Evaluation of Adjustable Loop Suspensory Anterior Cruciate Ligament Fixation Devices

AbstractAlong with increasing enthusiasm for sports comes an increase of sport related injuries. One of the most common injuries in the human knee is the tear of the anterior cruciate ligament (ACL). The selection of a graft fixation device is an important factor that determines the outcome of an anterior cruciate ligament reconstruction. Before the healing process is completed, the graft is dependent on tibial and femoral fixation devices to maintain normal ACL graft tension. Among various devices, the use of an adjustable loop suspensory fixation device (ALD) in soft-tissue graft reconstruction attracts current interest. An advantage of the ALD is the ability to draw the graft to the depth of the bone tunnel to achieve adequate graft tension while minimizing the empty space in the tunnel. In this study a comprehensive controlled laboratory investigation is performed to examine the biomechanical properties of commonly used cortical fixation devices, with the aim of implementing a standard testing procedure for adjustable loop devices. The procedure consists of three test series, a loop shortening test and two different stability test series (singe device and tendon device test). Those test series are used to compare the performance of a new ALD from Arthrex (Naples, USA) with five competitor devices already on the market. In order to obtain representative results eight samples of each device are tested. In comparison to the previously performed studies, a complete unloading is applied in the stability tests, which allows for a detailed examination of the ALDs locking mechanisms in dynamically loaded test situations. Furthermore, the performed loop shortening tests reveal important aspects, such as the shortening accuracy and settling effects of the loops, that are not found in previous studies. Therefore, the used test protocol can be recommended for further testing.

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How Four Weeks of Implantation Affect the Strength and Stiffness of a Tendon Graft in a Bone Tunnel

The American Journal of Sports Medicine ◽

10.1177/03635465020300041001 ◽

2002 ◽

Vol 30 (4) ◽

pp. 506-513 ◽

Cited By ~ 81

Author(s):

Wamis Singhatat ◽

Keith W. Lawhorn ◽

Stephen M. Howell ◽

Maury L. Hull

Keyword(s):

Anterior Cruciate Ligament ◽

Cruciate Ligament ◽

Tendon Graft ◽

Interference Screw ◽

Bone Tunnel ◽

Fixation Device ◽

Fixation Devices ◽

Soft Tissue Graft ◽

Anterior Cruciate ◽

Strength And Stiffness

Background For a tendon graft to function as an anterior cruciate ligament, the tendon must heal to the bone tunnel. We studied the effect of 4 weeks of implantation on the strength and stiffness of a tendon in a bone tunnel using two different fixation devices in an ovine model. Hypothesis The type of fixation device in anterior cruciate ligament reconstruction may affect early healing, which can be measured as the strength and stiffness of a tendon in a bone tunnel. Study Design Controlled laboratory study. Methods An extraarticular tendon graft reconstruction was performed in ovine tibias. The graft was fixed with either a bioresorbable interference screw or a WasherLoc. After 4 weeks of implantation the strength and stiffness of the complex and the tendon graft-bone tunnel interface were determined by incrementally loading specimens to failure. Results For the interference screw, the strength deteriorated 63% and the stiffness deteriorated 40%. For the WasherLoc, the strength was similar and the stiffness improved 136%. Conclusions The type of fixation device determines whether the strength and stiffness of a tendon in a bone tunnel increases or decreases after implantation. Clinical Relevance The pace of rehabilitation may need to be adjusted based on the type of fixation device used to secure a soft tissue graft.

