Soft-tissue Anterior Cruciate Ligament Graft Research Articles

Clinical and Functional Outcomes of Anterior Cruciate Ligament Reconstruction at a Minimum of 2 Years Using Adjustable Suspensory Fixation in Both the Femur and Tibia: A Prospective Study.

Background:The success of anterior cruciate ligament (ACL) reconstruction requires reliable and rigid graft fixation. Cortical suspensory fixation (CSF) devices have become an acceptable alternative to interference screws for soft tissue ACL grafts. However, CSF devices have been reported to be associated with tunnel widening and increased postoperative anterior laxity compared with interference screw fixation. Adjustable CSF devices were introduced to avoid these problems but have been associated with graft lengthening and inconsistent outcomes.Purpose:To (1) report the side-to-side difference (SSD) in anterior laxity at 150 N, clinical scores, and failure rates 2 years after ACL reconstruction with 4-strand semitendinosus autografts using an adjustable CSF device and (2) determine the preoperative factors associated with clinical outcomes.Study Design:Case-control study; Level of evidence, 3.Methods:A total of 131 patients who had undergone primary ACL reconstruction, performed with 4-strand semitendinosus grafts that were secured using Pullup adjustable-length CSF devices with femoral and tibial fixation techniques, were prospectively enrolled in this study; 34 patients were excluded because of contralateral instability or ipsilateral knee injuries that required additional surgery. This left a cohort of 97 patients who were evaluated preoperatively and at 6, 12, and 24 months. The evaluation consisted of measuring the SSD in anterior laxity and patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Lysholm scores). Regression analyses were performed to determine associations between these outcomes and 9 preoperative variables.Results:Only 2 patients could not be reached, 2 could not be evaluated because of contralateral ACL tears, and 2 had graft failure. At 2-year follow-up, the remaining 91 patients had a mean SSD in anterior laxity of 0.8 ± 1.8 mm (range, –4.2 to 5.3 mm), mean IKDC score of 87.6 ± 10.6 (range, 43.7-100.0), and mean Lysholm score of 90.8 ± 9.3 (range, 56.0-100.0). At final follow-up, compared with knees with partial ruptures, those with complete ruptures had equivalent laxity (P = .266) and Lysholm scores (P = .352) but lower IKDC scores (P = .009). Multivariable regression revealed that the IKDC score decreased with increased preoperative laxity (β = –1.35 [95% CI, –2.48 to –0.23]; P = .019).Conclusion:The novel adjustable-length CSF device produced satisfactory anterior laxity and clinical outcomes, with a failure rate of 2.1%, which compare favorably with those reported for nonadjustable CSF devices.

Can a Novel, Low-Cost Simulation Model be Used to Teach Anterior Cruciate Ligament Graft Preparation?

This study evaluated an anterior cruciate ligament (ACL) graft preparation simulation learning model for use by orthopaedic surgery trainees. A simulation model for ACL graft preparation was constructed using shoelace as graft material and a wooden graft preparation board that matched the dimensions of existing products. A 12-minute instructional video targeted at novice learners was created to accompany the simulation model. A prospective randomized controlled trial was conducted on orthopaedic surgery residents divided into 2 groups with equal distributions of postgraduate year (PGY) status. The intervention group learned ACL graft preparation via the Shoelace ACL Simulation Guide, whereas a control group viewed a standard instructional video. All participants then prepared an 8-strand ACL graft using allograft materials and were evaluated via a checklist of critical steps and a global assessment rating as provided by an expert blinded to group allocation. Participants' preintervention and postintervention self-assessment scores were also collected. Ten orthopaedic surgery residents from a single institution participated in the study, with even distributions across study groups of PGY-1, PGY-3, and PGY-4 residents. Preintervention self-assessments of knowledge and technical ability were similar between participant groups. The mean overall performance score was significantly greater in the shoelace simulation intervention group (22.6±1.5) than in the instructional video only control group (16.0±5.1) (P=0.043). Participants in the intervention group showed greater improvement in self-confidence in their technical ability than those in the control group (P=0.012). Groups demonstrated similar postintervention improvements in self-reported knowledge of ACL graft preparation (P=0.128). All participants who learned via the Shoelace ACL Simulation Guide strongly agreed that they would use the learning tool to prepare for ACL reconstruction surgery. A self-directed low-cost simulation model for soft tissue ACL graft preparation utilizing shoelaces resulted in improved performance metrics compared with standard video instruction. The teaching model may be incorporated easily and inexpensively into simulation curricula at other training programs. Level II-therapeutic study.

