How Cyclic Loading Affects the Migration of Radio-Opaque Markers Attached to Tendon Grafts Using a New Method: A Study Using Roentgen Stereophotogrammetric Analysis (RSA)

2004 ◽  
Vol 126 (1) ◽  
pp. 62-69 ◽  
Author(s):  
P. J. Roos ◽  
M. L. Hull ◽  
S. M. Howell
Keyword(s):  
Cyclic Loading ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
In Vivo Studies ◽  
Repeated Loading ◽  
Acl Graft ◽  
Anterior Laxity ◽  
Tendon Grafts ◽  
Anterior Cruciate

An increase in anterior laxity following reconstruction of the anterior cruciate ligament (ACL) can result from lengthening of the graft construct in either the regions of fixation and/or the region of the graft substance between the fixations. RSA could be a useful technique to determine lengthening in these regions if a method can be devised for attaching radio-opaque markers to soft tissue grafts so that marker migration from repeated loading of the graft is limited. Therefore, the objectives of this study were 1) to develop a method for attaching radio-opaque markers to an ACL graft that limits marker migration within the graft, 2) to characterize the error of an RSA system used to study migration, and 3) to determine the maximum amount of migration and the time when it occurs during cyclic loading of ACL grafts. Tendon markers were constructed from a 0.8-mm tantalum ball and a stainless steel suture. Ten double-looped tendon grafts were passed through tibial tunnels drilled in bovine tibias and fixed with a tibial fixation device. Two tendon markers were sewn to one tendon bundle of each graft and the grafts were cyclically loaded for 225,000 cycles from 20 N to 170 N. At specified intervals, simultaneous radiographs were obtained of the tendon markers and a radiographic standard of known length. The bias and imprecision in measuring the length of the radiographic standard were 0.0 and 0.046 mm respectively. Marker migration was computed as the change in distance between the two tendon markers along the axis of the tibial tunnel. Marker migration was greatest after 225,000 cycles with a root mean square (RMS) value of less than 0.2 mm. Because the RMS value indicates the error introduced into measurements of lengthening and because this error is small, the method described for attaching markers to an ACL graft has the potential to be useful for determining lengthening of ACL graft constructs in in vivo studies in humans.

Migration of Radio-Opaque Markers Injected Into Tendon Grafts: A Study Using Roentgen Stereophotogrammetric Analysis (RSA)

2005 ◽  
Vol 127 (5) ◽  
pp. 887-890 ◽  
Author(s):  
Conrad Kay Smith ◽  
M. L. Hull ◽  
S. M. Howell
Keyword(s):  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
In Vivo Studies ◽  
Single Loop ◽  
Roentgen Stereophotogrammetric Analysis ◽  
Anterior Laxity ◽  
Tendon Grafts ◽  
Anterior Cruciate ◽  
Viable Method

An increase in anterior laxity following reconstruction of the anterior cruciate ligament (ACL) can result from lengthening of the graft construct either at the sites of fixation and/or between the sites of fixation (i.e., graft substance). Roentgen stereophotogrammetric analysis (RSA), which requires that radio-opaque markers be attached to the graft, has been shown to be a useful technique in determining lengthening in these regions. Previous methods have been used for attaching radio-opaque markers to the graft, but they all have limitations particularly for single-loop grafts. Therefore, the objective of this study was to evaluate injecting markers directly into the substance of a tendon as a viable method for measuring lengthening of single-loop graft constructs by determining the maximum amount of migration after cyclic loading. Tantalum spheres of 0.8 mm diameter were used as tendon markers. Ten single-loop tendon grafts were passed through tibial tunnels drilled in calf tibias and fixed with a tibial fixation device. Two tendon markers were inserted in one tendon bundle of each graft and the grafts were cyclically loaded for 225,000 cycles from 20 N to 170 N. At specified intervals, simultaneous radiographs were obtained of the tendon markers. Marker migration was computed as the change in distance between the two tendon markers parallel to the axis of the tibial tunnel. Marker migration had a root mean square (RMS) value of less than 0.1 mm. Because the RMS value indicates the error introduced into measurements of lengthening and because this error is negligible, the method described for attaching markers to single-loop ACL grafts has the potential to be useful for determining lengthening of single-loop ACL graft constructs in in vivo studies in humans.

Does Graft Construct Lengthening at the Fixations Cause an Increase in Anterior Laxity Following Anterior Cruciate Ligament Reconstruction in vivo?