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An Implantable Transducer for Measuring Tension in an Anterior Cruciate Ligament Graft

Journal of Biomechanical Engineering ◽

10.1115/1.2797998 ◽

1998 ◽

Vol 120 (3) ◽

pp. 327-333 ◽

Cited By ~ 9

Author(s):

C. P. Ventura ◽

J. Wolchok ◽

M. L. Hull ◽

S. M. Howell

Keyword(s):

Anterior Cruciate Ligament ◽

Measurement Accuracy ◽

Femoral Tunnel ◽

Cruciate Ligament ◽

Full Range ◽

Fixation Device ◽

Anterior Cruciate Ligament Graft ◽

Graft Tension ◽

Load Cells ◽

Anterior Cruciate

The goal of this study was to develop a new implantable transducer for measuring anterior cruciate ligament (ACL) graft tension postoperatively in patients who have undergone ACL reconstructive surgery. A unique approach was taken of integrating the transducer into a femoral fixation device. To devise a practical in vivo calibration protocol for the fixation device transducer (FDT), several hypotheses were investigated: (1) The use of a cable versus the actual graft as the means for applying load to the FDT during calibration has no significant effect on the accuracy of the FDT tension measurements; (2) the number of flexion angles at which the device is calibrated has no significant effect on the accuracy of the FDT measurements; (3) the friction between the graft and femoral tunnel has no significant effect on measurement accuracy. To provide data for testing these hypotheses, the FDT was first calibrated with both a cable and a graft over the full range of flexion. Then graft tension was measured simultaneously with both the FDT on the femoral side and load cells, which were connected to the graft on the tibial side, as five cadaver knees were loaded externally. Measurements were made with both standard and overdrilled tunnels. The error in the FDT tension measurements was the difference between the graft tension measured by the FDT and the load cells. Results of the statistical analyses showed that neither the means of applying the calibration load, the number of flexion angles used for calibration, nor the tunnel size had a significant effect on the accuracy of the FDT. Thus a cable may be used instead of the graft to transmit loads to the FDT during calibration, thus simplifying the procedure. Accurate calibration requires data from just three flexion angles of 0, 45, and 90 deg and a curve fit to obtain a calibration curve over a continuous range of flexion within the limits of this angle group. Since friction did not adversely affect the measurement accuracy of the FDT, the femoral tunnel can be drilled to match the diameter of the graft and does not need to be overdrilled. Following these procedures, the error in measuring graft tension with the FDT averages less than 10 percent relative to a full-scale load of 257 N.

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Biological enhancement of graft-tunnel healing in anterior cruciate ligament reconstruction

Joints ◽

10.11138/jts/2016.4.3.174 ◽

2016 ◽

Vol 04 (03) ◽

pp. 174-182

Author(s):

Maristella Saccomanno ◽

Luigi Capasso ◽

Luca Fresta ◽

Giuseppe Milano

Keyword(s):

Anterior Cruciate Ligament ◽

Clinical Practice ◽

Clinical Studies ◽

Cruciate Ligament ◽

Healing Process ◽

Bone Tunnel ◽

Therapeutic Effects ◽

Tunnel Length ◽

Acl Graft ◽

Anterior Cruciate

The sites where graft healing occurs within the bone tunnel and where the intra-articular ligamentization process takes place are the two most important sites of biological incorporation after anterior cruciate ligament (ACL) reconstruction, since they help to determine the mechanical behavior of the femur-ACL graft-tibia complex. Graft-tunnel healing is a complex process influenced by several factors, such as type of graft, preservation of remnants, bone quality, tunnel length and placement, fixation techniques and mechanical stress. in recent years, numerous experimental and clinical studies have been carried out to evaluate potential strategies designed to enhance and optimize the biological environment of the graft-tunnel interface.Modulation of inflammation, tissue engineering and gene transfer techniques have been applied in order to obtain a direct-type fibrocartilaginous insertion of the ACL graft, similar to that of native ligament, and to accelerate the healing process of tendon grafts within the bone tunnel. Although animal studies have given encouraging results, clinical studies are lacking and their results do not really support the use of the various strategies in clinical practice. Further investigations are therefore needed to optimize delivery techniques, therapeutic concentrations, maintenance of therapeutic effects over time, and to reduce the risk of undesirable effects in clinical practice.

