ESTIMATION OF THE OPTIMAL FIBULAR GRAFT ANGLE FOR PROXIMAL HUMERUS FRACTURES USING FINITE ELEMENT ANALYSIS

Proximal humerus fracture is a common injury and is usually treated using an internal fixation. However, clinical studies have reported that such treatments are associated with problems such as varus deformity and screw penetration. Therefore, to solve these problems, a surgical method using fibular allografts (FAs) is recently reported. Thus, this study is aimed to confirm the effective insertion angle ([Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) of the FA. We applied axial and shear loads to finite element models used in our study. Finite element simulations using these models were repeated five times for each fibular insertion angle. We evaluated the construct stiffness, stress distribution on the plate and fibula, and fracture micromotion. Results showed that the method using the FA caused less stress on the plate and provided higher structural stability than the method without using the FA. In particular, the axis perpendicular condition yielded significantly greater construct stiffness and caused less von Mises stresses than the other conditions. In conclusion, the finite element analysis results showed that the FA inserted horizontally was effective in the treatment of proximal humerus fracture with an unstable medial support.

Anterior Cruciate Ligament Graft Tunnel Placement and Graft Angle Are Primary Determinants of Internal Knee Mechanics After Reconstructive Surgery

Background: Graft placement is a modifiable and often discussed surgical factor in anterior cruciate ligament (ACL) reconstruction (ACLR). However, the sensitivity of functional knee mechanics to variability in graft placement is not well understood. Purpose: To (1) investigate the relationship of ACL graft tunnel location and graft angle with tibiofemoral kinematics in patients with ACLR, (2) compare experimentally measured relationships with those observed with a computational model to assess the predictive capabilities of the model, and (3) use the computational model to determine the effect of varying ACL graft tunnel placement on tibiofemoral joint mechanics during walking. Study Design: Controlled laboratory study. Methods: Eighteen participants who had undergone ACLR were tested. Bilateral ACL footprint location and graft angle were assessed using magnetic resonance imaging (MRI). Bilateral knee laxity was assessed at the completion of rehabilitation. Dynamic MRI was used to measure tibiofemoral kinematics and cartilage contact during active knee flexion-extension. Additionally, a total of 500 virtual ACLR models were created from a nominal computational knee model by varying ACL footprint locations, graft stiffness, and initial tension. Laxity tests, active knee extension, and walking were simulated with each virtual ACLR model. Linear regressions were performed between internal knee mechanics and ACL graft tunnel locations and angles for the patients with ACLR and the virtual ACLR models. Results: Static and dynamic MRI revealed that a more vertical graft in the sagittal plane was significantly related ( P < .05) to a greater laxity compliance index ( R2 = 0.40) and greater anterior tibial translation and internal tibial rotation during active knee extension ( R2 = 0.22 and 0.23, respectively). Similarly, knee extension simulations with the virtual ACLR models revealed that a more vertical graft led to greater laxity compliance index, anterior translation, and internal rotation ( R2 = 0.56, 0.26, and 0.13). These effects extended to simulations of walking, with a more vertical ACL graft inducing greater anterior tibial translation, ACL loading, and posterior migration of contact on the tibial plateaus. Conclusion: This study provides clinical evidence from patients who underwent ACLR and from complementary modeling that functional postoperative knee mechanics are sensitive to graft tunnel locations and graft angle. Of the factors studied, the sagittal angle of the ACL was particularly influential on knee mechanics. Clinical Relevance: Early-onset osteoarthritis from altered cartilage loading after ACLR is common. This study shows that postoperative cartilage loading is sensitive to graft angle. Therefore, variability in graft tunnel placement resulting in small deviations from the anatomic ACL angle might contribute to the elevated risk of osteoarthritis after ACLR.

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

Background: Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement. Purpose: To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling. Study Design: Controlled laboratory study. Methods: Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement. Results: Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof. Conclusion: The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement. Clinical Relevance: Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Comparison of MRI Results of Grafts Obtained by Unilateral Anterior Cruciate Ligament Reconstruction Either Using Anteromedial Portal Only or Transtibial Method with Contralateral Healthy Knee

Objectives: Our aim is to compare graft angles and tibial tunnel insertion in patients undergone single bundle ligament reconstruction using anatomical anteromedial (AM) and transtibial (TT) method with the contralateral healthy knee by using MR imaging. And to investigate correlation of this evaluation with functional results. Methods: We investigated 96 knees of 48 patients undergone anterior cruciate ligament (ACL) reconstruction with AM or TT method. 23 of 48 patients were operated with AM method. These patients were named as Group A. 25 patients were operated with TT method and named as group B. MRI was taken for both knees in each group postoperatively at the mean 10.47 (9-15) and 11.72 (9-17) months, respectively. Angle between ACL graft and anatomical axis of tibia in coronal and sagittal plane, [Sagittal ACL graft angle (SAGA), Frontal ACL graft angle (FAGA)], middle insertion point on tibial articular surface, [ Sagittal ACL middle point (SGMP), Frontal ACL tibial tunnel middle point (FTMP), and Sagittal ACL tibial tunnel middle point(STMP)] was assessed by three orthopaedic surgeons. Values in both groups, inter observer, values between operated and healthy knees and differences between two groups were statistically evaluated. Functional scores between operated and healthy knees were evaluated with the Lysholm scoring system. Results: Inter observer results were statistically significant in group A between operated and healthy knees for 1st and 2nd observers in SAGA values and for 1st and 3rd, and 2nd and 3rd observers in FAGA values (p<0.05). In group B there was statistically significant difference in SAGA values for 1st and 2nd, and for 2nd and 3rd observers and in FTMP values for 1st and 3rd, and 2nd and 3rd observers (p<0.05). Statistically significant difference was detected between SAGA, FAGA and SGMP values of operated and healthy knees of A and B groups in all three observers’ evaluation (p<0.05). No statistically significant difference was detected between STMP values of operated knees and SGMP values of healthy knees in both groups (p>0.05). Statistically significant difference was detected between SAGA and FAGA values of operated knees in both groups (p<0.05). There was statistically significant difference in Lysholm scores between group A and B (p<0.05). Nonetheless there was no statistically significant difference between the Lysholm scores of operated knees in A and B groups (p>0.05). Conclusion: ACL reconstruction surgery with TT and AM methods do not provide anatomical reconstruction in Sagittal plane. Moreover, functional results were not as good as contralateral healthy knees. Although tibial tunnel was in anatomical position in both TT and AM methods, the posterior insertion of graft is thought to be the result of anterior placement of interference screw.

Graft Angle and Its Relationship to Tomato Plant Survival

Growing transplants that can withstand the rigors of open-field production is imperative for the successful adoption of grafting in large-scale commercial fields and especially for those who seek to adopt this technology as an alternative to soil fumigation. This study examines the relationship of tensile strength to graft angle and plant survival. Tomato (Solanum lycopersicum) seedlings of ‘FL-47’ and ‘Rutgers’ were used as scions on ‘Roma’ rootstock under greenhouse and healing chamber conditions. Scions were grafted at angles of 20°, 45°, and 70°. After a period of 10 days, the plants were severed near ground level and subjected to pull force analysis. Pull force of the graft increased significantly with the increased graft angle. Pull force between the 20° vs. 70° angles increased significantly as well as those of 45° vs. 70° grafts (P ≤ 0.001). Increase in graft angle resulted in greater survival of grafted plants from 79% (20°), 81% (45°), and 92% (70°). Fifteen commercial rootstocks grafted at 70° had survival percentage rates between 97% and 100%. These studies demonstrate that the angle can significantly impact graft integrity and plant survival.