<i>In vivo</i> tensile behavior of a four‐bundle hamstring graft as a replacement for the anterior cruciate ligament

Wallace, Michael P.; Howell, Stephen M.; Hull, Maury L.

doi:10.1002/jor.1100150409

Cited by 62 publications

(58 citation statements)

References 17 publications

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“…Thus, this phenomenon does not imply impingement against the roof of the femoral intercondylar notch. This is supported by the results of Wallace et al [36], whose surgical procedure involved steps to avoid impingement [23]. These experiments, therefore, provide evidence to support the recommendation that ACL graft tension should be set by the surgeon with the knee at or near to full extension [4].…”

Section: Discussionsupporting

confidence: 74%

The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior?posterior laxity patterns

Zavras

Race

Amis

2004

Knee Surg Sports Traumatol Arthrosc

103

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The issue of the best place to attach an anterior cruciate ligament graft to the femur is controversial, and different anatomic or isometric points have been recommended. It was hypothesised that one attachment site could be identified that would be best for restoring normal anterior-posterior laxity throughout the range of knee flexion. It was also hypothesised that these different attachment sites would cause different graft tension patterns during knee flexion. Using six cadaver knees, an isometric point was found 3 mm distal to the posterior edge of Blumensaat's line, at the 10:30-11:00 o'clock position in right knees, at the antero-proximal edge of the anatomic ACL attachment. Anterior-posterior laxity was measured at +/-150 N draw force at 20-120 degrees flexion with the knee intact and after anterior cruciate ligament transection. The graft was placed at the isometric point, and AP laxity was restored to normal at 20 degrees flexion, then measured at other angles. Graft tension was measured throughout, and also during passive flexion-extension. This was repeated for four other graft positions around the isometric point in every knee. Laxity was restored best by grafts tensioned to a mean of 9 +/- 14 N, positioned isometrically and 3 mm posterior to the isometric point. Their tension remained low until terminal extension. Grafts 3 mm anterior to the isometric point caused significant overconstraint, and had higher tension beyond 80 degrees knee flexion. Small changes in attachment site had large effects on laxity and tension patterns. These results support an isometric/posterior anatomic femoral graft attachment, which restored knee laxity to normal from 20 to 120 degrees flexion and did not induce high graft tension as the knee flexed. Grafts attached to the roof of the intercondylar notch caused overconstraint and higher tension in the flexed knee.

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Section: Discussionsupporting

confidence: 74%

The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior?posterior laxity patterns

Zavras

Race

Amis

2004

Knee Surg Sports Traumatol Arthrosc

103

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“…In the intact ACL, the pattern of tension exhibits a sharp rise as the joint is moved passively from 10" of flexion into full extension so that the ligament tension is 67 N on average for specimens at 0" of flexion [28]. Based on this finding in conjunction with the finding that double-loop hamstring tendon grafts reconstructed using the surgical procedures described herein exhibit a similar tension pattern to that of the intact ACL as the knee is passively extended [43] it was expected that 25 N of initial tension at full extension would result in no subluxation. While the 0 N posterior limit was overconstrained by less than 1 mm on average at 0", the 0 N posterior limit became increasingly overconstrained as the flexion angle increased.…”

Section: Importance and Interpretutionsupporting

confidence: 55%

“…The anterior cruciate ligament was reconstructed using a technique that provides acceptable clinical outcome [22] and reciprocal tension behavior in the DLSTG graft similar to that of the intact ACL [43]. screw with bone compaction 575 N/mmh "Stiffness of fixation determined using porcine tibia [24].…”

Section: Evpc>riri Icii Tsmentioning

confidence: 99%

“…The selection of the graft construct [1, 25,26,34], placement of the femoral and tibial tunnels [9,16,17,21,43], choice of the fixamethod, which can affect the anterior-posterior (A/P) load-displacement behavior of the knee, is the stiffness. It has been demonstrated that the stiffness of the graft influences the A/P load-displacement behavior of the knee [7].…”

Section: Introductionmentioning

confidence: 99%

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How the fixation method stiffness and initial tension affect anterior load?displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft