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In Vivo Calibration of a Femoral Fixation Device Transducer for Measuring Anterior Cruciate Ligament Graft Tension: A Study in an Ovine Model

Journal of Biomechanical Engineering ◽

10.1115/1.1385842 ◽

2001 ◽

Vol 123 (4) ◽

pp. 355-361 ◽

Cited By ~ 10

Author(s):

Isaac Zacharias ◽

Stephen M. Howell ◽

M. L. Hull ◽

Keith W. Lawhorn

Keyword(s):

Anterior Cruciate Ligament ◽

Cruciate Ligament ◽

Fixation Device ◽

Ovine Model ◽

Femoral Fixation ◽

Graft Tension ◽

Tibial Metaphysis ◽

Anterior Cruciate ◽

Graft Insertion

Toward developing a transducer for measuring in vivo tension in anterior cruciate ligament grafts in humans, the objectives of this study were to determine the following: (1) whether the calibration of a previously reported femoral fixation device transducer (FDT) (Ventura et al., 1998) is affected by the presence of the graft when implanted in the tibial metaphysis of an ovine model, (2) whether the FDT remains calibrated at 4 weeks postoperatively, and (3) whether the biological incorporation of the graft occurs prior to a change in the FDT calibration. The FDT was implanted in the hind limb of five sheep using an extra-articular procedure. Both the proximal common digital extensor tendon (i.e., graft) and a Teflon-coated wire were looped around the FDT inside a tunnel in the tibial metaphysis. The FDT was calibrated on three occasions using the loop of wire: once intraoperatively before graft insertion, once intraoperatively after graft insertion, and once postoperatively after the animals had been sacrificed at 4 weeks. Following sacrifice, the load transmitted to the FDT by the graft was also determined. The FDT exhibited linear calibration intraoperatively both before and after graft insertion with an average error relative to the calibration before insertion of the graft of −4.6 percent of full-scale load (150 N) and this average relative error was not significantly different from zero p=0.183. After 4 weeks of implantation, the average relative percent error was −5.0 percent and was not significantly different from zero p=0.434 indicating that the FDT remained calibrated in the in vivo environment. Because only 15 percent of the graft tension was transmitted to the FDT after 4 weeks, biological incorporation of the graft preceded the loss of calibration. In light of these findings, the FDT offers the capability of measuring the intra-articular ACL graft tension in vivo in animal models and possibly humans before the biological bond develops and also of monitoring the formation and maturation of the biological bond between a graft and bone tunnel.

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Bioresorbable Stent in Anterior Cruciate Ligament Reconstruction

Polymers ◽

10.3390/polym11121961 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1961

Author(s):

Krzysztof Ficek ◽

Jolanta Rajca ◽

Mateusz Stolarz ◽

Ewa Stodolak-Zych ◽

Jarosław Wieczorek ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Healing Process ◽

Tendon Graft ◽

Bone Tunnel ◽

Control Group ◽

Microstructural Parameters ◽

Beneficial Effects ◽

Anterior Cruciate

The exact causes of failure of anterior cruciate ligament (ACL) reconstruction are still unknown. A key to successful ACL reconstruction is the prevention of bone tunnel enlargement (BTE). In this study, a new strategy to improve the outcome of ACL reconstruction was analyzed using a bioresorbable polylactide (PLA) stent as a catalyst for the healing process. The study included 24 sheep with 12 months of age. The animals were randomized to the PLA group (n = 16) and control group (n = 8), subjected to the ACL reconstruction with and without the implantation of the PLA tube, respectively. The sheep were sacrificed 6 or 12 weeks post-procedure, and their knee joints were evaluated by X-ray microcomputed tomography with a 50 μm resolution. While the analysis of tibial and femoral tunnel diameters and volumes demonstrated the presence of BTE in both groups, the enlargement was less evident in the PLA group. Also, the microstructural parameters of the bone adjacent to the tunnels tended to be better in the PLA group. This suggested that the implantation of a bioresorbable PLA tube might facilitate osteointegration of the tendon graft after the ACL reconstruction. The beneficial effects of the stent were likely associated with osteogenic and osteoconductive properties of polylactide.

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