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Conrad K. Smith ◽  
M. L. Hull ◽  
S. M. Howell
Keyword(s):  
Anterior Cruciate Ligament ◽  
Cruciate Ligament ◽  
Bone Tunnel ◽  
Anterior Cruciate Ligament Graft ◽  
Potential Increase ◽  
Anterior Laxity ◽  
Fresh Frozen ◽  
Anterior Cruciate

A millimeter-for-millimeter relation between an increase in length of an anterior cruciate ligament graft construct and an increase in anterior laxity has been demonstrated in multiple in vitro studies. Based on this relation, a 3 mm increase in length of the graft construct following surgery could manifest as a 3 mm increase in anterior laxity in vivo, which is considered clinically unstable. Hence, the two primary objectives were to determine whether the millimeter-for-millimeter relation exists in vivo for slippage-resistant fixation of a soft-tissue graft and, if it does not exist, then to what extent the increase in stiffness caused by biologic healing of the graft to the bone tunnel offsets the potential increase in anterior laxity resulting from lengthening at the sites of fixation. Sixteen subjects were treated with a fresh-frozen, nonirradiated, nonchemically processed tibialis allograft. Tantalum markers were injected into the graft, fixation devices, and bones. On the day of surgery and at 1, 2, 3, and 4 months, Roentgen stereophotogrammetric analysis was used to compute anterior laxity at 150 N of anterior force and the total slippage from both sites of fixation. A simple linear regression was performed to determine whether the millimeter-for-millimeter relation existed and a springs-in-series model of the graft construct was used to determine the extent to which the increase in stiffness caused by biological healing of the graft to the bone tunnel offset the increase in anterior laxity resulting from lengthening at the sites of fixation. There was no correlation between lengthening at the sites of fixation and the increase in anterior laxity at 1 month (R2=0.0, slope=0.2). Also, the increase in stiffness of the graft construct caused by biologic healing of the graft to the bone tunnel offset 0.7 mm of the 1.5 mm potential increase in anterior laxity resulting from lengthening at the sites of fixation. This relatively large offset of nearly 50% occurred because lengthening at the sites of fixation was small.

Non-Linear Viscoelastic Mechanics of Native and Engineered Ligaments and Tendons

2011 ◽  
Author(s):  
Jinjin Ma ◽  
Ellen M. Arruda
Keyword(s):  
Cruciate Ligament ◽  
Viscoelastic Behavior ◽  
Biomechanical Properties ◽  
Acl Graft ◽  
Non Linear ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Anterior Cruciate ◽  
Acl Replacement

Patellar tendon (PT) autografts and allografts are the most common methods currently used to replace a torn anterior cruciate ligament (ACL). The PT is not only much stiffer than the ACL it replaces it also exhibits qualitatively and quantitatively different non-linear viscoelastic behavior from those of the ACL. These mis-matched biomechanics may be contributing to the high incidence of early onset osteoarthritis suffered by patients who have had ACL surgeries. Thus there is a need for an ACL graft that can reproduce normal ligament biomechanics and knee function. This talk examines the inhomogeneous, non-linear viscoelastic response of native ACL and of a tissue engineered ACL graft designed to rapidly grow and remodel in vivo to restore the proper biomechanical properties of native ligament. The results using this graft as an ACL replacement are compared against those using a PT autograft for the ACL replacement. Uniaxial loading reveals that after nine months as an ACL replacement, the tissue-engineered graft develops a strain contour pattern closely resembling that of native ACL whereas the PT graft fails to similarly remodel in vivo.

A Preclinical Model to Study the Influence of Graft Force on the Healing of the Anterior Cruciate Ligament Graft

2018 ◽  
Vol 32 (05) ◽  
pp. 441-447
Author(s):  
Richard Ma ◽  
Mark Stasiak ◽  
Xiang-Hua Deng ◽  
Scott Rodeo
Keyword(s):  
Anterior Cruciate Ligament ◽  
Acl Reconstruction ◽  
Knee Flexion ◽  
Cruciate Ligament ◽  
Tunnel Position ◽  
Anterior Cruciate Ligament Graft ◽  
Acl Graft ◽  
Anterior Cruciate ◽  
Femoral Graft