EAGAR

2004

Journal of Orthopaedic Research

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There were two objectives to this study. The first was to investigate the relationship of graft fixation stiffness and graft initial tension on the anterior load-displacement behavior of knees reconstructed with a double-loop hamstrings tendon graft. The second was to determine the corresponding graft tensions at 225 N of anterior force applied to the knee. To satisfy these objectives, the anterior-load displacement curves were measured for seven cadaveric knees with the ACL intact a t flexion angles ranging from 0" to 90". The ACL was reconstructed in the same knees using a double-loop hamstrings graft. A/P load-displacement curves of the knee and graft tension were measured as the fixation method stiffness and the initial tension applied at full extension were varied (25-326 N/mm and 25-300 N). The 0 N posterior limit (unloaded position of tibia) and the anterior laxity (difference between the 0 N posterior limit and 225 N anterior limit) were computed to characterize the A/P load-displacement of the intact and reconstructed knees. The key results were that the 0 N posterior limit of the tibia was insensitive to changes in stiffness (p > 0.6503) but that increasing initial tension caused increasing posterior subluxation of the tibia with respect to the femur (p = 0.0001). The tibia was subluxed posteriorly by 5-6 mm on average at high levels of initial tension. Both initial tension and stiffness significantly affected the anterior laxity (p = 0.0001 for both factors). Anterior laxity was restored closely to normal (i.e. < I mm difference) by relatively high initial tension of 200 N in combination with low stiffness of 25 N/mm and by low initial tension of 25 N in combination with higher stiffness ranging between 94 and 326 Nlmm. When anterior laxity is restored to normal using a high initial tension-low stiffness combination however, the tibia undergoes a large posterior subluxation with respect to the femur in the unloaded state (approximately 5 mm) and a relatively high graft tension of 275 N is developed at 225 N of anterior force. Both the tibial subluxation and graft tension are reduced substantially with low initial tension-higher stiffness combinations because the amount of initial tension required to restore anterior laxity to normal is reduced by about 200 N.

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“…The tendons were harvested and trimmed so that when folded in half sideby side they fit snugly inside a 9 mm diameter sizing cylinder (Sizing Sleeves, Arthrotek, Inc., Warsaw, IN). The free ends of each tendon were trimmed and sewn with 1-0 suture using a criss-cross stitch to facilitate passage of the graft in the knee [21,40].…”

Section: Methodsmentioning

confidence: 99%

Tension in a double loop tendon anterior cruciate graft during a simulated open chain knee extension exercise

Karchin

Hull

Howell

2005

Journal Orthopaedic Research

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Concerns exist regarding the tension developed in a reconstructed anterior cruciate ligament (ACL) during open chain knee extension exercises used to rehabilitate the knee. Therefore, the primary objective was to measure tension in an ACL graft during a simulated open chain knee extension exercise as a function of ankle weight. A secondary objective was to determine whether the graft tension was reduced with relatively high stiffness fixation. The open chain exercise was simulated in seven cadaveric specimens in which the ACL had been reconstructed with double loop tendon grafts. Graft tension was measured at 15" of flexion as the effective ankle weight was increased from 22.5 to 67.5 and then to 112.5 N for three different fixation stiffnesses (25, 125, and 225 Nlmrn). The initial tension was set to restore the 225 N anterior limit of motion to that of the intact knee at 30" of flexion. Increasing the ankle weight caused the graft tension to increase significantly (p < 0.0001), but the increase with the highest ankle weight was only 62 N on average. Increasing the fixation stiffness caused the graft tension to decrease significantly @ < 0.0001) because the initial tension decreased by 107 N as the fixation stiffness increased. Because the graft tension with the highest ankle weight was limited to 112 N on average, high stiffness fixation methods, which are also resistant to lengthening in the region of the fixation, may reduce the risk of graft construct lengthening during open chain knee extension exercises.

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In vivo tensile behavior of a four‐bundle hamstring graft as a replacement for the anterior cruciate ligament

Cited by 62 publications

References 17 publications

The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior?posterior laxity patterns

The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior?posterior laxity patterns

How the fixation method stiffness and initial tension affect anterior load?displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft

Tension in a double loop tendon anterior cruciate graft during a simulated open chain knee extension exercise

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