Effects of modified trans-tibial versus trans-portal technique on stress patterns around the femoral tunnel in anatomical single-bundle ACL reconstruction with different knee flexion angles using finite element analysis.

BACKGROUND: It is unclear whether different anterior cruciate ligament (ACL) graft trajectories in the distal femur would have different effects on stress generated within the distal femur around the femoral tunnel during knee motion. Thus, the purpose of this study was to determine differences in stress patterns around the femoral tunnel created by trans-portal (TP) vs. modified trans-tibial (TT) technique in anatomical ACL reconstruction at different knee flexion angles. METHODS: Twelve male subjects' right knees were scanned with a high-resolution computed tomography (CT) scanner (slice thickness: 1 mm) at four different knee flexion angles (0°, 45°, 90°, and 135°). Three-dimensional (3D) models of these four different flexion angles were created and manipulated with several modelling programs. For the TP group, the virtual femoral tunnelling procedure was performed in a 135° flexion model from the low far anteromedial (AM) portal. For the modified TT group, the same knee models were drilled through the modified TT technique at 90° of flexion separately. Virtual grafts under tension of 40 N were put into corresponding bone tunnel and fixed at the outer aperture of femoral tunnels to simulate the suspensory fixation, followed by fixation of the grafts at the middle of tibial tunnels in the 0° knee flexion models. Finally, the models were exported to a finite element analysis package and analysed using ABAQUS/Explicit code (ABAQUS, USA) to monitor the stress occurring at the node where stress distribution occurred most significantly in the femoral bone around the bone tunnel. RESULTS: In general, both groups showed a high stress distribution in bony structures around inner and outer orifices of the femoral tunnel. Mean maximal stresses occurring at the lateral femoral condyle around the inner orifice of the femoral tunnel in the TP group were found to be significantly greater than those in the modified TT group at all flexion angles except 90° of flexion. Mean maximal stresses monitored around the outer orifice of the femoral tunnel in the TP group were also significantly greater than those in the modified TT group at all flexion angles. CONCLUSIONS: Different tunnelling technologies could yield different stress patterns in the lateral femoral condyle around the femoral tunnel. During knee motion, higher stresses were noticed in the TP group than in the modified TT group, especially around inner and outer orifices of the tunnel. Position of the tunnel after reconstruction with the TP technique can have a greater effect on the stress increase in the femur compared to that with the modified TT technique.

Iatrogenic injury of posterolateral structures during femoral tunneling in anterior cruciate ligament reconstruction: A cadaveric study.

OBJECTIVE: Creating Femoral tunnel in Anterior Cruciate Ligament (ACL) reconstruction can be done through some portal. Transportal technique commonly preferred by Orthopedic Surgeon. However, this technique may possess some iatrogenic injury to knee structure especially in the posterolateral during the drilling. This study aim is to describe the most susceptible injured posterolateral structure of the knee during femoral tunneling from trans portal technique Anterior Cruciate Ligament (ACL) reconstruction. METHODS: Twenty knees from ten cadavers was examined. Anterior Cruciate Ligament (ACL) reconstruction was simulated using the trans portal technique. Femoral drilling was performed with knee in 120 flexion. The cadaver was dissected to identify the injured posterolateral structure during femoral tunneling. The data collected was anatomy structure and the wound size. RESULTS: All Twenty knees were included in the study. 90% of injured structure was iliotibial band. The next most common was plantaris (50%) dan gastrocnemius (45%) muscle. The other was biceps femoris muscle (20%). The least common injury was vastus lateralis (5%). No injury was observed in Lateral Collateral Ligament (LCL), popliteus tendon, and peroneal nerve. CONCLUSION: Transportal technique during femoral drilling in Anterior Cruciate Ligament (ACL) reconstruction does do damage to some of the posterolateral structure. The injury was considered minimal and may not result in function deterioration. There is also no risk to common peroneal nerve.

Endoscopic ultrasonography guided transgastric trans-portal system fine needle aspiration for diagnosing pancreatic head and uncinate process malignancy.

BACKGROUND: Endoscopic ultrasonography guided fine needle aspiration (EUS-FNA) is a well-established technique for diagnosing pancreatic malignancy. In general, tissue of pancreatic head and uncinate process lesions is obtained via a transduodenal approach. However, this tissue-acquisition modality is not applicable in cases of pyloric obstruction and duodenal bulb ulceration. The aim of this study is to determine the feasibility and safety of a novel EUS-guided transgastric trans-portal system FNA in the diagnosis of pancreatic head and uncinate process cancer. METHODS: This study retrospectively analyzed 26 consecutive inpatient patients who had undergone EUS-FNA for highly suspected malignancy of pancreatic head or uncinate process between December 2013 and December 2018. EUS-guided transgastric trans-portal vein (trans-PV, n=2) or trans-superior mesenteric vein (trans-SMV, n=24) FNA was performed in the patients under conscious sedation. Feasibility, diagnostic yield and complication rates of the technique were evaluated. RESULTS: Specimens obtained by EUS-guided transgastric trans-portal system FNA were adequate for cytological evaluation in all 26 patients. Cytological diagnosis of adenocarcinoma was established in 22 patients, while the remaining 4 patients were negative. The diagnostic accuracy, sensitivity and specificity were 92.3%, 91.7% and 100% respectively. No immediate or delayed procedure-related complications were observed. CONCLUSIONS: EUS-guided transgastric trans-portal system FNA is a feasible and probably safe method for diagnosing pancreatic head and uncinate process malignancy. Careful selection of the potential candidates and close periprocedural observation are mandatory.