AbstractThe purpose of this study is to establish a small animal anterior cruciate ligament (ACL) reconstruction research model where ACL graft force can be varied to create different graft force patterns with controlled knee motion. Cadaveric (n = 10) and in vivo (n = 10) rat knees underwent ACL resection followed by reconstruction using a soft tissue autograft. Five cadaveric and five in vivo knees received a nonisometric, high-force femoral graft tunnel position. Five cadaveric and five in vivo knees received a more isometric, low-force graft tunnel position. ACL graft force (N) was then recorded as the knee was ranged from extension to 90 degrees using a custom knee flexion device. Our results demonstrate that distinct ACL graft force patterns were generated for the high-force and low-force femoral graft tunnels. For high-force ACL grafts, ACL graft forces increased as the knee was flexed both in cadaveric and in vivo knees. At 90 degrees of knee flexion, high-force ACL grafts had significantly greater mean graft force when compared with baseline (cadaver: 7.76 ± 0.54 N at 90 degrees vs. 4.94 ± 0.14 N at 0 degree, p = 0.004; in vivo: 7.29 ± 0.42 N at 90 degrees vs. 4.74 ± 0.13 N at 0 degree, p = 0.007). In contrast, the graft forces for low-force ACL grafts did not change with knee flexion (cadaver: 4.94 ± 0.11 N at 90 degrees vs. 4.72 ± 0.14 N at 0 degree, p = 0.41; in vivo: 4.78 ± 0.26 N at 90 degrees vs. 4.77 ± 0.06 N at 0 degree, p = 1). Compared with nonisometric ACL grafts, the graft force for grafts placed in an isometric position had significantly lower ACL graft forces at 15, 30, 45, 60, 70, and 90 degrees in both cadaveric and in vivo knees. In conclusion, we have developed a novel ACL reconstruction model that can reproducibly produce two ACL graft force patterns. This model would permit further research on how ACL graft forces may affect subsequent graft healing, maturation, and function.

Comparison of Anterior Cruciate Ligament Graft Isometry between Paired Femoral and Tibial Tunnels

2017 ◽  
Vol 30 (09) ◽  
pp. 960-964 ◽  
Author(s):  
E. Cain ◽  
Marcus Biggers ◽  
Benton Emblom ◽  
Jeffrey Dugas ◽  
David Beason
Keyword(s):  
Anterior Cruciate Ligament ◽  
Range Of Motion ◽  
Femoral Tunnel ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
Tunnel Placement ◽  
Posterior Aspect ◽  
Acl Graft ◽  
Posterior Tibial ◽  
Anterior Cruciate

AbstractAccurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstruction. Controversy exists concerning the preferred method of femoral tunnel preparation, with proponents of both medial portal and transtibial drilling techniques. Current ACL literature suggests that placement of the femoral ACL attachment site posterior or “low” in the ACL footprint leads to more anatomically correct ACL mechanics and better rotational control. There is limited literature focusing on ACL graft displacement through knee range of motion based on specific paired placement of femoral and tibial tunnels. Our purpose was to assess ACL isometry between multiple combinations of femoral and tibial tunnels. We hypothesized that placement of the graft at the posterior aspect of the ACL footprint on the femur would be significantly less isometric and lead to more graft displacement as compared with central or anterior placement. The ACL of matched pairs of cadaveric knees was arthroscopically debrided while leaving the soft tissue footprint on the femur and tibia intact. One knee from each pair underwent notchplasty. In all knees, three femoral and three tibial tunnels were created at the anterior, central, and posterior aspects of the ACL footprint. A suture was passed through each tunnel combination (nine potential pairs), and the change in isometry was measured throughout full knee range of motion. Placement of the femoral tunnel along the posterior aspect of the ACL footprint was less isometric compared with a central or anterior position in the femoral footprint. Placement of a posterior tibial tunnel also led to decreased isometry, but tibial tunnel placement affected isometry to a lesser extent than femoral tunnel placement. The combination of a posterior femoral and posterior tibial tunnel resulted in greater than 1 cm of graft excursion from full flexion to extension. Placement of ACL tunnels at anisometric sites may adversely affect the mechanical properties and behavior of the ACL graft, resulting in either graft laxity in flexion or overconstraint and loss of extension.

The Tissue Engineering Approach to Ligament Reconstruction

1993 ◽  
Vol 331 ◽  
Author(s):  
Michael G. Dunn ◽  
J. B. Liesch ◽  
M. L. Tiku ◽  
S. H. Maxian ◽  
J. P. Zawadsky
Keyword(s):  
Acl Reconstruction ◽  
Patellar Tendon ◽  
Cruciate Ligament ◽  
Collagen Scaffold ◽  
In Vivo Studies ◽  
Collagen Scaffolds ◽  
Tissue Engineering Approach ◽  
Anterior Cruciate

AbstractPrevious studies in our laboratory showed that acellular collagen scaffold implants induce tissue ingrowth and perform similar to autografts following reconstruction of rabbit Achilles tendon or anterior cruciate ligament (ACL). We chronologically review these and related studies, and report preliminary development of fibroblast-seeded collagen scaffolds potentially useful for ACL reconstruction. The ‘healing potential’ of fibroblasts was measured within collagen scaffolds in vitro, as a function of fibroblast source. Aligned collagen scaffolds were seeded with fibroblasts from rabbit ACL, synovium, patellar tendon, or skin. Fibroblast viability, adherence, spreading, proliferation, and protein and collagen deposition were measured on collagen scaffolds. The fibroblasts attached to the scaffolds, and spread along the long axis of the collagen fibers. ACL fibroblasts adhered better than other fibroblast types; however, the ACL fibroblasts proliferated at the slowest rate. Patellar tendon fibroblasts proliferated at the most rapid rate. All four of the fibroblast types secreted protein and collagen within the collagen scaffolds.Preliminary in vivo studies suggest that fibroblasts seeded onto collagen scaffolds can remain viable following reimplantation into the donor rabbit. Ongoing studies will elucidate the role of autogenous seeded fibroblasts in neoligament formation/remodeling. These ‘ligament analogs’ are potentially useful for clinical ACL reconstruction: fibroblasts would be obtained from biopsy, cultured, seeded onto a collagen scaffold, and implanted as an ACL substitute into the same patient.

