic results were evaluated via linear regression. Results were compared between 2 ACLR groups and controls using 1-way analysis of variance. RESULTS: Femoral tunnel angle had significant correlations with peak external knee flexion moment and posterior shear force during early stance. The TT group had a significantly smaller (more vertical) mean femoral tunnel angle (19.4° ± 4.1°) than the AMP group (36.4° ± 5.8°). Significant reductions were found in the normalized peak external knee flexion moment (TT, 0.15 ± 0.12 Nm/kg·m; AMP, 0.25 ± 0.12 Nm/kg·m; control, 0.25 ± 0.16 Nm/kg·m) (P = .032) and posterior shear force (TT, 0.64 ± 0.55 N/kg; AMP, 1.10 ± 0.58 N/kg; control, 1.35 ± 0.55 N/kg) (P = .024) in the TT group compared with controls, but not in the AMP group. Moreover, a significantly greater medial shear force was found in the TT group during the late stance phase (TT, 1.08 ± 0.32 N/kg; AMP, 0.89 ± 0.26 N/kg; control, 0.83 ± 0.22 N/kg) (P = .038). A greater peak external knee adduction moment was found in both ACL groups during the early stance phase (TT, 0.25 ± 0.07 Nm/kg·m; AMP, 0.25 ± 0.07 Nm/kg·m; control, 0.19 ± 0.05 Nm/kg·m) (P < .01). CONCLUSION: Knee joint kinetic changes are seen within months (~10 months) after ACLR. This study revealed significant relationships between femoral tunnel orientation and postoperative knee joint flexion moment and posterior shear force during walking. The AMP technique provides better restoration of these knee kinetic parameters compared with the TT technique at this postoperative time point. CLINICAL RELEVANCE: The femoral tunnel angle measured from plain radiographs can be used as an important metric of postoperative knee joint kinetics. This information provides a better understanding of the knee joint's biomechanical environment after ACLR using commonly used single-bundle techniques.