Contact area between femoral tunnel and interference screw in anatomic rectangular tunnel ACL reconstruction: a comparison of outside-in and trans-portal inside-out techniques.

PURPOSE: The purpose of this study was to compare the femoral tunnel length, the femoral graft bending angle at the femoral tunnel aperture, and the contact area between the femoral tunnel wall and an interference screw used for fixation in anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction (ART ACLR). METHODS: The study included 149 patients with primary ACL injury who underwent ART ACLR. Preoperatively, flexion angle of the index knee was checked under general anaesthesia. Those of less than 130° of passive flexion were assigned to the outside-in (OI) technique (78 patients), while the others to the trans-portal inside-out (TP) technique (71 patients). The patients underwent computed tomography with multiplanar reconstruction at 3-5 weeks post-operatively. Femoral tunnel length, graft bending angle, and contact ratio between the IFS and femoral tunnel were assessed. P < 0.05 was considered statistically significant. RESULTS: The femoral tunnel length in the OI technique was significantly longer than that in the TP technique (P < 0.001). The femoral graft bending angle in the OI technique was significantly more acute than that in the TP technique (P < 0.001). The contact ratio in the OI technique was significantly larger than that in the TP technique at every point in the femoral tunnel (P < 0.001). CONCLUSIONS: The OI technique resulted in a more acute femoral graft bending angle, longer mean femoral tunnel length, and larger contact ratio than the TP technique after ART ACLR. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

No difference in graft healing or clinical outcome between trans-portal and outside-in techniques after anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to compare femoral tunnel geometry including tunnel position, length, and graft bending angle between trans-portal and outside-in techniques in anterior cruciate ligament (ACL) reconstruction and discover whether such differences in tunnel geometry could influence graft healing or clinical outcome. METHODS: Sixty-four patients with anatomical single-bundle ACL reconstruction performed with either trans-portal technique (32 patients, one centre) or outside-in technique (32 patients, the other centre) were included in this retrospective study. Femoral tunnel location and length, and graft bending angle at the femoral tunnel were analysed on 3D CT knee model. The location and length of the femoral tunnel and graft bending angle were compared between the two techniques. All patients underwent MRI scans at around 1 year following ACL reconstruction. It was found that all patients had intact ACL graft on MRI images. On oblique axial image taken after ACL reconstruction to determine graft healing at femoral and tibial tunnels and the intra-articular portion, graft signal intensity ratio was calculated by dividing signal intensity (SI) of the reconstructed ACL by that of posterior cruciate ligament (PCL) in the region of interest selected with Marosis software. Clinical outcomes regarding Tegner activity scores, the International Knee Documentation Committee (IKDC) evaluation scores, Lachman test, and pivot shift test results were also compared between the two groups. RESULTS: While the location of femoral tunnel was similar to each other in both groups, the femoral tunnel length was longer in the outside-in technique (37.0 vs. 32.4 mm, p = .02). Meanwhile, the outside-in technique showed significantly more acute graft tunnel angle than the trans-portal technique (106.7° vs. 113.8°, p = .01). However, signal intensity ratios of grafts (compared with SI of PCL) were similar in femoral and tibial tunnels and intra-articular portions. Moreover, there were no statistically significant differences in terms of IKDC scores (89.4 vs. 90.5, n.s.) or Tegner activity scores (6.2 vs. 6.4, n.s.) between the two groups. There was no significant difference in measurement of Lachman or Pivot shift test either between the two groups. CONCLUSION: Even though the outside-in technique in ACL reconstruction created a more acute femoral graft bending angle and a longer femoral tunnel length than the trans-portal technique, these had no negative effect on graft healing. In addition, trans-portal and outside-in techniques in ACL reconstruction showed similar femoral tunnel positions and clinical outcomes. Acceptable graft healing and clinical outcomes can be obtained for both trans-portal and outside-in techniques in ACL reconstruction. LEVEL OF EVIDENCE: III.

Comparison of tunnel variability between trans-portal and outside-in techniques in ACL reconstruction.

PURPOSE: Although trans-portal and outside-in techniques are commonly used for anatomical ACL reconstruction, there is very little information on variability in tunnel placement between two techniques. METHODS: A total of 103 patients who received ACL reconstruction using trans-portal (50 patients) and outside-in techniques (53 patients) were included in the study. The ACL tunnel location, length and graft-femoral tunnel angle were analyzed using the 3D CT knee models, and we compared the location and length of the femoral and tibial tunnels, and graft bending angle between the two techniques. The variability in each technique regarding the tunnel location, length and graft tunnel angle using the range values was also compared. RESULTS: There were no differences in the average of femoral tunnel depth and height between the two groups. The ranges of femoral tunnel depth and height showed no difference between two groups (36 and 41 % in trans-portal technique vs. 32 and 41 % in outside-in technique). The average value and ranges of tibial tunnel location also showed similar results in two groups. The outside-in technique showed longer femoral tunnel than the trans-portal technique (34.0 vs. 36.8 mm, p = 0.001). The range of femoral tunnel was also wider in trans-portal technique than in outside-in technique. Although the outside-in technique showed significant acute graft bending angle than trans-portal technique in average values, the trans-portal technique showed wider ranges in graft bending angle than outside-in technique [ranges 73° (SD 13.6) vs. 53° (SD 10.7), respectively]. CONCLUSIONS: Although both trans-portal and outside-in techniques in ACL reconstruction can provide relatively consistent in femoral and tibial tunnel locations, trans-portal technique showed high variability in femoral tunnel length and graft bending angles than outside-in technique. Therefore, the outside-in technique in ACL reconstruction is considered as the effective method for surgeons to make more consistent femoral tunnel. LEVEL OF EVIDENCE: III.