Femoral Aperture Fixation Improves Anterior Cruciate Ligament Graft Function When Added to Cortical Suspensory Fixation: An In Vivo Computer Navigation Study.

Background:Recommendations for bone tunnel placement during anterior cruciate ligament (ACL) reconstruction have become more precise. However, these recommendations differ neither with the choice of graft nor with the method of fixation used. The influence of the method of femoral fixation used on the biomechanical function of a soft tissue ACL graft remains unknown.Hypothesis:Our null hypothesis was that adding femoral aperture fixation to femoral cortical fixation, using the same bone tunnels, will not alter the control of anterior translation (AT) and internal rotation (IR) during ACL reconstruction using a hamstring graft.Study Design:Controlled laboratory study.Methods:A total of 22 patients with an acute isolated ACL rupture underwent reconstruction using a single-bundle autologous hamstring graft. Computer navigation was used intraoperatively to plot the AT and IR during the pivot-shift test before reconstruction, after ACL reconstruction using cortical suspensory fixation, and after the addition of femoral aperture fixation. Statistical analysis (analysis of variance) was used to compare the AT and IR during the pivot shift at each stage in the procedure.Results:Before ACL reconstruction, the mean (±SD) AT was 14.2 ± 7.3 mm and mean IR was 17.2° ± 5.5°. After reconstruction using femoral cortical suspension, these figures were significantly reduced to 6.2 ± 3.5 mm and 12.5° ± 3.20°, respectively (P < .001). The addition of the aperture fixation was associated with a further significant reduction to 4.6 ± 3.2 mm and 10.4° ± 2.7°, respectively (P < .001).Conclusion:The addition of femoral aperture fixation to suspensory fixation results in a significant reduction in both the AT and IR that occurs during the pivot-shift assessment immediately after ACL reconstruction using autologous hamstring graft.Clinical Relevance:The most precise positioning of bone tunnels during soft tissue ACL reconstruction needs to take into consideration the type of fixation being used.

Femoral Cortical Suspension Devices for Soft Tissue Anterior Cruciate Ligament Reconstruction

Background: Optimization of anterior cruciate ligament (ACL) fixation is desired to improve graft healing. New soft tissue cortical suspension devices for femoral tunnel fixation should be biomechanically evaluated. Hypothesis: All femoral fixation devices would prevent a clinically significant amount of displacement and support loads significantly larger than in situ forces experienced by the ACL during early rehabilitation. Study Design: Controlled laboratory study. Methods: Four cortical soft tissue ACL graft suspension devices were tested under cyclic and pull-to-failure loading conditions in both an isolated device-only setup and as a complete bone-device-tendon construct in porcine femurs using a tensile testing machine. Results: There were significant differences in the ultimate failure loads among the devices. The highest ultimate failure loads when tested as a construct were observed for the XO Button (1748 N), followed by the Endobutton CL (1456 N), ToggleLoc with ZipLoop (1334 N), and TightRope RT (859 N). Cyclic displacement after 1000 cycles during isolated device testing was less than 1 mm for all devices. Cyclic displacements after 1000 cycles in the porcine construct were 1.88 mm, 2.74 mm, 3.34 mm, and 1.82 mm for the Endobutton, TightRope, ToggleLoc, and XO Button, respectively; all were significantly different from each other except when the Endobutton was compared with the XO Button. The ToggleLoc exceeded the 3.0-mm displacement threshold defined as a clinical failure. The most displacement occurred during the first cycle, especially for the adjustable-length loop devices. Stiffness reapproximated the native ACL stiffness for all constructs. Conclusion: The Endobutton, TightRope, and XO Button have the necessary biomechanical properties with regard to ultimate failure strength, displacement, and stiffness for initial fixation of soft tissue grafts in the femoral tunnel for ACL reconstruction. The ToggleLoc had sufficient ultimate failure strength but crossed our 3.0-mm clinical failure threshold for cyclic displacement. Although this study was not designed to compare fixed and adjustable-length loop devices, it was noted that both fixed-loop devices allowed less cyclic displacement and initial displacement. Clinical Relevance: Adjustable-length loop devices may need to be retensioned after cycling the knee and fixing the tibial side to account for the increased initial displacement seen with these devices.