scholarly journals Comparison of two methods of femoral tunnel preparation in single-bundle anterior cruciate ligament reconstruction: a prospective randomized study

2012 ◽  
Vol 27 (8) ◽  
pp. 572-576 ◽  
Author(s):  
Qiang Zhang ◽  
Shu Zhang ◽  
Rui Li ◽  
Ya Liu ◽  
Xuecheng Cao
Keyword(s):  
Anterior Cruciate Ligament ◽  
Femoral Tunnel ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
Single Bundle ◽  
Knee Score ◽  
Lysholm Knee Score ◽  
Anterior Laxity ◽  
Kt 1000 ◽  
Anterior Cruciate

PURPOSE: To prospectively compare therapeutic effect of femoral tunnel preparation through the tibial tunnel and the anteromedial (AM) portal in single-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: Between June 2008 and October 2010, 76 patients underwent single-bundle ACL reconstruction by autogenous grafting of semitendinosus and gracilis tendon. All cases were randomly divided into two groups according to the method of femoral tunnel preparation: transtibial (TT) group (n=38) and anteromedial (AM) group (n=38). Lysholm knee score and the KT-1000 anterior laxity at 30° of pre-and post-operation were assessed for two groups. RESULTS: Sixty-five patients (TT group, 34; AM group, 31) were followed up for more than 12 months, with a follow-up rate of 86%. The Lysholm knee score and the KT-1000 anterior laxity 12 months after operation were significantly better than before reconstruction. The Lysholm knee score and the KT-1000 anterior laxity were not significantly different between the TT and AM groups after operation. CONCLUSION: Femoral tunnel preparation through tibial tunnel or the anteromedial portal in single-bundle anterior cruciate ligament reconstruction shows same therapeutic effects.

Lengthening of a Single-Loop Tibialis Tendon Graft Construct After Cyclic Loading: A Study Using Roentgen Stereophotogrammetric Analysis

2005 ◽  
Vol 128 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Conrad Kay Smith ◽  
M. L. Hull ◽  
S. M. Howell
Keyword(s):  
Cyclic Loading ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
Three Dimensional ◽  
Hamstring Tendon ◽  
Tendon Graft ◽  
Single Loop ◽  
Roentgen Stereophotogrammetric Analysis ◽  
Average Value ◽  
Anterior Laxity

Although single-loop tibialis tendon allografts have increased in popularity owing to their many advantages over patellar tendon and double-loop hamstring tendon autografts, some percentage of the patient population do not have clinically stable knees following anterior cruciate ligament reconstruction with single-loop tibialis tendon allografts. Therefore, it would be advantageous to determine the causes of increased anterior laxity which ultimately must be traced to lengthening of the graft construct. One objective of this study was to demonstrate the feasibility of using Roentgen stereophotogrammetric analysis (RSA) to determine the causes of lengthening of a single-loop graft construct subjected to cyclic loading. A second objective was to determine which cause(s) contributes most to an increase in length of this graft construct. Radio-opaque markers were inserted into ten grafts to measure the lengthening at the sites of the tibial and femoral fixations and between the sites of fixation. Each graft was passed through a tibial tunnel in a calf tibia, looped around a rigid cross-pin, and fixed to the tibia with a Washerloc fixation device. The grafts were cyclically loaded for 225,000 cycles from 20to170N. Prior to and at intervals during the cyclic loading, simultaneous radiographs were taken. RSA was used to determine the three-dimensional coordinates of the markers from which the lengthening at the sites of fixation and between the sites of fixation was computed at each interval. The sites of the femoral and tibial fixations were the largest contributors to the increase in length of the graft construct, with maximum average values of 0.68 and 0.55 mm, respectively, after 225,000 cycles. The graft substance between the sites of fixation contributed least to lengthening of the graft, with a maximum average value of 0.31 mm. Ninety percent of the maximum average values occurred before 100,000 cycles of loading for the largest contributors. RSA proved to be a useful method for measuring lengthening due to all three causes. Lengthening of the graft construct at the sites of both fixations is sufficiently large that the combined contributions may manifest as a clinically important increase in anterior laxity.

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