Lateral Femoral Cortical Breach During Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis

The purpose of our study was to determine whether secondary fixation is needed when lateral femoral wall breach occurs and whether the diameter of the femoral tunnel affects the cyclical and ultimate load to failure of 3 different suspensory fixation devices. Sixty fresh-frozen porcine femora were dissected to isolate the anterior cruciate ligament (ACL) footprint. Femoral ACL tunnels were then drilled at diameters of 7, 8, 9, and 10 mm. We conducted 5 separate cyclical and ultimate load testing trials, at each tunnel diameter, for 3 different cortical suspension devices. The mean load to failure decreased as the tunnel size enlarged for all 3 devices. In 7-mm tunnels, mean failure load ranged from 1,163.7 to 1,455.0 N across the 3 devices; in 8-mm tunnels, 1,154.7 to 1,643.2 N; in 9-mm tunnels, 820.8 to 1,125.21 N; and in 10-mm tunnels, 314.7 to 917.8 N. Modes of failure also varied as the tunnel sizes enlarged. The ultimate load was not different among the 3 manufacturers (P = .08), but there was a difference in the ultimate load across the 4 tunnel diameters (P < .05), except when we compared the 7-mm tunnel with the 8-mm tunnel (P = .91). With 7- and 8-mm-diameter tunnels, failure loads with each of the suspensory devices tested exceeded the documented interference screw load to failure. Our findings suggest that, for soft-tissue ACL grafts, femoral tunnels of 8 mm or less can be drilled through the lateral femoral cortex while still using a suspensory device for graft fixation. With pediatric, double-bundle, and anatomic ACL reconstructions, smaller and shorter tunnels are routinely used. Thus, breaching the lateral cortex when using suspensory fixation may increase tunnel length while still achieving stable fixation.

Transverse Femoral Implant Prominence: Four Cases Demonstrating a Preventable Complication for ACL Reconstruction

Anterior cruciate ligament (ACL) tear is a commonly occurring injury that often demands surgical reconstruction. Although the utility of this operation is widely accepted, many specific components, including graft fixation technique, remain controversial. Many clinicians favor transverse femoral implant fixation for soft tissue ACL grafts. This technique can be accomplished successfully; however, in a minority of the cases, the femoral implant can be excessively prominent, leading to iatrogenic postoperative iliotibial band syndrome. This article presents 4 patients that developed postoperative iliotibial band syndrome resulting from transverse femoral implant prominence. Despite achievement of knee ligamentous stability, implant prominence compromised final clinical results following ACL reconstruction. Through change in Lysholm value, we reviewed the clinical outcomes of these patients following femoral implant hardware removal for treatment of iliotibial band syndrome. On hardware removal, all patients demonstrated complete symptomatic improvement, mirroring an average Lysholm value increase of 38. We believe transverse femoral implant prominence is avoidable, and subsequent iliotibial band syndrome is a preventable postoperative complication.

The 1:1 versus the 2:2 Tunnel-Drilling Technique

Background Double-bundle anterior cruciate ligament (ACL) reconstructions involve drilling 2 tibial tunnels separated by a narrow 2-mm bone bridge. The sequence of reaming and drilling the tibial tunnels for double-bundle ACL reconstructions has not been defined. Hypothesis Fixing a graft in the posterolateral ACL tibial tunnel before reaming the anteromedial tibial tunnel will reduce the number of complications, as compared with drilling both the anteromedial and posterolateral tunnels before graft fixation, when performing double-bundle ACL reconstructions. Study Design Controlled laboratory study. Methods Twelve porcine tibias were divided into 2 groups of 6 specimens. Fresh bovine extensor tendons grafts were fixed in 7-mm tunnels reamed using an inside-out method. Grafts were fixed in a retrograde fashion with 7-mm bioabsorbable retrograde screws. The tibias in group 1 were reconstructed by reaming and reconstructing the posterolateral tunnel before reaming and securing the graft for the anteromedial tunnel (ie, 1:1 method), whereas those in the second group were reconstructed by reaming both tunnels before graft fixation in either (ie, the 2:2 method). The specimens were biomechanically tested with cyclic and load-to-failure parameters. Results Cyclic testing revealed no significant difference between the 2 methods in displacement or stiffness. In load-to-failure testing, the 1:1 group withstood significantly higher initial failure loads and ultimate loads. Pullout displacement was significantly higher for the 1:1 group. Whereas no tibias in the 1:1 group sustained fractures, 4 from the 2:2 group demonstrated a bone bridge fracture. Conclusion Soft tissue ACL grafts fixed in the tibia with the 1:1 method withstood significantly higher initial and ultimate failure loads and were stiffer than the grafts fixed with the 2:2 method. Tibias fixed with the 1:1 method were also less susceptible to bone bridge fracture. Clinical Relevance The potential for a lower complication rate and greater pullout strength seen with the 1:1 method may prove useful to surgeons performing anatomic double-bundle ACL reconstructions, in addition to other procedures involving reconstructing 2 closely positioned tunnels, including anatomic posterolateral corner and medial collateral reconstructions.

Roentgen Stereophotogrammetric Analysis Methods for Determining Ten Causes of Lengthening of a Soft-Tissue Anterior Cruciate Ligament Graft Construct

There are many causes of lengthening of an anterior cruciate ligament soft-tissue graft construct (i.e., graft+fixation devices+bone), which can lead to an increase in anterior laxity. These causes can be due to plastic deformation andor an increase in elastic deformation. The purposes of this in vitro study were (1) to develop the methods to quantify eight causes (four elastic and four plastic) associated with the tibial and femoral fixations using Roentgen stereophotogrammetric analysis (RSA) and to demonstrate the usefulness of these methods, (2) to assess how well an empirical relationship between an increase in length of the graft construct and an increase in anterior laxity predicts two causes (one elastic and one plastic) associated with the graft midsubstance, and (3) to determine the increase in anterior tare laxity (i.e., laxity under the application of a 30 N anterior tare force) before the graft force reaches zero. Markers were injected into the tibia, femur, and graft in six cadaveric legs whose knees were reconstructed with single-loop tibialis grafts. To satisfy the first objective, legs were subjected to 1500 cycles at 14 Hz of 150 N anterior force transmitted at the knee. Based on marker 3D coordinates, equations were developed for determining eight causes associated with the fixations. After 1500 load cycles, plastic deformation between the graft and WasherLoc tibial fixation was the greatest cause with an average of 0.8+/-0.5 mm followed by plastic deformation between the graft and cross-pin-type femoral fixation with an average of 0.5+/-0.1 mm. The elastic deformations between the graft and tibial fixation and between the graft and femoral fixation decreased averages of 0.3+/-0.3 mm and 0.2+/-0.1 mm, respectively. The remaining four causes associated with the fixations were close to 0. To satisfy the remaining two objectives, after cyclic loading, the graft was lengthened incrementally while the 30 N anterior tare laxity, 150 N anterior laxity, and graft tension were measured. The one plastic cause and one elastic cause associated with the graft midsubstance were predicted by the empirical relationships with random errors (i.e., precision) of 0.9 mm and 0.5 mm, respectively. The minimum increase in 30 N anterior tare laxity before the graft force reached zero was 5 mm. Hence, each of the eight causes of an increase in the 150 N anterior laxity associated with the fixations can be determined with RSA as long as the overall increase in the 30 N anterior tare laxity does not exceed 5 mm. However, predicting the two causes associated with the graft using empirical relationships is prone to large errors.

The WasherLoc and Bone Dowel: A Rigid, Slippage-Resistant Tibial Fixation Device for a Soft Tissue Anterior Cruciate Ligament Graft

The WasherLoc is a tibial fixation device for soft tissue anterior cruciate ligament (ACL) reconstruction that combines superior fixation properties (945 N strength, 507 N/mm stiffness, and high resistance to slippage) with a simple surgical technique. The WasherLoc is a washer with 13 short spikes that penetrate the soft tissue ACL graft in multiple locations and 4 long peripheral spikes that contain the graft beneath the washer. A cancellous screw is used to compress the WasherLoc against the soft tissue ACL graft and posterolateral wall of the tibial tunnel. The WasherLoc does not cause hardware symptoms because it is recessed in a counterbore drilled at the distal end of the tibial tunnel. A bone dowel harvested from the tibial tunnel is used as a joint-line fixation device in a series with the WasherLoc to improve fixation stiffness (58 N/mm) and increase the fit, which is known to enhance tendon graft-to-bone healing in the tibia. The bone dowel, which is driven to the level of the joint line anterior to the WasherLoc and soft tissue graft, prevents tunnel enlargement.

Early Tension Loss in an Anterior Cruciate Ligament Graft

The tensile force applied to an anterior cruciate ligament graft determines the maximal anterior translation; however, it is unknown whether the tensile force is transferred to the intra-articular portion of the graft and whether the intra-articular tension and maximal anterior translation are maintained shortly after ligament reconstruction. Ten cadaveric knees were reconstructed with a double-looped tendon graft. The graft was looped through a femoral fixation transducer that measured the resultant force on the proximal end of the graft. A pneumatic cylinder applied a tensile force of 110 N to the graft exiting the tibial tunnel with the knee in full extension. The graft was fixed sequentially with four tibial fixation devices (a spiked metal washer, double staples, a bioabsorbable interference screw, and a WasherLoc). Three cyclic loading treatments designed to conservatively load the graft and its fixation were applied. The combined loss in intra-articular graft tension from friction, insertion of the tibial fixation device, and three cyclic loading treatments was 50% for the spiked washer (p = 0.0004), 100% for the double staples (p < 0.0001), 64% for the interference screw (p = 0.0001), and 56% for the WasherLoc (p < 0.0001). The tension loss caused an increase in the maximal anterior translation from that of the intact knee of 2.0 mm for the spiked washer (p = 0.005), 7.8 mm for the double staples (p < 0.0001), 2.7 mm for the interference screw (p = 0.001), and 2.1 mm for the WasherLoc (p < 0.0001). The tensile force applied to a soft-tissue anterior cruciate ligament graft is not transferred intra-articularly and is not maintained during graft fixation. The loss in tension is caused by friction in the tibial tunnel and wrapping the graft around the shank of the screw of the spiked washer, insertion of the tibial fixation device, and cyclical loading of the knee. The amount of tension loss is sufficient to increase the maximal anterior translation.

Neurovascular risk of bicortical tibial drilling for screw and spiked washer fixation of soft-tissue anterior cruciate ligament graft

Purpose: As the use of soft-tissue anterior cruciate ligament (ACL) grafts, including hamstring grafts, has become more prominent and the benefits of aggressive rehabilitation have become clear, maximizing fixation with screw and spiked washers is important. Bicortical fixation may be superior. We were concerned about potential neurovascular risks and designed this study to define the posterior neurovasculature structures at risk when drilling for bicortical tibial screw fixation during ACL reconstruction. Type of Study: Consecutive sample. Methods: We placed the tibial tunnel arthroscopically in 10 cadaveric knees using a standard tibial drill guide. Accurate tibial tunnel position was documented in each knee by lateral radiograph. A 4.5-mm bicortical drill hole was placed perpendicular to the tibial surface 1 cm distal to the tibial tunnel. The distances from the posterior tibial drill exit point to nearby neurovascular structures were measured with a caliper. Results: The closest structure to the exit point was the bifurcation of the popliteal artery/vein (11.4 ± 0.6 mm; range, 8.4 to 14.0 mm). The next closest was the anterior tibial vein (11.7 ± 1.6 mm; range, 3.5 to 22.8 mm). The closest any individual hole came to a neurovascular structure was 3.5 mm from the anterior tibial vein. Conclusions: Bicortical drilling for fixation of soft tissue grafts appears reasonably safe. The structures at greatest risk for injury are the bifurcation of the popliteal artery/vein and the anterior tibial vein.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 3 (March), 2001: pp 244–247

Simultaneous measurements of sagittal knee laxity with an external device and radiostereometric analysis

The Journal of Bone and Joint Surgery. British volumeVol. 80-B, No. 1 ResearchFree AccessSimultaneous measurements of sagittal knee laxity with an external device and radiostereometric analysisL. P. Jorn, T. Fridén, L. Ryd, A. LindstrandL. P. JornSenior Registrar in Orthopaedic SurgeryLund University Hospital, S-221 85 Lund, Sweden.Search for more papers by this author, T. FridénAssociate Professor, Orthopaedic SurgeonLund University Hospital, S-221 85 Lund, Sweden.Search for more papers by this author, L. RydAssociate Professor, Orthopaedic SurgeonLund University Hospital, S-221 85 Lund, Sweden.Search for more papers by this author, A. LindstrandAssociate Professor, Orthopaedic SurgeonLund University Hospital, S-221 85 Lund, Sweden.Search for more papers by this authorPublished Online:1 Jan 1998https://doi.org/10.1302/0301-620X.80B1.0800169AboutSectionsPDF/EPUB ToolsAdd to FavouritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InRedditEmail AbstractWe obtained simultaneous measurements of sagittal knee laxity in 12 consecutive patients after reconstruction of the anterior cruciate ligament (ACL), using the Stryker laxity tester and radiostereometric analysis (RSA).The mean anteroposterior (AP) displacement when a 90 N load was applied in both directions was 5.3 ± 2.7 mm with RSA and 9.8 ± 1.6 mm with the external device (p < 0.001). The corresponding measurements at a load of 180 N were 5.7 ± 2.4 mm and 13.8 ± 3.7 mm, respectively (p < 0.001).More than 50% of the sagittal knee movement, as measured by the external device at a load of 180 N, was not true femorotibial displacement of the joint but was due to soft-tissue deformation.FiguresReferencesRelatedDetailsCited ByReliability and Validity of an Innovative Device for ACL Testing: The Mobil-Aider™Journal of Sport Rehabilitation, Vol. 29, No. 2The Laxity of the Native KneeJournal of Bone and Joint Surgery, Vol. 101, No. 12Roentgen Stereophotogrammetric Analysis Methods for Determining Ten Causes of Lengthening of a Soft-Tissue Anterior Cruciate Ligament Graft Construct16 May 2008 | Journal of Biomechanical Engineering, Vol. 130, No. 4Fluoroscopic validation of electrogoniometrically measured femorotibial translation in healthy and ACL deficient subjectsScandinavian Journal of Medicine and Science in Sports, Vol. 12, No. 4 Vol. 80-B, No. 1 Metrics History Published online 1 January 1998 Published in print 1 January 1998 InformationCopyright © 1998, The British Editorial Society of Bone and Joint Surgery: All rights reservedPDF download